While opioids appeared to be effective for the treatment of non-cancer pain in short durations, the long-term efficacy of these medications is not well understood. Using a longitudinal cohort format, this study followed patients with polyneuropathy, in order to examine the relationship between the duration of opioid therapy and functional status.

Data were obtained from the Rochester Epidemiology Project database, documenting residents of Olmsted County Minnesota since 1966. The study harvested prescription data from ambulatory practice professionals beginning January 1, 2006. From this database, the duration and dose of opioids was determined. Medical records were reviewed for medical diagnoses, with long-term opioid prescription defined as 90 continuous days or longer.

Data were obtained for 17，327 patients from among whom 2，892 with polyneuropathy were identified. Compared with controls, patients with polyneuropathy were more often prescribed long-term opioids (5.4% versus 18.8%, respectively). Of those with polyneuropathy, 18.8% received long-term opioid therapy. Oxycodone accounted for 45.9% of the prescriptions. Compared with short-term use, long-term opioid use was correlated with female gender (P<0.001), and having a medical comorbidity. Of the long-term prescribers, 69.5% were internal medicine, and 13.2% were family medicine physicians. Pain specialists had been consulted in 26.3% of the long-term use cases. Long term users had greater difficulty with ADLs and function than did those receiving short term opioids. Adverse events were more likely among long-term opioid users.

This study found that polyneuropathy increases the likelihood of long-term opioid use, with long-term use associated with poorer functional status.