Accurate monitoring of the HIV epidemic in the United States: case duplication in the national HIV/AIDS surveillance system.

Objective: To assess the degree of duplicate reporting in the US HIV/AIDS surveillance system as compared with a performance standard of <5%, and to assess the effect of duplicate removal on epidemiologic trends.
Methods: Multistate evaluation of HIV/AIDS case surveillance. Potential duplicate HIV or AIDS case reports in the national surveillance system matched on Soundex, birth date, and sex were assessed for duplication by state and territorial health departments.
Results: Of the 990,175 cases of HIV infection and AIDS in the surveillance system on December 31, 2001, 44,945 (4.5%) were identified as duplicate reports. The duplication rate was higher for HIV cases (8.2%) than for AIDS cases (3.8%). The median of 322 duplicate AIDS reports per area (range: 1 to 3947) represented a median of 5% of all AIDS reports per area (range: 1% to 11%). The median of 369 duplicate HIV reports per area (range: 1 to 1247) represented a median of 11% of all HIV reports per area (range: 1% to 30%).
Discussion: The overall duplication rate was within acceptable limits in the national HIV/AIDS surveillance system but did not meet the standard for HIV cases. Ongoing centrally coordinated efforts are necessary to minimize duplicate reporting in the future.