Chronic pain in Parkinson's disease: Frequency, characteristics, independent factors, and relationship with health-related quality of life.

BACKGROUND Although there are studies evaluating pain in Parkinson's disease (PD), to our knowledge, there is no study evaluating the following topics in a cohort of PD patients; (1) frequency of chronic pain, (2) characteristics of chronic pain, (3) severity of chronic pain, (4) types of chronic pain, (5) independent predictors of chronic pain, (6) impact of chronic pain on health-related quality of life (HRQoL), and (7) the role of chronic pain among the independent predictors of HRQoL. OBJECTIVE The purpose of this study was to evaluate the frequency, characteristics, severity, types, and independent factors of chronic pain, as well as the relationship of chronic pain with HRQoL in a cohort of PD patients. METHODS One-hundred and thirteen individuals with a confirmed diagnosis of PD who were consecutively referred to the Ministry of Health Ankara Diskapi Yildirim Beyazit Training and Research Hospital, Movement Disorders Outpatient Clinic were included in the study. Demographic variables, disease characteristics, disease-related motor symptoms and motor complications, comorbid conditions, and health-related quality of life were evaluated and recorded. Pain lasting longer than three months was defined as `chronic pain' and participants were questioned relating to the characteristics of the chronic pain. The Visual Analogue Scale was used for assessment of pain. RESULTS Seventy-three patients (64.6%) suffered from chronic pain. Of these, 12 (16.4%) had previous pain at the time of diagnosis of PD. The sources of pain experienced by patients were 89.0% musculoskeletal, 31.5% radicular/peripheral neuropathic, 15.1% dystonic, and 4.1% central parkinsonian, respectively. Twenty-six patients (35.6%) had different types of pain simultaneously. The pain type with the highest severity was a central parkinsonian pain.The independent predictors of chronic pain included gender (female), Unified Parkinson's Disease Rating Scale (UPDRS) part II (activities of daily living), UPDRS part III (motor symptoms) rigidity subscore, and depression.When compared with individuals not having chronic pain, Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) Physical Component Summary and Mental Component Summary scores were lower in patients with chronic pain. Also, it was shown that the most significant factor on SF-36 was chronic pain. CONCLUSIONS This study demonstrated that chronic pain is a common problem in patients with PD, that different pain types may co-exist, and that they may negatively affect the HRQoL of patients. Chronic pain was correlated with both disease-related factors such as rigidity and daily living activities and also general factors such as gender and depression. We found that chronic pain is the most significant predictor of quality of life in PD patients. We believe, that in addition to treating motor symptoms and complications associated with them, treatment of comorbid conditions such as pain and depression bear significance for improving the quality of life in PD patients. The study indicates that PD patients who are optimally treated, may require additional rehabilitation treatment for non-motor associated pain and thus improve their HRQoL.