Survival after AIDS diagnosis in Washington State: trends through 1989 and effect of the case definition change of 1987.

Survival analysis was performed for AIDS cases diagnosed in Washington state from 1982 through 1989 and reported through October 31, 1991. No difference in survival time among diagnosis years 1987, 1988, and 1989 (p = 0.29) was found. Since September 1987, survival time was longest for cases with human immunodeficiency virus (HIV) wasting syndrome and HIV encephalopathy. Adjusted risk for death was significantly lower for these cases relative to all other cases (relative risk, 0.5; 95% confidence interval, 0.4-0.6). Explanations for the absence of continuing increase in survival time between 1987 and 1989 include changes in the frequency and timing of anti-HIV therapy. Longer survival time among cases diagnosed with HIV wasting or HIV encephalopathy is likely due to diagnosis earlier in the course of HIV disease. These results emphasize how changes over time in the definition of AIDS and evolving therapeutic standards may affect assessment of survival time when using surveillance data.