Comparison of Comorbidity Models Within a Population-Based Cohort of Older Adults With Non-Hodgkin Lymphoma

PURPOSE Compare the association of individual comorbidities, comorbidity indices, and survival in older adults with non-Hodgkin lymphoma (NHL), including in specific NHL subtypes. METHODS Data source was SEER-Medicare, a population-based registry of adults age 65 years and older with cancer. We included all incident cases of NHL diagnosed during 2008-2017 who met study inclusion criteria. Comorbidities were classified using the three-factor risk estimate scale (TRES), Charlson comorbidity index (CCI), and National Cancer Institute (NCI) comorbidity index categories and weights. Overall survival (OS) and lymphoma-specific survival, with death from other causes treated as a competing risk, were estimated using the Kaplan-Meier method from time of diagnosis. Multivariable Cox models were constructed, and Harrel C-statistics were used to compare comorbidity models. A two-sided P value of <.05 was considered significant. RESULTS A total of 40,486 patients with newly diagnosed NHL were included. Patients with aggressive NHL had higher rates of baseline comorbidity. Despite differences in baseline comorbidity between NHL subtypes, cardiovascular, pulmonary, diabetes, and renal comorbidities were frequent and consistently associated with OS in most NHL subtypes. These categories were used to construct a candidate comorbidity score, the non-Hodgkin lymphoma 5 (NHL-5). Comparing three validated comorbidity scores, TRES, CCI, NCI, and the novel NHL-5 score, we found similar associations with OS and lymphoma-specific survival, which was confirmed in sensitivity analyses by NHL subtypes. CONCLUSION The optimal measure of comorbidity in NHL is unknown. Here, we demonstrate that the three-category TRES and five-category NHL-5 scores perform as well as the 14-16 category CCI and NCI scores in terms of association with OS and lymphoma-specific survival. These simple scores could be more easily used in clinical practice without prognostic loss.