The prevalence of inflammatory back pain in a UK primary care population

Objective. Inflammatory back pain (IBP) is the earliest and most common symptom of axial SpA. However, there is very little information about the prevalence of IBP in the UK. In this cross-sectional cohort study we examined the prevalence of IBP in a UK primary care population using three published IBP criteria. Methods. Potential participants aged 18-80 years were identified from the records of a large general practice in Norfolk, UK, with 17 177 patients. Read codes were used to identify those who had consulted their general practitioner on at least one occasion with back pain. A self-completed screening questionnaire was sent to a sample of 978 patients, enquiring about symptoms of IBP and extra-spinal manifestations of SpA. Questionnaire responses were used to determine whether patients met the Assessment of SpondyloArthritis international Society (ASAS), Calin and Berlin IBP criteria. Results. Five hundred and five completed questionnaires were returned (response rate 51.6%). The median age of respondents was 60 years [interquartile range (IQR) 48-67] and 44.8% were male. The minimum prevalence of IBP among patients with at least one previous consultation for back pain was 7.7% (95% CI 6.2, 9.5) using the ASAS criteria, 13.5% (11.5, 15.8) using the Calin criteria and 15.4% (13.3, 17.8) using the Berlin criteria. There was no significant difference in prevalence between men and women, and between different age groups. Extrapolated to the practice population as a whole, the minimum prevalence of IBP in a UK primary care population is 1.7-3.4%. Conclusion. The prevalence of IBP varies significantly depending on the criteria used for classification.