Psychological disorders and chronic constipation.

TO THE EDITOR: I read with interest Hosseinzadeh et al's paper (1). The aim of their study was to screen two categories of psychiatric disorders in chronic functional constipation, using HADS (Hospital Anxiety and Depression Scale) and MINI (Mini International Neuropsychiatric Interview) on fifty four constipated patients. They concluded that the prevalence of mood and anxiety disorders in constipated patients is much higher than general population and in order to reduce health care costs for constipated patients, we need to have an intervention program for co-morbid psychological dysfunctions which affect the course of gastrointestinal disorders.

We know that although constipation is less common in the Iranian population than in western countries (2, 3), there is substantial burden of it in Iranian population (4, 5). So determining the social and demographic factors of this disorder would be beneficial.

In Hosseinzadeh et al's paper (1) the authors claimed that constipated patients have a higher rate of both mood and anxiety disorders compared to general population by referring to some other studies about mood and anxiety in Iran (6) but this is not a justified conclusion because the authors did not study any controls in order to compare with constipated group. Therefore, this conclusion might not be realistic.

On the other hand, the sample size of this study seems to be low. We know that in clinical studies, if the sample size is too small, a well conducted study may fail to support the research hypothesis or may fail to detect important effects and associations (7). So a full case-control study with adequate sample size is recommended to compare the rate of psychological disorders in constipated people and healthy people.

THE AUTHORS REPLY: I read the letter of Dr. Pourhoseingholi on our paper entitled “Psychological disorders in patients with chronic constipation” which was published in the previous version of “Gastroenterology and Hepatology from Bed to Bench” (1). As he has mentioned in the letter, without a control group of healthy subjects, our conclusion about high rate of mood and anxiety disorders in constipated patients is unreliable. In research projects which use self-report instruments to study research variables, especially in the instruments which do not have cut-off points that make it possible for the researcher to get a clear image of his sample with regard to the variables of the study, control group makes it possible for the researcher to judge about the subjects more exactly. But in the research projects which take advantage of clinical interviews based of DSM-IV criteria of psychiatric disorders, in which the researcher can get a clinical and diagnostic image of the subject and the results of the diagnostic interview shows exactly the existence or absence of psychiatric disorders, the case can be different. In these projects you get the rate of disorders in the sample and just comparing it with the rate of same disorders in healthy subjects will make the health status of patient sample much clearer. So, in these cases that epidemiological studies based on DSM-IV criteria in healthy population exists, this studies can play the role of control group for your study.

On the other hand, using clinical interviews such as MINI which take longer time to be completed than self-report instruments usually used in studies concerning psychological status of medical patients such as SCL-90 and SF-36 (2), makes data collection more difficult and usually in the studies using these time-consuming methods the sample size is smaller (3).