Single-blind randomized trial of combination antibiotic therapy in rheumatoid arthritis.

To determine the potential clinical efficacy of combination antibiotic therapy in treating rheumatoid arthritis (RA).Twenty-one patients with active RA despite second-line treatment were randomized to receive either combination antibiotic therapy (treatment group, n = 11) or no additional therapy (control group, n = 10). Antibiotic therapy was given for 12 months and comprised oral tetracycline 250 mg twice daily, 3 times per week, and intravenous clindamycin infused on 5 consecutive days (300, 300, 600, 600, and 900 mg) followed by weekly infusions of 900 mg for 3 weeks and then fortnightly infusions for the remainder of the 12 months. The primary outcome measure was the American College of Rheumatology 20% (ACR20) response at the end of the initial treatment period of 12 months.Five patients in the treatment group (45%) achieved an ACR20 response at 1 year compared to none in the control group (p = 0.04). Eight patients in the treatment group and 1 in the control group had a greater than 20% improvement in tender joint count (p = 0.008). There were also significant differences between the groups in physician and patient global assessments. Nine patients in the treatment group completed the 6 months' followup; of these, 3 sustained the ACR20 response.Combined antibiotic therapy with intravenous clindamycin and oral tetracycline may be useful in the management of active RA. A double-blind, placebo-controlled trial of therapy is justified.