To the Editor:
I read with great interest the comprehensive review by Sayuk and Gyawali
1
on irritable bowel syndrome. They carefully analyzed modern treatment options with peripherally acting agents for the 2 main subtypes by predominant stool pattern, namely the constipation-predominant and diarrhea-predominant subtypes. Surprisingly, they did not similarly consider treatment options for mixed irritable bowel syndrome, a subtype defined in Table 2, or for alternating irritable bowel syndrome, which refers to a change between diarrhea-predominant and constipation-predominant forms over time.2
Yet, the mixed irritable bowel syndrome prevalence approximately equals those of diarrhea-predominant and constipation-predominant forms,2
or is even up to 44%-50% of all subtypes.3
, 4
The alternating subtype would be the most prevalent in primary care.3
There is evidence suggesting that peripherally acting treatment of mixed and alternating irritable bowel syndrome should not simply consist of sequentially prescribing antidiarrheal or anticonstipation agents/measures according to the current predominant transit disorder. Although they may include bouts of diarrhea with liquid stools and rectal urgency supervening when fecal bowel loading reaches a critical level, called overload and overflow form of irritable bowel syndrome,
5
mixed and alternating irritable subtypes are more closely related to the constipation-predominant than to the diarrhea-predominant subtype in their stool pattern over time6
: the predominant problem is likely one of constipation.5
As recently outlined,7
many patients with mixed subtype report periods of overt constipation, followed by periods of multiple stools of variable consistency that they interpret as “diarrhea,” but most of them actually have constipation-predominant irritable bowel syndrome, with periods of progressive stool accumulation culminating in bowel purging. Indeed, anticonstipation agents are effective in treating mixed irritable bowel syndrome patients.8
Finally, in the latter patients, constipation followed by intermittent bouts of overflow diarrhea may indeed be the correct interpretation
4
and basically allow anticonstipation rather than antidiarrheal treatment, although it is difficult to convince patients with unformed/liquid stools of such a treatment.8
, References
- Irritable bowel syndrome: modern concepts and management options.Am J Med. 2015; 128: 817-827
- Functional bowel disorders.in: Drossman D.A. Corazziari E. Delvaux M. Rome III: The Functional Gastrointestinal Disorders. 3rd ed. Degnon Associates, Inc, McLean, VA2006: 487-555
- Functional bowel disorders.Gastroenterology. 2006; 130: 1480-1491
- Characterization of symptoms in irritable bowel syndrome with mixed bowel habit pattern.Neurogastroenterol Motil. 2014; 26: 36-45
- Symptom classification in irritable bowel syndrome as a guide to treatment.Scand J Gastroenterol. 2009; 44: 796-803
- A prospective assessment of bowel habit in irritable bowel syndrome in women: defining an alternator.Gastroenterology. 2005; 128: 580-589
- Irritable bowel syndrome. A clinical review.JAMA. 2015; 313: 949-958
- Tegaserod for female patients suffering from IBS with mixed bowel habits or constipation: a randomized controlled trial.Am J Gastroenterol. 2008; 103: 1217-1225
- Irritable bowel syndrome.Lancet. 1993; 341: 568-569
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- Irritable Bowel Syndrome: Modern Concepts and Management OptionsThe American Journal of MedicineVol. 128Issue 8
- PreviewIrritable bowel syndrome is the most common functional gastrointestinal disorder, manifesting as abdominal pain/discomfort and altered bowel function. Despite affecting as many as 20% of adults, a lack of understanding of etiopathogenesis and evaluation strategies results in diagnostic uncertainty, and in turn frustration of both the physician and the patient. This review summarizes the current literature on the diagnosis and management of irritable bowel syndrome, with attention to evidence-based approaches.
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- The ReplyThe American Journal of MedicineVol. 129Issue 2
- PreviewWe appreciate Matuchansky's interest in our recent American Journal of Medicine review on irritable bowel syndrome.1 We agree completely with his comment that the mixed and alternating subtypes of irritable bowel syndrome, as defined by the Rome criteria, are common in both tertiary referral practices and the community, and may account for as many as 50% of irritable bowel syndrome patients.2 We concur with the notion that some presumed “mixed” irritable bowel syndrome patients indeed are constipation-predominant patients who experience looser, or more frequent stools after successful mobilization of the constipated bowel.
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