Consequences of Opioid-Induced Constipation

A large-scale investigation of patients starting long-term opioid analgesics demonstrated relatively low rates of therapy-induced constipation needing medical attention. However, such cases incurred significantly higher healthcare utilization costs, so strategies for minimizing this side effect of opioids are important.

Writing in the March 2010 edition of Managed Care, researchers described a study retrospectively examining medical claims data during a 7-year period from a large population of managed care enrollees to determine the impact of constipation in those who had started on long-term opioid analgesics. They identified 39,485 patients in this group, of whom 2,519 (6.4%) sought medical care for opioid-induced constipation within one year of starting therapy. Most were female (66%) and ≥45 years of age (68%). Outcomes were contrasted with a matched cohort of patients (controls) who did not have medical claims for constipation as a result of being prescribed long-term opioid therapy.

Compared with controls, the constipation group had significantly higher rates of concurrently taking ≥2 opioid analgesics and being switched or rotated between opioids. Patients with constipation claims also had significantly greater rates of physician office visits, other outpatient or ancillary care, emergency department visits, hospital admissions, home health services, nursing home care, and laboratory tests. Consequently, as a group, those with constipation incurred much higher healthcare costs as compared with patients without constipation.

COMMENTARY: The rate of opioid-induced constipation requiring medical attention in this study actually seems low (6.4%); however, it is not known if a great many more patients developed less severe constipation and either did not seek care or self-treated the condition with OTC remedies. Furthermore, it is interesting to note that 8% of patients in the control group, without constipation-related medical claims, had been prescribed laxatives, probably as preventive therapy to minimize constipation at the outset. Most opioid-therapy guidelines recommend immediately starting patients on a “bowel regimen,” often including prescribed laxatives, to minimize the risk or severity of constipation. Finally, it should be mentioned that the authors of this study were all associated with or funded by Pfizer Inc. (previously, Wyeth Research), a manufacturer of laxative products, which might have influenced a reporting bias.

REFERENCE: Iyer S, Davis KL, Candrilli S. Opioid use patterns and health care resource utilization in patients prescribed opioid therapy with and without constipation. Managed Care. 2010(Mar):44-51 [article here].
INFO for Your Patients: Constipation: A Common Side Effect of Opioid Use by Kevin Zacharoff, MD, at PainAction.com [available here].