Searching for a prodrome for rheumatoid arthritis in the primary care record: a case-control study in the Clinical Practice Research Datalink

Background: Rheumatoid arthritis (RA) has articular and non-articular manifestations. Early, intensive treatment has substantial benefit for both. This requires patients be identified as soon as symptoms develop. Objectives: To determine whether selected signs and symptoms can be identified in the primary care records of patients prior to a formal diagnosis of RA being made and, if so, how early they can be identified. Methods: A case-control study was constructed within the UK Clinical Practice Research Datalink (CPRD). 3577 individuals with 'definite' RA, were matched to 14287 individuals without inflammatory arthritis. An index date was established (i.e. date general practitioner (GP) first appeared to suspect RA). Rates of consultation and consultations for suspected early RA symptoms were compared in cases and controls in the two years prior to the index date using conditional logistic regression, adjusted for number of consultations. Results: The mean (standard deviation) age of participants was 58.8 (14.5) years and 66.8% were female. Rates of any consultation were significantly higher in RA cases than in controls for at least two years prior to the index date. Cases were more likely to have a pre-diagnosis coded consultation for joint, and particularly hand symptoms (aOR 11.44 (9.60, 13.63)), morning stiffness (8.10 (3.54, 18.5)), carpal tunnel syndrome (4.57 (3.54, 5.88)) and other non-articular features. Conclusions: In patients who develop RA, GP consultation rates are higher for at least two years prior to the first recorded suspicion of RA. This study highlights symptoms that should raise a GP’s index of suspicion for RA