Characterization and Associated Costs of Constipation Relating to Exposure to Strong Opioids in England: An Observational Study.

PURPOSE

Opioid use is associated with gastrointestinal adverse events, including nausea and constipation. We used a real-world dataset to characterize the health care burden associated with opioid-induced constipation (OIC) with particular emphasis on strong opioids.

METHODS

This retrospective cohort study was conducted using the Clinical Practice Research Datalink, a large UK primary care dataset linked to hospital data. Patients prescribed opioids during 2016 were selected and episodes of opioid therapy constructed. Episodes with ≥84 days of exposure were classified as chronic, with date of first prescription as the index date. The main analysis focused on patients prescribed strong opioids who were laxative naive. Constipation was defined by ≥2 laxative prescriptions during the opioid episode. Patients for whom initial laxative therapy escalated by switch, augmentation, or dose were defined as OIC unstable, and the first 3 lines of OIC escalation were classified. Health care costs accrued in the first 12 months of the opioid episode were aggregated and compared.

FINDINGS

A total of 27,629 opioid episodes were identified; 5916 (21.4%) involved a strong opioid for patients who were previously laxative naive. Of these patients, 2886 (48.8%) were defined as the OIC population; 941 (33.26%) were classified as stable. Of the 1945 (67.4%) episodes classified as unstable, 849 (43.7%), 360 (18.5%), and 736 (37.8%) had 1, 2, and ≥3 changes of laxative prescription, respectively. Patients without OIC had lower costs per patient year (£3822 [US$5160/€4242]) compared with OIC (£4786 [US$6461/€5312]). Costs increased as patients had multiple changes in therapy: £4696 (US$6340/€5213), £4749 (US$6411/€5271), and £4981 (US$6724/€5529) for 1, 2, and ≥3 changes, respectively. The adjusted cost ratio relative to non-OIC was 1.14 (95% CI, 1.09-1.32) for those classified as stable and 1.19 (95% CI, 1.09-1.32) for those with ≥3 laxative changes. Similar patterns were observed for patients taking anyopioid, with costs increased for those classified as having OIC (£3727 [US$5031/€4137] vs £2379 [US$3212 /€2641),and for those patients classified as unstable versus stable (£3931 [US$5307/€4363] vs £3432 [US$4633/€3810). Costs increased with each additional line of therapy from £3701 (US$4996/€4108), £3916 (US$5287/€4347), and £4318 (US$5829/€4793).

IMPLICATIONS

OIC was a common adverse event of opioid treatment and was poorly controlled for a large number of patients. Poor control was associated with increased health care costs. The impact of OIC should be considered when prescribing opioids. These results should be interpreted with consideration of the caveats associated with the analysis of routine data.