Evaluating the Evidence for More Frequent Than Annual HIV Screening of Gay, Bisexual, and Other Men Who Have Sex With Men in the United States: Results From a Systematic Review and CDC Expert Consultation

Abstract

The Centers for Disease Control and Prevention (CDC) recommended in 2006 that sexually active gay, bisexual, and other men who have sex with men (MSM) be screened for human immunodeficiency virus (HIV) at least annually. A workgroup comprising CDC and external experts conducted a systematic review of the literature, including benefits, harms, acceptability, and feasibility of annual versus more frequent screening among MSM, to determine whether evidence was sufficient to change the current recommendation. Four consultations with managers of public and nonprofit HIV testing programs, clinics, and mathematical modeling experts were conducted to provide input on the programmatic and scientific evidence. Mathematical models predicted that more frequent than annual screening of MSM could prevent some new HIV infections and would be more cost-effective than annual screening, but this evidence was considered insufficient due to study design. Evidence supports CDC’s current recommendation that sexually active MSM be screened at least annually. However, some MSM might benefit from more frequent screening. Future research should evaluate which MSM subpopulations would benefit most from more frequent HIV screening.

The Centers for Disease Control and Prevention (CDC) estimates that in 2014, 15% of all people living with human immunodeficiency virus (HIV) had undiagnosed infections.¹ HIV testing is the critical first step for people who are infected with HIV to become aware of their status, receive appropriate medical care, and obtain lifesaving medications and other services that will allow them to maintain healthy and productive lives. Early HIV diagnosis enables prompt initiation of antiretroviral therapy,^2–4 which can also reduce the risk of HIV transmission.⁵ Knowledge of infection status also helps decrease transmission of HIV, because people who know they are infected have been shown to reduce their HIV transmission risk behaviors.⁶ Furthermore, the new HIV tests approved by the US Food and Drug Administration and recommended by CDC⁷ have improved the detection of early infection: combination antigen/antibody HIV tests can detect greater numbers of people during the highly infectious, acute stage of HIV infection^8–10 and thereby improve the likelihood of early referral to medical care.¹¹

Participants in 1 or More Expert Consultations With Centers for Disease Control and Prevention About HIV Screening in Gay, Bisexual, and Other Men Who Have Sex With Men, 2013-2014 Webinars.

External Consultants

• Cornelius Baker, PhD, National Black Gay Men’s Advocacy Coalition, Washington, DC

• Matt Beymer, MPH, Los Angeles Gay and Lesbian Center, Los Angeles, CA

• Susan Blank, MD, MPH, New York City Department of Health and Mental Hygiene, New York, NY

• Barry Callis, MSW, Massachusetts Department of Public Health, Boston, MA

• Natalie Cramer, MSW, National Alliance of State & Territorial AIDS Directors, Washington, DC

• Manuel Diaz-Ramirez, La Clinica Del Pueblo, Washington, DC

• Steve Gibson, Magnet Clinic, San Francisco AIDS Foundation Program, San Francisco, CA

• Steve Goodreau, PhD, University of Washington, Seattle, WA

• David Katz, PhD, MPH, University of Washington, Seattle, WA

• Dustin Kerrone, Los Angeles Gay and Lesbian Center, Los Angeles, CA

• Elisa Long, PhD, University of California, Los Angeles, Los Angeles, CA

• Greg Millett, MPH, amfAR, The Foundation for AIDS Research, Washington, DC

• Terrance Moore, National Alliance of State & Territorial AIDS Directors, Washington, DC

• Doug Owens, MD, PhD, Stanford University, Palo Alto, CA; member, US Preventive Services Task Force, Rockville, MD

• Tracey Packer, MPH, San Francisco Department of Public Health, San Francisco, CA

• Susan Phillip, MD, MPH, San Francisco Department of Public Health, San Francisco, CA

• Eli Rosenberg, PhD, Emory University, Atlanta, GA

• Susan Scheer, PhD, MPH, New York City Department of Health and Mental Hygiene, New York, NY

• Julia Schillinger, MD, MSc, CAPT, US Public Health Service, New York City Department of Health and Mental Hygiene, New York, NY

• Patrick Sullivan, PhD, Emory University, Atlanta, GA

• Coleman Terrell, MPH, Philadelphia Department of Public Health, Philadelphia, PA

• Benjamin Tsoi, MD, MPH, New York City Department of Health and Mental Hygiene, New York, NY

• Dan Wohlfeiler, MJ, MPH, California Department of Public Health, Sacramento, CA

Centers for Disease Control and Prevention Workgroup Members: Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA

• Kristina Bowles, MPH

• Bernie Branson, MD, PhD

• Kevin Delaney, PhD

• Elizabeth DiNenno, PhD

• Gema Dumitru, MD, MPH

• Angela Hutchinson, PhD, MPH

• Kathleen Irwin, MD, MPH

• Amy Lansky, PhD, MPH

• Tricia Martin, MPH

• Mary Mullins, MSLS

• Alexa Oster, MD

• Phil Peters, MD

• Joseph Prejean, PhD

• Lamont Scales, MPH

• Luke Shouse, MD, MPH

• Amrita Tailor, MPH

• Michele Van Handel, MPH

• Rich Wolitski, PhD, MPH

Gay, bisexual, and other men who have sex with men (hereinafter referred to as MSM) are disproportionately affected by HIV in the United States. In 2015, MSM (including MSM who inject drugs) accounted for 70% of new HIV diagnoses in the United States.¹² HIV infection is particularly devastating for some young MSM: during 2008-2014, diagnoses of HIV infection decreased 18% among MSM aged 13-24 but increased 35% among those aged 25-34.¹³

CDC testing initiatives, guidelines, and recommendations promote testing among MSM and other groups severely affected by HIV infection. Since 2001, CDC has recommended HIV screening of asymptomatic people in clinical and nonclinical settings; the recommendations for testing people in clinical settings were updated in 2006.¹⁴ In the 2006 guidelines, CDC recommended that people at high risk of HIV infection—defined as people who inject drugs and their sex partners, people who exchange sex for money or drugs, sex partners of HIV-infected people, and MSM or heterosexual people who themselves or whose sex partners have had more than 1 sex partner since their most recent HIV test—should be screened at least annually. These conclusions from 2006 (based on expert opinion, not a systematic review of the literature) for repeat screening were focused on groups at high risk, including heterosexuals and MSM in nonmonogamous partnerships. Subsequent analyses cast doubt on the recommendation that only nonmonogamous MSM be screened annually.^15–17 A 2009 model estimated that in 5 US cities, 68% of HIV transmissions among MSM occurred from main sex partners.¹⁵ Other investigators raised concerns that MSM may incorrectly assume the HIV status of their sex partners¹⁶ or that sex partners may not disclose sexual encounters outside the partnership.¹⁷ These concerns led to broadening the recommendation for annual screening to all sexually active MSM. Since 2010, through reports and media campaigns, CDC has supported the recommendation that all sexually active MSM—not only those in nonmonogamous relationships—undergo annual screening.^18–21 The 2010 Sexually Transmitted Disease (STD) Treatment Guidelines also recommended that all sexually active men be routinely screened for STDs and HIV at least annually,²² although the 2015 version reverted to the earlier recommendation that men in nonmonogamous relationships be screened annually.²³

Several publications since 2006 have suggested that some MSM might benefit from more frequent than annual HIV screening.^24,25 In 2011, CDC published the results of an analysis of MSM interviewed and tested in 2008 as part of the National HIV Behavioral Surveillance system: 7% of MSM who reported a negative HIV test result in the past 12 months were found to have HIV infection when tested through the National HIV Behavioral Surveillance system.¹⁸ The report concluded that sexually active MSM, regardless of high-risk behaviors, might benefit from more frequent HIV testing (eg, every 3 or 6 months). In subsequent reports, media campaigns, and fact sheets, CDC has continued to suggest that sexually active MSM might benefit from more frequent testing.^26–28 In April 2013, the US Preventive Services Task Force, after conducting a systematic literature review, updated its 2005 recommendations for HIV screening²⁹ and recommended routine screening of all people aged 15-65 at least once in their lifetime, as well as more frequent screening for people at increased risk of HIV, such as MSM.³⁰ The US Preventive Services Task Force did not find sufficient evidence to specify a rescreening interval for MSM but said that a reasonable approach would be to conduct annual screening of groups at very high risk of HIV infection. In 2014, CDC recommended that HIV-uninfected MSM at substantial risk of HIV infection be prescribed preexposure prophylaxis³¹ and retested every 3 months and immediately whenever signs and symptoms of acute HIV infection are reported.

Studies have found that although 63% to 91% of MSM have been tested for HIV at least once in their lifetime,^32,33 only 39% to 67% are tested annually^34,35 and HIV testing of males, particularly those aged <19, in physicians’ offices is likely suboptimal.³⁶ Nevertheless, some local public health officials in large US cities have endorsed more frequent rescreening of MSM, in some cases even before the updated CDC recommendations in 2006 (Table 1).^37–40 In their cities, clinicians are encouraged to offer HIV tests to all MSM, especially those who are not taking preexposure prophylaxis, every 3 or 6 months.

Table 1.

Characteristics of 3 public-sector programs offering more frequent than annual HIV screening to gay, bisexual, and other MSM, 2014

Characteristic	Public Health–Seattle & King County, Washington 37	New York City Department of Health and Mental Hygiene, New York 38	California Department of Public Health, California 39
Rationale for offering HIV screening to MSM more than annually	Evidence showed that 80% of newly diagnosed cases were among MSM. A prediction model suggested that MSM at the highest risk of infection could be identified for more frequent testing. A transmission model later demonstrated that increasing testing frequency among high-risk MSM had the potential to decrease incidence.	Evidence among MSM of high burden of HIV and lower-than-optimal rates of annual HIV screening	In 2009, the local health department reconsidered optimal screening frequencies for MSM after reviewing local National HIV Behavioral Surveillance data showing that only 55% of MSM in 2008 reported receiving an HIV test in the previous 6 months. The local health department estimated that screening all MSM in the city every 6 months would require 70 000 tests per year, which would not be affordable. Based on anticipated federal, state, and local funds for HIV screening, the local health department proposed to increase HIV screening tests among MSM by 30 000.
Policy	In 2005, the local health department recommended that providers should screen all sexually active MSM annually and screen all high-risk MSM quarterly. High risk was defined as having ≥1 of these characteristics in the past year: ≥10 oral or anal sex partners; condomless sex with HIV-positive/unknown partner; bacterial STD diagnosis; or methamphetamine or popper use.	In 2006, the local health department recommended that clinicians offer HIV screening “as often as every 3-6 months” to all high-risk MSM and other high-risk individuals (ie, have multiple or anonymous sex partners or engage in illicit drug use). In 2008, opt-out testing was offered to MSM in public STD clinics with rapid HIV tests. In 2010, STD clinics in New York City began offering opt-out rapid HIV tests to all MSM who had sex with a man within 3 months since most recent test. MSM who had sex in the past 2 months also screened with pooled nucleic acid tests. In 2013, the local health department recommended that providers should screen all low-risk MSM for STDs at least annually and screen MSM with multiple sex partners for STDs every 3-6 months.	In 2009, the local health department recommended that providers in high-volume HIV screening sites offer MSM HIV screening every 6 months.
Sites that offered more than annual screening	Public STD clinics, community outreach sites, private providers that follow local guidelines	CDC and Ryan White–funded HIV screening programs, public-sector STD clinics	High-volume screening sites in neighborhoods with large numbers of MSM households
Populations offered more than annual screening	All MSM meeting aforementioned high-risk criteria	MSM attending these sites who reported multiple sex partners or if attending STD clinic; all MSM	All MSM attending these sites
Funding source for HIV screening kits and processing	CDC, state, and local governments State-funded community-based organization that conducts community outreach	CDC and Ryan White–funded HIV screening programs Other state and local funds	CDC, state, and local governments
Types and costs of HIV tests used through December 2014	Finger-stick rapid test Third-generation enzyme immunoassay tests Negative specimens tested with pooled nucleic acid test to assess acute infection Tests free to clients	Oraquick rapid test Negative specimens tested with pooled nucleic acid test to assess acute infection All MSM who tested negative during the past 2 months were screened with pooled nucleic acid test (pooled nucleic acid test not repeated if most recent pooled nucleic acid test was performed within past 3 weeks). Tests free to clients	Fingerstick blood rapid tests Negative specimens tested with pooled nucleic acid test to assess acute infection in 3 sites with highest test positivity rates Considering using fourth-generation antigen/antibody test (eg, Alere Determine HIV 1/2 Ag/Ab Combo) pending state approval and phlebotomy training Tests free to clients
Linkage to medical care following diagnosis	Linked 95% of newly diagnosed HIV-positive people to HIV medical care within 3 months	Surveillance data showed that 85% of newly diagnosed HIV-positive people were linked to HIV care in publicly funded CDC/Ryan White–funded screening sites.	Linked 84% to 89% of newly diagnosed people to HIV medical care within 3 months
Conclusions about facilitators making frequent screening acceptable	Tests were free to patients and provided in convenient outreach settings or clinics. Frequent screening was supported by an internet-based social marketing campaign40 and recommendations from providers. MSM were offered reminders for rescreening at public health testing sites and through social media campaigns. Many MSM seek care with providers who specialize in MSM/STD/HIV care and may therefore be more likely to implement local guidelines.	HIV screening was integrated into other opt-out screening services. A 2008 health department policy to offer opt-out HIV screening to MSM was successful in public STD clinics. Surveillance data found that STD clinics were successful at screening MSM frequently, resulting in substantial proportions (30%) of newly diagnosed acute infection among MSM who were screened in STD clinics ≥2 times in the previous 12 months. More MSM than non-MSM in community settings agreed to be tested multiple times per year. Many providers believe that MSM should be tested for HIV more than annually.	HIV screening was “normalized” by routinely linking HIV screening to sexually transmitted infection screening. Messaging was consistent (“sexually transmitted infection screening, including HIV screening, should occur every 3 months”). Pretest counseling for all MSM and posttest counseling for HIV-negative people was waived, which reduced time commitment. Screening program could provide many posttest services for newly diagnosed MSM. Since 2009, screening sites have increased ability to offer screening with tests for acute HIV infection that can hasten linkage to HIV medical care for highly infectious MSM.
Conclusions about barriers to more than annual screening	Although recommendations are directed to all providers, publicly funded testing sites are most likely to adhere to the guidelines and endorse testing recommendations to their patients. Uptake of frequent screening may be lower among MSM whose providers do not endorse it or who are not offered electronic reminders.	Program cannot assess the impact of frequent HIV screening or whether MSM view frequent screening as acceptable because of difficulties with systems that do not currently collect these data.	The current policy to rescreen MSM for HIV every 6 months, and in some cases every 3 months, can be confusing for MSM and screening providers. Current funding does not allow program to offer screening to all MSM every 6 months or to implement screening reminder systems.

Abbreviations: CDC, Centers for Disease Control and Prevention; HIV, human immunodeficiency virus; MSM, men who have sex with men; STD, sexually transmitted disease.

Since 2006, a high prevalence of HIV among some MSM has persisted, and the number of published articles about more frequent HIV screening has increased. In light of these events, CDC scientists reviewed recent published and unpublished information about the benefits and harms of annual versus more frequent screening to determine whether the evidence was sufficient to change the current recommendations for HIV screening among MSM in the United States. The recommendation is published in a separate document.⁴¹

Methods

During 2013-2014, a workgroup of CDC scientists comprising epidemiologists, clinicians, behavioral scientists, health policy experts, and health economists conducted a systematic review of the literature and hosted 4 expert consultations to review the findings and gather unpublished program evaluations and opinions about the appropriate frequency for HIV testing of MSM in clinical settings.

Systematic Review

The primary goal of the systematic review was to compare the individual and societal benefits and harms of annual versus more frequent HIV screening among MSM who do not know whether they are HIV infected. Secondary goals were to compare the feasibility and acceptability of annual versus more frequent HIV screening. The CDC workgroup applied systematic review methods of the Community Preventive Services Task Force,⁴² which issues evidence-based recommendations about community preventive services. In 2013, the CDC workgroup slightly adapted the tools of The Guide to Community Preventive Services (The Community Guide) to complete the review. This rating tool assessed 5 categories of study execution to assess threats to validity: description (how well the study population and intervention information is described), sampling (eg, whether the sampling frame is specified, and selection biases and screening criteria are specified), measurement (valid exposure, outcome, and predictor variables), data analysis (eg, appropriate statistical testing was applied), and interpretation of results (eg, identifying biases, confounders, and limitations). For our analysis, each study was assigned 1 point per element in each category that it did not satisfy. For example, for the category of how well the study is described, 1 element was how well the study population was defined and another element was whether the authors described the type of HIV testing technology in their analysis. Each category had 5 or 6 elements, for a possible total of 27 points. We modified the tool from that of The Community Guide, which weights the categories and scores each study on a total scale of 9 points; a study with few limitations and higher points would earn a high study execution rating.

We did not assign different weights to the 5 categories, because each category was considered equally important. We assigned limitations to studies with threats to validity in each category. For example, a study that did not specify the sampling frame or selection for the study population received 1 limitation. We rated studies with 0 to 4 of 27 total limitations as having strong study execution, those with 5 to 8 limitations as moderate, and those with ≥9 limitations as low. Another adaptation from The Community Guide was to add the use of mathematical models to supplement the systematic review.

Before beginning the review, the CDC workgroup conducted a series of internal meetings to develop the conceptual approach and the research questions needed to evaluate the evidence from published studies. The internal workgroup identified 4 research domains: (1) benefits, either to individuals or society; (2) potential harms, to the individual or to society; (3) acceptability; and (4) feasibility. Individual benefits are the likely health benefits accruing to individual MSM as a result of being screened for HIV every 3 to 6 months rather than annually, such as reduced mortality and improved quality of life. Societal benefits are those that accrue to society as a whole as a result of more frequent than annual screening, such as averted HIV transmissions or cost savings of a more frequent than annual HIV screening intervention. Individual harms include stigma, out-of-pocket costs that men might have to pay if insurance does not cover HIV screening more than once per year, or increased false-positive HIV tests. Societal harms refer to an increase in MSM risk behavior as a result of frequent screening or an increase in societal resources (costs, personnel) required to maintain a more frequent screening program. Acceptability is the extent to which MSM agree to or are accepting of being screened every 3 to 6 months instead of annually and the conditions under which they would prefer to receive screening. Feasibility refers to the potential barriers or facilitators to health departments or local programs screening MSM at 3- to 6-month intervals compared with annual screening. Staffing levels, methods of identifying MSM to screen, adequate reimbursement, and other issues would reflect the feasibility of a program to implement more frequent screening.

Search Strategy

The CDC workgroup developed search criteria for the automated search. The search was restricted to articles that included indexing terms or keywords in the following areas: (1) HIV seropositivity, HIV infections, AIDS serodiagnosis, or STD/infections; (2) “men who have sex with men” or “high risk”; and (3) test or “screen.” No language restriction was applied to the automated search. The literature search was further restricted to studies published from January 1, 2005 (to overlap with the most recent CDC update of HIV testing recommendations¹⁴), through December 31, 2014. The last search was performed in January 2015. The CDC workgroup supplemented an automated search of databases (MEDLINE, EMBASE, PsycINFO, and CINAHL) with a manual search of gray literature, focusing on (1) national and international abstracts from conferences that address HIV testing or screening and (2) CDC’s unpublished mathematical modeling studies about HIV rescreening intervals. The literature search included studies from clinical and nonclinical settings to maximize the chance of finding studies about screening intervals in settings with clinical and nonclinical components. A detailed description of the search is available from the corresponding author.

Study Selection

After the automated search, duplicates were removed manually. The duplicated abstracts were distributed equally to 3 CDC workgroup experts, who worked in overlapping independent pairs to review the titles and content of abstracts using an article-screening tool to identify relevant studies. Disputed abstracts were resolved in a meeting of the relevant pair of experts; ties were broken by the third expert. The 3 experts reviewed the full-text articles and abstracted the content. Only articles that met the following criteria were included in the analysis: (1) the study was conducted in the United States or the following upper–middle-income countries: Canada, Australia, New Zealand, and all countries in Western Europe (other countries, including China, were excluded to focus on countries in which trends in HIV infection were similar to those in the United States); (2) the study was written in English; (3) the study mentioned annual versus more frequent screening among MSM or described another testing frequency such as inter-test intervals (a count of the number of months between testing events); (4) the study addressed 1 of the 4 aforementioned research domains; and (5) the study was conducted in a clinical setting or was a modeling study that used data parameters that would be relevant to clinical settings. Articles considered for the feasibility research domain had to originate in the United States, because studies from countries with different health care systems (eg, publicly funded health care systems) were not comparable with the US setting.

The 3 CDC workgroup members rated each included study for each of the inclusion criteria, the research domains (benefits, harms, acceptability, and feasibility), quality of study execution (description, sampling, measurement, data analysis, and interpretation of results), and key findings by using the quantitative study assessment tool. The CDC workgroup members did not identify any established methods for rating the quality of execution of mathematical models. The 3 reviewers resolved disagreements about the rating of each article through discussion and consensus.

After each article was rated individually, the quality of the body of evidence was evaluated by taking all studies that addressed 1 of the 4 research domains and evaluating each group of studies as a whole. One additional area that was considered during this phase of the review was whether the studies had findings that were consistent: that is, whether the studies as a group documented a similar magnitude of effect of more frequent than annual screening compared with annual screening.^42,43

We used The Community Guide Task Force categorical rating system⁴⁴ to describe our findings. Recommended means that the systematic review of available studies provides strong or sufficient evidence that the intervention is effective. The categories of strong and sufficient evidence reflect the Task Force’s degree of confidence that an intervention has beneficial effects. The categorization is based on several factors, such as study design, number of studies, and consistency of the effect across studies. Recommended against means that the systematic review of available studies provides strong or sufficient evidence that the intervention is harmful or not effective. Insufficient evidence means that the available studies do not provide sufficient evidence to determine if the intervention is, or is not, effective. This rating does not mean that the intervention does not work but, rather, that additional research is needed to determine whether or not the intervention is effective.

CDC Expert Consultation

During August–December 2014, CDC held 4 virtual conferences (through webinar or conference call) with people who had expertise in 1 of the following areas: research on frequency or cost-effectiveness of HIV screening, experience managing public-sector HIV testing programs for MSM, or knowledge about the attitudes of MSM concerning HIV screening. The purpose was to obtain individual feedback from external consultants on the systematic review and the preliminary conclusions (body of evidence), identify studies missed in the literature review, identify data for future reassessments of the optimal frequency of HIV screening among MSM, and obtain feedback from representatives of programs that provided more frequent than annual screening to MSM. Because of the number of mathematical models identified by the literature review and their relevance to the outcomes of interest, CDC held a separate conference call with mathematical modeling and economic evaluation experts to inform the workgroup’s assessment of the studies.

Before each consultation, the experts provided feedback on agendas and summary documents and read summaries of the systematic literature review and full-text articles under discussion. After each webinar, CDC provided a summary of the minutes for review and revision by the expert consultants.

Results

Systematic Literature Review

The automated search and review of gray literature resulted in 6479 abstracts, 111 of which met the inclusion criteria and were reviewed in full (Figure). Reviewers found 13 articles^{24,25,43,45–54} (including 1 study⁴⁷ that was unpublished at the time of the review) that addressed at least 1 research domain (Table 2). Of these 13 studies, 11 were categorized as pertaining to the societal benefits of more frequent screening^{24,25,43,45-52} and 2 addressed acceptability of more frequent HIV screening.^53,54 None of the 13 studies addressed the other research domains: individual benefits, individual or societal harms, or feasibility.

Table 2.

Studies found during a systematic literature review to assess HIV screening among gay, bisexual, and other men who have sex with men (MSM) in clinical settings, 2005-2014^a

Study Reference	Key Outcome Variable	Type of Study	Rating of Quality of Execution	Country	Comparison Made	Study Population	Study Main Findings
Baker et al (2013)43	Utility of risk assessment tool to identify MSM who should be screened for HIV	Observational	Low	Australia	Testing for HIV every 6 months vs every 3 months	MSM attending level 3 sexual health clinic	Increasing screening in Australia from every 6 months to every 3 months among high-risk MSM would result in diagnosing STIs and HIV earlier. Three of 17 (20%) HIV diagnoses and 17 of 59 (18.3%) STI diagnoses potentially would have been diagnosed earlier if screening had been increased from every 6 months to every 3 months.
Feigin et al (2013)45	Proportion of HIV diagnoses classified as newly acquired during 10 years	Observational	Low	Australia	NA	All new cases of HIV infection; MSM composed 85% of new infections	Following Australian recommendations, from 2007 to 2010, the total number of HIV tests per year at clinics increased 41% among MSM and HIV incidence declined by 52%. Conclusion: More frequent testing of high-risk men detects infections earlier. Risk behaviors remained relatively stable.
Gray et al (2013)49	Impact of HIV interventions, including increased screening, on HIV incidence	Health impact model	Not rated	New South Wales, Australia	Screening annually vs every 3 months vs never tested	MSM (all)	During a 10-year period, if all MSM were screened for HIV every 3 months, it would result in a 13.8% reduction in incidence (range, –4.2% to 20.6% across simulations). Screening all MSM for HIV annually would result in an 11% reduction in incidence (range, –0.08% to 20.8% across simulations).
Guy et al (2010)53	HIV rescreening rates of MSM attending primary care clinics	Observational	Low	Australia	NA	Past-year MSM; high-risk MSM	The rate of repeat screening (for sexually active MSM and for higher-risk MSM) was substantially lower than the level called for in national guidelines.
Helms et al (2009)54	Factors associated with HIV screening frequency and positivity	Observational	Low	United States (4 cities: Denver, Colorado; Washington, DC; San Francisco, California; and King County, Washington)	HIV inter-test ratio, 2002 vs 2006	MSM (all)	As a result of providers offering more frequent than annual screening to MSM, the inter-test interval decreased between 2002 and 2006. As a result, more MSM are screening annually. The authors suggest that increased frequency of screening is also partially due to MSM seeking out more frequent tests.
Hutchinson et al (2016)47 ,a	Cost-effectiveness of screening every 3 or 6 months vs annually	Cost-effectiveness model	Not rated	United States	Screening annually vs every 3 or 6 months	MSM and people who inject drugs	If all MSM were screened every 6 months instead of annually, the ICER would result in a cost savings; if MSM were screened every 3 months instead of every 6 months, the ICER would be cost saving or $48 000 depending on the test technology. Screening 10 000 MSM every 6 months instead of annually would avert 1.75 or 2.00 infections per year depending on the testing technology, and screening 10 000 MSM every 3 months instead of every 6 months would avert an additional 0.91 or 1.20 infections per year.
Katz et al (2013)46	Change in inter-test interval, 2003-2010	Observational	Low	United States (Seattle & King County)	NA (inter-test interval)	Past-year MSM; high-risk MSM	From 2003 to 2010, the median inter-test interval among MSM decreased. The introduction of rapid testing and pooled nucleic acid testing in 2003 and recommendations for quarterly screening among high-risk MSM in 2005 likely contributed to increased screening.
Khanna et al (2015)50,b	Effect of interventions, including frequent screening, on reducing new HIV infections	Health impact model	Not rated	United States	Screening every 3 or 6 months vs screening every 2 years, 351 days, or 10 years	Sexually active, at-risk MSM	Compared with baseline scenarios of yearly screening, during 10 years, screening MSM every 6 months would avert about 25 new infections. Screening MSM every 2 years would avert about 74 new infections compared with screening every 10 years. Screening MSM every 3 months vs every 6 months would avert an additional 29 cases in the scenario in which baseline screening occurs every 2 years. Screening interventions based on individual risk, such as a combination of time and number of sex partners since last test, perform substantially better than screening alone (eg, screening every 6 months per 6 sex partners averts about an additional 34 infections vs screening every 3 months only in the scenario in which MSM test every 2 years at baseline).
Long et al (2010)48	Cost-effectiveness of annually screening high-risk people	Cost-effectiveness model	Not rated	United States	Screening annually vs one-time screening, and screening annually vs less than annually	High-risk populations (including MSM and other high-risk groups) and low-risk populations	Screening high-risk people annually vs screening less frequently than annually results in an ICER of $22 382. Screening annually vs less frequently than annually, if >75% of those found to have HIV infection are prescribed antiretroviral therapy, results in an ICER of $20 628. A one-time screening of low-risk people and an annual screening of high-risk people could prevent 6.7% of a projected 1.23 million HIV infections.
Long (2011)25	Cost-effectiveness of screening annually or every 6 months using fourth-generation immunoassay vs immunoassay + pooled nucleic acid testing	Cost-effectiveness model	Not rated	United States	Cost-effectiveness of screening every 6 months vs annually	Populations at low, medium, and high risk (which includes MSM)	Screening every 6 months vs annually results in an ICER of $18 300 if an antigen/antibody combination immunoassay test is used; $138 200 with the same immunoassay and nucleic acid tests. During a 20-year period, screening every 6 months instead of annually would reduce HIV incidence by 1.9%.
Lucas and Armbruster (2013)24	Cost-benefit analysis of screening every 3 months for MSM	Cost-benefit optimization model	Not rated	United States	Screening every 3 months vs every 6 months vs annually	Populations at low, medium, and high risk (which includes MSM)	The optimal frequency that would optimize cost-effectiveness varies by annual HIV incidence of population: MSM, considered a high-risk population with HIV incidence of 1%, have an optimal screening frequency of every 3 months.
White et al (2014)51	Number of primary HIV infections caught and transmissions averted with increased HIV screening	Health impact model	Not rated	United Kingdom	Number of HIV transmissions occurring among undiagnosed people with recently acquired infection vs those screened every 2 months vs those screened 2 times per month	MSM (with primary HIV infection)	Frequent screening averts a substantial number of infections, but less frequent screening results in quickly diminishing improvements in averted infections. Of 98 MSM in the study cohort, immediate diagnosis (eg, daily HIV screening) would have averted 64% to 65% of new infections. Resources to conduct very frequent screening, such as daily screening for MSM, may not be available.
Wilson et al (2009)52	New HIV diagnoses identified per increased percentage of MSM screening annually	Health impact model	Not rated	Australia	Current levels (50%-60% of MSM) screening annually vs 10% increases in annual screening	MSM (all)	For every 10% additional MSM who are screened annually, the number of HIV infections would decrease by about 22 to 27 HIV infections each year. The benefits of screening increase over time. However, a 100% coverage of annual screening would produce the maximum reduction in incidence that can be possible from screening alone.

Abbreviations: HIV, human immunodeficiency virus; ICER, incremental cost-effectiveness ratio; NA, not applicable; STI, sexually transmitted infection.

^aSome studies (Khanna et al,⁵⁰ Hutchinson⁴⁷) were first identified as gray literature or through expert consultants and published after 2014.

^bStudy was identified through input from expert consultants.

Evidence Synthesis

Studies that addressed societal benefits

Of the 11 studies that addressed societal benefits of more frequent testing, 8 were based on mathematical models and 3 were observational studies. Of the 8 modeling studies, 4 were economic evaluations of HIV screening frequency, of which 3 assessed the cost-effectiveness of more frequent than annual HIV screening^24,25,47 and 1 assessed the cost-effectiveness of annual screening compared with less frequent than annual screening.⁴⁸ The primary outcome was the cost per quality-adjusted life year (QALY) saved reported as an incremental cost-effectiveness ratio, which is the ratio of the difference in costs and effectiveness between 2 alternatives. Although some scientists and policy makers disagree about what is considered cost-effective, incremental cost-effectiveness ratios of $100 000 to $200 000 per QALY saved and lower are generally considered economically efficient.⁵⁵ The incremental cost-effectiveness ratios across these 3 studies ranged from cost saving (more frequent than annual testing resulted in net savings) through $138 200 per QALY depending on HIV testing frequency and test technology. One of the economic studies was a cost-benefit optimization model, which converted outcomes to incremental cost per QALY.²⁴ The remaining 4 were health impact models,^49–52 which refer to models that assess the long-term effects of more frequent than annual HIV screening on reducing HIV transmission.

The 8 models were not rated for quality of study execution because there is no established method for incorporating a modeling study design into guidelines.^67,68 The CDC experts rated the 3 observational studies as low, primarily because of their sampling design. However, the key findings and designs of the studies were well described.

The CDC experts judged the 8 modeling studies to have inconsistent results. Three of 4 cost-effectiveness or cost-benefit studies^24,25,47 found more frequent than annual testing to be more economically efficient than their respective base-case scenarios (eg, annual screening). Of the 4 health impact studies,^49–52 1 study⁵¹ found greater reductions in new infections because of more frequent than annual screening only if MSM were screened; 2 studies^49,52 found that more frequent than annual screening had a small or negligible effect on new infections; and 1 study⁵⁰ found that screening more frequently than annually had a greater effect when risk behaviors, such as having sex with multiple partners, were considered as screening criteria along with frequency (eg, screening every 3 months among those with 3 sex partners) than if only increased screening frequency was implemented.

Overall, the CDC experts determined that the body of evidence concerning the societal benefits of more frequent than annual screening of MSM was insufficient because the available studies did not provide sufficient or direct evidence to determine if the intervention was, or was not, effective in reducing HIV transmissions.

Studies that addressed acceptability

The CDC experts rated both studies that addressed acceptability^53,54 as having a moderate quality of study execution, although the study design was of low quality because they were observational studies. Both studies showed that test intervals for some high-risk MSM had been decreasing over time, particularly when screening was at no cost to the client and was obtained in public health clinics. Overall, the CDC experts classified the body of evidence from these 2 studies describing an increase in frequency of screening among MSM as insufficient, because their study designs were not well suited to assessing the acceptability of annual versus more frequent screening.

Studies that addressed individual benefits

No studies identified the benefits to individual men screened more than annually compared with annually. However, several recent studies that did not meet inclusion criteria (because they did not address screening frequency) showed that earlier initiation of HIV therapy (starting at higher CD4 counts²) yields better HIV-related and non–HIV-related clinical outcomes than later initiation of HIV therapy.

Studies that addressed individual or societal harms

No studies identified overt individual harms of more than annual screening (eg, stigma, out-of-pocket costs, lost productivity, or complacency about practicing behaviors) that would reduce the risk of HIV acquisition. However, 1 study⁴⁵ found relatively stable risk behaviors reported by MSM attending clinics in Victoria, Australia, from 2007 to 2010, when more frequent screening (between 3 and 6 months) was instituted. This finding suggested that more frequent testing is not associated with an increase in a potential societal harm, such as the proportion of MSM who engage in higher-risk behaviors.

Studies that addressed feasibility

No studies addressed the extent to which more frequent than annual screening would be feasible by health departments and other programs in the United States. However, the evaluations of 3 public-sector MSM screening programs in large, high-HIV-prevalence US cities described during the expert consultation noted several factors that enhanced the feasibility of screening programs, such as free screening funded by federal or state programs.

Expert Consultation Series

The CDC experts participating in the first 2 webinars were provided information on the current evidence, and the CDC workgroup then solicited their individual viewpoints. An analysis of the feedback from individual experts revealed that the literature was insufficient to conclude that more frequent screening had demonstrated benefits over annual screening, although opinions were diverse; however, some experts suggested that information from the mathematical models was sufficient. During the second webinar, managers and research staff members involved in 3 HIV testing programs (Table 1) presented information on their experience with offering MSM more frequent screening and provided evidence to suggest that MSM in their communities found the offer of more frequent than annual screening acceptable. The evidence included data from representatives in Seattle & King County, which showed an increase in uptake of frequent screening among high-risk MSM, compared with the screening rates of other high-risk groups, suggesting increasing acceptance of more frequent than annual HIV screening programs.

In the third webinar, experts discussed the likely benefits of more frequent screening in jurisdictions that routinely provide prompt linkage to high-quality medical care soon after diagnosis. Representatives from health departments in Seattle & King County, New York City, and San Francisco described the successful implementation of more frequent than annual HIV screening programs and presented information suggesting that these programs contributed to a decrease in the proportion of MSM with undiagnosed HIV infection. Expert consultants weighed these programs’ benefits with contextual factors in other jurisdictions and cautioned that some MSM communities implementing frequent HIV screening programs would realize greater benefits than others. For example, communities in which HIV prevalence is high or MSM who screen HIV positive can quickly initiate antiretroviral therapy would experience greater reductions in incidence than would communities with low HIV prevalence or in which those who screen HIV positive are not promptly offered antiretroviral therapy.

An analysis of comments received from the individual experts to review the mathematical and economic modeling studies (Box) also suggests that the modeling studies provided inconsistent information and demonstrated limited impact. Experts recognized that the models estimated that screening every 3 or 6 months was cost-effective compared with annual screening largely because the high lifetime treatment costs of even a few cases of HIV infection would exceed the incremental costs of more frequent than annual screening. In addition, most experts concluded that, because of the variability in methods, uncertainty of the validity of parameters (particularly pertaining to the benefits of slightly earlier initiation of antiretroviral therapy and infectiousness during the early acute stage), and magnitude of effect, the suitability of the study design for mathematical models for use in a guideline was low and should not provide the sole evidence upon which to base new recommendations.⁵⁶ Experts also noted other studies^57–64 that suggested additional risk factors that may place MSM at increased risk of HIV acquisition and, thus, may be useful for identifying MSM who would most benefit from more frequent screening. Factors suggested by experts included diagnosis of bacterial STD, unprotected intercourse with sex partners who are HIV infected or anonymous, multiple sex partners, seeking sex partners from sexual networks likely to have high HIV prevalence (defined by geography or population characteristics), use of nonprescription drugs, sex with people who inject drugs, African American race or Hispanic/Latino ethnicity, and age <25.

Box.

Questions asked of expert consultants concerning mathematical modeling of the health and economic impact of HIV screening intervals on MSM in the United States and other high-income countries, December 2014, with consultants’ answers

1. What mathematical model studies (n = 8) were expert consultants asked to evaluate? (see Table 2)

   • Six published studies were reviewed during the consultation.^{24,25,48–50,52}
   • One study undergoing peer review at a journal was recommended by consultants, and an earlier version of the analysis was also identified through a search of the gray literature; this article was discussed at the consultation but was published after the consultation.⁴⁷
   • One study was identified after the consultation and was not discussed at the consultation.⁵¹
   • Two studies^49,52 were considered not generalizable to the United States because of different epidemiologic, health care utilization, and economic characteristics.
2. What model outcomes are useful to estimate the health and economic impact of various HIV screening intervals on MSM?

   • QALYs saved (captures data on individual and public health benefit of more frequent screening)
   • Incremental cost-effectiveness ratio
   • HIV infections averted in sex partners of screened MSM
   • HIV incidence
   • Averted HIV infections
3. Other than aforementioned benefits, what additional benefits of more frequent than annual screening do the models address?

   • The potential to increase sexually transmitted disease screening
   • The potential to assess individual men’s eligibility for preexposure prophylaxis
   • Screening could provide an opportunity for counseling on risk reduction, although evidence is scarce.
   • Identification of acute HIV infection
4. What do available models conclude about the health impact of more frequent than annual screening versus annual screening of MSM?

   • The predicted impact of more frequent than annual screening on averting new infection in sex partners would be modest. This conclusion is based on limitations inherent to mathematical models: (1) models were based on parameter estimates that are uncertain or may vary substantially by locale, and (2) some models used deterministic methods that did not generate confidence intervals that would reflect the range of possible effect sizes.
   • Participants in the consultation concluded that the current evidence suggests that, compared with annual screening, screening MSM every 3 to 6 months would be moderately effective at averting HIV transmissions and cost-effective. Evidence cited includes the following:

     • Long²⁵ estimated that increasing the screening frequency for MSM from annually to every 6 months would reduce the incidence by 1.9% (MSM only) or 2.6% (MSM and injection drug users) and would cost $20 000 per QALY gained.
     • Hutchinson et al⁴⁷ estimated that testing MSM as frequently as every 3 months would avert HIV infections and would be cost-effective compared with annual testing. However, the model estimated that 1.75 or 2.00 infections per 10 000 MSM would be averted during a 1-year period in a 6-month screening program compared with annual screening.
     • In Lucas and Armbruster,²⁴ the optimal screening frequency for high-risk people (HIV incidence >1%) was estimated to be every 3 months.
     • The model by Gray et al⁴⁹ that compared the impact of screening every 3 months versus annually on reducing the number of new infections in Australia generated a broad effect size range in which the time intervals had overlapping confidence intervals and were not statistically different from one another, indicative of no effect or a reduction in the number of new infections.
     • The model by Khanna et al⁵⁰ estimated that among MSM in the United States, programs that would offer screening to MSM who had reported ≥3 new sex partners since their last negative test would avert a substantial number of new HIV transmissions, whereas programs that would offer screening based on a fixed time interval of 3 months would not.
     • The model by Khanna et al⁵⁰ also estimated that screening MSM based on risk and sex partner change interval (screening every 3 to 6 months for every 3 to 6 new sex partners accrued since last test) had 5 times the impact (on number of infections averted) than screening prompted only by a fixed time interval.
     • The model by Wilson et al⁵² estimated that increasing the proportion of MSM who screen annually (in Australia) would incrementally decrease the number of new infections each year, but the authors also stated that 100% coverage of annual screening would yield the maximum possible reduction in incidence that can be achieved through screening alone. Wilson and colleagues concluded that more frequent than annual screening would not result in a substantial additional decrease in the total expected number of new HIV infections.
   • If MSM are screened more frequently than annually using combination antigen/antibody tests (that are highly sensitive for acute infection), and if programs can routinely link acutely infected MSM to HIV treatment faster than MSM with chronic infection or infection of unknown duration, more frequent than annual screening may result in higher QALYs and more averted infections in sex partners, because risk of transmission is higher when MSM are in the acute stage of infection.²⁵
   • Two models^25,47 estimated that screening tests had an effect on QALYs or infections averted; another model⁵⁰ compared the impact of screening using tests with a 1-day window period and tests with a 22-day window period but found little difference in the number of infections averted (or QALYs).
5. What do available models conclude about the cost-effectiveness of more frequent than annual screening versus annual screening among MSM? Do these findings allow decision makers to draw solid conclusions about the economic impact of various screening intervals?

   • More frequent than annual screening is cost-effective or cost saving compared with annual screening. Estimates of HIV incidence, the proportion of screen-positive MSM linked to HIV medical care after diagnosis, and the extent of behavior change after diagnosis all affect cost-effectiveness. In models by Long et al,⁴⁸ more frequent than annual screening was cost-effective (using a threshold of $100 000 per QALY gained) across wide ranges of these 3 parameter estimates.
   • The model by Hutchinson et al⁴⁷ shows that, compared with annual screening, more frequent than annual screening is cost saving for all MSM. Many model parameters that influence cost-effectiveness are uncertain (see sections G and F), particularly those on the benefits of slightly earlier initiation of antiretroviral therapy.
6. Which factors are most likely to influence the primary and secondary benefits or cost-effectiveness of more frequent than annual versus annual screening among MSM?

   • Areas with high HIV incidence in the screened population. In areas with high HIV incidence, both cost-effectiveness and number of averted infections would be increased. Experts noted, however, that national estimates of HIV incidence among MSM are uncertain and vary greatly by locale, race/ethnicity, and other factors. Further, few communities know their local HIV prevalence or HIV incidence.
   • High-risk characteristics. Directing screening to MSM at increased risk of acquiring HIV will improve the health impact (ie, averting new infections) and cost-effectiveness of more than annual screening. These characteristics include factors such as diagnosis of bacterial sexually transmitted diseases, unprotected intercourse with HIV-infected or anonymous sex partners, multiple sex partners, having partners from sexual networks who are likely to have a high prevalence of unsuppressed HIV infection (defined by geography or population characteristics), use of illicit nonprescription drugs, sex with injection drug users, African American or Latino race/ethnicity, and age <25. Khanna et al⁵⁰ found that risk-based screening was 5 times more effective than interval-based screening alone. Other unpublished research (not reviewed at the time of the consultation) shows similar results.
   • Rates of linkage to HIV care. The health impact (ie, number of averted infections) and cost-effectiveness of more than annual screening would likely be greater if newly diagnosed MSM promptly started HIV care and antiretroviral therapy and achieved viral suppression.
   • The rate and timing with which HIV-negative MSM adopt safer behaviors. Behavior change is common among MSM who are diagnosed with HIV. Similarly, the health impact of more than annual screening would be greater if MSM who tested negative rapidly adopted safer behaviors that would reduce their future risk of HIV exposure.
   • The cost of HIV screening in clinical settings relative to other types of interventions. Centers for Disease Control and Prevention resource allocation studies have compared the benefits of various interventions on preventing HIV transmission (eg, screening, linkage and retention assistance, HIV treatment, behavioral risk-reduction interventions, and partner services). Screening is often the most cost-effective intervention compared with other interventions because opportunistic screening in clinical settings does not rely on special recruitment by staff members, thereby reducing costs.
   • Other factors. Other factors that may have an impact on access to and acceptability of frequent screening include MSM residing in rural versus urban settings, younger versus older MSM, MSM who are white versus from a racial/ethnic minority group, and out-of-pocket costs (eg, free tests versus individually billable tests).
7. What factors limit the validity of current models of the health and economic impact of HIV screening intervals on MSM in the United States?

   • Model outcomes are uncertain because of the variability in the underlying parameter estimates that substantially affect model results. These uncertainties include the following:

     • The number of new infections detected over time in hypothetical or actual cohorts of MSM who screen at different intervals.
     • The clinical or transmission benefits of treating an MSM 3 to 6 months earlier.
     • The per-act risk of HIV transmission from MSM practicing anal intercourse who have acute versus chronic infection. (Some models use estimates of per-act risk of HIV transmission using data from serodiscordant heterosexual couples with acute or chronic HIV who practice vaginal sex.)
     • Levels of viral load and level of infectivity during the first 2 to 3 months after infection.
     • The extent to which risk of HIV transmission is a direct, linear function of changes in viral load or is modified by other immune and inflammatory responses during acute infection.
     • The effectiveness of antiretroviral therapy in reducing infectiousness during the first 3 months of infection (early vs acute infection).
     • Rates and timing of linkage to HIV medical care after screening in various communities; MSM with HIV infection who might wait 4 months to start antiretroviral therapy will accrue less benefit from frequent screening than MSM who are linked to care more quickly.
     • The extent to which screened MSM adopt safer behaviors after a screening test, particularly MSM testing HIV positive.
     • The association between recent risk behavior and preferred screening interval (eg, are low risk; “worried well” more likely to seek or accept more frequent than annual screening than high-risk MSM). If low-risk MSM are more likely to screen than high-risk MSM, all models could overestimate the benefits of more frequent than annual screening.
     • The long-term costs of clinical and nonclinical screening programs and variability of cost data because of differences in geography, health infrastructure, public versus private sectors, or other factors.
   • Existing modeling studies have important limitations, such as the following:

     • There is limited empirical evidence behind some parameter estimates, such as benefits to the index client for being diagnosed 3 to 6 months earlier, infectivity, and transmission at various stages of disease.
     • Many assume a base-case scenario in which 100% of MSM are screened annually. The US estimates of MSM who screen annually range from 39% in 2006-2010 (National Survey of Family Growth)³⁴ to 67% in 2011 (National HIV Behavioral Surveillance System).³⁵ If models, particularly dynamic compartmental models, used the actual proportions of MSM who screen annually, the marginal benefits of more frequent than annual screening may decline.
     • Most do not specify incremental benefits of screening MSM with differing levels of behavioral risk at fixed, more frequent than annual intervals.
     • Most do not evaluate the effects if low-risk MSM were to preferentially undergo more frequent than annual screening than high-risk MSM. If so, the benefit of detecting new infections would decrease and costs may increase.
     • Most do not address differences in screening rates by locale. Although MSM in some locales screen frequently, many MSM in other locales have been screened only once or have never been screened.
     • The costs of implementing screening at more frequent intervals are not clearly known. Most studies do not account for resources needed to screen more frequently than annually, including outreach, recruitment, testing costs, and other associated costs.
     • Both deterministic and stochastic models have uncertainties; no one model type is ideal, particularly when modeling a communicable disease such as HIV that is affected by constantly changing sexual and drug-use networks and sexual partnerships. Deterministic models do not generate confidence intervals and so cannot measure uncertainty of estimates.
   • Other comments include the following:

     • When results of different model types are consistent, guideline developers have more confidence in using these data to guide decisions about screening intervals. When model results vary substantially, guideline developers should be cautious about making decisions based largely on models.
     • Little is known about the characteristics of MSM who have never been screened for HIV, and these MSM represent a larger population than is commonly understood.
     • There were concerns with the use of risk-based factors to identify populations with higher HIV incidence that might improve the effectiveness of more frequent than annual screening. Some programs have or may wish to incorporate these factors into their screening activities; however, which risks should be emphasized is unknown. Furthermore, experts noted that assessing risk when offering screening in primary care and other clinical settings is challenging. Many studies show that MSM do not accurately report their HIV-related risks to their providers.
8. What recommendations do you have for future studies, including mathematical modeling studies and others?

   • Studies that compare annual screening at prevailing rates (an estimated 34%-67% in the United States) with annual screening at higher rates (>80%).
   • Studies that compare annual screening at prevailing rates with annual screening at higher rates (>80%), plus more frequent than annual screening of a small proportion of MSM at high risk for HIV.
   • Studies that consider risk level among MSM (eg, number of sex partners, number of new sex partners) and local epidemic factors (eg, race, age, other factors).
   • Multicomponent intervention models and resource allocation models are needed. These studies would compare the potential impact that other interventions may have on reducing HIV incidence, such as increasing the proportion of newly diagnosed MSM who are promptly linked to HIV medical care, with greater than annual screening. Other interventions may have more impact on reducing HIV incidence.
   • A demonstration or cohort study would be beneficial to answer many of the assumptions currently being made in the mathematical models. Such a study would screen some MSM with various risk profiles (eg, multiple sex partners or new sex partners compared with those with fewer sex partners) every 3 months, and others every 6 months, to determine how many new infections would be detected.

Recommendations

The CDC workgroup, informed by the opinions of individual experts, concluded that the available evidence in the published literature was insufficient to support changing CDC’s current recommendation (ie, screen all sexually active MSM at least annually) to a new recommendation (ie, routinely offer HIV screening every 3 or 6 months to sexually active MSM).

However, several, but not all, modeling studies predicted that more frequent screening, compared with annual screening, might avert a greater number of new HIV infections and be cost-effective (incremental cost-effectiveness ratio <$100 000 per QALY) compared with annual screening, largely by averting the lifetime costs of HIV medical care of secondary HIV cases. We found no studies that assessed harms.

Future Research

Members of the CDC workgroup and expert consultants recommended the following topics for future research (Box):

1. Comparisons of annual versus more frequent screening in subpopulations of MSM with respect to factors thought to affect HIV acquisition: the racial composition of sexual networks, HIV risk behaviors, and the community prevalence of HIV infection.

2. Evaluation of the benefits of increasing the proportion of MSM who receive annual HIV tests, relative to the benefit of a smaller proportion of MSM receiving more frequent tests.

3. Development of multicomponent intervention models that compare more frequent screening and other interventions, such as increasing the proportion of MSM who are promptly linked to HIV medical care after diagnosis for those testing positive and to preexposure prophylaxis care for those testing negative with indications for its use, to evaluate the relative impact of annual versus more frequent screening on reducing HIV incidence. The expert consultants encouraged the development of these multicomponent mathematical models to improve the ability to weigh evidence comparing benefits and harms. Given the difficulty of conducting studies with high or moderate study design suitability (ie, randomized controlled trial or case-control study) to identify the circumstances under which more frequent than annual HIV screening is beneficial, the addition of new models with varying methods and inputs that demonstrate benefits may provide evidence to make a recommendation for more frequent than annual HIV screening. Studies with suitable designs that would provide adequate evidence for a recommendation include randomized studies comparing more frequent than annual screening efforts in one community with annual screening in another community to determine how many new infections were detected, or transmissions averted, in each as a result of more frequent than annual screening. However, expert consultants have said that randomized studies would be difficult and costly to implement.

Limitations

This analysis had several limitations that may have biased the literature review and the conclusions drawn. During our screening of studies, some non-English studies, unpublished studies, and relevant studies that were published after the review but before the publication of the current report may have been omitted. CDC workgroup members modified The Community Guide study quality methods by giving equal weight to all recommended elements for evaluating the quality of execution of each study (ie, description of study, sampling methods, measurement, data analysis, and interpretation of results). The rationale for this modification was that it was determined that all elements were important when evaluating modeling studies that comprised most of the identified articles. However, this modification may have biased the results by overemphasizing study quality. Furthermore, most studies were mathematical models; however, there is no clear consensus on the appropriate role of modeling in the development of recommendations in clinical guidelines.^66-68 Models have informed systematic reviews in the past, such as the US Preventive Services Task Force’s 2007 updated recommendation for colorectal cancer screening.⁶⁵ However, there has been no consensus to date on a grading system to evaluate mathematical models.⁶⁶ The lack of observational studies or randomized trials was an important limitation of our analysis. Model-based studies are subject to the quality of the parameters used and other study design limitations that may affect their validity or the generalizability of their conclusions.⁵⁶ Therefore, we did not rate the quality of execution of the mathematical modeling studies. These findings may not be generalizable to clinical settings that do not offer free screening visits or free screening tests or do not have personnel dedicated to HIV screening, particularly on an immediate, walk-in basis. Finally, the dearth of data on program evaluation from various jurisdictions, including those in low-incidence areas, limited the representativeness of the results across the country.

Public Health Implications

Consistent with CDC’s recommendation in 2006, clinicians should continue to screen asymptomatic sexually active MSM for HIV at least annually. However, providers can consider the potential benefits of more frequent screening (eg, every 3 or 6 months) for some sexually active MSM based on their individual risk factors, local HIV epidemiology, and local policies and discuss other risk-reduction options, including preexposure prophylaxis, when indicated.⁴¹ When making a determination about more frequent HIV screening, providers should also consider barriers to individual MSM (eg, potential stigma, discrimination, or reimbursement of out-of-pocket costs to patients). Additional research is needed to ascertain the individual- or community-level factors that could be used to identify which sexually active MSM would most benefit from more frequent screening to improve health outcomes and avert new infections.