Rheumatoid arthritis prevalence in Quebec

Area of Science:

• Rheumatology
• Epidemiology
• Health Services Research

Background:

• Administrative health data is increasingly used for epidemiological research.
• Estimating rheumatoid arthritis (RA) prevalence requires accurate case ascertainment.
• Regional variations in RA prevalence may exist within Quebec.

Purpose of the Study:

• To estimate rheumatoid arthritis (RA) prevalence in Quebec using administrative health data.
• To compare RA prevalence across different regions within Quebec.
• To adjust for potential biases in administrative health data for RA prevalence estimation.

Main Methods:

• RA cases were identified from physician billing and hospitalization records (1992-2008).
• Three case definitions were used, incorporating diagnosis codes (ICD-9: 714, ICD-10: M05).
• Bayesian hierarchical latent class models adjusted for data sensitivity and specificity.

Main Results:

• Unadjusted RA prevalence was 9.9 per 1000 residents.
• Adjusted prevalence was 5.6 per 1000 females and 4.1 per 1000 males.
• Older females had the highest adjusted RA prevalence (9.9 per 1000); rural areas showed lower prevalence in younger individuals and older males.

Conclusions:

• Administrative data without error adjustment overestimates RA prevalence in Quebec.
• Adjusted RA prevalence is significantly lower than unadjusted estimates.
• Lower rural RA prevalence may indicate true risk differences or under-ascertainment in rural Quebec.