Opioid-induced constipation in patients with cancer pain in Japan (OIC-J study): a post hoc subgroup analysis of patients with gastrointestinal cancer

BACKGROUND Constipation is a common side effect of opioid therapy. An observational study of opioid-induced constipation (OIC) in Japanese patients with cancer (OIC-J) included 212 patients with various tumor types. This post hoc analysis of OIC-J evaluated a subgroup of patients with gastrointestinal (GI) cancer. METHODS Patients were aged ≥ 20 years, starting strong opioid therapy, had an ECOG PS of ≤ 2, and must have had ≥ 3 bowel movements during the week before enrollment. OIC was evaluated for 2 weeks after opioid initiation using the Rome IV diagnostic criteria for colorectal disorders, as well as physician's diagnosis, number of spontaneous bowel movements, Bowel Function Index score, and patient's self-assessment. Relationships between baseline characteristics and OIC incidence, and the effects of OIC on quality of life (QOL) were also explored. RESULTS Fifty patients from OIC-J who had GI cancer [colon (50%), stomach (28%), and esophageal (22%)] were included. OIC incidence varied by which diagnostic criteria were used (46.0-62.0%) and occurred rapidly after initiating opioid therapy. The use of prophylactic laxatives reduced the overall incidence rate of OIC from 71.0% to 47.4%. No baseline characteristics, except comorbidities, were associated with OIC incidence. Change from baseline to day 15 in PAC-SYM total score was significantly greater for patients with OIC versus those without OIC (0.188 versus -0.362; P = 0.0011). CONCLUSIONS This post hoc analysis suggests that OIC occurs rapidly in patients with GI cancer after initiating opioid therapy, and negatively impacts QOL. Early and effective intervention strategies may be particularly useful in this group. ADDITIONAL INFORMATION Coauthor Makio Gamoh is deceased.