Comparison of subjective and objective measures of constipation - Employing a new method for categorizing gastrointestinal symptoms

INTRODUCTION: Correlations between subjective and objective measures of constipation have seldom been demonstrated. This could be due to multiple confounding factors in clinical studies and the broad span of symptoms represented in questionnaires used to assess constipation. We developed a new method for categorizing gastrointestinal (GI) symptoms into relevant symptom groups, and used this in a controlled experimental study aimed to investigate whether GI transit times and colonic volumes were correlated to self-reported GI symptoms.

METHODS: Twenty-five healthy male participants were enrolled in a randomized, double-blinded, placebo-controlled, five-day crossover study with the treatments oxycodone and placebo. Objective measures of GI transit times and colonic volumes were obtained by the means of the 3D-Transit System and magnetic resonance colonography, whereas subjective GI symptoms were measures via three validated questionnaires. The symptoms were then categorized into five groups; "abdominal symptoms", "defecation difficulties", "incomplete bowel evacuation", "reduced bowel movement frequency", and "stool symptoms". Spearman's rank order correlation was used to determine correlations between the five groups of symptoms and the objective measures.

RESULTS: No correlations between the GI symptoms and transit times or colonic volumes were found (all P > 0.05).

DISCUSSION: GI transit times and colonic volumes were not correlated to self-reported GI symptoms even in a controlled experimental study and when symptoms were categorized into relevant symptom groups. Thus, both subjective and objective measures must be considered relevant when assessing constipation in clinical and research settings, ensuring that both physiological aspects as well as the severity and impact of symptoms experienced by patients can be assessed.