Validation of the General Health Questionnaire 12 for assessing psychological distress in patients with chronic low back pain

BACKGROUND: The General Health Questionnaire 12 (GHQ-12) is a short easy-to-use scale to assess psychological distress. The GHQ-12 has not been validated for assessing psychological distress in patients with chronic low back pain (LBP). OBJECTIVE: To investigate the psychometric properties of the GHQ-12 in patients with chronic LBP. METHODS: The study involved a population of patients undergoing functional restoration for chronic LBP. The intraclass coefficient correlation was used for test-retest reliability (good if > 0.7) and the standard error measurement for absolute reliability. Construct validity was assessed with the Spearman correlation coefficient (moderate and high if r⩾ 0.35 and 0.5, respectively) and internal consistency with Cronbach’s alpha (suitable if > 0.7). Responsiveness was assessed by the Wilcoxon test and effect size. RESULTS: Four hundred and five patients were included. The intraclass coefficient correlation was 0.73 and standard error measurement 2.49. The GHQ-12 showed high convergence with the Beck Depression Inventory and subscales of the Dallas Pain Questionnaire for anxiety and depression and for sociability. It showed moderate convergence with the Quebec Back Pain Disability Scale and subscales of the Dallas Pain Questionnaire for daily activities and for leisure and occupation. Cronbach’s alpha was 0.89. The GHQ-12 score changed after functional restoration. It was lower (better) with than without improvement. CONCLUSIONS: We provide validation of the GHQ-12 for assessing psychological distress in patients with chronic LBP.