Patient enablement and health-related quality of life for patients with chronic back and knee pain: a cross-sectional study in primary care

BACKGROUND: Chronic back and knee pain impairs health- related quality of life (HRQoL) and patient enablement can improve HRQoL. AIM: To determine whether enablement was a moderator of the effect of chronic back and knee pain on HRQoL. DESIGN AND SETTING: A cross-sectional study of Chinese patients with chronic back and knee problems in public primary care clinics in Hong Kong. METHOD: Each participant completed the Chinese Patient Enablement Instrument-2 (PEI-2), the Chinese Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Pain Rating Scale (PRS). Multivariable regression examined the effects of PRS score and PEI-2 score on WOMAC total score. A moderation regression model and simple slope analysis were used to evaluate whether the interaction between enablement (PEI-2) and pain (PRS) had a significant effect on HRQoL (WOMAC). RESULTS: Valid patient-reported outcome data from 1306 participants were analysed. PRS score was associated with WOMAC total score (β = 0.326, P<0.001), whereas PEI-2 score was associated inversely with WOMAC total score (β = −0.260, P<0.001) and PRS score. The effect of the interaction between PRS and PEI-2 (PRS × PEI-2) scores on WOMAC total score was significant (β = −0.191, P<0.001) suggesting PEI-2 was a moderator. Simple slope analyses showed that the relationship between PRS and WOMAC was stronger for participants with a low level of PEI-2 (gradient 3.056) than for those with a high level of PEI-2 (gradient 1.746). CONCLUSION: Patient enablement moderated the impact of pain on HRQoL. A higher level of enablement can lessen impairment in HRQoL associated with chronic back and knee pain.