Overdose in Patients Prescribed Opioids

The rate of overdose among patients with chronic noncancer pain treated long-term with opioids is unknown. To address this, researchers conducted surveillance for overdose events among 9940 patients receiving care from a single Health Maintenance Organization who had received 3 or more opioid prescriptions in the 90 days before study entry. The 90-day average daily dose in morphine equivalents was tracked through pharmacy files. Fatal and nonfatal opioid overdoses were identified by electronic medical record and death certificate review. Participants, 60% of whom were women (mean age, 54 years; mean opioid dose, 13 mg per day), were followed for a mean of 42 months.

• Of 51 identified opioid-related overdoses, 40 were serious (6 deaths and 34 serious nonfatal events), while 11 were not serious.

• The annual overdose rate increased as average daily dose, in morphine equivalents, increased:
  • 0.2% for 1 to <20 mg per day;
  • 0.3% for 20 to <50 mg per day; − 0.7% for 50 to <100 mg per day; and
  • 1.8% for ≥100 mg per day.
• Compared with those receiving the lowest opioid doses, patients receiving the highest doses were more likely to be men, to be current smokers, to have more comorbid conditions, and to have a history of depression or substance abuse treatment.

Comments:

The rate of opioid-related overdose was greatest among patients receiving higher doses. Although the rate of overdose was low in patients receiving <50 mg per day, the absolute number of overdoses exceeded that of higher dose groups because more patients received lower doses. The results underscore the need to carefully monitor all patients who receive long-term opioid therapy for chronic noncancer pain.

Kevin L. Kraemer, MD, MSc

Reference:

Dunn KM, Saunders KW, Rutter CM, et al. Opioid prescriptions for chronic pain and overdose: a cohort study. Ann Intern Med. 2010;152(2):85–92.