Cost-effectiveness of screening for microalbuminuria using immunochemical dipstick tests or laboratory assays in diabetic patients.

To analyse the cost-effectiveness ratio of screening for microalbuminuria in diabetic patients using either dipstick tests or laboratory assays, 506 diabetic patients were screened for microalbuminuria using both a traditional laboratory assay (strategy I) or a laboratory assay only in the case of a positive dipstick result (strategy II). Dipstick pre-screening was considered positive if at least one of the tests performed by the two different operators showed an albumin excretion rate > 20 micrograms min-1. It was performed using a new dipstick, Micral-Test, designed to distinguish low albumin concentrations. Biological assay was the reference method. Costs were related to laboratory assays (strategy I) or to dipstick tests and laboratory assays for positive results (strategy II). The loss of effectiveness was related to false negative results of strategy II. The double dipstick pre-screening showed a sensitivity of 90.8% and a specificity of 80.1%. Its predictive value was 97% for a negative result and 55.6% for a positive result. False positive results were associated with elevated urinary volumes. Compared with strategy I, strategy II showed a sensitivity of 90.8%, a specificity of 100%, and predictive values of 100% and 97.5%, respectively, for positive and negative results. In a fictitious cohort of 10,000 patients, strategy II yielded a gain of 16,750 pounds on the first year, which decreased to 5345 pounds after 30 years. The loss in effectiveness was estimated at 2.38 quality adjusted life years of a diabetic patient (QALYd) initially, and decreased to 0.91 QALYd after 30 years, the annual cost-effectiveness ratio being close to 6600 pounds QALYd-1.(ABSTRACT TRUNCATED AT 250 WORDS)