Performance characteristics of scintigraphic colon transit measurement in health and irritable bowel syndrome and relationship to bowel functions

Abstract

Background: The inter- and intra-subject variations of scintigraphy, which are used to identify colonic transit disturbances in irritable bowel syndrome (IBS), are unclear. The relationship between colonic transit and bowel functions is incompletely understood. To assess inter- and intra-subject variations of scintigraphic colonic transit measurements in 86 IBS patients and 17 healthy subjects and to quantify the relationship between colonic transit and bowel symptoms in 147 IBS patients and 46 healthy subjects.

Methods: Data from participants with multiple colonic transit measurements were analysed. Primary end points were colonic filling at 6 h (CF6h) and geometric center (GC) at 24 and 48 h for colonic transit. Bowel functions were assessed by daily stool diaries.

Key results: Inter- and intra-subject variations were greater for small intestinal than colonic transit. Overall, inter- and intra-subject variations were relatively narrow for colonic transit (both GC24h and GC48h, with lower COV at 48 h); there was little intra-subject variation in health and IBS-constipation over a period of <or=3 weeks and over 2.0 years (median, range 0.1, 11.0 years). Significant intra-individual differences in GC24h were observed only in IBS-D patients. Colonic transit was significantly associated with stool form (accounting for 19-27% of the variance), frequency (19%), and ease of stool passage (12%).

Conclusions & inferences: Despite inter-subject variation in scintigraphic colonic transit results, the intra-subject measurements are reproducible over time in healthy volunteers and patients with IBS; significant changes in colonic transit at 24 h were observed only in IBS-D. Colonic transit is associated with stool form, frequency and ease of passage.

Keywords: inter-subject; intra-subject; reproducibility; variation.

Figure 1

Bland-Altman plots showing short-term intra-subject variation of colonic transit at 24h and 48h in IBS patients with diarrhea or constipation. Plot shows 1 standard deviation as the interrupted lines. Note most data are well within 1 SD which is ~0.7 GC units (y axis)

Figure 2

Bland-Altman plots showing long-term intra-subject variation of colonic transit at 24h and 48h for participants in different subgroups. Plot shows 1 standard deviation as the interrupted lines. Note most data are well within 1 SD which is ~0.9 GC units (y axis). Note that the greatest variation occurs in IBS patients with diarrhea and the variation is greater at 24h than at 48 h.

Figure 3

Change in geometric center in different subgroups expressed as means and 95% confidence intervals. Note that the 95% confidence interval for IBS-D subgroup does not cross the zero line, indicating a significant difference in colonic transit for the IBS-D subgroup, but not for the other groups.

Figure 4

Effect of time interval in years between consecutive measurements on colonic transit measurements. There does not appear to be a difference in the variation of colonic transit when the interval is between 1 and 6 years. The numbers of participants studied > 6 years apart is too small to assess the variation beyond 6 years.

Figure 5

Relationship between bowel function and colonic transit: the regression formulae are shown for the relationships between colonic transit at 24h and stool form, frequency and ease of passage and the relationship between colonic transit at 48h and stool form. The full lines represent the regression. Confidence and prediction interval lines our represented by the interrupted and dotted lines respectively.