Abstract
BACKGROUND: Psychological symptoms are frequently present in patients scheduled for shoulder surgery. The perception of functional disability, activity level and pain in the shoulder is negatively influenced by psychological symptoms, which leads to higher scores of the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. The aim of this study was to determine the influence of psychological symptoms on the minimal clinically important difference (MCID) of the DASH score in patients after shoulder surgery. METHODS: In this prospective longitudinal cohort study, 176 patients were included. Group 1 (32 patients) had symptoms of psychological disorders before and after surgery; group 2 had no symptoms of psychological disorders (110 patients). In the remaining patients (34 patients), psychological disorders changed after surgery. Clinical outcome was measured with the change of DASH score and anchor questions for perceived improvement of pain and function after surgery. Symptoms of psychological disorders were identified with the Four-Dimensional Symptom Questionnaire. An anchor-based mean change score technique was used to determine the MCID of the DASH score. RESULTS: DASH scores before and 12 months after shoulder surgery were significantly higher in patients with symptoms of psychological disorders; change of DASH score was not different between the two groups. The MCID of the DASH score was 13.0 [SD 20.7] in the group with symptoms of psychological disorders and 12.7 [SD 17.6] in the group with no symptoms of psychological disorders. We observed no difference (p = 0.559) in the MCID between the group with and the group without symptoms of psychological disorders. CONCLUSION: Symptoms of psychological disorders had a negative effect on the DASH score but no influence on the MCID of the DASH score. The DASH score could be used in future studies to assess the influence of psychological factors on the clinical outcome of treatment.