Use of the inactivated influenza vaccine by adults with autoimmune rheumatic diseases significantly reduced their risk of influenza-like illness, hospitalization for pneumonia and chronic obstructive pulmonary disease, and death from pneumonia, according to findings from an observational study of more than 30,000 patients in the U.K. Clinical Practice Research Datalink.
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Although the inactivated vaccine has been recommended for patients with autoimmune rheumatic diseases (AIRDs), including rheumatoid arthritis and spondyloarthritis, the vaccine’s impact on patient outcomes including pneumonia, hospitalization, and death has not been well studied, wrote Georgina Nakafero, PhD, of the University of Nottingham, England, and colleagues.
In a study published in Rheumatology, the researchers identified 30,788 adults with AIRDs from the longitudinal Clinical Practice Research Datalink database in the United Kingdom. Of these, 66% were women, 76% had rheumatoid arthritis, and 61% had been prescribed methotrexate. The study included a total of 125,034 flu cycles between 2006 and 2009 and between 2010 and 2015.
Overall, vaccination with the inactivated influenza vaccine (IIV) reduced the risk of primary care consultation for influenza-like illness (adjusted odds ratio, 0.70), hospitalization for pneumonia (aOR, 0.61), exacerbation of chronic obstructive pulmonary disease (aOR, 0.67), and death caused by pneumonia (aOR, 0.48) in the study population. In a propensity score–adjusted analysis, only protection from influenza-like illness lost statistical significance.
In addition, vaccination was associated with a reduction in all-cause mortality among AIRDs patients, but restricting the outcomes to the active influenza periods may have confounded this result, the researchers said.
The study findings were limited by several factors including observational design, the use of a single vaccine efficacy estimate for each outcome, potential missed vaccination cycles, and potential confounding by indication and healthy user bias that could inflate the vaccine effectiveness, the researchers noted. However, the results were strengthened by the large sample size, including a range of AIRDs, and the use of both diagnostic and prescription codes, they said.
“The findings of this study, together with the results of our previous study demonstrating the safety of IIV in people with AIRDs, provides evidence to promote seasonal flu vaccination in this population,” they concluded. They still emphasized that randomized, controlled trials are needed for an assessment of vaccine efficacy.
The study was supported by Versus Arthritis and the National Institute of Health Research. Lead author Dr. Nakafero had no financial conflicts to disclose. Several coauthors disclosed relationships with companies, including AstraZeneca, Roche, and Pfizer.
SOURCE: Nakafero G et al. Rheumatology. 2020 Mar 11. doi: 10.1093/rheumatology/keaa078.