Patient adherence to long-term medical treatment of kidney stones

Purpose: We determine patient adherence to and quality of outcome of medical kidney stone treatment during a 30-year duration at a single university based referral clinic. We also analyze time trends in adherence and timing of followup measurements, and supersaturation reduction during treatment. Materials and Methods: Data on all patients who entered the University of Chicago Kidney Stone Prevention Program from 1970 to 2000 were analyzed. Fractions of new patients who had any followup and those remaining in followup at increasing intervals were analyzed. Timing of followup was measured. Changes in adherence during the 3 decades were also analyzed, as was reduction in supersaturation in regard to calcium oxalate, calcium phosphate and uric acid. Results: A total of 70% to 80% of patients were retained at each successive followup cycle with 2 physicians, and a clinical protocol that always required 6-week followup with 24-hour urine collection and a yearly one thereafter for stone risk factors. Retention decreased during the last 5 years of the 1990s. Supersaturation reduction was present by the first followup and remained constant or improved with time. Timing of followup measurements was in accord with our protocol. Conclusions: At best, one can retain only 70% to 80% of patients in a followup program at each interval, and achieve supersaturation reductions that are constant and significant during the long term. Timing of followup measurements can be close to that of the protocol in use.