Osteoarthritis Diagnoses are Under-recorded in Primary Care Electronic Health Records in New Zealand

BackgroundEffective planning of healthcare services for osteoarthritis requires accurate estimates of its prevalence in primary care. There is growing evidence to suggest that osteoarthritis prevalence estimates in primary care are inaccurate owing to under-recording of codified diagnoses within electronic health records. AimTo quantify the gap in recording of osteoarthritis diagnoses in primary care in New Zealand. MethodsWe linked data from the electronic health records of a cohort of 72,861 patients enrolled with primary care providers in the lower North Island of New Zealand with public hospital discharge records to identify all patients in the cohort with a total hip or knee replacement surgery for osteoarthritis between 2013-2018. We then calculated the proportion of patients who had at least one matching osteoarthritis diagnosis code in the primary care records prior to joint replacement surgery. We conducted subgroup analyses stratifying the cohort by joint, year of surgery, age, sex, ethnicity, socioeconomic deprivation, primary care practice, and frequency of contact with the practice. ResultsAmong the 591 patients with hip replacement and 609 with knee replacement, 48.2% and 49.8% respectively had an osteoarthritis diagnosis code in the primary care records prior to the time of surgery. There was little difference between the rates of osteoarthritis diagnosis coding for demographic subgroups, but wide variations were observed amongst practices. ConclusionsThere is substantial under-recording of osteoarthritis diagnoses in primary care in New Zealand due to delayed or absent coding within electronic health records. Efforts should be made to improve recording of osteoarthritis diagnoses to aid in future policy decision-making and research.