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More than 30 million people in the United States have irritable bowel syndrome.
In diarrhea-predominant irritable bowel syndrome, there are several mechanisms that underly the textbook symptoms of the disease. Two of the most important are small bacterial overgrowth and the interaction between the brain and the gut. We currently have three primary agents available to use by the time a patient reaches a gastroenterologist. Before we know which agent to use, first we have to determine what the underlying causes are.
Xifaxan
The first is Xifaxan (rifaximin, Salix), which was studied by Mark Pimentel, MD, out of Cedars-Sinai. He was able to define the bacterial overgrowth mechanism that eventually lead to the development of IBS. When a patient experiences a food poisoning event, or gastroenteritis, they will very quickly develop an antibody that will attack that bacteria. What can happen, however, is that antibody attacks the intestines and causes inflammation in a way that you cannot identify through a colonoscopy or standard biopsies. He was able to develop a diagnostic test that can highlight patients who have IBS based on that mechanism. There is then a build-up of bacteria in the small intestine, which is how patients develop small intestinal bacterial overgrowth (SIBO). While IBS is the presentation, SIBO is the underlying problem. It is very important for clinicians to remember this when prescribing rifaximin for IBS-D. Patients might come to the clinic reporting problems from IBS, but the mechanism of IBS being treated is SIBO.
Viberzi
Another underlying cause of IBS that we target is the connection between the brain and the gut. For that we often use tricyclic agents and other neuromodulators. These are helpful to turn down the volume of sensations coming from the gut that are interpreted by the brain, which improves the way the brain communicates back down with the gut to improve gut motility.
Viberzi (eluxadoline, Allergan) is an important agent that targets this mechanism. Eluxadoline is a mixed opioid receptor agonist/antagonist. Eluxadoline impacts visceral hypersensitivity and abnormal brain-gut interactions by more directly targeting these interactions and slowing motility patterns. Among these three options, it comes down to a bedside decision and what the clinician feels is the most important mechanism by which the patient is having IBS.
However, the full menu of available treatment options can be limited in practice because of payer coverage. Unfortunately, patients can be in a situation where they may not be able to afford one of the treatment options that may actually be most beneficial. It is not only up to us as clinicians and patients alone to be thinking about this. It is also for policy makers, industry and payers to recognize that these treatment options are not necessarily competing against each other. It may be very reasonable to expand access to these drugs so that patients can get the right therapies they need to target their disease.
Earlier this year, my team and I published a study in Clinical Gastroenterology and Hepatology that addressed value-based pricing methods for rifaximin, specifically in treating IBS-D. What we intended to highlight was the issue surrounding access problems to therapies that have been deemed safe and effective by the regulatory agencies. These agencies, by law, do not and cannot consider cost. However, policymakers, payers, clinicians, and patients certainly feel the effects of cost given the overall cost of health care in this country, compounded by the costs related to missed time at work due to IBS. Thus, it behooves us to consider how drugs might be priced in a way that can break down barriers to access. Can there be a framework around which this discussion can be started? As we know in the U.S., drug pricing has been a very hot topic, and certain states, policy makers and payers are all looking to find better ways to get drugs out to the right patients.
In our study we created a decision analytic model to evaluate quality of life, cost and cost effectiveness of rifaximin for patients with IBS-D in three scenarios:
- complete noncoverage (insurer pays none of the drug cost);
- unrestricted access (insurer pays 100% of the cost), and
- formulary-restricted access (insurer pays 100% of the cost after patients fail initial therapy).
We found that quality of life improved in the unrestricted and formulary-restricted scenarios, and fell if rifaximin was not easily covered by payers. However, both of those coverage models would also be more expensive at the current price. What we found was that a lower agreed-on price of rifaximin, based on how well rifaximin improves IBS, would be cost effective to payers and may even save on budget costs — which would ultimately help our patients.
It is important to recognize that this kind of modelling is not intended for individual patient care, and that the threshold prices we found are not fixed — these depend on local circumstances within payer networks. Overall, this type of model could be adapted to each payer network in a way that benefits all stakeholders and especially our patients. As providers, we need to be doing what is best for our patients, and as part of that — we do not want our patients to be limited in their ability to get the therapies they need.
- Reference:
- Shah ED, et al. Clin Gastroenterol Hepatol. 2019;doi:10.1016/j.cgh.2019.02.039.
- For more information:
- Eric D. Shah, MD, MBA, is director of the Gastrointestinal Motility Center at Dartmouth-Hitchcock Medical Center. He can be reached at eric.d.shah@hitchcock.org.
Disclosure: Shah reports no relevant financial disclosures.