Author Affiliation: Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.
Although Gomes et al1 concluded that the daily dose of opioid is strongly associated with opioid-related deaths in patients with chronic nonmalignant pain, the analysis used to determine this requires further consideration.
An unadjusted analysis based on primary analysis data in Figure 3 of their article revealed no significant association between dose category and proportions of overall deaths in each category. There was no difference in the proportion of total deaths in the 50 to 99 mg of morphine equivalents per day and 100 to 150 mg/d categories compared with the 1 to 19 mg/d categories and although the proportion of deaths were greater in the greater than 200 mg/d category than the 1 to 19 mg/d category, it was not greater than the proportion of deaths in the 20 to 49 mg/d category. The adjusted analysis reported that deaths increased with increasing dose categories above 50 mg/d, but the 95% confidence intervals overlapped in higher dose categories. Mortality does not appear to be associated with opioid dose alone.
Williamson OD. Opioids and Dose-Related Deaths—Association or Causation?. Arch Intern Med. 2011;171(18):1687-1689. doi:10.1001/archinternmed.2011.452