Trimethoprim-Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess.
- Trimethoprim-Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess.
P : outpatients older than 12 years of age who had an uncomplicated abscess that was being treated with drainage.
E : trimethoprim-sulfamethoxazole (at doses of 320 mg and 1600 mg, respectively, twice daily, for 7 days)
C : placebo
O : clinical cure of the abscess occurred in 507 of 630 participants (80.5%) in the trimethoprim-sulfamethoxazole group versus 454 of 617 participants (73.6%) in the placebo group (difference, 6.9 percentage points; 95% confidence interval [CI], 2.1 to 11.7; P=0.005).
T : RCT
Overall rates of adverse events were similar in the trimethoprim–sulfamethoxazole group and the placebo group, and most events were considered to be mild. The most common adverse events involved the gastrointestinal system (42.7% and 36.1%, respectively); no cases of Clostridium difficile–associated diarrhea occurred. No treatment-associated serious or life-threatening adverse events occurred. Rates of treatment discontinuation due to adverse events were also similar in the two groups (1.9% and 0.6%, respectively). There were two deaths (one in each group); they were considered to be unrelated to the active drug or placebo.
- First, although patients with common coexisting conditions, such as diabetes, were not excluded, physicians may have been biased against enrolling some patients who were perceived as being at higher risk.
- Second, although a combination of 160 mg of trimethoprim and 800 mg of sulfamethoxazole twice daily should achieve serum and blister fluid levels above MRSA minimal inhibitory concentrations, we chose a dose of 320 mg of trimethoprim and 1600 mg of sulfamethoxazole twice daily to best test efficacy and for consistency with existing recommendations.
- Third, we had some degree of nonadherence, which would bias against trimethoprim–sulfamethoxazole, but the higher dose may have mitigated against inadequate treatment.
- Fourth, we provided training for adequate abscess drainage; however, to the extent that some abscesses may not have been fully drained, potential cure rates could be higher, particularly in the placebo group.
- Fifth, the standardized methods we created to determine clinical failure that necessitated a change in the study regimen may not be valid, although we are unaware of any validated method, and ours had good interrater agreement and were associated with a high cure rate among those who could be assessed by this method (i.e., the per-protocol population).
- Finally, significant differences between treatment groups with respect to secondary outcomes may be due to chance, although these generally favored trimethoprim–sulfamethoxazole, and, in the case of subsequent infections at new sites, were consistent with results of secondary outcome analyses in previous studies.