More opioids, more constipation? Evaluation of longitudinal total oral opioid consumption and self-reported constipation in patients with cancer.

Abstract

211 Background: Constipation is a distressing physical symptom inadequately assessed in patients with cancer. Total opioid consumption may impact opioid-induced constipation (OIC) prevalence. This study examined total daily opioid consumption on self-reported constipation in patients with cancer. Methods: We performed a retrospective analysis in patients who had a histologically-confirmed cancer diagnosis and completed at least 2 outpatient PC visits at an academic palliative care (PC) clinic. At each PC visit, we collected self-reported constipation scores (11-point scale, 0 [no symptom] to 10 [worst symptom]) and 24-hour oral morphine equivalents (OME) for up to 5 visits. Spearman correlation examined the association between OME and presence of constipation rated ≥3 and Wilcoxan-Mann-Whitney examined OME between patients with or without constipation. Univariable logistic regression examined associations of independent variables on constipation. Results: We identified 404 patients with cancer (mean age 55.5±14.3 years, 61.9% women, 89% metastatic disease). The most common cancer types were gastrointestinal (n = 115; 31%) and gynecologic (n = 47; 13%). Stimulant laxative use was observed in 172 (44.9%) patients. Across all visits, we observed a weak association between OME and patient-reported constipation score (r = 0.16-0.24, p < 0.05 for 4 of 5 visits). Mean OME increased, while mean constipation score decreased across visits. At the first visit, higher mean OME was seen in patients who self-reported constipation (128.8 vs 92.3; p < 0.05). In contrast, for each subsequent clinic visit there was no difference in mean OME in patients with or without constipation. Age, sex, metastatic disease, and stimulant laxative use were not associated with constipation. Conclusions: A weak association was observed between OME and self-reported constipation in cancer patients across multiple palliative care visits. Except for the first clinic visit, there was no difference in OME and self-reported constipation scores. These results suggest a lack of a clear association between total opioid consumption and patient-reported constipation.