The prevalence of constipation in adult psychiatric out‐patients on clozapine treatment at a regional public hospital in Hong Kong

Abstract

AbstractObjectiveTo determine the occurrence of constipation in local patients on clozapine treatment, and to compare the demographical and clinical characteristics of patients on clozapine treatment with or without constipation.MethodsThis is a cross‐sectional, observational study. All adult psychiatric out‐patients on clozapine treatment attending follow‐up at a regional hospital were recruited for clinical interview and medical record review. The Enhanced Asian Rome III Questionnaire (EAR3Q) was used to define patients with constipation. The Bristol Stool Form Scale (BSFS) was used to assess stool form. The Brief Psychiatric Rating Scale‐Anchored (BPRS‐A) was used to measure psychiatric symptoms. The Brief Medication Adherence Scale (BMAS) was used to assess treatment adherence. Logistic regression was conducted to identify independent associating factors of constipation in patients on clozapine treatment.ResultsThe prevalence of constipation in patients on clozapine treatment was 26.3%, (95% CI [21.5%, 31.6%]). Independent associating factors included disorder of psychological development (aOR = 6.98, 95% CI [1.24, 39.18]), anxiety (very mild: aOR = 9.23, 95% CI [2.59, 32.87]; mild: aOR = 2.66, 95% CI [1.26, 5.62]), prescription with combination of laxatives (aOR = 0.40, 95% CI [0.17, 0.95]), and concomitant use of amisulpride (aOR = 2.52, 95% CI [1.09, 5.82]), quetiapine (aOR = 5.92, 95% CI [1.11, 31.56]) and metamucil (aOR = 9.30, 95% CI [1.53, 56.58]).ConclusionThis study examined the prevalence of clozapine‐associated constipation in Hong Kong using a validated questionnaire. The identification of independent factors associated with constipation could facilitate better risk stratification and risk modification in clinical practice.