Comorbidities in osteoarthritis (ComOA) : a combined cross-sectional, case-control and cohort study using large electronic health records in four European countries
Introduction Osteoarthritis (OA) is one of the leading chronic conditions in the older population. People with OA are more likely to have one or more other chronic conditions than those without. However, the temporal associations, clusters of the comorbidities, role of analgesics and the causality and variation between populations are yet to be investigated. This paper describes the protocol of a