Patients with moderate or severe idiopathic pulmonary fibrosis (IPF) treated with trimethoprim-sulfamethoxazole (co-trimoxazole) did not experience a reduced time to death, transplant, or hospitalization, according to the results of a study published in JAMA.

In a double-blind, placebo-controlled, parallel randomized trial (ISRCTN: 17464641), patients with moderate or severe IPF were randomly assigned to receive either co-trimoxazole or matched placebo. The primary outcomes were all-cause time to death, lung transplant, or first nonelective hospital admission.

Of the 342 participants with moderate or severe idiopathic pulmonary fibrosis, 170 were randomly assigned to receive 960 mg oral co-trimoxazole twice daily, while 172 were matched placebo control individuals. The mean participant age was 71.3 years; 13% of the study participants were women. Median follow-up duration was 10.2 years (interquartile range, 0.35-1.73). Events per person-years of follow-up were 0.45 and 0.38 in the co-trimoxazole and placebo groups, respectively (hazard ratio 1.2; 95% CI, 0.9-1.6; P =.32), and there were no statistically significant differences in composite outcome of time to death, transplant, or nonelective hospitalization compared with placebo.

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Study limitations included a lack of evaluation of the lung microbiome and no quantitation of the influence of co-trimoxazole on its composition, an inability to determine if co-trimoxazole reduced infection-related events, and exclusion criteria limiting the generalizability of the results.

“[T]here was no significant reduction in the incidence of the composite outcome of death, lung transplant, or nonelective hospitalization with co-trimoxazole in patients with moderate or severe IPF,” the researchers concluded. “The results of this study do not disprove the hypothesis that the ‘lung microbiome’ influences disease progression and outcomes in IPF.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Wilson AM, Clark AB, Cahn T, et al; on behalf of the EME-TIPAC team. Effect of co-trimoxazole (trimethoprim-sulfamethoxazole) vs placebo on death, lung transplant, or hospital admission in patients with moderate and severe idiopathic pulmonary fibrosis: The EME-TIPAC randomized clinical trial. JAMA. 2020;324(22):2282-2291.