Objective: To study neutropenia hospitalization (NH) incidence and risk factors in a population-based sample of older adults with non-Hodgkin's lymphoma (NHL) and evaluate the validity of inferences from Surveillance, Epidemiology and End Results (SEER)-Medicare linked databases.
Methods: NHL cases receiving first-course chemotherapy were identified from Iowa SEER-Medicare. Survival methods evaluated NH risk factors. Medical record and Medicare claims data on chemotherapy and NH were compared.
Results: Of 761 subjects, 165 (21.7%, 95% CI: 18.8, 24.6) were hospitalized for neutropenia. Of those hospitalized, 41% were hospitalized in cycle 1 and 22% in cycle 2. Significant multivariable risk factors for NH were diffuse large cell histology, renal disease, Charlson comorbidity index, and anthracycline chemotherapy but not patient age. Medicare and medical records agreed on month of chemotherapy initiation 95% of the time and chemotherapy type 95% of the time. ICD-9 code 288.0 sensitivity for NH was 80%.
Conclusions: Neutropenia hospitalizations were common in the first 2 chemotherapy cycles, especially among older adults with comorbidity. Findings conflict with a prior medical records study in which age was a risk factor for NH and dose intensity a negative confounder. Valid inferences about age effects on chemotherapy toxicity require more clinical detail than is available in administrative data.