A retrospective study of the impact of comorbidity, polypharmacy and demographic factors on patient inclusion and healthcare delivery in phase I oncology trials

Background Phase I trials include patients with metastatic cancer and complex health conditions. Understanding baseline comorbidity and demographic features is critical to improving trial design. Methods We used electronic patient records to study the association of comorbidity, polypharmacy, and demographic factors on trial recruitment, time on trial, and health service utilisation. Results A cohort of 1671 patients was considered for allocation to a phase I study, of whom 518 patients were recruited to a phase I study and 1153 patients were not. A multivariable analysis revealed polypharmacy was associated with lower recruitment to phase I trials with an odds ratio of 0.95 (95% CI: [0.92, 0.99], p = 0.01), and a greater number of emergency admissions with a risk ratio of 1.1 (95% CI: [1.03, 1.17], p = 0.01). Interestingly, comorbidity was not associated with lower recruitment but was associated with a lower time on trial with a hazard ratio of 0.75 (95% CI: [0.62, 0.90], p ≤ 0.001). Demographic factors, including ethnicity, distance of residence from the hospital, and index of multiple deprivation, did not significantly influence these parameters. Conclusion Polypharmacy and comorbidity should be considered both in the design of phase I oncology trials and in planning for healthcare utilisation during these trials.