Predictive factors for plasma cell disorders in African American patients: A community practice perspective.

Abstract

e19508 Background: African Americans have over two-fold higher incidence of multiple myeloma (MM) compared to other ethnic groups in the United States. Screening tests for MM are most often done when patients present with features suggestive of anemia, renal impairment, hypercalcemia, hypergammaglobulinemia or lytic bone disease, although MM may present with other manifestations. We carried out a retrospective study to investigate the potential clinical variables predictive of plasma cell disorders (PCD) in African American population. Methods: We reviewed the charts of African American patients who had serum protein electrophoresis, immunofixation and serum free light chain levels from 2007 to 2012. We defined traditional triggers for MM workup as hemoglobin (Hb) < 11 g/dL, serum creatinine (Cr) > 1.3 mg/dL, corrected serum calcium (Ca) > 10.5 mg/dL, albumin to globulin ratio (A:G ratio) < 1, and osteopenia or lytic lesion on DEXA scan/X-ray. PCD was defined as monocloncal gammopathy of unknown significance (MGUS), smoldering MM, MM, light chain MGUS or light chain only MM. Results: 254 patients were eligible. Mean and range of age, Cr, Ca, A:G ratio, Hb, total white blood cell, absolute neutrophil and platelet counts were 60 years (21 - 95), 1.05 mg/dL (0.49 - 9.6), 9.5 mg/dL (8.5 - 11), 1.07 (0.31 - 3.08), 11.7 g/dL (5.7 - 16.5), 6 x 103/mm3 (1.9 - 26), 3675 x 103/mm3 (192 - 11765) and 237 x 103/mm3 (22 - 1262), respectively. Twelve (13%) out of 92 patients without traditional trigger variables had PCD. In contrast, 50 (31%) out of 162 patients with trigger variables had PCD (composed of 48% MGUS, 8% smoldering MM, 14% MM, 25% light chain MGUS and 2% light chain only MM). There is a significant association between the presence of trigger variables and PCD (χ2= 9.16, p = .002). The number of trigger variables is positively correlated with the likelihood of a PCD (Spearman’s rho = .22, p < .001). So is increasing age (Spearman’s rho = .29, p < .001) in patients with trigger variables. However, age is not predictive of PCD in patients without trigger variables (rho = .1, p = .34). Conclusions: The number of traditional trigger variables and increasing age (especially over 50 years) are predictive of PCD in African American population.