Screening Urine Specimen Populations for Normality Using Different Dipsticks: Evaluation of Parameters Influencing Sensitivity and Specificity

Abstract

The reagent test strip Combur-9 Test-RL (Boehringer Mannheim) and the 8-SG Multistix (Ames) were simultaneously evaluated as a rapid method for screening urines for normality. Differences between the two methods are for a considerable part determined by adjustment of the lowest detection limits of the leukocyte and erythrocyte dipstick fields. Patient populations (243 specimens presented to the routine laboratory and 230 specimens submitted for microbiological culture), sediment analysis (routine or standardized) and composition of the screening protocol strongly influence values obtained for the sensitivity, specificity and predictive values, whereas use of a different dipstick is of minor importance on the final results. Higher sensitivity and specificity are observed when relating positive dipstick screening to positive culture than when relating positive standardized sediment to positive culture. Evaluation of dipstick method, using microscopic sediment analysis as a reference parameter appears to be very dependent on the quality of the latter, which is therefore relatively unsuitable for this purpose. Apart from standardization, additional clinically significant findings are obtained using dipstick screening.