Determinants of clinical trial participation in multiple myeloma: A population-based cohort study from British Columbia.

BACKGROUND

Clinical trials play a central role in advancing therapy for multiple myeloma (MM), yet participation remains limited and may be influenced by clinical, geographic, and socioeconomic factors. The extent to which these factors shape trial participation and whether participation is independently associated with overall survival (OS) in real-world MM populations remain uncertain, particularly within centralized healthcare systems.

METHODS

We conducted a retrospective cohort study of adult patients with MM treated at two tertiary referral centers in British Columbia between 2000 and 2023. Patients were classified as clinical trial participants or non-participants. Demographic, clinical, geographic, and socioeconomic variables, including area-level measures of deprivation, were compared between groups. Univariable and multivariable Cox proportional hazards models were used to evaluate associations with OS.

RESULTS

The cohort included 599 patients, of whom 80 (13.4%) participated in at least one clinical trial. Trial participants were more likely to reside closer to the treating center, live in urban areas, and demonstrate better performance status and lower comorbidity burden. Age and most socioeconomic measures were not associated with trial participation, except for situational vulnerability. Clinical trial participation was associated with improved OS on univariable analysis (median OS 121.7 vs. 93.9 months; hazard ratio [HR] 0.69, 95% CI 0.51-0.95). Autologous stem cell transplantation and performance status remained the strongest independent predictors of OS.

CONCLUSIONS

In this real-world cohort, clinical trial participation in MM was primarily associated with clinical fitness and geographic proximity rather than socioeconomic status. Apparent survival differences between trial participants and non-participants were largely explained by selection effects. Efforts to improve trial access should prioritize reducing geographic and logistical barriers and broadening eligibility where appropriate.