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Table of Contents
Year : 2021  |  Volume : 35  |  Issue : 2  |  Page : 95-98

The Prevalence of Constipation and Its Risk Factors in Patients with Schizophrenia

1 Department of Psychiatry, Taipei Veterans General Hospital Yuli Branch, Hualien, Taiwan
2 Department of Geriatric Psychiatry, Yuli Hospital, Ministry of Health and Welfare, Hualien, Taiwan

Date of Submission11-Nov-2020
Date of Decision19-Feb-2021
Date of Acceptance20-Feb-2021
Date of Web Publication22-Jun-2021

Correspondence Address:
M.D., M.P.H. Hsing- Kang Chen
No. 448, Chung-Hwa Road, Yuli Township, Hualien
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/tpsy.tpsy_20_21

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Objective: Constipation is a common symptom in schizophrenia population. Patients treated with antipsychotic drugs are more likely to have constipation. In this study, we intended to identify possible associations and risk factors between schizophrenia patients and constipation. Methods: Patients with schizophrenia (n = 240) were recruited. In this cross-sectional study, we collected information of their socio-demographic and clinical details. Their psychotic symptoms were evaluated using clinical interview with positive and negative syndrome scale (PANSS). Results: In this study, the prevalence of constipation was 59.8%. Odds ratio (OR) (95% confidence interval [CI]) of PANSS average score, 1.018 (1.003–1.034), p < 0.05); OR (95% CI) of using second-generation antipsychotics (SGAs) solely, 3.475 (1.201–10.056), p < 0.05); and OR (95% CI) of using anticholinergic drugs, 1.853 (1.024–3.353), p < 0.05) were significantly associated with constipation. Conclusion: The prevalence of constipation is extremely high in this sample. In those patients who had severe psychotic symptoms, prescription of SGAs or anticholinergic agents, the focus should be on early detection, monitoring the constipation side effect, and early intervention.

How to cite this article:
Chang CC, Chen HK. The Prevalence of Constipation and Its Risk Factors in Patients with Schizophrenia. Taiwan J Psychiatry 2021;35:95-8

How to cite this URL:
Chang CC, Chen HK. The Prevalence of Constipation and Its Risk Factors in Patients with Schizophrenia. Taiwan J Psychiatry [serial online] 2021 [cited 2023 Jan 28];35:95-8. Available from: http://www.e-tjp.org/text.asp?2021/35/2/95/319008

  Introduction Top

Constipation is a prevalent symptom in psychiatric populations and is associated with poor health outcome and quality of life [1]. Patients with schizophrenia have a higher risk of constipation than those in general population [2],[3]. Previous studies showed that 20% - 30% of patients taking antipsychotic drugs develop constipation [4],[5]. Some investigators even pointed out that prevalence is up to 50% in patients with schizophrenia [6]. In one study on a systemic evaluation of the prevalence and severity of constipation in patients with schizophrenia, de Hert et al. [6] have found the prevalence up to 36.3% of patients with this symptom, usually needing medical intervention. Koizumi et al. [7] interviewed 503 schizophrenia inpatients about their constipation and found that 184 (36.6%) of them meet the diagnosis of constipation and that 80% of those constipation patients do not inform their condition to their physicians.

The study on the use of antipsychotics in Belgium was found that the prevalence of constipation is around 20% [8]. Another single-center study showed that 20% of patients on antipsychotics, receive laxatives [4]. Despite such a high prevalence, constipation does not get much attention as other physical diseases such as metabolic syndrome. But if patients left untreated, severe conditions can develop bowel obstruction, intestinal infarction, and some even death [9],[10],[11],[12],[13],[14],[15],[16],[17].

A study on patients with schizophrenia in southern Taiwan showed that female, older age, greater psychiatric symptom severity, and comorbid medical diseases are factors associated with the constipation [18]. Several studies also showed that antipsychotic drugs [19], anticholinergic drugs [20], antidepressants especially those with dual action [21], have constipation side effect.

Given the high prevalence from antipsychotic use in schizophrenia, a study was found that compared with those without using antipsychotics, patients with long-term use of antipsychotics, have increased risk of constipation by 1.9 times [2]. But antipsychotic agents differ in their liability for inducing constipation. In clozapine-medicated patients, the prevalence of constipation is increased from 14% to 60% [13],[22],[23]. A recent systematic review has shown a pooled prevalence of clozapine-associated constipation of 31.2%, and that patients taking clozapine have higher rates of constipation compared with those taking nonclozapine antipsychotics [24]. In addition, second-generation antipsychotics (SGAs), and SGAs combined with first-generation antipsychotics (FGAs) are more likely to cause constipation than FGAs alone [18].

Yuli Hospital, Ministry of Health and Welfare, Hualien is situated in the rural area of eastern Taiwan. Patients here are mostly those with chronic schizophrenia (over 90%). Current research of this issue of constipation in Taiwan is limited. To the best of our knowledge, no studies exist exploring the prevalence and predicting risk factors of constipation in patients with schizophrenia. In this study, we intended to study the prevalence of constipation and its risk factors among patients with chronic schizophrenia.

  Methods Top

Study subjects

All the patients were recruited from Yuli Hospital in 2016. The inclusion criteria for the study were patients with (a) the DSM-IV-TR diagnosis of schizophrenia, (b) age being 20 years or older, (c) ability to communicate fluently with Mandarin, and (d) having relatively stable psychotic symptoms being without medication adjustments in the previous three months. Exclusion criteria for the study were patients with having (a) a diagnosis of dementia, (b) a severe medical condition, (c) cancer, (d) a history of abdominal surgery, (e) intellectual disability, or (f) inability to sign informed consent. The institutional review board of Yuli Hospital approved the study protocol (IRB protocol number = YLH-IRB-10422 and date of approval = December 18, 2015) with the stipulation of obtaining informed consents from all participants before the study.

Assessment of symptoms and profile

Patients' psychotic symptoms were evaluated using a clinical interview with a positive and negative syndrome scale (PANSS) [25]. At the same time, we collected their socio-demographic details, including age, gender, year of education, the onset of illness, duration of psychiatric illness, body mass index (BMI), physical activity, high fiber diet, comorbidity index, current antipsychotics, and current anticholinergics.

Physical activity was defined as whether the patient had been attending activity arranged by the hospitals rehabilitation program (such as taking a stroll) three times a week in the previous six months. Those who had high fiber diet over three times a week over the previous six month was defined as taking regular high fiber diet.

Antipsychotic medications were divided into FGAs, SGAs, or concomitant use of both. Laxative use was taken as a proxy for constipation. Patients receiving at least one prescription for a laxative in the previous three months were considered having constipation.

Statistical analysis

Descriptive statistics included age, gender, year of education, duration of psychiatric illness, BMI, chronic diseases, anticholinergics, antipsychotics, PANSS, which were presented as average or percentage. The prevalence of constipation was calculated and presented with a percentage.

We used bivariate analyses with the independent t-test and the Chi-squared test to compare patients with and those without constipation. Then backward logistic regression analysis was done to determine the predictors of constipation. In this model, the independent variables were age, gender, year of education, duration of psychiatric illness, BMI, physical activity, high fiber diet, comorbidity index, antipsychotics, anticholinergic agent, and PANSS score.

Statistical analysis was done using Statistical Package for Social Science software version 11 (International Business Machine SPSS Statistics, Chicago, Illinois, USA). The differences between groups were considered significant if p-values were smaller than 0.05.

  Results Top

Initially, we recruited 324 patients. Eight of them refused to sign inform consent, 52 had poor cognitive function, and 24 had severe medical condition. Eventually, we collected 240 effective samples, with final enrolled sample being 74.1%.

[Table 1] describes sample demographic and clinical characteristics. [Table 2] compares the demographic and clinical characteristics between patients with and without constipation. Those with constipation had significantly higher PANSS average scores (p < 0.05), and a significantly lower concomitant use of FGA and SGA than those without (p < 0.05). We did not find other significant differences in demographic data, medications, and other clinical variants.
Table 1: Demographic and clinical characteristics in patients with schizophrenia (n=240)

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Table 2: Comparing clinical variables between patients with or without constipation

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The results of regression analysis for odds ratio (OR) (95% confidence interval [CI]) of the risk factor for constipation showed PANSS were 1.018 (1.003– .034), p < 0.05), that of using SGAs solely 3.475 (1.201–10.056, p < 0.05) and that of using anticholinergics 1.853 (1.024–3.353), p < 0.05) were all significant to predict constipation. Other medications, physical illness, demographic data did not show significance [Table 3].
Table 3: Logistic regression analysis of constipation in patients with schizophrenia

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  Discussion Top

In this study [Table 1], the prevalence of constipation was 59.8% (142/240). This number is higher than that in other studies. In general, constipation occurs in around 30% of patients using antipsychotics [18], although some studies showed a percentage over 50% [6],[7]. A possible explanation for this finding was that our patients referring from different counties or cities in Taiwan were generally chronically ill, longer in the duration of illness, and higher percentage of clozapine use (35.4% in this study, data not shown). In addition, patients in our hospital had easy access to a medical facility; medical staff could evaluate the possible constipation risks, which in turn resulted in having higher prescription of laxative use.

Compared to the patients without constipation group, those with constipation group [Table 2] had significantly higher PANSS average score (p < 0.05), and significantly lower concomitant use of FGA and SGA (p < 0.05). But multivariate statistical analysis [Table 3] showed that significantly higher PANSS (p < 0.05), using SGAs solely (p < 0.05) and using anticholinergics (p < 0.05) were significant risk factors of developing constipation. High PANSS implies more severe psychotic symptoms, which affects the patient's ability to do personal hygiene and self-care, putting these patients at risk of developing constipation. Regarding antipsychotics and constipation risk, Lu et. al. [18] pointed out that the use of SGAs and SGAs combined with FGAs is more likely to cause constipation than the use of FGAs alone. Our study [Table 3] also showed that using SGAs solely was significantly associated with constipation (p < 0.05). The reason using SGA solely results in higher association with constipation may also come from the mechanism the anticholinergic characteristics possessed by SGAs. But the concomitant use of FGAs and SGAs is not related to constipation in our study. This finding is contrary to the results of the study by Lu et al. [18]. We suggest that patients with concomitant use of SGAs and SGAs are more likely to have non multi-acting receptor-targeted antipsychotics, such as risperidone, ziprasidone, amisulpride, since 39.2% of patients in this study had a prescription of those drugs (data not shown).

Constipation is a disease easily neglected in the clinical setting and is hard to reveal unless asked actively by medical staff. Studies showed that 80% of schizophrenia patients have not reported their constipation problem to their physician [7]. Paralytic ileus, intestinal infarction, increased comorbidity even mortality may develop if a diagnosis of constipation was delayed or without appropriate treatment. Therefore, early examination and prevention are crucial in clinical practice.

Study limitations

The readers are warned not to over-interpret the study results because this study has five limitations:

  • The enrolled subjects were not randomly sampled from all institutionalized patients with schizophrenia in Taiwan. Thus, generalization of the results to populations with different backgrounds may be limited.
  • Although large samples were collected, the chronicity nature of this institute may only be able to present only a proportion of schizophrenia patients.
  • Our copies of questionnaire, such as levels of physical activity, high fiber diet, were not validated for its reliability, which may result in possible bias.
  • Although we considered the association of the previous history of cancer and abdominal surgery with constipation and put it into the exclusion criteria, there may still be other physical disease that could contribute to the possibility of constipation that we did not consider.
  • The existence of having a prescription of laxative in this study was considered having the condition of constipation could be erroneous. Many patients with laxative use can be habituated psychologically to the unneeded continuous use of laxative even their constipation was improved. Those patients could have refused the discontinuation of laxative, resulting in an increased prevalence of constipation.

Study summary

The prevalence of constipation in this study was around 60%. In this study, the risk factors of constipation in patients with schizophrenia included higher PANSS, using SGA solely, and using anticholinergic agents. In those who had severe psychotic symptoms, prescription of SGA or anticholinergic agents, the focus should be on early detection, monitoring the constipation side effect, and early intervention. By doing so, we can possibly prevent, decrease, or even delay the progression of constipation, eventually to achieve the goal of a better health care and quality of life for these patients.

  Financial Support and Sponsorship Top

This work was supported by a grant from the Yuli Hospital, Ministry of Health and welfare (YLH-IRP-10515 ), Hualien, Taiwan.

  Conflicts of Interests Top

The authors have no conflicts of interest to report.

  References Top

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  [Table 1], [Table 2], [Table 3]


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