Susanna Every-Palmer1, Stephen J Inns2, Pete M Ellis3. 1. Department of Psychological Medicine, University of Otago, Wellington, New Zealand. Electronic address: susanna.every-palmer@otago.ac.nz. 2. Department of Medicine (Gastroenterology), University of Otago, Wellington, New Zealand. 3. Department of Psychological Medicine, University of Otago, Wellington, New Zealand.
Abstract
OBJECTIVE: Clozapine is the favoured antipsychotic for treatment-refractory schizophrenia but its safe use requires careful adverse-effect management. Clozapine-induced gastrointestinal hypomotility (CIGH or 'slow-gut') is one of the most common and serious of clozapine's adverse effects. CIGH can lead to paralytic ileus, bowel obstruction, gastrointestinal ischaemia, toxic megacolon, and death. Enquiring about constipation is a simple and commonly used screening method for CIGH but its diagnostic accuracy has not previously been assessed. METHODS: First, we examined the reliability of asking about constipation compared with asking about Rome constipation criteria in inpatients treated with clozapine (n = 69). Second, we examined the diagnostic accuracy of (1) self-reported constipation and (2) the Rome criteria, compared with the reference standard of gastrointestinal motility studies. RESULTS: After 30 motility tests, it was clear constipation screening had very poor diagnostic properties in this inpatient group and the study was terminated. Although 73% of participants had objective CIGH on motility testing, only 26% of participants self-reported constipation, with sensitivity of 18% (95% CI: 5-40%). Specificity and positive predictive values were higher (95% CI: 63-100% and 40-100%, respectively). Adding in Rome criteria improved sensitivity to 50% (95% CI: 28.2-71.8%), but half the cases were still missed, making this no more accurate than tossing a coin. CONCLUSIONS: CIGH is often silent, with self-reported constipation having low sensitivity in its diagnosis. Treating CIGH based on self-reported symptoms questions will miss most cases. However, universal bowel motility studies are impractical. In the interests of patient safety, prophylactic laxatives are suggested for people taking clozapine.
OBJECTIVE:Clozapine is the favoured antipsychotic for treatment-refractory schizophrenia but its safe use requires careful adverse-effect management. Clozapine-induced gastrointestinal hypomotility (CIGH or 'slow-gut') is one of the most common and serious of clozapine's adverse effects. CIGH can lead to paralytic ileus, bowel obstruction, gastrointestinal ischaemia, toxic megacolon, and death. Enquiring about constipation is a simple and commonly used screening method for CIGH but its diagnostic accuracy has not previously been assessed. METHODS: First, we examined the reliability of asking about constipation compared with asking about Rome constipation criteria in inpatients treated with clozapine (n = 69). Second, we examined the diagnostic accuracy of (1) self-reported constipation and (2) the Rome criteria, compared with the reference standard of gastrointestinal motility studies. RESULTS: After 30 motility tests, it was clear constipation screening had very poor diagnostic properties in this inpatient group and the study was terminated. Although 73% of participants had objective CIGH on motility testing, only 26% of participants self-reported constipation, with sensitivity of 18% (95% CI: 5-40%). Specificity and positive predictive values were higher (95% CI: 63-100% and 40-100%, respectively). Adding in Rome criteria improved sensitivity to 50% (95% CI: 28.2-71.8%), but half the cases were still missed, making this no more accurate than tossing a coin. CONCLUSIONS: CIGH is often silent, with self-reported constipation having low sensitivity in its diagnosis. Treating CIGH based on self-reported symptoms questions will miss most cases. However, universal bowel motility studies are impractical. In the interests of patient safety, prophylactic laxatives are suggested for people taking clozapine.
Authors: Madeleine S A Tan; Faraz Honarparvar; James R Falconer; Harendra S Parekh; Preeti Pandey; Dan J Siskind Journal: Psychopharmacology (Berl) Date: 2021-01-07 Impact factor: 4.530
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