Intestinal transit time in the population calculated from self made observations of defecation

To assess the feasibility of estimating intestinal transit time in the general population using self recorded data on stool form, frequency of defecation, and the interdefecatory time interval.

Prospective measurement of bowel function.

Bristol, Avon, UK between 1987 and 1989.

Subjects were drawn from 1897 people who comprised 72.2% of a stratified random sample of all men aged 40-69 years and women aged 25-69 years on the lists of 19 general medical practitioners. Altogether 1561 subjects (59.4%) recorded bowel function and a subsample of 98 (50 women and 48 men) had intestinal transit time measured.

The interdefecatory time interval and stool form (on a validated 1-6 scale sensitive to transit time) were recorded prospectively from three consecutive defecations. In the subsample the mean intestinal transit time was measured simultaneously using a four marker, two stool x ray technique. Multiple regression analysis was used to assess the extent to which intestinal transit time could be predicted from the defecatory data. The formulas obtained were then applied to the whole study population. In women, intestinal transit time was best predicted by the formula 103-1.23 (DF)--4.69 (SFS)+0.638 (IDTI), where DF is the stated defecation frequency per week, IDTI is the interdefecatory time interval, and SFS is the sum of the three stool form scores, for which the correlation coefficient r = 0.736. For men the intestinal transit time = 79-1.33 (DF)--1.88 (SFS)+0.329 (IDTI), for which the correlation coefficient r = 0.541. The predicted intestinal transit time was longer in women than men at equivalent ages. Women of childbearing age had longer transit times than older women.

Observations made by untrained subjects can be used to estimate intestinal transit time in epidemiological studies. A gender related difference in transit time exists.