Osteoarthritis and the Rule of Halves

BACKGROUND: Symptomatic osteoarthritis poses a major challenge to primary health care but no studies have related accessing primary care ('detection'), receiving recommended treatments ('treatment'), and achieving adequate control ('control'). OBJECTIVE: To provide estimates of detection, treatment, and control within a single population adapting the approach used to determine a Rule of Halves for other long-term conditions. SETTING: General population. PARTICIPANTS: 400 adults aged 50+ years with prevalent symptomatic knee osteoarthritis. DESIGN: Prospective cohort with baseline questionnaire, clinical assessment, and plain radiographs, and questionnaire follow-up at 18 and 36 months and linkage to primary care medical records. OUTCOME MEASURES: 'Detection' was defined as at least one musculoskeletal knee-related GP consultation between baseline and 36 months. 'Treatment' was self-reported use of at least one recommended treatment or physiotherapy/hospital specialist referral for their knee problem at all three measurement points. Pain was 'controlled' if characteristic pain intensity <5 out of 10 on at least two occasions. RESULTS: In 221 cases (55.3%; 95%CI: 50.4, 60.1) there was evidence that the current problem had been detected in general practice. Of those detected, 164 (74.2% (68.4, 80.0)) were receiving one or more of the recommended treatments at all three measurement points. Of those detected and treated, 45 (27.4% (20.5, 34.3)) had symptoms under control on at least two occasions. Using narrower definitions resulted in substantially lower estimates. CONCLUSION: Osteoarthritis care does not conform to a Rule of Halves. Symptom control is low among those accessing health care and receiving treatment.