Human Immunodeficiency Virus Testing Among People Who Inject Drugs in Rural West Virginia

Abstract

Background

Limited research exists on factors associated with human immunodeficiency virus (HIV) testing among people who inject drugs (PWID) in rural America. The purpose of this research is to identify factors associated with rural PWID in Appalachia having not been tested for HIV in the past year.

Methods

Cross-sectional data (n = 408) from a 2018 PWID population estimation study in West Virginia were used to examine factors associated with PWID having not been tested for HIV in the past year.

Results

Most participants identified as male (61%), white, non-Hispanic (84%), and reported having recently injected heroin (81%) and/or crystal methamphetamine (71%). Most (64%) reported having been tested for HIV in the past year, 17% reported having been tested but not in the past year, and 19% reported never having been tested. In multivariable analysis, not having been in a drug treatment program in the past year was associated with PWID not having been tested for HIV in the past year (adjusted prevalence ratio, 1.430; 95% confidence interval, 1.080–1.894).

Conclusions

Drug treatment programs may be important venues for rural PWID to access HIV testing; however, testing services should be offered at multiple venues as most PWID had not engaged in drug treatment in the past year.

Factors that place people who inject drugs (PWID) at sustained high-risk for infectious disease acquisition are complex and extend beyond individual-level risk behaviors [1–7]. For example, social and economic factors (eg, homelessness) paired with limited access to evidence-based substance use treatment programs and human immunodeficiency virus (HIV) prevention strategies, such as pre-exposure prophylaxis (PrEP), impede the ability of PWID to avoid behaviors that carry high risks of HIV infection [8–17]. Pervasive stigmatization of substance use also contributes to risks for disease outbreaks among rural PWID [18]. Furthermore, rural communities may not have access to syringe services programs (SSPs) that provide essential harm reduction services [11]. Several decades of research have demonstrated the public health utility of SSPs, including preventing HIV and viral hepatitis transmission among PWID via increased access to sterile injection equipment [19]. SSP implementation also yields substantial cost savings in averted HIV treatment costs [20]. A 2019 study found that SSP implementation in Philadelphia, Pennsylvania, led to an estimated cost savings of $2.4 billion in averted HIV treatment costs among PWID over a 10-year period [21].

Approximately 38% of new HIV infections in the United States were transmitted from 15% of people living with HIV who did not know they were infected [22]. To identify and stop HIV transmission, it is essential to scale up HIV prevention interventions such that all persons at risk are tested and linked to care, if needed [22, 23]. Limited research has examined factors associated with HIV testing among rural PWID in Appalachia; a 2018 systematic review of HIV/hepatitis C virus (HCV)–related services in nonurban areas of the United States, for example, found that no studies reported results related to the availability of HIV testing [24]. However, research among a sample of patients at a mental health and substance abuse clinic in rural Appalachia found that persons reported several barriers to HIV testing, including not knowing where to get tested and fear of being recognized at the HIV testing site [25]. Such findings are especially concerning given Centers for Disease Control and Prevention (CDC) HIV testing guidelines stating that persons at risk for HIV should be tested at least once a year [26]. The dearth of research that examines HIV testing among rural PWID warrants study given the potential for HIV outbreaks in rural communities.

In 2016, PWID accounted for 9% of HIV diagnoses in the United States, and HIV diagnoses among PWID have remained stable since 2013 after declining by almost half between 2008 and 2013 [27, 28]. After the 2015 HIV outbreak in Scott County, Indiana, 220 counties were identified as being vulnerable to HIV outbreaks among PWID [29]. In that analysis, rural states had disproportionate risks for HIV outbreaks; for instance, more than half of the counties in West Virginia were identified as vulnerable to an HIV outbreak [29, 30].

Historically, the incidence of HIV in West Virginia has been very low; there were 406 incident HIV infections in West Virginia from 2012–2016, with 9% of newly diagnosed individuals reporting past injection drug use [31]. Approximately 1 in 4 persons newly diagnosed with HIV in West Virginia during this time were simultaneously given an AIDS diagnosis, suggesting infrequent HIV testing [31]. These statistics are troubling as delayed diagnosis is associated with increased risks for suboptimal treatment response, mortality, and HIV transmission [32–36]. A large HIV cluster was identified in 2019 among PWID in Cabell County, West Virginia, a county with an estimated 2.4% population prevalence of recent injection drug use [37, 38]. These data highlight the need for a better understanding of HIV testing behaviors among PWID in rural Appalachia. The purpose of this research is to identify factors associated with not being tested for HIV in the past year among rural PWID in Appalachia (Cabell County, West Virginia).

METHODS

This research used data from the 2018 West Virginia COUNTS! study, which used the capture-recapture method for population estimation to estimate the size of the PWID population in Cabell County, West Virginia [38–40]. The parent study has been described in related publications [38–44]; an overview of its methods is included here. The capture-recapture method for population estimation was implemented over two 2-week phases in June and July 2018 in Cabell County. During each phase, PWID completed an anonymous survey via audio computer-assisted self-interview. The survey included measures related to sociodemographics, structural vulnerabilities, substance use, and testing for HIV/sexually transmitted infections. Inclusion criteria were broad: any history of using illicit drugs of any form or route of administration and age ≥18 years.

The first phase occurred at the Cabell-Huntington Harm Reduction Program (CHHRP), which is located at the Cabell-Huntington Health Department and offers comprehensive harm reduction services, including access to sterile injection equipment and HIV/sexually transmitted infection testing. The second phase occurred in locations throughout Cabell County where PWID were known to congregate, such as public parks and neighborhoods known for drug use. To avoid duplication, items were included on the survey that ascertained whether persons had previously participated in the study, and resulting data were excluded. Individuals received either a $10 grocery gift card or a snack bag as an incentive. The Institutional Review Board at the Johns Hopkins Bloomberg School of Public Health approved this research.

Measures

Our outcome of interest was whether PWID had been tested for HIV in the past year, which was assessed via 2 questions. First, we asked whether persons had ever been tested for HIV (yes/no). Those who indicated having been tested were then asked about the recency of testing: “When was the last time you were tested for HIV?” Answer options included within the last 3 months, 4–6 months ago, 7–12 months ago, more than a year ago, and don’t know. Given current CDC HIV testing recommendations, we constructed a dichotomous variable that indicated whether persons had been tested in the past year [26].

Sociodemographic measures included age, sex, race/ethnicity, relationship status, sexual minority status (defined as identifying as any orientation other than heterosexual), and Cabell County residence. Structural vulnerability measures included education level, current homelessness, unemployment, food insecurity (defined as going to bed hungry at least once a week), arrest within the past 6 months, lack of health insurance, and recent engagement in sex work (within the past 6 months).

We also included an item that assessed whether PWID felt judged by healthcare providers (yes/no). Two measures were included that ascertained the anticipated level of comfort in discussing sex and drug use with physicians: “How comfortable would you be talking to your doctor about your drug use?” and “How comfortable would you be talking to your doctor about your sexual behaviors, such as using condoms?” Responses for these items were on a 4-point Likert scale, ranging from very comfortable to very uncomfortable and responses were dichotomized to “comfortable” (very or somewhat comfortable) and “uncomfortable” (very or somewhat uncomfortable).

In terms of substance use, we constructed a variable that indicated the number of years since first injection by subtracting participants’ reported age of first injection from their current age. Participants also reported the number of times they inject on a typical day, and responses (n = 2) in which persons reported anomalous data (ie, injecting ≥50 times per day) were recoded as missing. We included 4 measures of recent receptive injection equipment sharing, asking “In the last 6 months, did you use any of the following items that you knew had been used by someone else? Select all that apply.” Answer options included syringes, cookers, cottons, and rinse water. Participants also reported how many people they typically use drugs with and whether their drug use (in the past 6 months) had increased, decreased, or stayed the same. We asked participants if they had attempted to quit using drugs in the past 6 months (yes/no). We also included an item that ascertained whether persons had ever accessed services at the CHHRP.

Participants were asked to select all of the drugs they injected in the past 6 months from the following: “cocaine by itself,” “cocaine and heroin together (speedball),” “heroin by itself,” “crystal methamphetamine,” “painkillers including: Oxycontin, Percocet, Codeine, Darvon, Percodan, Dilaudid, Demerol,” “fentanyl or fentanyl analogues,” and “buprenorphine or Suboxone.” Participants reported (yes/no) if they had ever been in a drug treatment program and, if applicable, how recently they had been in such a program. Given our interest in past-year HIV testing, we constructed a dichotomous measure that reflected whether persons had been in a drug treatment program in the past year. We also included an item that assessed whether persons had ever been tested for HCV infection (yes/no), as well as inquiring about the recency of testing (if applicable). Using these data, we constructed a binary variable that indicated whether persons had been tested for HCV in the past year. Those who reported having ever been tested for HCV were also asked whether they had ever been diagnosed with hepatitis C (yes/no).

Analytic Sample

In total, 421 survey respondents reported injection drug use in the past 6 months. One participant identified as transgender and was excluded to preserve anonymity. We also excluded persons that reported having been diagnosed with HIV more than a year ago (n = 5) and individuals who reported not knowing when they were diagnosed with HIV (n = 3) as we were unable to ascertain if they were in compliance with CDC HIV testing guidelines. Additionally, we excluded 3 persons who did not disclose whether they had ever been tested for HIV and one person who did not disclose how recently they were last tested for HIV. Collectively, these exclusions resulted in an analytic sample of n = 408 PWID.

Statistical Analyses

Tests for association with PWID not having been tested for HIV in the past year were calculated using Pearson χ ² and independent samples t tests. Variables that were significant at the P < .05 level were considered for inclusion in the multivariable analysis. HCV testing was excluded from the multivariable model given the likelihood of simultaneous HIV testing. Due to its high prevalence, multivariable log-binomial regression was used to evaluate the independent effects of covariables on PWID having not been tested for HIV in the past year. Statistical analyses were conducted using SAS Enterprise Guide v7.1.

RESULTS

The mean age of participants was 35.8 years (Table 1). Most reported being male (61%), white, non-Hispanic (84%), and single (54%). On average, persons reported injecting 4.4 times on a typical day. Approximately four-fifths reported having injected heroin in the past 6 months, and 34% reported not having been tested for HCV in the past year. Among those who had ever been tested for HCV, 68% reported any history of HCV diagnosis. The majority (64%) of PWID reported having been tested for HIV in the past year, 17% reported having been tested but not in the past year, and 19% reported never having been tested. Collectively, 36% of PWID surveyed were not in compliance with CDC HIV testing guidelines (ie, had not been tested in the past year).

Table 1.

Characteristics by Human Immunodeficiency Virus Testing in the Past Year Among People Who Inject Drugs in Cabell County, West Virginia

	PWID, No. (%)
Characteristic	Total (N = 408)	Tested in Past 1 y (n = 261)	Not Tested in Past 1 y (n = 147)	P Value
Sociodemographics
Age, mean (SD), y	35.8 (8.6)	35.9 (8.3)	35.7 (9.0)	.76
Sex
Male	249 (61.0)	149 (57.1)	100 (68.0)	.03
Female	159 (39.0)	112 (42.9)	47 (32.0)
Race/ethnicity
White, non-Hispanic	336 (84.4)	216 (84.7)	120 (83.9)	.84
Other	62 (15.6)	39 (15.3)	23 (16.1)
Relationship status
Single	218 (53.6)	143 (54.8)	75 (51.4)	.51
Married or in a relationship	189 (46.4)	118 (45.2)	71 (48.6)
Sexual minority	67 (16.4)	47 (18.0)	20 (13.6)	.25
Cabell County resident	363 (89.0)	233 (89.3)	130 (88.4)	.80
Structural vulnerabilities
Educational level
Less than high school graduation	112 (27.5)	69 (26.4)	43 (29.3)	.54
High school graduation, GED, or above	296 (72.6)	192 (73.6)	104 (70.8)
Homelessness	228 (55.9)	158 (60.5)	70 (47.6)	.01
Unemployment	270 (66.2)	167 (64.0)	103 (70.1)	.21
Food insecurity	265 (65.0)	169 (64.8)	96 (65.3)	.91
Arrested within past 6 mo	138 (33.8)	89 (34.1)	49 (33.3)	.88
No health insurance	114 (27.9)	62 (23.8)	52 (35.4)	.01
Transactional sex work within past 6 mo	74 (18.1)	46 (17.6)	28 (19.1)	.72
Believed that doctors judge people who use drugs	333 (81.8)	215 (82.4)	118 (80.8)	.70
Comfortable talking to doctors about drug use	125 (30.8)	76 (29.3)	49 (33.3)	.40
Comfortable talking to doctors about sex	118 (28.9)	67 (25.7)	51 (34.7)	.054
Substance use
Interval since first injection, mean (SD), y	11.0 (9.2)	11.0 (9.1)	11.1 (9.6)	.93
No. of injections on a typical day, mean (SD)	4.4 (3.9)	4.5 (4.0)	4.2 (3.9)	.50
Receptive injection equipment sharing within past 6 mo
Syringes	173 (42.4)	112 (42.9)	61 (41.5)	.78
Cookers	178 (43.6)	126 (48.3)	52 (35.4)	.01
Cottons	150 (36.8)	98 (37.6)	52 (35.4)	.66
Rinse water	171 (41.9)	109 (41.8)	62 (42.2)	.94
Uses drugs alone	130 (31.9)	78 (29.9)	52 (35.4)	.25
Drug use level within past 6 mo
Decreased or stayed the same	308 (75.5)	189 (72.4)	119 (81.0)	.054
Increased	100 (24.5)	72 (27.6)	28 (19.1)
Never accessed services at Cabell-Huntington Harm Reduction Program	176 (44.1)	104 (40.3)	72 (51.1)	.04
Attempted to quit drugs within past 6 mo	305 (74.8)	199 (76.3)	106 (72.1)	.36
Injection drug use within past 6 mo
Cocaine	138 (33.8)	93 (35.6)	45 (30.6)	.30
Heroin	332 (81.4)	212 (81.2)	120 (81.6)	.92
Speedball	156 (38.2)	108 (41.4)	48 (32.7)	.08
Crystal methamphetamine	287 (70.5)	187 (71.9)	100 (68.0)	.41
Painkillers	93 (22.8)	59 (22.6)	34 (23.1)	.90
Fentanyl	223 (54.7)	146 (55.9)	77 (52.4)	.49
Buprenorphine/Suboxone	120 (29.4)	79 (30.3)	41 (27.9)	.61
No drug treatment program within past 1 y	230 (56.4)	134 (51.3)	96 (65.3)	.006
Not tested for HCV within past 1 y	139 (34.2)	42 (16.2)	97 (66.0)	<.001

Abbreviations: GED, General Educational Development; HCV, hepatitis C virus; SD standard deviation.

Compared with those PWID who had been tested for HIV in the past year, those who had not were significantly (P < .05) more likely to report being male (68% vs 57%, respectively), not having health insurance (35% vs 24%), and not having been tested for HCV in the past year (66% vs 16%). PWID who had not been tested in the past year were also significantly less likely than those who had been tested to consider themselves homeless (48% vs 61%, respectively). In terms of substance use behaviors, PWID who had not been tested in the past year were less likely than those who had been tested to report having recently used cookers they knew had been used by someone else (35% vs 48%, respectively) and more likely to report never having accessed services at the CHHRP (51% vs 40%) and not having been in a drug treatment program in the past year (65% vs 51%). As shown in Table 2, not having been in a drug treatment program in the past year was associated with not being tested for HIV in the past year (adjusted prevalence ratio, 1.430; 95% confidence interval, 1.080–1.894).

Table 2.

Adjusted Prevalence Ratios for Characteristics of People Who Inject Drugs in Cabell County, West Virginia, and Reported Not Being Tested for Human Immunodeficiency Virus in the Past Year (n = 408)

Characteristic	aPR (95% CI)	P Value
Female sex	.756 (.569–1.003)	.053
Homelessness	.767 (.584–1.007)	.056
No health insurance	1.252 (.963–1.627)	.09
Receptive cooker use within past 6 mo	.827 (.613–1.116)	.21
Never accessed services at Cabell-Huntington Harm Reduction Program	1.221 (.935–1.595)	.14
No drug treatment program within past 1 y	1.430 (1.080–1.894)	.01

Abbreviations: aPR, adjusted prevalence ratio; CI, confidence interval.

DISCUSSION

This study is one of the first to examine HIV testing among a large sample of rural PWID in Appalachia. In adjusted analysis, we found that PWID who reported not having been in a drug treatment program in the past year were 43% more likely to report not having been tested for HIV in the past year than their counterpart PWID. These data suggest that drug treatment programs can be an important venue for PWID to access HIV testing services. However, the majority of our sample reported not having been in a drug treatment program in the past year, underscoring that efforts to prevent rural HIV outbreaks must include the expansion of routine HIV testing in these communities. Increased HIV testing among rural PWID may be achieved through a multitude of strategies, such as offering PWID access to home-based testing, integrating routine HIV testing services across the medical system, implementing community-wide testing campaigns, expanding the number and location of harm reduction and syringe services programs, enhancing partner testing services, testing in criminal justice and social services settings, and developing innovative rural HIV testing service delivery models.

There is an urgent need to expand access to evidence-based opioid and polysubstance use response strategies in rural communities as approximately 1 in 3 PWID reported not having been tested for HIV in the past year, less than half reported having been in a drug treatment program in the past year, and 42% reported engaging in syringe sharing. Increasing access to evidence-based opioid response strategies, including medications for opioid use disorder treatment, has the potential to not only support PWID in achieving in stopping substance usecessation but also decrease risks for HIV and viral hepatitis outbreaks via increased testing, early identification of new infections, and linkage to treatment services.

Additionally, enhanced access to biomedical approaches to HIV prevention, such as PrEP, may increase individual- and community-level protections against HIV outbreaks [1]. Research has shown that PrEP is a viable HIV prevention strategy for PWID [45]. Communities should consider investing heavily in efforts to increase PrEP utilization among PWID as well as scale up other harm reduction and structural HIV prevention initiatives as reductions in HIV transmission are optimized when combination HIV prevention strategies are implemented [1].

Furthermore, access to substance use disorder treatment should be one component of a larger comprehensive strategy that includes all available approaches for HIV risk reduction, such as harm reduction services, biomedical strategies, and campaigns to eliminate the stigmatization of people who use drugs. Eliminating stigmatization of drug use should be prioritized in rural Appalachia; >80% of PWID in our study reported that they felt judged by physicians. Stigma is a significant barrier to HIV prevention and may leave persons feeling that they have few options for receiving healthcare. In addition, initiatives aimed at controlling the spread of viral hepatitis should include efforts to increase screenings for viral hepatitis and ensure that PWID receive vaccinations against hepatitis A and B, and, when necessary, receive curative treatment for hepatitis infections.

Increasing routine HIV testing and linking persons diagnosed to care are essential components of comprehensive HIV prevention strategies as approximately 38% of new HIV infections in the US were transmitted from 15% of people living with HIV, but do not know their HIV status [46]. On average, 5403 West Virginians were tested for HIV per year from 2012–2016 [31]. Further, 26.4% of individuals in West Virginia newly diagnosed with HIV during that period were concurrently given an AIDS diagnoses, and another 7.3% progressed to AIDS within 12 months of HIV diagnosis [31]. These statistics align with research demonstrating rural persons newly diagnosed with HIV are more likely to be diagnosed at a later stage of infection – which increases their risk for transmission to others as well as for poorer outcomes [32, 33].

Thirty-six percent of our sample had not been tested for HIV in the past year, and nearly 1 in 5 reported having never been tested for HIV. While these findings speak to the need for expanded access to routine HIV testing, it also suggests that existing testing initiatives are reaching a relatively large proportion of the PWID population. The high coverage of HIV testing among PWID in Cabell County is likely reflective of recent efforts to identify incident infections; as a result of a 2018 multistate hepatitis A outbreak, the Cabell-Huntington Health Department revised its infectious disease testing protocols to include offering more frequent and on-demand HIV testing services at its harm reduction program. However, work remains to be done as there are an estimated 1857 PWID in Cabell County with a large proportion engaging in receptive injection equipment sharing [38].

At the bivariate level, there was an association between PWID reporting having never accessed services at the CHHRP and having not been tested for HIV in the past year. Harm reduction programs not only offer communities protection from HIV outbreaks through the provision of HIV prevention services, but also afford public health the ability to reach at risk and vulnerable PWID populations to implement crisis response efforts rapidly [46]. Without these programs, communities would likely experience significant challenges to implement HIV response initiatives that are scaled to effectively and expeditiously contain an HIV epidemic among rural PWID. Our study adds to extensive scientific research that empirically demonstrates the benefits of harm reduction by showing that PWID who reported having never accessed services at the CHHRP were more likely to be out of compliance with CDC HIV testing guidelines [47]. Given more than one-third of PWID in our study had not been tested for HIV in the past year and that large proportions reported engaging in high-risk injection practices, establishing and maintaining comprehensive harm reduction programs are necessary components of community-wide HIV prevention strategies in Appalachia.

Our findings should be interpreted with consideration for when data were collected. This study occurred in 2018; however, in early 2019, officials identified an HIV cluster among PWID in Cabell County and immediately began scaling up HIV testing services [37]. As such, our findings may not reflect the current HIV testing landscape in Cabell County, but rather a time several months preceding the identification of an HIV cluster. The fact that Cabell County had both a high prevalence of HIV testing among PWID and an operational harm reduction program in the time preceding the identification of an HIV cluster should not be interpreted as a failure of public health, but rather a reminder of the importance of ensuring that services are scaled to meet population-level needs and in ways that align with best practices. Harm reduction service provision in rural Appalachia is vital to preventing infectious disease transmission among PWID; in the absence of the harm reduction program at the Cabell-Huntington Health Department, the HIV cluster would have likely been far more severe and widespread. Future work should be conducted to compare access and utilization of HIV prevention and substance use treatment services before and after the identification of the HIV cluster to understand where gaps may exist.

This research is subject to limitations. While our outcome measure was informed by CDC HIV testing guidelines, more frequent testing may be warranted for persons who engage in high-risk behaviors. Another limitation is that our measure of past-year drug treatment lacked specificity. It is possible that the association between drug treatment and HIV testing may vary based on the type of treatment program persons accessed. An additional limitation is that of social desirability bias; however, this is likely a minor limitation as all data were collected anonymously and via audio computer-assisted self-interview (ACASI). Further, although more than 80% of Cabell County is considered rural, differences in HIV testing behaviors may exist based on relative levels of rurality [48]. Lastly, our sample lacked racial and ethnic diversity. Even with these limitations, we were able to characterize HIV testing behaviors among a large sample of rural PWID and glean insights into a variety of measures that have only been explored to a limited extent among this population.

In conclusion, this study demonstrates that HIV testing disparities exist among rural PWID and that drug treatment programs could play an important role in preventing future HIV outbreaks. However, HIV testing services should be offered at a variety of venues frequented by PWID as more than half of the participants in our study reported having not accessed drug treatment in the past year. Given that our data were collected in the months preceding the identification of an HIV cluster, our findings are both informative for other rural communities and serve as a baseline to assess the impact of the scale-up of HIV prevention interventions throughout Cabell County. Future work should be conducted to understand the integration of HIV prevention initiatives with other services PWID access and how to ensure rural PWID have consistent access to HIV testing services.

Notes

Acknowledgments. We are grateful for the collaboration of the Cabell-Huntington Health Department, without whom this project would not have been possible. We are especially grateful to Tim Hazelett, Thommy Hill, Tyler Deering, Kathleen Napier, Jeff Keatley, Michelle Perdue, Chad Helig, and Charles “CK” Babcock for all their support throughout the study implementation. We are also grateful for the hard work of the West Virginia COUNTS! research team: Megan Keith, Anne Maynard, Aspen McCorkle, Terrance Purnell, Ronaldo Ramirez, Kayla Rodriguez, Lauren Shappell, Kristin Schneider, Brad Silberzahn, Dominic Thomas, Kevin Williams, and Hayat Yusuf. We gratefully acknowledge the West Virginia Department of Health and Human Resources. We also wish to acknowledge Josh Sharfstein, Michelle Spencer, Dori Henry, and Akola Francis for their support throughout each phase of this research. Most importantly, we are grateful to our study participants.

Disclaimer. The funders had no role in study design, data collection, or in analysis and interpretation of the results, and this article does not necessarily reflect the views or opinions of the funders. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Financial support. This work was supported by the Bloomberg American Health Initiative at the Johns Hopkins Bloomberg School of Public Health (grant to S. T. A.), the Johns Hopkins University Center for AIDS Research (grant P30AI094189), the District of Columbia Center for AIDS Research (grant AI117970), and the National Institutes of Health (grant K01DA046234 to S. T. A.).

Supplement sponsorship. This supplement is sponsored by the Centers for Disease Control and Prevention.

Potential conflicts of interest. S. G. S. is an expert witness for the plaintiffs in opioid litigation. All other authors report no potential conflicts. The author has submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.