SAN DIEGO, CA—Vaccination with heptavalent pneumococcal conjugate vaccine tended to reduce the risk of putative serious pneumococcal infections with about 45% compared to unvaccinated patients, according to results from an observational cohort study, as presented at the 2013 ACR/ARHP Annual Meeting.

Johanna Bengtsson, MD, and colleagues from the Department of Rheumatology, Lund University, Lund, Sweden, examined the risk of putative pneumococcal infections between adult patients with arthritis on different antirheumatic drugs immunized with heptavalent pneumococcal conjugate vaccine (Prevnar7; PCV7) and non-vaccinated individually matched patients with arthritis.

A total of 505 patients with rheumatoid arthritis (RA) and spondylarthropathy (SpA) including psoriatic arthritis, were immunized with a single dose of PCV7. Of these, 497 patients (RA=248, SpA=249) were included. At vaccination, RA patients were treated with methotrexate (n=84), anti-TNF + methotrexate (n=87) or anti-TNF as monotherapy (n=77). SpA patients were treated with anti-TNF as monotherapy (n=81), anti-TNF + methotrexate (n=82) or NSAIDs/analgesics (n=86). 

Each vaccinated patients was matched with four reference subjects (n=1988) from the same geographic area–this cohort was considered unexposed to the conjugate pneumococcal vaccination. All events occurring 4 years before vaccination and up to 4.5 years after vaccination were divided into serious infections (eg, pneumonia, other lower respiratory infections, meningitis, sepsis, septic arthritis) and non-serious infections (eg, upper respiratory infections, otitis media and sinusitis). 

Dr. Bengtsson and her team concluded that the point estimate of ratios of relative risk suggested a 45% reduced risk (non-significant) of serious infection in vaccinated patients compared to the unexposed group (0.55, 95% CI 0.25–1.22). However, time to first event of all infections pre- and post-vaccination did not differ between the groups (0.82, 95% CI 0.49–1.38). In addition, mean time to first serious infection was significantly longer for immunized patients compared to the unexposed group (48.5 months [47.9–49.0] vs. 47.0 months [46.7-47.3]), respectively.