Randomised double-blind trial of combination antibiotic therapy in rheumatoid arthritis

Objective. A combination of intravenous clindamycin and oral tetracycline has been used for many years as a treatment for active rheumatoid arthritis (RA), despite the absence of good evidence for its efficacy. A single-blind pilot study of this therapy suggested that a double-blind placebo-controlled trial was warranted. Methods. Patients with active RA were randomised in a 2 : 1 ratio to receive active treatment or placebo for 25 weeks. The active treatment consisted of intravenous clindamycin in a reducing regime, and oral tetracycline twice daily three times a week. 50 patients were to be recruited. The primary outcome measure was the proportion of patients achieving an ACR20 response. Results. An interim statistical analysis was performed after 20 patients had completed the study. Two patients in the active group achieved an ACR20 response, with none in the placebo group (NS). There was a better ESR20 response in the placebo group (P = .02). There were no other significant differences between the groups. The results indicated that it was unlikely that a significant difference in ACR20 response would emerge if the remaining 30 patients were recruited. The trial was therefore halted. Conclusion. This antibiotic regime is unlikely to be a valuable therapy for active rheumatoid arthritis.