Cost-Effectiveness of Asymptomatic-Bacteriuria Screening Strategies During Pregnancy

Abstract

Objective: To estimate the cost-effectiveness for Colombia of four asymptomatic-bacteriuria (ABU) screening alternatives in pregnant women: a) urine culture, b) Gram stain, c) urianalysis and d) urianalysis followed by urine culture after a positive result.Methods: Two decision trees were built in TreeAge® with outcomes measured in avoided pyelonephritis cases and avoided preterm births. The costs were included from the perspective of the Health System in Colombia. Pharmaceutical costs were obtained from 2008 SISMED (1) and the value of the procedures was calculated by adjusting the values of the Tariff Manual ISS 2001 30%, these values were compared with information of costs supplied by three EPS. All monetary figures are expressed in Colombian pesos of 2010. The discount rate was 0%. Sensitivity univariate and probabilistic analyzes were performed for costs and effectiveness.Results: The incremental cost-effectiveness ratio (ICER) of urine culture for avoided pyelonephritis is $877,494; for avoided preterm birth is $13,895,576. The ICER of the Gram stain for pyelonephritis avoided is $314,914; for preterm briths avoided is $1,399,593. Urine culture to confirm urianalysis positive results is a dominated strategy. The ICER of urine culture is sensitive to the probability of pyelonephritis when ABU is neither detected nor treated in time, and to the Gram-stain specificity. The variability of ICERs for the alternatives for avoided preterm births is affected by the cost of screening with urine culture, the probability of preterm birth when ABU is neither detected nor treated in time, and by the Gram-stain specificity.Conclusions: Urine culture is the ABU screening that avoids the higher number of pyelonephritis and preterm birth cases. If the health-system willingness-to-pay threshold is higher than $970,000 per additional avoided case of pyelonephritis, or than $14,550,000 per additional avoided preterm birth, urine culture is cost effective. For thresholds between $350,000 and $970,000 per additional avoided pyelonephritis, or between $2,500,000 y $14,550,000 per additional avoided preterm birth, Gram stain would be cost effective. For lower thresholds, urianalysis alone is cost effective.