Chapter 3: Methods for Clinical Research in Constipation: Subjective Measurement of Constipation

In the study by (Connell et al., 1965) of bowel habits in a healthy population 64 people considered themselves to be constipated. Of these, 39 had at least five bowel movements each week. Were these 39 people deluded?

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To put it simply, one can make no judgment about the quality of the study group's bowel function on the basis of this one measure. Other sensations, such as frequent straining, incomplete evacuation and rectal or abdominal pain, contribute to the symptom complex that is constipation, and may be more important to the individual than mere frequency of defecation.

This is not to deny that a sub-group of patients exists who have chronic complaints of constipation but in whom no defect of intestinal function can be found. These patients have been reported to contrast with those who have similar complaints, but whose intestinal transit time is found to be extended. Normal transit patients appear more likely to have an abnormal psychological profile in terms of somatization, depression and anxiety (Wald, Hinds and Caruana, 1990), and hypochondriasis and disease affirmation (Chattat et al., 1997), as compared with slow transit patients. It cannot be known how many such patients were present in Connell's study population.

Clearly, the effective therapies might differ between the two populations of constipated patients, one centering on correction of bowel motility, and the other on educational and behavioral techniques. In a constipation study that was testing the efficacy of a mode of treatment, it might therefore be important to know how many of each sort of patient was present in the group under investigation. Such a study would need both subjective and objective measures of constipation among its outcomes. Note that we are considering here otherwise healthy people who have a chronic history of complaints of constipation. Patients with normal transit may be quite common among this group (10 out of 25 in the study by Wald et al. Both groups had had symptoms for a mean of 10-15 years). Their symptoms may or may not be explained by abnormalities of defecation.

The situation among medically ill patients is different, in that few have previously had persistent problems with constipation. Those who have can readily be identified by a screening question. Among 93 palliative care patients with cancer, 78 reported that prior to illness they had rarely or never been constipated and only 4 had always been constipated. Now 50 of them experienced constipation all or most of the time (Sykes, unpublished observations). Thus, in the investigation of patients who have only recently become constipated, the likelihood that psychological factors are strongly influential in their symptomatology is much diminished. Hence, although subjective measures of constipation are always important in any clinical study, accompanying objective measures and perhaps psychological testing assume their greatest importance in the investigation of chronic idiopathic constipation.