Screening and treatment of asymptomatic bacteriuria of pregnancy to prevent pyelonephritis: a cost-effectiveness and cost-benefit analysis.

OBJECTIVE To compare the effectiveness, benefits, and costs of two asymptomatic bacteriuria screening and treatment strategies to prevent pyelonephritis in pregnancy. METHODS A decision analytic model was created to compare strategies based on either 1) a leukocyte esterase-nitrite dipstick, or 2) on urine culture, with a policy of no screening or treatment. A literature search was conducted to generate probability estimates. Cost estimates were based on a local pharmacy and laboratory survey and supplemented by recent literature estimates. Sensitivity analyses were performed over wide ranges of probability and cost estimates. RESULTS Under baseline assumptions, no screening resulted in 23.2 cases of pyelonephritis per 1000 pregnancies, versus 16.2 cases with the dipstick strategy and 11.2 with the culture strategy. The cost of screening and treatment of asymptomatic bacteriuria per 1000 pregnancies was $1968 with dipstick and $19,264 with culture. The cost of treating pyelonephritis with no screening was $57,562, versus $40,257 with dipstick and $27,832 with culture. Therefore, both the dipstick strategy and the culture strategy were cost-beneficial (based on a pyelonephritis cost of $2485) when compared with no screening. However, because it cost $3492 to prevent each additional case of pyelonephritis with culture that was not prevented by dipstick, the culture strategy was not cost-beneficial compared with the dipstick strategy. These results were sensitive to varying estimates for the prevalence of asymptomatic bacteriuria, the rate of progression of asymptomatic bacteriuria to pyelonephritis, the sensitivity of the dipstick, culture costs, and the cost of a case of pyelonephritis. CONCLUSION When compared with a policy of no screening, screening for and treatment of asymptomatic bacteriuria to prevent pyelonephritis in pregnancy is cost-beneficial whether based on the leukocyte esterase-nitrite dipstick or on urine culture. However, the culture strategy is not cost-beneficial when compared with the dipstick strategy.