Serum beta 2-microglobulin and prediction of progression to AIDS in HIV-infected injection drug users.

Several immunological and serological variables have become established in recent studies as valuable markers to identify human immunodeficiency virus (HIV)-positive individuals at the highest risk for rapid disease progression. These studies have been performed mainly in cohorts of homosexual men. In this study, we assessed the usefulness of CD4 lymphocyte count, serum beta 2-microglobulin concentration, and the presence of p24 antigen as predictors of AIDS in a cohort of 130 HIV-positive injection drug users (IDUs) followed-up for 1 to 67 months. Progression to AIDS was most strongly associated with reduced absolute numbers of CD4+ lymphocytes at baseline, but increases in beta 2-microglobulin levels at baseline were an independent predictor of outcome. After stratification by baseline CD4 count, beta 2-microglobulin concentration added significant prognostic information to CD4 count among IDUs with > 500/mm3 CD4 cells (Breslow statistic value, 5.84, p = 0.01). Thus among seropositive IDUs with normal CD4 counts, increases in beta 2-microglobulin may be used as an early marker of individuals with higher risk of progression to AIDS, who may benefit from more intensive laboratory monitoring or clinical management.