Abstract
Background/Aims Studies to identify early chronic kidney disease (CKD) among patients with diabetes are important. However, collecting blood samples from patients to measure new biomarkers of kidney function can be invasive, inconvenient, and may not be well-accepted. The purpose of this study was to describe the methods for collecting cystatin C measures, using both capillary and venous blood samples, to measure early CKD.
Methods We recruited members who were English-speakers, non-pregnant, aged 25–74 years, enrolled in the Kaiser Permanente Georgia diabetes registry, and reported an eGFR > 60 ml/min/1.73m2. Members were recruited using an initial introductory letter with a follow-up phone call. A one-time clinic visit was scheduled for the collection of capillary and venous blood samples, anthropometric measures, and questionnaire data. Patients received a $25 gift card for participating in the study. Clinic visits lasted 20–30 minutes. At the end of the study, a debriefing session was conducted to discuss feasibility issues and barriers to recruitment.
Results A total of 343 patients were contacted with initial mailings (a second repeat mailing to 88 patients was done halfway through the recruitment period). Over 7 weeks, 315 members were contacted by telephone; 56% (177 of 315) could not be reached after 3 follow-up phone calls, 10% (32 of 315) had bad or disconnected numbers, 7% (23 of 315) declined, and 26% (83 of 315) agreed to participate. (Among members we spoke to, the response rate for participation was 78% [83 of 106]). Some patients did not show up for their scheduled appointment, leaving a total of 59 completed visits. Feedback from study staff included having a shorter time window between mailings and calls, appointment reminder cards, and proper labeling of samples going to the laboratory. In general, the protocol was easy to follow and patients were eager to participate.
Conclusion Our pilot study indicated that collecting blood samples to measure cystatin C in a clinic setting can be done with minimal inconvenience to the patient. Our study methods were well received by patients and clinic staff. For future studies, the use of appointment reminder postcards may reduce the number of no-shows.
