Table 1.

Frequently used assessment tools and outcome measures for OIC²⁶

Category	Assessment tool/outcome measure
Objective measures*	Bowel movement frequency/change in bowel movement frequency Time to laxation Laxation within 4 h Gastrointestinal (or short bowel) transit time Bristol Stool Form scale
Patient-reported outcome measures†	Bowel Function Index Patient Assessment of Constipation – Symptoms Global Clinical Impression of Change
Patient-reported burden measures of OIC‡	Constipation distress Patient Assessment of Constipation – Quality of Life

^*Objective measures: Could theoretically be collected by an investigator as well as by the patient (eg, defecation frequency).

^†Patient-reported outcome measures: ‘Reports coming directly from patients about how they feel or function in relation to a health condition and its therapy without interpretation by healthcare professionals or anyone else’.⁶¹

^‡Patient-reported burden measures of OIC: Patient-reported outcome measures that directly relate to the patient’s distress and the impact on their daily activities or QoL and are most obviously caused by OIC. OIC, opioid-induced constipation.