Limited clinical utility of pain drawing in assessing patients with low back pain.

OBJECTIVE: The aim of this study was to assess the use of pain drawing by studying its ability to identify patients with low back pain and abnormal psychological profile. The intraevaluator repeatability of the penalty point method of scoring of pain drawing was also evaluated.
METHODS: A total of 331 consecutive patients with low back pain were prospectively recruited. The psychologic profile was assessed using the Hospital Anxiety and Depression Scale. The pain drawings were scored with the penalty point method. The ability of pain drawing to identify patients with significant anxiety and depression was assessed by calculating the sensitivity, specificity, and positive predictive value. The intraevaluator repeatability was calculated for scoring done at an interval of 1 month using the kappa statistic.
RESULTS: There were statistically significant differences in the anxiety and depression scores in patients with normal (n = 200) and abnormal (n = 131) pain drawing (anxiety: 9 +/- 4 vs 10.3 +/- 3.7; depression: 8.1 +/- 3.5 vs 8.8 +/- 3.6; P < 0.005). The pain drawing had a low sensitivity for detecting patients with any degree of anxiety (43%) or depression (40%). The positive predictive value of pain drawing for anxiety and depression was 78% and 69%, respectively. The kappa value for intraobserver assessment was 0.6 (P < 0.05).
CONCLUSION: Though there are differences in anxiety and depression scores in patients with normal and abnormal pain drawing, the performance characteristics of pain drawing are less than acceptable and therefore limit its use in clinical practice.