Prevalence of monoclonal gammopathy of undetermined significance in an elderly urban Korean population

Research on the epidemiology of monoclonal gammopathy of undetermined significance (MGUS) is limited in Korea. The aim of this study was to determine the prevalence and characteristics of MGUS in an elderly urban Korean population. A random sample of 1118 Korean elders was selected from residents aged 65 years or older living in Seongnam, Korea 1 year from August 2005. We obtained plasma samples remaining after scheduled tests for the Korean Longitudinal Study on Health and Aging. The mean age of the study population was 72 years (range, 65-97 years). To screen for MGUS, immunofixation and free light-chain (FLC) assays were performed. Age-adjusted and gender-adjusted MGUS prevalence rates in 680 responders were estimated as 3.3% [95% confidence interval (CI) = 2.0-4.6%], and the estimated age-adjusted prevalence of MGUS was 4.3% in men (95% CI = 1.9-6.6%) and 2.6% in women (95% CI = 1.0-4.2%). Abnormal FLC ratios were detected in 10% of MGUS cases. Multivariate analysis of 945 participants revealed that significant risk factors for MGUS included advanced age, male sex, hyperproteinemia, increased erythrocyte sedimentation rate, and abnormal FLC ratio. MGUS is less prevalent among elderly Koreans (3.3%) than other races. This is the first study to estimate the prevalence of MGUS in the Korean elderly population. Our findings should be confirmed with additional studies analyzing follow-up samples from 2010.