Amitriptyline
Three-quarters of participants adhered to the therapy over the 6 months, which was particularly notable given that the trial was conducted during the COVID-19 pandemic, according to the researchers.
An intent-to-treat analysis found that at 6 months, amitriptyline was superior to placebo, with a significant mean difference in IBS-SSS score between groups of –27.0 (95% confidence interval, –46.9 to –7.1; P = .0079; mean IBS-SSS, 170.4 vs. 200.1 with amitriptyline and placebo). A secondary outcome showed an increased likelihood of relief of IBS symptoms by subjective global assessment (odds ratio, 1.78; 95% CI. 1.19-2.66; P = .0050).
At 3 months, the difference in mean change in IBS-SSS score between groups was also significant, at –23.3 (95% CI, –42.0 to –4.6; P = .014), the researchers reported.
People who took the drug were 70% more likely to report relief of symptoms on SGA than those who took placebo (P = .08), according to the researchers.
The researchers reported no effect of low-dose amitriptyline on psychiatric symptoms, such as distressing thoughts, anxiety, and depression, during the 6-month follow-up, nor was there any effect on ability to work or go about social activities.
“This was a pragmatic trial performed in a large number of participants with IBS, with an average duration of symptoms of 10 years and with 80% having moderate to severe symptoms at baseline,” Alexander Ford, MD, professor of gastroenterology at the University of Leeds, England, and a coinvestigator on the study, told this news organization. “The fact that amitriptyline showed such a strong effect over placebo in this group of patients, with a mean decrease in IBS-SSS of almost 100 points at both 3 and 6 months, is therefore all the more impressive.”
Mild adverse events, such as dry mouth and drowsiness, were more frequent with low-dose amitriptyline than with placebo,
Dr. Everitt said the ATLANTIS findings could change practice. Previous trials of low-dose amitriptyline for IBS had mostly been small and were conducted in secondary care settings such as gastroenterology clinics with relatively short follow-up times.
“This is a problem for a long-term condition that fluctuates over time and is diagnosed and managed mostly in primary care,” she said. “The ATLANTIS trial is the largest trial of low-dose amitriptyline for IBS undertaken worldwide and was rigorously conducted with 6 months follow-up, providing reliable results that can help inform GPs and patients’ treatment decision-making in usual clinical practice.”
On a pragmatic level, the research group developed a dose titration document for use by patients and GPs. “Both the GPs and participants found the ATLANTIS dose titration document acceptable and helpful,” Dr. Everitt pointed out. She noted, “We’ve made the dose titration document freely available to support patients and clinicians to try low-dose amitriptyline for IBS.”
Dr. Ford and Dr. Everitt received grant funding (institutional) from the National Institute for Health and Care Research.
A version of this article first appeared on Medscape.com.