Illness behavior in patients on long-term sick leave due to chronic musculoskeletal pain

Background and purpose Methods for identification of patients with illness behavior in orthopedic settings are still being debated. The purpose of this study was to test the association between illness behavior, depressed mood, pain intensity, self-rated disability, and clinical status in patients with chronic musculoskeletal pain (CMP). Methods We examined 174 consecutive sick-listed patients (90 women). Musculoskeletal function was estimated by range of motion, muscle strength, and motor and sensory function. The degree of illness behavior was measured by Waddell signs (WS). Results WS were observed in 47/174 (27%) of the patients, 16% of whom manifested excessive illness behaviour. In general, more patients with WS were depressed (OR = 4.4; 95% CI: 1.8–11) and experienced greater pain (OR = 2.9; CI: 1.1–7.7). No abnormal physical function could be observed in two-thirds of the patients. Other predictive factors for manifesting WS at the clinical examinations were longer sick leave and previous full sick leave (p < 0.05). Interpretation Excessive illness behavior is related to psychological distress in patients with CMP and long-term disability. Thus, some patients may also require psychological assessment. Looking for WS during consultation is useful for targeting other factors that may be important in the diagnostic process.