Validity of pain drawings for predicting psychological status outcome in patients with recurrent or chronic low back pain

Objectives: To investigate the association between baseline pain drawings and future psychological status, and estimate the prognostic value of pain drawing assessment for predicting somatization, distress, and depression at one-year follow-up, in patients with recurrent or chronic low back pain (RCLBP). Methods: This was a multi-center prospective cohort study of 138 patients with RCLBP. Participating patients completed at baseline and one-year follow-up: a blank pain drawing; the Modified Somatic Perceptions Questionnaire; modified Zung Depression Scale; and Distress and Risk Assessment Method. Pain drawings were analyzed quantitatively using the Pain Sites Score (PSS) and Simple Body Region (SBR) method. The association between baseline pain drawing assessment and one-year psychological status was estimated using correlation and Relative Risk (RR) statistics. Results: We obtained complete data from 81 patients (59%). Psychological status and pain drawings did not differ significantly between completers and non-completers. Pain drawing area at baseline was associated with depression and somatization at one-year follow-up (Spearman's Rho 0.25, P=0.022; 0.31 P=0.006, respectively). Stronger associations resulted from analyses using the PSS, compared with the SBR. Patients with abnormal PSS pain drawings at baseline had significantly greater RR of depression (RR 6.1, 95% CI 1.1, 33.5), somatization (RR 4.1, 95% CI 1.7, 9.9) and distress (RR 6.8, 95% CI 1.9, 25.3) at one-year follow- up. Discussion: These results provide the first evidence that abnormal baseline pain drawings predict greater risk of abnormal psychological states or poor psychological outcome at one-year follow-up, in patients with RCLBP.