Effect of depression and neuropathic pain using questionnaires on quality of life in patients with low back pain; cross-sectional retrospective study.

PURPOSE: The present study investigated the percentage of low back pain (LBP) patients who have depressive symptoms and neuropathic pain and analyzed the effects of these on the quality of life (QOL) in these patients. METHODS: Of the 650 new patients with LBP that visited the hospital between June 2012 and December 2013, 309 patients who completed questionnaires to assess LBP and QOL were included in the study. The questionnaire included demographic items, the self-rated depression scale (SDS)-Zung, the Japanese version of the PainDETECT questionnaire (PDQ-J), numerical pain rating scale (NRS), and QOL assessments. The patients were divided into two groups according to their SDS-Zung scores: a nondepressed group with SDS scores <40 and a depressed group with SDS-Zung scores ≥50. RESULTS: One hundred twenty-five patients (40.5 %) were classified as nondepressed and 63 (20.4 %) as depressed. The mean PDQ-J score was higher in depressed patients than in nondepressed patients. The frequency of neuropathic pain was greater in depressed patients, with neuropathic pain observed in 17 of the 63 (27 %) depressed LBP patients and 11 of the 125 (9 %) nondepressed LBP patients. The SDS-Zung and PDQ-J scores of LBP patients were correlated significantly (r = 0.261, p < 0.001). Depressed patients had higher pain NRS scores and lower QOL scores compared with nondepressed patients. CONCLUSIONS: Both the depressed patients and those with neuropathic LBP had a higher level of pain, greater pain-related disability, and poorer QOL compared with nondepressed patients. This is the first study to use the SDS-Zung and PDQ-J screening questionnaires to estimate the presence of neuropathic pain associated with depressive symptoms in LBP patients and to evaluate the impact of these on QOL.