Cross-sectional review links illness perceptions to quality of life variance in Parkinson disease patients

Introduction Motor complications are major determinants of disability in Parkinsons disease (PD) yet clinician-rated motor complication severity does not fully explain variability in health-related quality of life (HRQoL). Research question To examine the contribution of illness perceptions and cognitive-behavioural responses to HRQoL alongside motor complication severity in people with PD. Methods This multi-centre cross-sectional study recruited 58 people with idiopathic PD (median age 68 years; 55.2% male; 48.3% from minoritised ethnic backgrounds; Hoehn & Yahr stage 2-3). All underwent assessment of motor complications (Movement Disorder Society-Unified Parkinsons Disease Rating Scale; MDS-UPDRS Part IV) and HRQoL (Parkinsons Disease Questionnaire-39 Summary Index; PDQ-39 SI). Illness perceptions were measured with Illness Perception Questionnaire-Revised (IPQ-R) Part-2 and cognitive-behavioural responses with Cognitive and Behavioural Responses Questionnaire (CBRQ). Regression models were adjusted for age, sex, disease duration, motor severity (MDS-UPDRS Part III), levodopa equivalent daily dose (LEDD), anxiety, depression, and cognitive function. A subset (n=47) completed 7-day Parkinsons KinetiGraph monitoring. Results Demographic and clinical covariates explained 77.3% of variance in HRQoL (R2=0.773). Adding motor complication severity explained a significant additional 3.7% (delta R2=0.037; P=0.004). Subsequent inclusion of illness consequences (IPQ-R) and catastrophising (CBRQ) explained a further 4.1% (delta R2=0.041, P=0.004) yielding a final adjusted R2=0.815. In the fully adjusted model catastrophising (B=0.797, P=0.027) and perceived consequences (B=0.767, P=0.013) remained independently associated with HRQoL. Conclusion HRQoL in PD appears to depend not only on motor complication severity but also on patients interpretations and responses. Clinicians should assess both to guide holistic care and support adaptive coping.