Insomnia and progression to total joint replacement in hip (41 737) and knee pain (81 958): a prospective UK biobank cohort study.

OBJECTIVE: Insomnia often co-exists with hip or knee pain and is associated with greater pain severity. However, there is limited evidence on whether insomnia contributes to progression to joint replacement. Using data from the UK Biobank, we tested whether symptoms of insomnia among people with hip or knee pain are associated with undergoing total hip or knee joint replacement surgery. METHODS: UK Biobank data from participants with hip (n=41 737) or knee pain (n=81 958) in the past 3 months were included. Using self-reported baseline data, participants were classified as 'never', 'sometimes' or 'usually' having insomnia symptoms (ie, trouble falling asleep or waking in the night). We examined associations between baseline symptoms of insomnia and undergoing total hip or knee replacement surgery using adjusted Cox proportional hazards models. RESULTS: In knee pain, 'usually' experiencing insomnia symptoms was associated with undergoing total knee replacement (adjusted HR 1.14 (95% CI 1.04 to 1.25)), within, but not beyond, 4.7 years of enrolment, compared with 'never' experiencing insomnia symptoms. No association was observed for 'sometimes' experiencing insomnia symptoms and total knee replacement among individuals with knee pain, nor for insomnia symptoms ('usual' or 'sometimes') and total hip replacement among individuals with hip pain. CONCLUSION: Insomnia may be a modifiable factor contributing to earlier progression to knee replacement. Targeting insomnia through interventions could form part of a holistic approach to managing chronic knee pain. Further research is needed to determine whether managing insomnia can reduce the risk of knee replacement surgery.