A validation study of a new classification algorithm to identify rheumatoid arthritis using administrative health databases : Case-control and cohort diagnostic accuracy studies. Results from the RECord linkage on Rheumatic Diseases study of the Italian Society for Rheumatology
Objectives: To develop and validate a new algorithm to identify patients with rheumatoid arthritis (RA) and estimate disease prevalence using administrative health databases (AHDs) of the Italian Lombardy region. Design: Case-control and cohort diagnostic accuracy study. Methods: In a randomly selected sample of 827 patients drawn from a tertiary rheumatology centre (training set), clinically vali