A Study of the Effect of Linaclotide on Abdominal Girth in Participants With Irritable Bowel Syndrome With Constipation (IBS-C)

Mean change in abdominal girth (physical measure of bloating/distension) as measured by area under the curve (AUC), determined by 24-hour abdominal inductance plesthymography (AIP; with hourly averages). The AUC was calculated using the Trapezoidal method from the first reliable hour of measurement to last measurement (bedtime). The AUC for each participant was then individually standardized by dividing the total AUC over the period by that patient's number of hours of measurement included in the AUC. (Therefore, the time element was removed from the standardized AUC, and the unit of measure for this outcome is centimeters [cm]).

Mean change in abdominal girth (physical measure of bloating/distention) as measured by AUC, determined by 24-hour AIP (with hourly averages). The AUC was calculated using the Trapezoidal method from the first reliable hour of measurement to last measurement (bedtime). The AUC for each participant was then individually standardized by dividing the total AUC over the period by that patient's number of hours of measurement included in the AUC. (Therefore, the time element was removed from the standardized AUC, and the unit of measure for this outcome is centimeters [cm]).

The maximum change in girth from the first hour, over the period from the 2nd hour to bedtime. The percentage change in maximum distension from baseline to 4 weeks will also be calculated.

Symptom severity was assessed daily on an 11-point numerical rating scale (NRS) from 0 to 10, where 0 represents no symptoms and 10 represents very severe symptoms. Participants rated their abdominal pain, discomfort, bloating, and distension at its worst over the last 24 hours. Weekly average scores were calculated individually for abdominal pain, discomfort, bloating, distension. The abdominal score was calculated as the weekly average from the daily scores of the individual items of pain, discomfort, bloating combined. The abdominal score plus distension was calculated as the weekly average from the daily scores of the individual items of pain, discomfort, bloating and distension combined.

Symptom severity was assessed daily on an 11-point NRS from 0 to 10, where 0 represents no symptoms and 10 represents very severe symptoms. Participants rated their abdominal pain, discomfort, bloating, and distension at its worst over the last 24 hours. Weekly average scores were calculated individually for abdominal pain, discomfort, bloating, distension. The abdominal score was calculated as the weekly average from the daily scores of the individual items of pain, discomfort, bloating combined. The abdominal score plus distension was calculated as the weekly average from the daily scores of the individual items of pain, discomfort, bloating and distension combined.

Symptom severity was assessed daily on an 11-point NRS from 0 to 10, where 0 represents no symptoms and 10 represents very severe symptoms. Participants rated their abdominal pain, discomfort, bloating, and distension at its worst over the last 24 hours. Weekly average scores were calculated individually for abdominal pain, discomfort, bloating, distension. The abdominal score was calculated as the weekly average from the daily scores of the individual items of pain, discomfort, bloating combined. The abdominal score plus distension was calculated as the weekly average from the daily scores of the individual items of pain, discomfort, bloating and distension combined.

Symptom severity was assessed daily on an 11-point NRS from 0 to 10, where 0 represents no symptoms and 10 represents very severe symptoms. Participants rated their abdominal pain, discomfort, bloating, and distension at its worst over the last 24 hours. Weekly average scores were calculated individually for abdominal pain, discomfort, bloating, distension. The abdominal score was calculated as the weekly average from the daily scores of the individual items of pain, discomfort, bloating combined. The abdominal score plus distension was calculated as the weekly average from the daily scores of the individual items of pain, discomfort, bloating and distension combined.

A digestive sensations questionnaire was used to record abdominal pain, discomfort, bloating, and distension symptoms on an hourly basis (waking hours only) during the 24 hours the participants are fitted with the AIP belt, using an 11-point NRS, with 0=no symptomatic sensations and 10=most severe symptomatic sensations. Daily diary scores for each of the digestive symptoms was averaged to obtain 'weekly' scores.

A digestive sensations questionnaire was used to record abdominal pain, discomfort, bloating, and distension on an hourly basis (waking hours only) during the 24 hours the participants are fitted with the AIP belt, using an 11-point NRS, with 0=no symptomatic sensations and 10=most severe symptomatic sensations. Daily diary scores for each of the digestive symptoms was averaged to obtain 'weekly' scores.

Daily stool consistency analyses were performed using the 7-point Bristol Stool Form Scale (BSFS), whereby a score of 1 = separate hard lumps like nuts (difficult to pass); 2 = sausage shaped but lumpy; 3 = like a sausage but with cracks on surface; 4 = like a sausage or snake, smooth and soft; 5 = soft blobs with clear-cut edges (passed easily); 6 = fluffy pieces with ragged edges, a mushy stool; and 7 = watery, no solid pieces (entirely liquid). Daily average recorded BSFS scores for each participant were computed for each week.