Potential System Utilization and Cost Savings of Advanced Microbial Testing for Urinary Tract Infections

Management of chronic and complex urinary tract infections can be a challenging problem for urologists, emergency department staff, and primary providers. A recent study evaluated the utility of a multiplex polymerase chain reaction–based urinary tract infection analysis, showing noninferiority to classic urine culture testing and possible improvement in identifying polymicrobial infections.1 In addition, this testing benefits from a shorter time to diagnosis with sensitivity testing than traditional culture. Questions remain regarding how this testing might improve patient outcomes and health care utilization. The authors should be commended on their efforts to answer these difficult questions. Ko et al2 found that using polymerase chain reaction technology with pooled antibiotic testing (mPCR/P-AST) in patients with recurrent or complicated urinary tract infections may lead to decreased inpatient utilization and cost savings for the systems compared with standard urine cultures. The average treatment cost for urinary tract infection–related care was decreased by $500 in the mPCR/P-AST group. In addition, 23 percent of patients undergoing the mPCR/P-AST population were able to be treated as an outpatient compared with 53 percent of patients undergoing standard urine cultures. The authors conclude that the mPCR/P-AST approach is associated with reduced resource utilization and costs. Using a matched case-control design, the researchers examined the potential of using mPCR/P-AST in a real-world analysis of a retrospective sample of Medicare beneficiaries with recurrent or complicated urinary tract infections. After an index infection, patients using either the mPCR/P-AST or the standard urine culture exclusively were compared for the following year. The researchers used propensity score matching to mimic randomization by selecting appropriate controls (patients with standard urine culture). They used different statistical models to compare multiple outcomes, including additional urinary tract infections, urinary tract infection–related medical resource utilization, and urinary tract infection–related costs. The ultimate goal of mPCR/P-AST is to improve the care of patients with complex infections by offering faster and possibly improved diagnosis. The primary finding here is an improved rate of outpatient management between testing modalities; however, there is no improvement in rate or number of additional infections. Given the goal of more rapid diagnosis, this shift to outpatient management may hint at earlier microbe-directed treatment of infections compared with a traditional culture, thus preventing hospital admission. However, there is bias introduced by the retrospective design as providers selected their testing modality. A complicated infection may not trigger the need for a PCR test like a chronically catheterized patient with a recurrent infection because of the possibility for improved polymicrobial identification. Thus, selection bias may exist that could lead to inherent management differences between populations. Although the propensity score analysis attempts to address this bias, it can only account for variables measured in the data set and cannot account for unmeasured confounding. Second, the authors found that there was a reduction in costs on a systems level associated with the introduction of polymerase chain reaction testing. They conclude that the use of this method will help to reduce cost secondary to reduction in hospitalization for patients managed with this modality. As this was a study intended to examine resource utilization, the authors elected not to include the cost of the polymerase chain reaction testing in their final costs. Although increased outpatient utilization is a benefit from the patient perspective, the increased cost of testing, upward of $1,000, may be prohibitive to payers. Additional cost-benefit analyses are warranted. This study takes on the admirable challenge of evaluating a real-world population with thoughtful population definitions and analyses. There is undoubtedly a potential benefit to more efficient testing both for patients and the health care system; however, further study is necessary to confirm these findings.