Associations between pharyngitis, tonsillitis, and incident rheumatic diseases

Determine the association between antecedent pharyngitis or tonsillitis and subsequent rheumatic disease.

This population-based, case-control study identified all incident, criteria-confirmed individuals with rheumatic diseases from 2002-2014, matched to controls 3:1 on age, sex, and length of preceding electronic health record. The primary exposure was pharyngitis or tonsillitis, defined by diagnostic codes (positive predictive value 89% and 70% respectively). We calculated odds ratios (OR) with 95% confidence intervals (CI) for each disease and disease group using logistic regression models adjusting for confounders. Sensitivity analyses studied these associations by time between exposure and incident rheumatic disease (>1-5, >5-10, >10 years), number of codes (1-3, 4-6, 7+), and smoking status.

We identified 1427 individuals with incident rheumatic disease matched to 4281 controls (mean age 61, 67% female). Prior pharyngitis occurred in 25% of cases and 27% of controls, corresponding to decreased odds of any rheumatic disease (OR 0.86, 95% CI 0.74-1.00), rheumatoid arthritis (RA, OR 0.79, 95% CI 0.65-0.98), and lupus (unadjusted OR 0.26, 95% CI 0.11-0.62). Statistically significant lower odds of rheumatic disease were associated with acute pharyngitis, first pharyngitis exposure >10 years prior to index date, and 1-3 pharyngitis codes. Associations between pharyngitis and smoking status also followed these trends. Tonsillitis occurred in only 2% of cases and 1% of controls and was not associated with incident rheumatic disease (OR 1.26, 95% CI 0.77-2.07).

Preceding pharyngitis was associated with decreased odds of developing rheumatic disease, including lupus and RA. Future studies should replicate these results.