THE ASSUMPTION OF NO LONG REPORTING DELAYS MAY RESULT IN UNDERESTIMATES OF UNITED-STATES AIDS INCIDENCE

Objective: To evaluate the effect of the assumption of no long reporti ng delays on estimates of AIDS incidence. Design: Reported AIDS cases must be adjusted for reporting delays to estimate AIDS incidence. We c ompared the adjustments supplied with the Centers for Disease Control and Prevention (CDC) AIDS Public Information Data Set with a set of ad justments that differ with respect to CDC assumption of no long delays . Both methods assume that no changes in delay have occurred throughou t the reporting period. Methods: Probability distributions of reportin g delays were calculated from the delay adjustment weights supplied by CDC, and from an alternative method that estimates the probability of long delays from the surveillance data. AIDS incidence estimates from these two approaches were calculated and compared. Results: The CDC a djustments assume that there will be no reporting delays longer than 6 1 months, whereas the alternative method estimates that 5.9% of case r eports will be delayed longer than 61 months. The CDC adjustments resu lt in lower estimates of AIDS incidence and a flattening of the epidem ic. Conclusions: In addition to a 6.2% reduction in total estimated AI DS incidence, the CDC assumption changes the shape of the estimated ep idemic. These may result in as much as 4-21% reductions in model estim ates of HIV incidence and prevalence.