Do Urine Cultures for Urinary Tract Infections Decrease Follow-up Visits?

Jeremy Daniel Johnson, MD, MPH; Heather M. O'Mara, DO; Hyrum F. Durtschi, DO; Branko Kopjar, MD PhD, MS

Disclosures

J Am Board Fam Med. 2011;24(6):647-655. 

In This Article

Discussion

In our study sample of 779 patients, the patients who had a urine culture ordered as part of their management did not show any significant decrease in follow-up visits compared with those who did not have a urine culture ordered. Similarly, there was no statistically significant difference between the cohorts when looking at either a second antibiotic being prescribed within 2 weeks of the initial visit or a telephone consult for continued UTI symptoms within 2 weeks of the initial visit, though the study was not powered for these outcomes. Multivariate analysis showed that ordering a urine culture was not associated with a significant change in follow-up rates.

This study had several strengths. To gather data, we used electronic patient records, which allowed us to track all outpatient visits, emergency department visits, inpatient visits, pharmacy prescriptions, ancillary tests, and telephone consults. We studied a facility with a very large patient population of 60,000 enrollees, which provided an adequate sample size over a relatively short period of time. We studied a facility where all medical care is provided free to all patients, which helped ensure that patients would not avoid follow-up visits because of the lack of ability to pay. Finally, we used a medical system that electronically records when a patient calls for a follow-up visit even if no visit is available.

Study weaknesses include the fact that this study was not a randomized controlled trial, but rather a cohort trial, so causality cannot be determined. Another limitation is that Madigan Hospital has a 15% E. coli resistance to the antibiotic TMP-SMX. The E. coli resistance levels vary around the world, and thus the results of this study may not apply to other populations. This study was conducted in three clinics in a military medical system, so results may not be generalizable. Race data were not always recorded in our EMR, yielding only 512 (67%) patients with specified race. Because of this, we could not use race as a factor in our multivariate analysis, although race data were not significant in our bivariate analysis (sees Table 4 and [5]). A final potential limitation is that we excluded patients that had UTIs in the prior 6 weeks. This may limit this study's applicability to patients with recurrent UTIs and very short asymptomatic intervals.

To our knowledge, this is the first published study looking specifically at whether ordering a urine culture at the time of diagnosis and treatment is associated with a decrease in follow-up rates for recurrent UTI symptoms. Several studies have recommended against ordering a urine culture based on assumptions of the effectiveness of urine cultures in decreasing symptom days or in looking at the number of resistant organisms that grew in cultures, but no other studies observed actual practice to determine the effectiveness of a urine culture in decreasing follow-up visits.[2,15] Our study agrees with a recent UK prospective cohort study in which a urine culture was performed for all patients and found that trimethoprim resistance was only 13.9%. This UK study found that 23 women required a urine culture to prevent one follow-up visit from resistance-based failure; thus, empiric treatment with no urine culture was recommended.[10] Our study had a similar TMP-SMX resistance rate and a similar outcome; however, only one cohort in our study had a urine culture ordered. We had a control group and a test group, which allowed us to perform statistical tests to determine if a urine culture made a difference.

This study agrees with the current body of literature that recommends against ordering a urine culture in this population. In our study, ordering a urine culture was not associated with a change in outcomes for patients, as evidenced by follow-up visits, but it did result in increased laboratory costs of $5,546.75, or $12.41 per patient. This study shows a large variation in practice patterns by providers at a single hospital, and it reinforces the limited effectiveness of the urine culture as a means to identify resistant organisms and help prevent follow-up visits. It is our feeling that clinicians should follow current guidelines by avoiding routine urine cultures when treating uncomplicated UTIs, and instead order a urine culture only to confirm the diagnosis of UTI in doubtful cases before treatment or when initial UTI management fails. Policymakers should also consider these results when evaluating the cost effectiveness of laboratory policies of conducting urine cultures reflexively on patients with a positive urinalysis.

Although our study found no association between ordering a urine culture in the management of uncomplicated UTI and outcomes in terms of decreased follow-up visits and decreased patient-initiated phone calls for continued symptoms, a randomized controlled trial would be ideal. A randomized controlled trial may allow for a more comprehensive cost-benefit analysis. This study should be replicated in settings in which E. coli resistance to TMP-SMX is greater than 15% to see if the urine culture in those settings is also ineffective at preventing follow-up visits. Future studies should also be conducted in facilities where patient race is always recorded because this could possibly have an effect that we could not find because we had race data on only 67% of our participants.

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