PURPOSE: The Dallas Pain Questionnaire (DPQ) assesses the impact of low back pain (LBP) on four components (0-100) of daily life. We estimated the minimal clinically important improvement (MCII) and the patient acceptable symptom state (PASS) values of DPQ in LBP patients.
METHODS: 142 patients with LBP lasting for at least 4 weeks completed a battery of questionnaires at baseline and 6 months later. Questions for MCII addressed patient-reported response to treatment at 6 months on a five-point Likert scale, while a yes/no question concerning satisfaction with present state was used to determine PASS. MCII was computed as the difference in mean DPQ scores between patients reporting treatment as effective vs. patients reporting treatment as not effective, and PASS was computed as the third quartile of the DPQ score among patients who reported being satisfied with their present state.
RESULTS: MCII values were 22, 23, 2 and 10 for daily activities, work and leisure, social interest, and anxiety/depression, respectively. PASS values were 29, 23, 20 and 21 for the four components, respectively. The PASS total score threshold of 24 correctly classified 84.1 % of the patients who reported being unsatisfied with their present state, and 74.7 % of patients reported being satisfied.
CONCLUSIONS: These values give information of paramount importance for clinicians in interpreting change in DPQ values over time. Authors should be encouraged to report the percentage of patients who reach MCII and PASS values in randomized clinical trials and cohort studies to help clinicians to interpret clinical results.