Impact of the 1993 CDC surveillance definition of AIDS in Texas, 1991-1994.

In 1993, the Centers for Disease Control and Prevention (CDC) expanded the surveillance case definition of AIDS to include all individuals showing immune suppression, measured by absolute CD4 lymphocyte count or CD4/CD8 ratio, as well as those presenting with the 23 clinical conditions from previous case definitions or with three new indicator conditions (pulmonary tuberculosis, recurrent pneumonia, and invasive cervical cancer). The greatest impact of the expanded definition is the dramatic increase in cases reported in 1993, largely due to a backlog of 1992-diagnosed cases that meet the new criteria. Texas reported a 136% increase in cases in 1993 compared with 1992. Despite a drop between 1993 and 1994, the number of reported cases increased 75% overall between 1992 and 1994. Most cases reported in 1993 and 1994 fall under the 1993 expanded surveillance case definition (59% and 60%, respectively). More than 90% of all cases reported under the new definition are classified under immunologic criteria. The Department of Health and Human Services (DHHS) Public Health Region 4 was the most affected, with a 213% increase in reported cases between 1992 and 1993, and a 163% increase between years 1992 and 1994. In Texas, the new definition shows the greatest impact among women, blacks, and "other" ethnic groups, persons 20 through 29 years of age, and cases attributable to heterosexual contact. From 1992 to 1993, cases reported in Texas increased 161% among females, 171% among blacks, 219% among persons 15 through 19 years old, and 189% among cases citing heterosexual contact. The new definition has successfully identified population subgroups affected most recently by the epidemic. The inflated growth in cases caused by the expanded case definition carries implications for program administrators and health care providers in both allocating resources and targeting prevention efforts.