Nocturnal Pain in Patients with Knee Osteoarthritis: A Single-Center Cross-Sectional Study

Objectives: The aim of this study was to determine the differences between groups with and without nocturnal pain (NP) in patients with knee osteoarthritis (KOA) in terms of radiographic stage, disease severity, neuropathic pain, central sensitivity, sleep quality, physical activity level, and number of hospital visits. Methods: The study included 150 patients with KOA (101 women, 49 men; mean age 64 years (IQR: 9; range: 40-81)). Kellgren-Lawrence (KL) grading was used for radiographic staging, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for KOA disease severity, the Douleur Neuropathique 4 (DN-4) questionnaire for neuropathic pain, the Central Sensitization Inventory (CSI) for central sensitization, the Pittsburgh Sleep Quality Index (PSQI) for sleep quality, and the International Physical Activity Questionnaire-Short Form (IPAQ-SF) for physical activity level. Results: In our KOA patient group, the prevalence of NP was found to be 64.7%. A multivariable binary logistic regression analysis was performed as the primary inferential analysis. Age, sex, educational level, body mass index, disease duration, KL grade, and WOMAC total score were entered simultaneously into the model. After adjustment for the included covariates, only the WOMAC total score remained independently associated with NP. Each one-point increase in the WOMAC total score was associated with an 11.7% increase in the odds of NP (adjusted OR = 1.117, 95% CI 1.068-1.168, p < 0.001). Conclusions: Given that it affects more than half of patients with KOA and is associated with higher disease severity, we emphasize the need for careful management of NP in KOA patients.