Multiple myeloma: unplanned diagnostic pathways and association with risk factors and survival - a nationwide register-based cohort study in Denmark.

Background: Multiple myeloma often presents with vague and non-specific symptoms. Many patients are diagnosed in unplanned rather than elective (planned) diagnostic pathways. This study investigates the diagnosis of multiple myeloma in unplanned pathways and the association with patient characteristics, disease profile, and survival.

Methods: We conducted a nationwide register-based study, including all patients diagnosed with multiple myeloma in Denmark in 2014-2018. Patients were categorised as diagnosed in an unplanned pathway if registered with an acute admission within 30 days prior to the multiple myeloma diagnosis and no other previously registered pathway to this diagnosis. Unplanned pathways were compared to all other pathways combined.

Results: We included 2,213 patients diagnosed with multiple myeloma, hereof 32% diagnosed in an unplanned pathway. Comorbidity, no prior cancer diagnosis, a history of few visits to the general practitioner (GP), multiple myeloma complications at diagnosis, high-risk cytogenetics, and advanced cancer stage were associated with a higher probability of being diagnosed in an unplanned pathway. For example, 24.4% (95% confidence interval (CI): 21.8-27.0) of patients with low comorbidity (Charlson Comorbidity Index (CCI) score 0) were diagnosed in an unplanned pathway as were 50.9% (95% CI: 45.6-56.1) of patients with high comorbidity (CCI score 3+). For patients with dialysis need at the time of diagnosis the probability was 66.0% (95% CI 54.2-77.8) and 30.9% (95% CI: 28.9-32.9) for patients with no dialysis need. Patients diagnosed in an unplanned pathway had inferior survival (hazard ratio 1.44 (95% CI: 1.26-1.64)). However, this association was not seen in analyses restricted to patients surviving for more than three years.

Conclusions: High comorbidity level, few usual GP visits, advanced disease status at diagnosis, and complications were associated with diagnosis in an unplanned pathway. Further, patients diagnosed in an unplanned pathway had inferior survival. Promoting earlier diagnosis and preventing unplanned pathways may help improve survival in multiple myeloma.