Effectiveness of opioid analgesics in chronic noncancer pain.

Background There is general agreement about the need to perform a screening test to assess the risk of opioid misuse prior to starting a long-term opioid treatment for chronic noncancer pain. The evidence supporting the effectiveness of opioid long-term treatment is weak, and no predictors of its usefulness have been assessed. Objective The aim of this study was to assess the effect on pain and quality of life of chronic opioid treatment, and detect the possible predictors of its effectiveness. Methods This observational, prospective study was conducted in 2 Italian Pain Relief Units on 77 patients affected by intractable chronic pain. Patients were submitted to psychological tests, investigating the individual pain experience, risk of opioid misuse, mood states, quality of life, and personality characteristics prior to starting treatment and at 2,4, and 6-month follow-up. Results Both maximum and habitual pain, as measured with VAS, underwent a statistically significant reduction at 2, 4, and 6-month follow-up. In multivariate analysis, lower scores in the Pain Medication Questionnaire (PMQ) were predictive of a major reduction in maximum VAS (P = 0.005). Both low PMQ and MMPI-cynicism scores were predictive of habitual VAS decrease (P = 0.012 and P = 0.028, respectively). Conclusion The results indicate that pain relief significantly improved over a 6-month period of opioid treatment, together with quality of life. The outcome was better in patients with a pretreatment low risk of opioid misuse, low scores in the Cynicism scale of MMPI-2, and no aberrant drug behaviors at follow-up. Therefore, a psychological screening and support is crucial for a good outcome of opioid therapy for chronic noncancer pain patients.