Reply to: 10.1007/s00464-013-3134-x: Colonic architectural changes after the use of psychotropic drugs: looking at the egg while forgetting the hen?

Abstract

To the Editor, Our research does not propose a change or cessation in the usage of psychotropic medications, especially in patients for which it is indicated. Instead, we are suggesting that a thorough medication history taken before colonoscopy, with attention to antipsychotic medications, would alert the endoscopist in anticipating possible challenges during the procedure. The study was designed with the endoscopist in mind: the outcome measure of colonic macroarchitecture change (using the terms ‘‘redundant,’’ ‘‘megacolon,’’ ‘‘featureless,’’ and ‘‘capacious’’) is of relevance to the safe conduct of colonoscopy [1]. Furthermore, recognizing these colonoscopic features carries with it important surgical implications, as sigmoid redundancy [2, 3] and megacolon [4–6] are associated with colonic volvulus. Although interobserver variability is an inherent limitation, we attempted to reduce this by having a third-party endoscopist review several factors such as endoscopy time relative to the endoscopists’ experience in addition to the actual pictures taken during the colonoscopy. We contend that colonoscopy is more accurate than barium enema in assessing colonic macroarchitecture, as every part of the colon can be maximally distended to demonstrate capaciousness and redundancy is more accurately assessed. However, we do not assert that endoscopic descriptions of changes in colonic macroarchitecture imply altered colonic physiology. High-amplitude propagated contractions described by Bassotti and Gaburri [7] may not have any relationship to endoscopic appearances of featureless and capacious megacolons. We recognize that constipation is a possible confounder of our results, and there might well be an association between constipation and change in colonic architecture and physiology [8]. Hence, we have taken great pains to include in our analysis all medications that the subjects have taken during the study period, including drugs that might potentially cause constipation. Our results demonstrate that constipation alone cannot fully explain the changes in colonic macroarchitecture. We have distinguished that of the psychotropic medications, only antipsychotics have been positively associated with colonic architecture change. As mentioned in our article, constipation is a known side effect of antidepressant medications [9] and calcium channel blockers, but our data show that these medications do not have a significant effect on colonic architecture change. On the contrary, opioids— a class of medications known to cause constipation—have shown decreased incidence of changes. The pathophysiology of psychotropic drugs on the anatomic architecture is not well studied. In our discussion, we included a number of animal studies that examined this association, as well as few case reports in humans [10–12]. The paucity of clinical literature on this topic does not negate the possibility of drugs modifying the macroarchitecture of the colon. This is the first study that lent statistical validity to this hypothesis and indicated that this association was more than likely. We acknowledge that the K. Y. Ngiam Department of General Surgery, Khoo Teck Puat Hospital, 90 Yishun Central, Singapore 768828, Singapore e-mail: ngiam.kee.yuan@alexandrahealth.com.sg