The Opioid Constipation 'Disconnect'

Pauline Anderson

September 09, 2014

LAS VEGAS, Nevada — Doctors don't seem to be aware of the effect of opioid-induced constipation (OIC) on their patients and of what these patients are doing to try to treat this sometimes devastating adverse effect, according to a new study.

The analysis suggests that there is a disconnect between how doctors and patients view the impact of OIC and the effectiveness of laxative therapy, said study author Hilary Wilson, PhD, senior research associate, Evidera, Bethesda, Maryland. "The gist was that physicians are not really aware of what patients are doing," she told Medscape Medical News.

Dr. Wilson presented the findings here during the PAINWeek meeting. The study was supported by AstraZeneca, which is developing a treatment for OIC called naloxegol.

Common Adverse Effect

An estimated 40% to 80% of patients receiving long-term opioid therapy experience OIC. Although some cross-sectional studies have looked at the incidence of OIC, this new study is the first to investigate the incidence longitudinally over time, said Dr. Wilson.

The study had 3 data sources. The first was a survey of 489 patients in the United States, Canada, Germany, and the United Kingdom who were being treated with oral opioids and had experienced OIC in the previous 2 weeks. Most patients were female (62%) and white (85%). The mean duration of their chronic pain and long-term opioid use was 9.8 and 6.4 years, respectively.

These patients completed a baseline questionnaire and other surveys over the course of 24 weeks. They were asked about constipation, the laxatives they were taking, and their health-related quality of life.

The study also included retrospective chart reviews: one at baseline covering the previous 12-month period and another at week 24. These reviews looked at healthcare utilization and concomitant medication use.

A third element of the study was a physician survey at baseline and at week 24. Doctors filled out a questionnaire for each patient. "So if a physician had 20 patients enrolled in the study, they completed the survey for all 20 of those patients," said Dr. Wilson.

Physicians were asked if they were aware that the patient had constipation and what the patient was using to treat that adverse effect.

"We were looking at what patients were saying and what physicians were saying," said Dr. Wilson.

At baseline, the agreement between patient and healthcare provider reports of constipation was 61%.

"So of patients that said yes, I am constipated, only 61% of physicians were aware that those patients were constipated," said Dr. Wilson. "That is the number one issue, that physician are not aware that their patients are even experiencing constipation."

About 25% of physicians said they didn't know if a patient was taking a laxative. "Most physicians will be aware that constipation is a potential side effect, but clearly the majority are not asking or aware, at least on an individual level, of what their patients are doing," said Dr. Wilson.

The study also indicated that the laxatives patients take to try to relieve constipation are not working that well. Most patients (55.6%) were dissatisfied with their constipation treatment at baseline, with only marginal improvement in satisfaction at week 12 (44.9%) and week 24 (45.9%).

Almost half (49%) of patients with constipation reported moderate or complete interference with the ability of their opioid medication to control pain.

As well, 8% of patients reported having changed how they used their opioid pain medication to facilitate a bowel movement. Most opted to reduce the amount of pain medication used or temporarily interrupted use.

This change in pain medication use resulted in constipation relief for 35% of patients at baseline, and for 29% to 60% of patients up to week 24.

New Disease State

Asked for his thoughts on these data, Lynn Webster, MD, a pain expert and vice president, scientific affairs, PRA Health Sciences, Salt Lake City, Utah, called it interesting.

"Opioid induced constipation occurs more frequently than most physicians appreciate," he told Medscape Medical News. "This is further evidence that physicians may need to inquire about constipation when prescribing opioids."

In addition, he said, it's likely that some of the patients are experiencing nausea and reflux secondary to the constipation. "This is becoming a new disease state that has an effect on many aspects of the individuals' life."

Funding for this research was provided by AstraZeneca. Dr. Wilson was part of a team that consulted for AstraZeneca. Dr. Webster has served as a consultant for AstraZeneca.

PAINWeek 2014. Posters 151 and 152. Presented September 4, 2014.

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