Measurement of opioid problems among chronic pain patients in a general medical population.

INTRODUCTION: Chronic opioid therapy for non-malignant pain has greatly expanded, increasing the urgency of identifying those experiencing problems related to prescribed opioids. The Prescription Drug Use Questionnaire (PDUQ), which shares substantial content with subsequently developed instruments, was developed within a pain clinic setting designed to identify problematic opioid use. The utility of the PDUQ and its relationship with the DSM-IV approach needs to be established for patients being treated in general medical settings.
METHODS: Patients (n=704) from a large HMO prescribed opioids chronically were interviewed using the PDUQ and the Composite International Diagnostic Interview (CIDI) DSM-IV opioid abuse and dependence instrument. The internal reliability of the PDUQ was assessed. Factor analytic procedures were utilized to determine the factor structure of the PDUQ alone and in combination with CIDI DSM-IV.
RESULTS: The internal reliability of the PDUQ in this population was poor (Cronbach's coefficient alpha=0.56) compared to the original development study (alpha=0.81). Factor analysis of a reduced set of PDUQ items yielded three factors: addictive behaviors, addictive concerns, and pain treatment problems. Factor analysis combining DSM-IV and PDUQ items indicated abuse and dependence were a single, distinct factor.
CONCLUSIONS: In this study of chronic pain patients on opioids in a general medical population, the PDUQ performed differently than in previously described pain clinic populations. CIDI DSM-IV items were distinct from a reduced set of PDUQ items, suggesting the need to reconsider approaches to the measurement of opioid problems for these patients. The four factors identified deserve further study, as they may signal the need for distinct interventions to improve the care of patients prescribed chronic opioid therapy for pain.