Success with metronidazole was more likely in patients 65 years and under but was about the same as with vancomycin in those patients.
Haley Appaneal, PharmD
Metronidazole and vancomycin showed similar results in initial mild C difficile infections in patients 65 years and older, according to a recent report.
Investigators from the Providence Veterans Affairs Medical Center conducted a 2-pronged study using the national cohort of veterans in order to guide clinicians in identifying patients who may be considered for metronidazole therapy. The investigators found patients who had their first episode of mild C difficile infection between 2010 and 2014 and looked at the factors that led to success, which they defined as the absence of all-cause mortality or recurrence 30 days after treatment.
For the second part of the study, which used patients with the predicted success factors from the first part of the study, the investigators compared clinical outcomes for patients treated with metronidazole compared to vancomycin. They examined the differences between 30-day all-cause mortality, infection recurrence, and failure.
“Our study demonstrated that younger age was predictive of successful outcomes among patients with initial mild C difficile infection treated with metronidazole,” study author Haley Appaneal, PharmD, told MD Magazine®. “This finding was somewhat expected as older patients are more likely than younger patients to have age-related weakening of the immune system, underlying co-morbid diseases, and be exposed to antibiotics and health care settings, all of which may increase their risk of poor outcomes.”
More specifically, the investigators found 3656 patients treated with metronidazole, of which 3282 were treated successfully. They determined that younger age was the only independent predictor of success. Being 65 years of age or younger was associated with odds of success 1.63 times higher than those over 65 years (95% CI, 1.29 — 2.06).
The study authors said that there are several other factors that could contribute to the increased risk for older patients, including immunosenescence, decreased functional status, or underlying comorbidities. For older patients, it might be important to avoid metronidazole treatment, they wrote; it is still an option for younger patients.
“Among patients 65 years old or younger with initial mild C difficile infection, success rates were similar with metronidazole and vancomycin treatment,” Appaneal added, noting that it was the most surprising observation from the study.
The investigators said that there were no significant differences between the treatment groups for any of the factors they measured: all-cause mortality, recurrence, or treatment failure.
“Previous studies have generally shown better outcomes for vancomycin compared to metronidazole, however findings were largely driven by patients with severe C difficile infection,” Appaneal said. “Our findings imply that for younger patients with an initial case of mild C difficile infection, metronidazole and vancomycin may be comparable treatment options with regards to clinical success.”
The study authors said that this is the first study to focus on the predictors of success and comparing treatment options for initial C difficile infection.
“These findings provide valuable data for the clinical use of metronidazole in cases of mild C difficile infection,” Appaneal concluded. “Prescribers should consider metronidazole as a treatment option in patients with an initial case of mild C difficile infection who are younger and generally healthy.”
The paper, “What is the role for metronidazole in the treatment of Clostridium difficile infection? Results from a national cohort study of Veterans with initial mild disease,” was published in Clinical Infectious Diseases.