Albuminuria is an early marker of kidney damage and an essential component of chronic kidney disease (CKD) risk stratification. Quantitative measurement of the urine albumin to creatinine ratio (ACR) in a spot, preferably morning, urine sample is the recommended standard. In low throughput laboratories and point of care settings, semiquantitative strip tests are sometimes used for screening, although their diagnostic performance is limited. To evaluate the clinical utility of a commercial semiquantitative urine strip test for albumin and creatinine by comparison with quantitative ACR measurement. Eighty-four spot urine samples were analysed. Semiquantitative ACR categories were obtained using an ACON Mission strip test, according to the manufacturer's instructions. Quantitative ACR was measured on a Beckman Coulter AU480 analyser (immunochemical albumin, enzymatic creatinine). Diagnostic performance was assessed using sensitivity, specificity, positive and negative predictive values, Matthew's correlation coefficient (MCC) and Cohen's κ. A decision threshold of 3 mg/mmol (30 mg/g) was applied. Sensitivity for detecting albuminuria (≥3mg/mmol, ≥30 mg/g) was 80.6% (95% CI 62.5 - 92.5) and specificity was 60.4% (95% CI 46.0 - 73.5). The negative and positive predictive values were 84.2% and 54.3%, respectively. Overall categorical agreement across A1 - A3 was 63.1% (κ = 0.334; MCC = 0.398). Most discrepancies reflected overclassification of low-grade albuminuria by the strip test in samples classified as normoalbuminuric by quantitative ACR. The semiquantitative strip test shows high sensitivity with moderate specificity and is suitable for screening for albuminuria. Positive results should be confirmed by quantitative ACR measurement in accordance with current guidelines.
Gabrysiak et al. (Wed,) studied this question.