Evaluation of a Dallas Pain Questionnaire classification in relation to outcome in lumbar spinal fusion

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Abstract
Several studies have suggested that psychosocial distress is an important predictor of negative outcome in lumbar spine surgery. Ozguler et al. [Spine 27:1783–1789, 2002, 18] described a classification tool for low back pain patients using the Dallas Pain Questionnaire (DPQ) which included a measure of distress. We wanted to evaluate the ability of this classification tool to predict the outcome in spinal fusion patients. Five hundred and sixty-six patients (239 men, 327 women; mean age 46, range 18–81) operated between 1992 and 2002, with a complete DPQ preoperatively and after a minimum of 1-year follow-up, were included. They were classified preoperatively and at follow-up into four groups: group 1 (slight disability), group 2 (intermediate disability), group 3 (major disability) and group 4 (major disability and emotional distress). Using logistic regression, seven predictor variables were investigated: age (−39 years/40–59 years/60+ years), Gender (male/female), Indication (spondylolisthesis/primary degeneration/secondary degeneration), Work status (working/without work or on sick leave/retired or pensioned), Duration of pain (less than 1 year/1–2 years/more than 2 years), Presence of radiating pain (yes/no) and disability/distress [intermediate disability (group 1–2)/major disability (group 3)/major disability and distress (group 4)]. The outcome variable was disability at follow-up (low = group1 + 2/high = group 3 + 4). Preoperative classification was group 1, 1%; group 2, 14%; group 3, 37%; group 4, 48%. Variables found to predict high disability at follow-up were secondary degeneration Odds Ratio (OR) 1.61 (P=0.020), being retired/pensioned OR 3.48 (PP=0.011), belonging to group 3 OR 2.69 (P=0.003) or belonging to group 4 OR 5.53 (P<0.0005). The classification based on the DPQ were able to identify lumbar spinal fusion patients with a considerable amount of psychological distress in their symptomatology. Furthermore, the presence of distress, as determined by this classification, was a highly significant risk factor for inferior outcome.