The 9-Item Patient Health Questionnaire (PHQ-9): an aid to assessment of patient-reported functional outcomes after spinal surgery

Background context: Preoperative depression is increasingly understood as an important predictor of patient outcomes after spinal surgery. In this study, we examine the relationship between depression and patient-reported functional outcomes (PRFOs), including disability and pain, at various time points postoperatively.

Purpose: The objective of this study was to analyze the use of depression, as measured by the 9-Item Patient Health Questionnaire (PHQ-9), as a means of assessing postoperative patient-reported disability and pain.

Study design/setting: This study includes an analysis of prospective non-randomized spine registry compiled through an academic multispecialty group practice model.

Patient sample: A total of 1,000 spinal surgery patients from an affiliated surgical registry, enrolled from January 2010 onward, were included in this study.

Outcome measures: Pain was assessed via the visual analog scale (VAS) for leg or back pain. Disability was measured by the Oswestry Disability Index (ODI). Depression was measured by the PHQ-9.

Methods: Patient data were collected preoperatively and at 1, 4, 10, and 24 months postoperatively. Data were analyzed via analysis of variance and Pearson correlation coefficient.

Results: All patient stratifications analyzed experienced improvements in pain and ability postoperatively, as measured by the VAS and the ODI, respectively. Moderately and severely depressed patients (as measured by preoperative PHQ-9) experienced decreases in the mean PHQ-9 score of -6.00 and -7.96 24 months after surgery, respectively.

Conclusions: In all groups, spinal surgery was followed by relief of pain and improved PRFO. Preoperative depression, as measured by the PHQ-9, predicted postoperative PRFO. Patients with moderate to severe depression as measured by the PHQ-9 experienced large mean decreases in the PHQ-9 score postoperatively. As a psychosocial metric, the PHQ-9 is a useful method of assessing value-added service of a spinal surgery.