Abstract
Background: Multiple myeloma (MM) is the most common hematologic malignancy in blacks with more than twice the incidence of non-black populations in national registry data. Prior studies have shown that blacks present with MM at an earlier age and have improved survival compared to non-blacks, contrary to the pattern in most malignancies. These findings have been theorized due to the effects of obesity, treatment variation, and disparities in care, in addition to alternate disease biology in black patients. In order to understand possible effects of race on outcomes while adjusting for confounders not available in other national datasets such as treatment, comorbidities, and baseline laboratory characteristics, we studied outcomes in a nationwide population of United States veterans with MM in the Veterans Health Administration (VHA).
Methods: Patients with MM were identified by the VHA Central Cancer Registry between September 1, 1999 and December 31, 2013 and followed through December 31, 2014. Age, sex, race, body mass index (BMI), Charlson (Romano) comorbidity index, treatment (including transplant), hemoglobin (hgb), albumin, renal function (eGFR), and statin use were included. Cox proportional hazards regression modeling was used to assess the association between black race and overall survival at five years while controlling for known prognostic factors. The study was approved the Saint Louis VA Medical Center institutional review board.
Results: 4805 patients were identified with MM, of which 1418 (29.5%) were black. Black patients were younger (66.2 years vs. 69.2, p<0.001) with increased mean comorbidity scores (3.7 vs. 3.0 p<0.001) compared to non-black patients. Black patients had lower mean BMI (27.0 years vs. 27.8, p<0.001) and higher rates of hgb <10 g/dL, 49.1% vs. 35.3%, p<0.001) and albumin below 3 g/dL (35.3% vs. 28.3% p<0.001) with similar rates of decreased renal function of eGFR <30 (22.1% vs. 21.2%, p=0.69) compared to non-black patients. Black patients underwent stem cell transplantation at similar rates (12.3% vs. 14.2%, p=0.09) and there no differences based on race in treatment with lenalidomide (35.1% vs. 36.0%, p=0.52), thalidomide (36.7% vs. 38.7%, p=0.20), or melphalan (32.7% vs. 34.8%, p=0.16). More black patients were treated with bortezomib compared to non-blacks (50.1% vs 44.4%, p<0.001). In unadjusted analyses, black race was associated with reduced risk of death at five years (Hazard Ratio [HR] 0.89, 95% CI 0.83-0.97). After controlling for age, comorbidity score, hgb, albumin, transplant, and treatment; black patients also had improved survival (HR 0.82, 95% CI 0.76-0.89). After adding BMI, year of diagnosis, and statin use to the final Cox model, black patients continued to have improved survival (HR 0.80, 95% CI 0.73-0.86).
Conclusions: Survival of black patients with MM was improved compared to non-blacks in the VHA, a national comprehensive care delivery system. Black patients also received similar therapies compared to non-blacks, while presenting at a younger age with more comorbidities. These results are strengthened after adjusting for treatments and patient characteristics not available in other large data studies. Despite increased incidence of MM in the black population, outcomes are improved, similar to other large studies of patients in the United States. Alternate disease biology may be responsible for improved survival and further studies of MM based on race are appropriate.
Carson:Flatiron Health: Employment; Washington University in St. Louis: Employment; Roche: Consultancy. Sanfilippo:BMS/Pfizer: Speakers Bureau.
