Objective: To investigate the association between allergic rhinitis (AR) and the risk of rheumatoid arthritis (RA).
Methods: Potentially eligible studies were identified from MEDLINE and EMBASE databases from inception to November 2019. Eligible cohort study must report relative risk with 95% confidence intervals (95% CIs) of incident RA between AR patients and comparators. Eligible case-control studies must include cases with RA and controls without RA, and must explore their history of AR. Odds ratio with 95% CIs of the association between AR and RA must be reported. Point estimates with standard errors from each study were combined using the generic inverse variance method.
Results: A total of 21,824 articles were identified. After two rounds of the independent review by three investigators, two cohort studies and 10 case-control studies met the eligibility criteria. The pooled analysis showed no association between AR and risk of RA (RR = 0.94; 95% CI, 0.73 to 1.20; I2 = 84%). However, when we conducted a sensitivity analysis including only studies with acceptable quality, defined as Newcastle-Ottawa score of seven or higher, we found that patients with AR had a significantly higher risk of RA (RR = 1.36; 95% CI, 1.12 to 1.65; I2 = 45%).
Conclusions: The current systematic review and meta-analysis could not reveal a significant association between AR and RA. However, when only studies with acceptable quality were included, a significantly higher risk of RA among patients with AR than individuals without AR was observed.
Keywords: allergic rhinitis; hay fever; meta-analysis; rheumatoid arthritis; systematic review.