Modified colonic transit test in healthy subjects and constipated patients: A triple-phase, two-center prospective study.

Background And Aim: Classic daily-ingestion single-film protocol using radiopaque markers for colonic transit time (CTT) is unsuitable for Chinese patients because of rapid colonic motility. A new modified method needs to be established.

Methods: The triple-phase study was performed. In Phase I, the classic protocol was assessed to evaluate its feasibility for Chinese subjects. In Phase II, a modified protocol was performed in two centers on 180 healthy subjects and 90 constipated patients to determine optimal conditions. In Phase III, the simplified protocol was validated on 90 constipated patients.

Results: All the subjects of the Phase I expelled more than 95% of the markers during the examination period, which means that the classic protocol is unsuitable for Chinese patients. The 20.9-h mean total CTT for healthy Chinese subjects was much faster than that seen in Western countries. As shown by Phase II, the numbers of subjects went beyond the upper limit were 22 in P1TCTT and 10 in P2TCTT (8.14% vs 3.70%, P = 0.029). The percentage of values fall outside of the measurement range of excretion ratio was around half of our study subjects (45-70%), whereas this percentage was only 3.70% using P2TCTT. The simplified protocol had a diagnostic accuracy for constipation of 0.81, with a sensitivity and specificity of 0.46 and 0.97, respectively.

Conclusions: Colon movement in Chinese individuals is significantly faster than that of Western populations. The modified protocol generated in this study is appropriate for diagnosis of constipation in population with rapid colon motility.