The impact of opioids, anticholinergic medications and disease progression on the prescription of laxatives in hospitalized palliative care patients: a retrospective analysis

Definitive risk factors for constipation in palliative care remain poorly defined. A retrospective analysis of 211 admissions to a palliative care unit was undertaken, with the main aim being to identify some factors, which influence laxative prescription. On univariate analysis, significant unadjusted associations were found between two or more prescribed laxatives and a diagnosis of malignancy, morphine equivalent dose, type of illness phase and the subsequent phase type, length of phase, anticholinergic load imposed by medications, symptom severity and functional status. Multiple ordinal logistic regressions revealed the prescription of one laxative to be significantly associated with oral morphine-equivalent dose, total anticholinergic load (odds ratio [OR] 1.4, 95% CI = 1.0 - 2.0), disease progression to terminal phase and death (OR 0.1, 95% CI = 0.0 - 0.3), and length of phase (OR 1.1, 95% CI = 1.0 - 1.2). Similar results were obtained for the prescription of two or more laxatives. Two additional measures of function, toileting (OR 3.6, 95% CI = 1.6 - 8.2) and transfer (OR 0.4 95% CI = 0.2 - 0.9), also became significant. Total anticholinergic load was significantly associated with the prescription of a single laxative (OR 1.4, 95% CI = 1.0 - 2.0) and two or more laxatives (OR 1.8, 95% CI = 1.3 - 2.5) for each unit increase in anticholinergic load. Opioids and in particular opioids prescribed at higher doses, the total anticholinergic load associated with prescribed medications, the degree of impaired physical function of a person, their length of stay in a palliative care unit and their proximity to death were all strongly related to the prescription of laxatives.