Abstract
Background and objectives
The effectiveness of targeted screening for identification of CKD is largely unknown. The See Kidney Disease (SeeKD) targeted screening project aimed to determine the prevalence of unrecognized CKD in Canada.
Design, setting, participants, & measurements
The SeeKD project was conducted across Canada using a convenience sample approach and events to identify adults with risk factors for CKD (i.e., diabetes, hypertension, vascular disease, family history of kidney problems, etc.). Participants with at least one risk factor received a point-of-care creatinine measurement to identify unrecognized CKD (CKD-Epidemiology Collaboration eGFR <60 ml/min per 1.73 m2). Baseline information included clinical characteristics, sociodemographics, and health knowledge. Semistructured telephone interviews were conducted with each Kidney Foundation of Canada branch (regionalized locations) after the screening events to characterize local screening strategies, which were subsequently categorized as individual-targeted (specifically targeting individuals at risk of CKD) and community-targeted (event in a community location in proximity to a high-risk population). We calculated the prevalence of unrecognized CKD overall, and by screening strategy.
Results
Between January 2011 and February 2014, 6329 Canadians participated in SeeKD screening events. Participants were predominantly female (65.3%), middle-aged (mean, 58.5 years), and the majority (88.9%) self-reported at least one risk factor for CKD. Of participants with at least one risk factor, 92.3% (n=5194) were screened, of whom 18.8% (95% confidence interval [95% CI], 17.8 to 19.9) had unrecognized CKD; the majority (13.8%) had stage 3a CKD (eGFR=45–60 ml/min per 1.73 m2). The prevalence of unrecognized CKD was higher for branches with individual versus community-targeted events (21.9% [95% CI, 20.5 to 23.4] versus 14.7% [95% CI, 13.2 to 16.2]).
Conclusions
Targeted screening identified a high proportion of individuals with risk factors for CKD and a high prevalence of unrecognized CKD. Future research will evaluate the ability of targeted screening to promote self-management behaviors addressing priorities for people with CKD.
Keywords: chronic kidney disease; targeted screening; Canada; creatinine; glomerular filtration rate; Humans; hypertension; kidney; Prevalence; Renal Insufficiency, Chronic
Introduction
CKD, defined as eGFR<60 ml/min per 1.73 m2, is an important public health problem with increasing prevalence worldwide (1–3). An estimated 2.9 million Canadian adults (4), and up to 22% of individuals aged >70 years, have CKD (5). Further, CKD increases the risk of cardiovascular disease and premature all-cause mortality (6). Clinical practice guidelines recommend early recognition of CKD (7,8) to enable implementation of interventions that can reduce morbidity and premature mortality (9). However, there is a paucity of evidence to inform the optimal strategy for early recognition of CKD.
Population-based screening for CKD has not been shown to be cost-effective; however, targeted screening of people with diabetes (10) and hypertension (11) has been shown to have a similar cost per quality adjusted life year gained as other publicly funded health care initiatives. Targeted screening is directed at individuals with an increased risk of CKD, such as individuals with diabetes, hypertension, clinically relevant cardiovascular disease, family history of kidney failure, or aged ≥60 years (8).
In the United States, the Kidney Early Evaluation Program (KEEP) screening program targeted populations at risk of CKD, and reported a prevalence of undiagnosed CKD of 28.7% (12). In Canada, the See Kidney Disease (SeeKD) Targeted Screening program was conducted by The Kidney Foundation of Canada and its branches (regionalized locations) to identify unrecognized CKD and promote kidney health and disease prevention strategies. In this paper, we report the prevalence of unrecognized CKD from the SeeKD program, and describe the targeted screening strategies used.
Materials and Methods
Overview of the SeeKD Screening Program
Eight Kidney Foundation of Canada branches, spanning ten provinces, participated in the SeeKD screening program using a standardized protocol. Branches chose the location and target population for their screening events based on community characteristics. Branches were encouraged to hold screening events in locations where those at risk of CKD would be greatest using a convenience sample approach, participant accessibility was adequate, and with a publicly accessible venue provided free of cost. At least one registered nurse or pharmacist attended each screening event, and used predefined guidelines for medical follow-up of patients, if necessary.
Eligible participants were adults aged ≥18 years who provided informed consent and were eligible to participate in one screening event. The screening event used a standardized 3-step protocol to ensure only those at risk of CKD would receive kidney-specific testing (Supplemental Appendix 1). In step 1, participants completed a health data form to determine baseline sociodemographic characteristics, risk factors for CKD, knowledge of kidney disease and its risk factors, and current health behaviors. CKD risk was defined as at least one of the following self-reported risk factors: diagnosed diabetes, diagnosed high BP, existing kidney problems, family history of kidney disease, member of high-risk ethnic population (Aboriginal, Hispanic, South Asian, Asian, or African descent), current vascular disease, and currently using tobacco products. Participants were not specifically asked if they had existing CKD, and therefore all participants with self-reported kidney problems, which may have included other conditions such as nephrolithiasis and infections, were included. Participants identified as at risk of CKD moved to step 2, where clinical measurements, including point-of-care creatinine testing (Stat Sensor) and urinalysis, were obtained. The StatSensor tool has demonstrated good sensitivity (96%) and moderate specificity (79%) for detecting CKD, and has been suggested for use in screening of CKD (13–16). However, the single random urine dipstick measurement does not capture albuminuria, and thus CKD was defined using a single creatinine measurement. Participants with no evidence of risk factors for CKD were provided with information about kidney health and self-management approaches to prevent kidney disease. GFR was estimated using a creatinine measure and the CKD- Epidemiology Collaboration equation (17). Finally, step 3 included a follow-up health survey sent to participants at risk of CKD within 2–4 weeks after attending the event (results reported separately). Of note, unrecognized CKD was defined as an eGFR<60 ml/min per 1.73 m2 and where the patient is unaware of a current diagnosis of CKD, though one may have been made by their primary care physician.
Information Obtained to Characterize Screening Events
To further characterize the SeeKD screening events we contacted the Kidney Foundation of Canada branches after the screening events were completed (between July 2014 and September 2014), to obtain additional detailed information. Telephone interviews were scheduled with the person in charge of the event at each branch, or their delegate. The semistructured interviews, which ranged from 30 to 60 minutes, obtained information about the population of interest for screening, methods of advertising, location of the screening events, screening criteria and registration, resources utilized, length of events, and approximate number of participants screened per event. Interviews were done by one member of the research team.
Based on this information we categorized the SeeKD events post hoc into two broad screening strategies: individual-targeted screening (defined as targeting individuals at high risk of CKD) and community-targeted screening (defined as an event in a community location in proximity to a high-risk population). The focus of events as individual-targeted or community-targeted was largely dependent upon available resources, as well as opportunities and relationships with communities at high risk of CKD.
Statistical Analyses
Descriptive statistics were used to characterize participants, including sociodemographics (age, sex), self-reported motivation to participate in screening, health knowledge of CKD, and risk factors for CKD, and were reported using numbers and proportions for binary and categorical variables, and means with SDs for continuous variables. Results were further stratified by screening strategy (individual-targeted and community-targeted).
Among individuals with self-reported risk factors for CKD who received point-of-care creatinine testing, we calculated the prevalence of unrecognized CKD, with 95% confidence intervals (95% CIs), overall, and by screening strategy and self-reported risk factors. Finally, we compared participants with unrecognized CKD to those with normal kidney function on sociodemographic data, risk factors for CKD, clinical characteristics (body mass index, urine protein, urine blood, random blood glucose, BP) and whether an individual required immediate medical attention at the screening event. Results were compared using Pearson chi-squared tests for proportions, the Wilcoxon rank sum test for multilevel categorical variables, and t tests for continuous variables. In a sensitivity analysis, we excluded participants that self-reported having kidney problems and had an eGFR<60 ml/min per 1.73 m2, to determine the prevalence of unrecognized CKD among participants without prior knowledge of kidney problems.
Qualitative descriptive methods were used to analyze and explore the variation in screening events collected through the interviews. Analysis was conducted by assigning codes to segments of the collected interview information, using a priori defined codes (categories). These segments of data were then organized in tabular format by category. Branches were invited to review and comment on the information to ensure accuracy.
The SeeKD targeted screening program received ethics approval from Health Canada as well as the Conjoint Health Research Ethics Board at the University of Calgary. All statistical analyses were conducted using Stata, version 11 (18).
Results
Of the eight Kidney Foundation of Canada branches participating, one did not follow the standardized protocol and was removed from this analysis. As such, we report on the SeeKD program representing nine of the ten Canadian provinces. Of the seven participating branches of the Kidney Foundation of Canada, four conducted individual-targeted screening (screening events that specifically targeted individuals at risk of CKD and commonly had people sign up in advance of the screening event) (Table 1) and three used a community-targeted screening strategy (held their screening events in public locations where high-risk individuals were expected, including those with limited health care access) (Table 2).
Table 1.
Description of individual-targeted screening events, by Kidney Foundation of Canada branch
| Description of Screening Events | British Columbia | Southern Alberta | Northern Alberta | Ontario |
|---|---|---|---|---|
| Who was targeted? | First Nations | Chinese | Seniors | Chinese |
| South Asian/Asian | ||||
| Seniors | ||||
| WorkSafeBC for those at risk | African | |||
| How were events advertised? | Self-advertised by the venue, but if enough people did not sign up the event was advertised externally | Through local community center, using their radio and print media | Advertised in the program section of senior’s residence | Advertised in the community, promoted by community partners in their newsletters, word of mouth |
| Where were the events held? | Community centers | Community center | Senior’s residence | Community center or church |
| Friendship centers | ||||
| Religious centers | ||||
| Screening criteria | Only those at risk | Anyone in targeted ethnic group | Any senior (as all considered at-risk) | Anyone in targeted ethnic group |
| Drop in or sign up? | Only sign up | Sign up or drop in | Sign up, but drop in allowed if space allowed | Drop-in |
| What unpaid resources were required for the events? | 1 pharmacist, provided by Superstore | 1 pharmacist provided by Loblaws | Kidney Foundation volunteers to hand out information | Volunteers to help set up the tables and work the room |
| Translators as needed from community center | Translators from community center | |||
| What paid resources were required for the events? | 1 nurse for testing | 1–3 nurses | 1 nurse | 2–3 nurses, who speak the dialect and/or represent the community |
| 2 nurses to discuss results with the patient | 1–2 KFOC staff | 1 KFOC staff | 1–2 KFOC staff | |
| 1 KFOC staff | ||||
| Other supplies needed for events | Expectation of food (at a minimum juice and raisins) | Expectation of full meal if staying for screening (e.g., after a church service) in some communities | ||
| Length of events | Either 1 full d or 1 half d | 1–3 full d | 1 full d | 3–5 hours |
| How many screened per event | 50 people per full d | 20 people per d | 25–35 people per d | 50–60 people per event |
BC, British Columbia; KFOC, Kidney Foundation of Canada.
Table 2.
Description of community-targeted screening events, by Kidney Foundation of Canada branch
| Description of Screening Events | Saskatchewan | Manitoba | Atlantic |
|---|---|---|---|
| Where were events usually held? | Safeway, usually near senior’s residence. | Grocery stores or health center buildings. | Communities at large that do not have a lot of health care access/opportunity. |
| How were events advertised? | Never advertised; when the screening event was set up Safeway would announce over the loudspeaker the availability to be tested. | Social media. Venue may put up posters. Sometimes a media release if it coincided with Diabetes Month or Kidney Month. | In each community health professionals were asked to do on the ground advertising. Radio stations and newspapers would run ads for free as well. |
| Drop in or sign up? | Drop in | Drop in | Drop in |
| What unpaid resources were required for the events? | 1 pharmacist, provided by Safeway. | 1–2 pharmacists | |
| What paid resources were required for the events? | 1 nurse | 1–2 nurses | 1 nurse |
| 1 KFOC staff | 1 KFOC staff | 1 KFOC staff | |
| Other supplies needed for events | None | None | None |
| Length of events | 1 d, 5–6 h | 1 d, 4 h | 1 d, 8 h |
| How many screened per event? | 10–20 people | 20–30 people | 30–35 people |
KFOC, Kidney Foundation of Canada.
Description of Screening Events
Among branches that conducted individual-targeted screening, the individuals targeted were typically part of ethnic groups at increased risk of CKD or seniors, with events held in community centers or other gathering places, and advertised by the venue or community itself (Table 1). Many events required sign-up prior to the event to ensure adequate resources were available and to avoid waiting lines for participants. Events were often repeated in the same venue to ensure that high-risk individuals had equal opportunity to participate. The number of participants screened also varied, as resources differed between screening events.
Among branches that conducted community-targeted screening, events were held at a variety of locations, including grocery stores or community centers, and all were drop-in, with advertisements being optional and varied (Table 2). Multiple events were often held in the same venue to foster relationships with communities. The number of participants screened varied, and was dependent on the number of people in the location on that specific day. Additional details and quotes from the qualitative interviews are provided in Supplemental Appendix 2.
Results of Screening Events
Overall, 6329 adults participated in the screening events, of whom 65.3% were female, with a mean age of 58.5 years (Table 3). Of the 88.9% of participants who indicated at least one risk factor for CKD, the three most common were being a member of a high-risk ethnic population, a previous diagnosis of hypertension, or a previous diagnosis of diabetes (59.0%, 38.5%, and 22.4% respectively). Fifty percent of participants were motivated to participate because of a personal concern about their health, whereas 25.6% of participants identified the recruitment efforts by the branches as their motivation to participate. With regards to health knowledge, the majority of participants (84.9%) were able to identify at least one risk factor for CKD.
Table 3.
Participant characteristics overall and by screening strategy
| Participant Characteristics | All Participants (n=6329) | Individual-Targeted Events (n=3623) | Community-Targeted Events (n=2706) | P Value |
|---|---|---|---|---|
| Sex, male, n (%) | 2197 (34.7) | 1234 (34.1) | 963 (35.6) | 0.23 |
| Age, yr, mean (SD) | 58.5 (15.9) | 60.5 (14.6) | 55.9 (17.2) | <0.001 |
| Motivation for participating, n (%) | ||||
| Concern for personal health status | 3170 (50.1) | 1983 (54.7) | 1187 (43.9) | <0.001 |
| Influence from external source | 1425 (22.5) | 776 (21.4) | 649 (24.0) | 0.02 |
| Recruitment efforts | 1623 (25.6) | 504 (13.9) | 1119 (41.4) | <0.001 |
| None | 1026 (16.2) | 745 (20.6) | 281 (10.4) | <0.001 |
| Self-reported risk factors for CKD, n (%) | <0.001 | |||
| At least one risk factor | 5627 (88.9) | 3346 (92.4) | 2281 (84.3) | |
| No risk factors | 702 (11.1) | 277 (7.7) | 425 (15.7) | |
| Self-reported risk factors, n (%) | ||||
| Diagnosed diabetes | 1416 (22.4) | 704 (19.4) | 712 (26.3) | <0.001 |
| Diagnosed hypertension | 2439 (38.5) | 1336 (36.9) | 1103 (40.8) | <0.01 |
| Problems with kidneys | 753 (11.9) | 464 (12.8) | 289 (10.7) | 0.01 |
| High-risk ethnic groups | 3735 (59.0) | 2565 (70.8) | 1170 (43.2) | <0.001 |
| Vascular disease | 1217 (19.2) | 677 (18.7) | 540 (19.9) | 0.21 |
| Family history of kidney problems | 811 (12.8) | 401 (11.1) | 410 (15.2) | <0.001 |
| Smoking or tobacco use | 1003 (15.9) | 256 (7.1) | 747 (27.6) | <0.001 |
| Health knowledge: recognition of risk factors for CKD, n (%) | <0.001 | |||
| Yes | 5375 (84.9) | 2946 (81.3) | 2429 (89.8) | |
| No | 954 (15.1) | 677 (18.7) | 277 (10.2) |
There were more participants recruited by individual-targeted events as compared with community-targeted (57.3% versus 42.8%, respectively). Individual-targeted also identified a higher proportion of participants with risk factors for CKD (92.4% versus 84.3%, respectively; P<0.001) (Table 3). Though participant characteristics were similar by screening strategy, participants’ motivation to participate in the screening events varied, with community-targeted events having a higher proportion of participants attending because of recruitment efforts (41.4% versus 13.9% for individual-targeted; P<0.001), while participants in the individual-targeted screening predominantly chose “concern for personal health status” (54.7% versus 43.9% for community-targeted; P<0.001).
Of the 5194 participants at risk of CKD who were screened, 50 people did not report their age and therefore eGFR could not be calculated (Figure 1). Among the 5144 participants with complete data, 18.8% (95% CI, 17.8 to 19.9) had unrecognized CKD, of whom 13.8% (95% CI, 12.9 to 14.7) had category 3a, 4.1% had category 3b, and <1% had category 4 or 5 CKD (Table 4). The prevalence of unrecognized CKD was highest among those with the greatest number of CKD risk factors. The individual-targeted screening identified a higher proportion of participants with unrecognized CKD overall, when compared with community-targeted (21.9% versus 14.7%, respectively).
Figure 1.
Criteria to determine the final number of participants screened for CKD.
Table 4.
Prevalence of unrecognized CKD overall and by screening strategy
| Clinical Characteristics | All Participants (n=5144)a | Individual-Targeted Events (n=2968) | Community-Targeted Events (n=2176) |
|---|---|---|---|
| eGFR, ml/min per 1.73 m2, mean (SD) | 81.4 (22.8) | 78.9 (22.2) | 84.9 (23.2) |
| CKD as eGFR<60 ml/min per 1.73 m2, n (%; 95% CI) | 969 (18.8; 17.8 to 19.9) | 650 (21.9; 20.5 to 23.4) | 319 (14.7; 13.2 to 16.2) |
| eGFR categories, n (%; 95% CI) | |||
| Category 1, eGFR≥90 ml/min per 1.73 m2 | 1918 (37.3; 36.0 to 38.6) | 960 (32.3; 30.7 to 34.1) | 958 (44.0; 42.0 to 46.1) |
| Category 2, eGFR=60–89 ml/min per 1.73 m2 | 2257 (43.9; 42.5 to 45.2) | 1358 (45.8; 44.0 to 47.6) | 899 (41.3; 39.3 to 43.4) |
| Category 3a, eGFR=45–59 ml/min per 1.7 3m2 | 708 (13.8; 12.9 to 14.7) | 489 (16.5; 15.2 to 17.9) | 219 (10.1; 8.9 to 11.4) |
| Category 3b, eGFR=30–44 ml/min per 1.73 m2 | 212 (4.1; 3.6 to 4.7) | 141 (4.8; 4.0 to 5.6) | 71 (3.3; 2.6 to 4.1) |
| Category 4, eGFR=15–29 ml/min per 1.73 m2 | 43 (0.8; 0.6 to 1.1) | 19 (0.6; 0.4 to 1.0) | 24 (1.1; 0.74 to 1.6) |
| Category 5, eGFR<15 ml/min per 1.73 m2 | 6 (0.1; 0.06 to 0.26) | 1 (0.03; 0.0 to 0.2) | 5 (0.2; 0.1 to 0.5) |
| Prevalence of CKD (eGFR<60 ml/min per 1.73 m2) for subgroups of patients with specific risk factors, n (%; 95% CI) | |||
| Diabetes or hypertension | 670 (13.0; 12.1 to 14.0) | 431 (14.5; 11.2 to 17.8) | 239 (10.9; 9.7 to 12.4) |
| Diabetes, hypertension, or vascular disease | 739 (14.4; 13.4 to 15.4) | 480 (16.2; 12.9 to 19.5) | 259 (11.9; 10.6 to 13.3) |
| Diabetes, hypertension, vascular disease, or family history | 773 (15.0; 14.1 to 16.0) | 503 (16.9; 13.6 to 17.2) | 270 (12.4; 11.1 to 13.9) |
| Diabetes, hypertension, vascular disease, family history, or member of high-risk ethnic population | 920 (17.9; 16.9 to 18.9) | 619 (20.9; 17.7 to 24.1) | 301 (13.8; 12.4 to 15.4) |
95% CI, 95% confidence interval.
Participants with at least one risk factor for CKD and screened for CKD who had complete data on risk factors, creatinine measure, age, and sex.
Compared with at-risk participants with no CKD, participants with unrecognized CKD were predominantly female (71.2% versus 47.8%; P<0.001) and older (mean age, 69.9 years versus 55.9 years; P<0.001) (Table 5). Participants with unrecognized CKD were more likely to have a previous diagnosis of hypertension, diabetes, or vascular disease, but were less likely to smoke compared with those with no CKD. Individuals with unrecognized CKD were also more likely to be overweight or obese, and present with heavy urine protein, hematuria, hypertension, and elevated random blood glucose.
Table 5.
Characteristics of participants with unrecognized CKD compared with those without CKD
| Participant Characteristics | CKD (n=969) | No CKD (n=4175) | P Value |
|---|---|---|---|
| Sex, male, n (%) | 279 (28.8) | 2178 (52.2) | <0.001 |
| Age, yr, mean (SD) | 69.9 (12.0) | 55.9 (15.7) | <0.001 |
| Self-reported risk factors, n (%)a | |||
| Diagnosed diabetes | 299 (30.9) | 1066 (25.5) | 0.001 |
| Diagnosed hypertension | 590 (60.9) | 1709 (40.9) | <0.001 |
| Problems with kidneys | 253 (26.1) | 458 (11.0) | <0.001 |
| High-risk ethnic population | 528 (54.5) | 2824 (67.6) | <0.001 |
| Vascular disease | 317 (32.7) | 821 (19.7) | <0.001 |
| Family history of kidney problems | 138 (14.2) | 639 (15.3) | 0.41 |
| Smoking or tobacco use | 154 (15.9) | 798 (19.1) | <0.05 |
| Body mass index, n (%) | <0.01 | ||
| Underweight, <18.5 kg/m2 | 10 (1.1) | 71 (1.8) | |
| Normal, 18.5–24.9 kg/m2 | 246 (26.3) | 1213 (30.5) | |
| Overweight, 25.0–29.9 kg/m2 | 327 (34.9) | 1317 (33.1) | |
| Obese, ≥30.0 kg/m2 | 353 (37.7) | 1373 (34.6) | |
| Proteinuria, n (%) | <0.001 | ||
| Normal: negative | 576 (65.7) | 2635 (76.2) | |
| Mild: trace and 1+ | 255 (29.1) | 756 (21.9) | |
| Heavy: 2+, 3+, and 4+ | 46 (5.3) | 67 (1.9) | |
| Hematuria: trace, 1+–4+; n (%) | 190 (21.8) | 609 (17.6) | <0.01 |
| Hypertensionb, n (%) | 507 (52.3) | 1932 (46.9) | <0.01 |
| BP, mean (SD) | |||
| Systolic BP | 136.3 (20.5) | 131.9 (19.7) | <0.001 |
| Diastolic BP | 77.7 (11.6) | 80.3 (11.3) | <0.001 |
| Sent to physician immediately, n (%)a | 28 (3.0) | 105 (2.7) | 0.56 |
| Check blood glucose | 6 (0.7) | 44 (1.1) | 0.21 |
| Check BP | 10 (1.1) | 51 (1.3) | 0.62 |
| Check urinalysis | 7 (0.8) | 46 (1.2) | 0.29 |
| Other | 16 (1.7) | 32 (0.8) | 0.01 |
Percentages may not sum to 100% as the denominator varied according to available data.
Hypertension defined as a systolic BP ≥140 mmHg or a diastolic BP ≥90 mmHg in any participant without self-reported diabetes. In those with diabetes, hypertension was defined as a systolic BP ≥130 mmHg or a diastolic BP ≥80 mmHg.
When the 753 participants with self-reported “kidney problems” and an eGFR<60 ml/min per 1.73 m2 were excluded, as these participants may have had known CKD, the prevalence of unrecognized CKD was 14.6% (95% CI, 13.7 to 15.7).
Discussion
In this national targeted screening program of >6000 Canadians, we found that the majority of participants reported at least one risk factor for CKD. The prevalence of unrecognized CKD in this targeted screening program (18.8%) was higher than previously published population-based estimates (7%) (19,20), demonstrating that targeted screening is able to detect a higher proportion of patients with unrecognized CKD than population-based screening. We also found that individual-targeted screening identified a higher proportion of unrecognized CKD (21.9%) than community-targeted screening (14.7%), which may inform future screening strategies aiming to capture the greatest proportion of unrecognized CKD.
Early recognition of CKD, as recommended by the Kidney Disease Improving Global Outcomes clinical practice guidelines (8), provides patients with an opportunity for preventative interventions to reduce their risk of cardiovascular events and slow the progression of CKD (2,9). With that in mind, several countries have conducted population-based screening programs, such as the national kidney disease mass screening program in Japan (21), in an effort to increase early recognition of CKD and reduce the burden of ESRD. However, population-based screening programs are not cost-effective (10). Targeted screening for CKD has shown promise. A recent systematic review found screening for CKD to be cost-effective among those at highest risk for CKD, namely patients with diabetes or hypertension (11). Our study highlights the effectiveness of targeted screening for CKD on the basis of diabetes and hypertension, as these self-reported risk factors identified the highest proportion of unrecognized CKD within the SeeKD participant population.
The SeeKD targeted screening program is similar to the KEEP in the United States, led by the National Kidney Foundation. Although both programs recruit individuals based on their risk factors for CKD, the KEEP concentrates their efforts on black populations, while the SeeKD considered other ethnic groups (Aboriginal, Hispanic, South Asian, Asian, and African) as being a risk factor for CKD (22). Targeting individuals from high-risk ethnic groups is not uncommon given the disproportionate burden of ESRD among different ethnic groups, and such screening programs have been established in Australia (23) and Canada (24). Further, the KEEP used a limited number of risk factors (personal history of diabetes or hypertension, or a family history of diabetes, hypertension, or kidney disease) (12,22,25) compared with the SeeKD program (diabetes, hypertension, existing kidney problems, family history of kidney disease, member of high-risk ethnic population, current vascular disease, or currently using tobacco products). The use of characteristics such as smoking and a broad definition of cardiovascular disease as risk factors for CKD may have included individuals with lower CKD risk. This may explain the lower prevalence of unrecognized CKD within the SeeKD program (18.8%) as compared with the KEEP (27.1%), or it may relate to differences in the ethnicity of the groups screened. This is highlighted by a higher proportion of participants with diabetes (37.6% versus 22.4%), hypertension (70.8% versus 38.5%), and family history of kidney disease (24% versus 12.8%) within the KEEP compared with the SeeKD program.
Both the KEEP and SeeKD programs identified a higher proportion of unrecognized CKD than population-based programs in the United States (12) and Canada (19), where prevalence rates of 13% and 7%, respectively, have been reported. When we excluded participants with self-reported kidney problems and an eGFR<60 ml/min per 1.73 m2, the prevalence of unrecognized CKD in the SeeKD program was 14.6%. As targeted screening aims to include all individuals at risk for CKD, and given the lack of definitive diagnosis of CKD for these participants, the SeeKD program included participants with self-reported kidney problems. Importantly we also found that individual-targeted screening, which included preselecting individuals with risk factors for CKD and often signing them up for the screening events in advance, identified an even higher proportion of patients with unrecognized CKD. Features of these screening strategies, and in particular the focus on targeting risk factors such as diabetes and hypertension, may be incorporated into future screening activities to improve the detection of patients with unrecognized CKD. The results from this study will also inform the second phase of the SeeKD program in Canada, particularly with respect to the populations being targeted.
Our results suggest that the SeeKD targeted screening program was successful in identifying a high proportion of individuals with risk factors and subsequently those with unrecognized CKD, therefore demonstrating potential as an effective method for early recognition of CKD. In fact, the majority of individuals with unrecognized CKD had category 3a CKD, emphasizing that targeted screening provides an important opportunity for early intervention to slow the progression of CKD. Consequently, these findings will inform prevalence estimates for future randomized controlled trials of screening programs. While the results demonstrate the feasibility of targeted screening for CKD, they also reveal the complexities of conducting targeted screening. The optimal strategies for targeted screening, including individual-targeted versus community-targeted, remain unknown due to the current paucity of evidence (7,9). Further research is required to determine the key components of a successful targeted screening program for CKD.
The SeeKD targeted screening program should be interpreted in light of its limitations. Firstly, there may be volunteer bias as participants self-selected to participate, and therefore may be systematically different from those who do not participate (26). This is evident by the SeeKD participant characteristics, where the majority of participants were older females who indicated that they participated because of a personal concern for their health, which may limit the generalizability of the study results. The inclusion of participants with self-reported kidney problems may contribute to an overestimation of the prevalence of unrecognized CKD, although we also provide an estimate of unrecognized CKD after excluding these individuals. There is potential misclassification of CKD, as participants were considered to have unrecognized CKD (eGFR<60 ml/min per 1.73 m2) on the basis of a single creatinine measurement and without using albuminuria. Finally, the StatSensor device is not calibrated to isotope dilution mass spectrometry standards and may underestimate eGFR levels (16). This will result in overestimation of CKD, although the expectation is that diagnosis of CKD will be confirmed by an individual’s health care provider. Given its performance characteristics, the StatSensor is a reasonable instrument for the purposes of screening, with confirmation of CKD diagnosis required.
The SeeKD screening program is the first national targeted screening initiative undertaken in Canada, and was able to identify a high proportion of participants at risk of CKD and a greater proportion of participants with unrecognized CKD, as compared with population-based estimates. These results highlight the importance of targeted screening for CKD, and demonstrate differences between two broad strategies for targeted screening (individual-targeted versus community-targeted screening) for CKD in Canada. This research is generalizable to the Canadian population with risk factors for CKD. Future research will evaluate the effectiveness of individual goal-setting and counseling held at the SeeKD targeted screening events for eliciting a health behavior change among participants.
Disclosures
None.
Acknowledgments
L.B. made substantial contributions to the qualitative data collection and data summary. L.G. conducted data cleaning and analysis. L.G., L.B., P.R., and B.H. made substantial contributions to the interpretation of results. All authors have been involved in drafting the manuscript or revising it critically for important intellectual content and all authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The authors thank the many Kidney Foundation of Canada staff, volunteers, nurses, and pharmacists who helped make the See Kidney Disease (SeeKD) program possible.
L.G. is supported by a strategic training in health research award from Knowledge Translation Canada. M.J. is supported by postdoctoral fellowships from the Canadian Institutes of Health Research, Albertan Innovates Health Solutions, and an early career fellowship from the National Health and Medical Research Council of Australia. B.M. is supported by the Svare Professorship in Health Economics and B.H. is supported by the Roy and Vi Baay Chair in Kidney Research. The Interdisciplinary Chronic Disease Collaboration is funded by Alberta Innovates Health Solutions–Collaborative Research and Innovation Opportunities Team Grants Program. The SeeKD targeted screening program was supported by the Kidney Foundation of Canada through a partnership with Canadian National Railway.
The sponsors of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.
Footnotes
Published online ahead of print. Publication date available at www.cjasn.org.
See related editorial, “Screening Strategies for Unrecognized CKD,” on pages 925–927.
This article contains supplemental material online at http://cjasn.asnjournals.org/lookup/suppl/doi:10.2215/CJN.11961115/-/DCSupplemental.
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