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02-04-2020 | Rheumatology | News | Article

Seasonal influenza vaccine recommended in patients with autoimmune rheumatic diseases

Hannah Kitt

medwireNews: Immunocompromised patients with autoimmune rheumatic diseases (AIRDs) who receive the influenza vaccine have a reduced risk for respiratory-related diseases, according to a longitudinal study published in Rheumatology.

Researcher Abhishek Abhishek (Nottingham City Hospital, UK) and team therefore propose that “people with AIRDs should be informed of the benefits of vaccination and offered [inactivated influenza vaccine] annually.”

They analyzed data pertaining to 30,788 people (65.7% female) who had AIRDs (75.5% rheumatoid arthritis), collected from a UK-based longitudinal anonymized electronic database. In all, 125,034 influenza cycles were recorded between 2006 and 2016, with each cycle lasting 12 months from the 1st September of one year to the 31st August the following year.

Over the follow-up period a mean of 3.78 vaccinations were administered per person, with 49.87% of the participants in the study receiving all possible vaccinations, yielding a total of 87,212 vaccinated influenza cycles.

In propensity score-adjusted analyses accounting for a raft of confounders, vaccinated patients were a significant 30% less likely to receive a primary care consultation for an influenza-like illness than those who were unvaccinated during periods when influenza virus was in circulation. They were also 39% and 33% less likely to be hospitalized for pneumonia and exacerbation of chronic obstructive pulmonary disease, respectively, and their risk for all-cause death or death due to pneumonia was 44% and 52% lower, respectively.

Significant associations of a similar magnitude were also seen in propensity score-matched analyses for 17,876 vaccinated influenza cycles using data for the influenza active period as well as data for the entire influenza cycle. The only exception was that there was no longer a significantly reduced risk for influenza-like illness during the influenza active period for those who were vaccinated versus those who were not, a result the researchers suggest could be related to the sample size decreasing by more than 70% in this analysis.

They highlight that the protective effects of the influenza vaccine extended to “people with greater immune dysfunction,” as seen in sub-analyses restricted to patients with rheumatoid arthritis, those above 65 years of age, and those exposed to corticosteroids or prescribed potent DMARDs.

Abhishek and study co-authors warn of the potential effects of residual confounding, particularly regarding all-cause mortality risk, as an unexpected protective effect with vaccination was seen in a sub-analysis in the pre-influenza active period.

“This residual confounding could be due to several reasons such as healthy user bias, and selective nonprescribing to people with poor functional status and short life-expectancy,” the investigators propose.

There was no evidence of residual confounding on influenza-like illness or death due to pneumonia, they note.

The team believes that their results “are encouraging,” adding that “together with the results of our previous study demonstrating the safety of [inactivated influenza vaccine] in people with AIRDS, provide evidence to promote seasonal flu vaccination in this population.”

medwireNews is an independent medical news service provided by Springer Healthcare. © 2020 Springer Healthcare part of the Springer Nature Group

Rheumatology 2020; doi:10.1093/rheumatology/keaa078

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