Racial differences in the prevalence of monoclonal gammopathy in a community-based sample of the elderly.
OBJECTIVE
To determine if there is an increased prevalence of monoclonal gammopathy in elderly blacks compared with whites, analogous to the difference in incidence of multiple myeloma reported for the two racial groups and to confirm age and gender relationships.


METHODS
Subjects were from the Duke Established Populations for the Epidemiologic Study of the Elderly, selected on the basis of stratified random household sampling. Blacks were oversampled to allow for increased statistical precision in racial comparisons. In all, 1,732 subjects (aged > 70 years) consented to blood drawing and constitute the sample for this study. Monoclonal immunoglobulins were determined by agarose gel electrophoresis and immunofixation.


RESULTS
One hundred six subjects (6.1%) had a monoclonal gammopathy. There was a greater than twofold difference in prevalence between blacks (8.4%) and whites (3.8%) (P < 0.001); monoclonal gammopathy prevalence increased with age, and was greater in men than women. Those with monoclonal gammopathy did not differ from those without in socioeconomic status, urban/rural residence, or education. The presence of monoclonal gammopathy was not associated with any specific diseases nor with impaired functional status. There was a slight increase in serum creatinine levels and decrease in hemoglobin and albumin levels in patients with monoclonal gammopathy, but no difference in interleukin-6 (IL-6) levels. Moreover, IL-6 levels were not correlated significantly with the level of monoclonal protein.


CONCLUSIONS
Prevalence of monoclonal gammopathy is significantly greater among blacks than whites in a community-based sample, in approximately the same ratio that multiple myeloma has been reported in the two groups. Given the absence of correlation with environmental factors, there may be a biological racial difference in susceptibility to an early event in the carcinogenic process leading to multiple myeloma.
Cohen
H J
HJ
Department of Medicine and Comprehensive Cancer Center, Duke University Medical Center, Durham, North Carolina 27710, USA.
Crawford
J
J
Rao
M K
MK
Pieper
C F
CF
Currie
M S
MS
D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008403:Mass Screening; D009101:Multiple Myeloma / Q000208:ethnology; D009657:North Carolina / Q000453:epidemiology; D010265:Paraproteinemias / Q000208:ethnology* / Q000276:immunology; D015995:Prevalence; D012494:Sampling Studies; D017678:Sex Distribution; D044465:White People; D001741:Black or African American
D015850:Interleukin-6