1711P - Opioid-induced constipation in patients with cancer pain in Japan: Prospective observational study using Rome IV OIC diagnostic criteria (OIC-J Study)

Abstract

Background: Opioid-Induced Constipation (OIC) is a common side effect of opioid analgesic therapy. However, there were no prospective studies to assess the incidence of OIC of cancer patients. The aim of this study was to evaluate the incidence of OIC from the start of opioid therapy. Methods: This study was a multicenter, prospective, observational study of cancer patients who started opioid therapy in Japan (UMIN000025864). The incidence of OIC was determined by ROME IV OIC diagnostic criteria based on the record of patient diary for 14 days. The proportion of patients with OIC was calculated for each 1-week period (Week 1 and Week 2) and overall 2-week period. Medication for constipation was allowed during the study period. Patients with <3 bowel movements in the previous week before starting opioid therapy were not allowed to be enrolled. Bowel Function Index (BFI; score >28.8), spontaneous bowel movement (SBM; <3 SBM/week), and physicians’ assessment were also utilized to assess OIC and compare the results. Results: In total, 212 cancer patients (145 males; mean age 69.1 years)—inpatients and outpatients—with ECOG Performance Status score of 0-2 were included in the study. Mean morphine equivalent dose was 21.9 mg/day. Overall incidence rate of OIC during 2 weeks by weekly diagnosis of Rome IV criteria (total proportion diagnosed as OIC in either Week 1 or Week 2) was 56.1%. The proportion of patients with OIC in Week 1 was 47.6% and in Week 2 was 36.8%. Use of prophylactic laxative reduced the overall incidence rate of OIC from 65.0% to 47.7%. Other diagnostic criteria instead of Rome IV criteria varied the rate; BFI (59.1%), physicians’ assessment (61.4%), SBM frequency (44.8%). When overall 2-week period data were applied to Rome IV OIC criteria, the incidence rate was reduced to 44.2%. Sex and age were not considered as risk factors as opposed to the previous report in some cross-sectional studies. The frequency of SBM/week before starting opioids was identified as the most influencing factor for OIC. Conclusions: OIC can occur quickly after the initiation of opioid therapy in cancer patients, even if laxatives were utilized prophylactically. The current tools for diagnosing OIC result in varied rates of diagnosis. Clinical trial identification: UMIN000025864. Legal entity responsible for the study: Shionogi & Co., Ltd. Funding: Shionogi & Co., Ltd. Disclosure: T. Harada: Honoraria: Taiho Pharmaceutical, AstraZeneca K.K., Boehringer Ingelheim, Hisamitsu Pharmaceutical Co, Inc. H. Sato: Employee: Shionogi & Co., Ltd. All other authors have declared no conflicts of interest.