Figure 1

Sensitivity estimates for the different case definitions based on International Classification of Diseases (ICD) codes for rheumatoid arthritis (RA), within administrative data: Variations in urban versus rural residence, according to age and sex groups. *2 billing codes by any physician for RA, at least 8 weeks apart but within 2 years. One or more hospital discharge diagnoses for RA, including, both primary and non-primary discharge diagnoses (up to 15). At least one billing code for RA by a rheumatologist.