Diagnostic accuracy of urine dipsticks for detecting albuminuria in indigenous and non-indigenous children in a community setting
Albuminuria predicts cardiovascular and end-stage kidney disease in indigenous populations. Early detection in indigenous children may identify those who could benefit from early treatment. Community-based detection of albuminuria needs to be performed using a reliable, inexpensive, and widely available test, such as a proteinuria dipstick. Dipstick accuracy for detecting albuminuria in a community setting has not been evaluated. We assessed the accuracy of Multistix 10 SG dipsticks to detect baseline albuminuria and predict for persistent albuminuria at a 2-year follow-up in a population-based cohort of Australian Aboriginal and non-Aboriginal elementary-school-aged children. Variability in the accuracy of dipsticks in subgroups of higher risk children was analyzed using the relative diagnostic odds ratio (RDOR). Using Multistix 10 SG dipsticks, index-test-positive cases were defined as ≥0.30 g/L (1+) proteinuria and index-test-negative cases as <0.30 g/L (negative or trace) proteinuria. Referent-test-positive cases were defined as spot albumin:creatinine (ACR) ≥3.4 mg/mmol, and referent-test-negative cases as ACR <3.4 mg/mmol. There were 2,266 children (55.1% Aboriginal, 51.0% boys, mean age 8.9 years) enrolled. At the 2-year follow-up, 1,432 (63.0%) children were retested (54.0% Aboriginal, 50.5% boys, mean age 10.5 years). Prevalence of baseline albuminuria was 7.3%, and persistent albuminuria was 1.5%. Dipsticks had a sensitivity of 62% and specificity of 97% at baseline. In predicting persistent albuminuria, sensitivity was 75% and specificity 93%. Accuracy did not vary with ethnicity, gender, or body mass index. Accuracy was less in younger children (4.0–7.9 years), and in those with hematuria. The performance characteristics of Multistix dipsticks make them suitable for albuminuria detection in Aboriginal and other higher-risk groups of children. More than two thirds of children detected at a single test will have transient rather than persistent albuminuria. Multistix dipsticks are particularly useful for detecting children who will have persistent albuminuria.