The association between allergic rhinitis and risk of rheumatoid arthritis: A systematic review and meta‐analysis

To investigate the association between allergic rhinitis (AR) and the risk of rheumatoid arthritis (RA).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.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%).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.