For older men with a urinary tract infection, taking antibiotics for more than 1 week does not reduce the rate of either early or late recurrence, compared with taking the drugs for 1 week, according to a report published online Dec. 3 in Archives of Internal Medicine.
Moreover, the longer course of antibiotics appeared to raise the risk of developing a Clostridium difficile infection in this retrospective observational study of 33,336 male outpatients, said Dr. Dimitri M. Drekonja of the Minneapolis Veterans Affairs Health Care System and his associates.
Dr. Dimitri Drekonja
The study findings indicate that randomized clinical trials are needed to directly assess the benefits and harms of shorter-duration vs. longer-duration antibiotic therapy for male UTI, "to guide optimal management for this common condition," Dr. Drekonja and his colleagues noted.
The investigators used a national Veterans Affairs database to assess the effect of treatment duration on outcomes, because no study to date has evaluated the adequacy of a 7-day course of antibiotics in men as compared to a 10- or 14-day course. "The optimal treatment duration for UTI in men is unknown," they said.
For this study, the investigators searched the database for outpatient visits associated with ICD-9 codes for acute UTI and a concurrent prescription for a UTI-related antimicrobial during a single year. They identified 33,336 index cases, as well as 1,772 early recurrences (within 30 days of an index case) and 4,041 late recurrences (more than 30 days after an index case).
The mean patient age was 68 years, and comorbidities were common. The study subjects also frequently had medical conditions that predisposed them to UTI, including diabetes (35%), prostate hypertrophy (33%), and a history of prior UTI (31%).
The most commonly used agents for index cases were ciprofloxacin (63%); trimethoprim-sulfamethoxazole (27%); nitrofurantoin (6%); amoxicillin, either alone or in combination with clavulanic acid (6%); and levofloxacin (4%). Some index cases were treated with multiple antibiotics.
In a univariate analysis, rates of early recurrence were not significantly different between patients who received shorter-duration therapy (3.9%) and patients who received longer-duration therapy (4.2%).This was true in the study population as a whole and when the data were broken down by individual antibiotics.
This lack of difference in early recurrence rates persisted in a multivariate analysis, the investigators said (Arch. Intern. Med. 2012 Dec. 3 [doi: 10.1001/2013.jamainternmend.829]).
In a univariate analysis, longer duration of antibiotic therapy not only failed to cut the rate of late recurrences, but increased them slightly. Late recurrence rates were 11% in patients who received longer-duration therapy and 8.4% in those who received shorter-duration therapy. This small difference persisted in a multivariate analysis.
However, since this was an observational study, residual confounding could account for the failure to demonstrate a clinical benefit with longer duration of antibiotic therapy. "For instance, patients at increased risk for recurrence because of some unmeasured factor (e.g., catheter use) may have been overrepresented in the group that received longer-duration treatment," Dr. Drekonja and his associates said.
That is why they called for randomized clinical trials of the issue.
The researchers also examined whether longer duration of antibiotic therapy was associated with a higher rate of C. difficile infection than short-term antibiotic therapy. There was a slight increase in C. difficile infection in a univariate analysis (0.5% with long-duration vs. 0.3% with short-duration treatment), but that difference lost statistical significance in a multivariate analysis.
"Together, our findings suggest that longer-duration treatment for male UTI in the outpatient setting is not associated with a reduction in early or late recurrence and may be associated with an increase in subsequent C. difficile infection," they said.
This study was supported by the Minneapolis Veterans Affairs Health Care System. Dr. Drekonja reported no financial conflicts of interest. One of his associates reported ties to Merck, Rochester Medical, and Syntiron.