Monitoring young people with type 1 diabetes for diabetic nephropathy: potential errors of annual ACR testing
Oke J, Farmer A, Neil A, Dalton RN, Dunger D, Stevens R.
AIM: Type 1 diabetes guidelines recommend annual monitoring of albumin-creatinine ratio (ACR) to detect nephropathy. Annual monitoring for conditions such as dyslipidemia leads to high rates of false-positive diagnoses. We estimated rates of false-positive and false-negative diagnoses under annual, biennial and triennial monitoring. METHODS: Using Oxford Regional Prospective Study (ORPS) data we modelled ACR over time. Using simulation we estimated numbers of positive and negative diagnoses and the proportion that are false, over 6 years of monitoring, when assessment intervals are 1, 2 or 3 years. RESULTS: Average increase per year (95%C.I.) in ACR was 3,5% (2,0-5,0%) for males and 4,8% (3,2-6,5%) for females. By 6 years, annual monitoring would lead to 56 (49-63) false-positive diagnoses for every 100 positive diagnoses of micro-albuminuria, biennial to 49 (42-57) false-positives and triennial to 46 (39-53). For every 100 negative diagnoses, annual monitoring would lead to 1,2 (0,8-1,5) false-negatives, biennial to 2,3 (1,7-3,0) and triennial to 3,0 (2,2-3,8). CONCLUSION: Less frequent monitoring would result in fewer false-positive diagnoses, but increased false negatives, or missed diagnoses. The clinical implications of these scenarios need further investigation through cost-benefit analysis.