Postanalytical external quality assessment of urine albumin in primary health care: an international survey.

BACKGROUND Microalbuminuria (MA) is recognized as an important risk factor for cardiovascular and renal complications in diabetes. We sought to evaluate how screening for MA is conducted and how urine albumin (UA) results are interpreted in primary care internationally. METHODS General practitioners (GPs) received a case history-based questionnaire depicting a male type 2 diabetes patient in whom UA testing had not been performed. Questions were related to type of urine sample used for UA testing, need for a repeat test, whether UA testing was performed in the office laboratory, and what changes in UA results were considered clinically important [critical difference (CD)]. Participants received national benchmarking feedback reports. RESULTS We included 2078 GPs from 9 European countries. Spot urine samples were used most commonly for first time office-based testing, whereas timed collections were used to a larger extent for hospital-based repeat tests. Repeat tests were requested by 45%-77% of GPs if the first test was positive. Four different measurement units were used by 70% of participants in estimating clinically important changes in albumin values. Stated CDs varied considerably among GPs, with similar variations in each country. A median CD of 33% was considered clinically important for both improvement and deterioration in MA, corresponding to an achievable analytical imprecision of 14%, when UA is reported as an albumin/creatinine ratio. CONCLUSIONS Guidelines on diagnosing MA are followed only partially, and should be made more practicable, addressing issues such as type of samples, measurement units, and repeat tests.