Understanding the Significance of Chronic Non-cancer Pain in Patients Undergoing Polysomnography and Identifying Predictors of Increased Pain Interference

BACKGROUND: Chronic non-cancer pain (CNCP) is a leading cause of disability; however, CNCP assessment is limited in those presenting with a primary sleep disorder. This study aimed to (i) measure the prevalence of CNCP in adults undergoing polysomnography (PSG) and (ii) assess the impact of CNCP on sleep architecture. METHOD: Patients (N = 245, mean age 50 years, 45.7% female) undertaking in-laboratory diagnostic PSG at a major public hospital in Australia completed validated questionnaires on sleepiness, sleep quality, anxiety, depression, and pain. CNCP was determined by ≥ 75 mm score on the Pain and Sleep three-item Questionnaire, or 'Yes' to item 1 on the Brief Pain Inventory. Comparisons between those with and without CNCP and correlations between pain interference and PSG parameters were performed. RESULTS: Most participants (59.6%) reported CNCP, with prevalence higher among females (72.3%). Participants with CNCP were older (48 vs 52 years, p = 0.046) and had higher body mass index (34.2 vs 31.0, p = 0.003), Epworth Sleepiness Scale (8.7 vs 7.4, p = 0.035), anxiety (8.3 vs 5.7, p < 0.001), and depression (6.7 vs 3.8, p < 0.001) scores. Pain interference was associated with higher apnoea hypopnea index and reduced rapid eye movement (REM) sleep (%REM, prolonged REM latency, p < 0.05). Significant factors associated with increased pain interference in a hierarchical model were depression, REM latency, and anxiety. CONCLUSION: Many people undertaking PSG in a hospital sleep service reported CNCP. Increased pain interference was associated with changes in sleep architecture and sleep-disordered breathing. PSG screening may unmask pain that impacts on sleep and has implications for treatment.