Evaluation of a surveillance case definition for anogenital warts, Kaiser Permanente northwest.

BACKGROUND

Most studies of anogenital wart (AGW) epidemiology have used large clinical or administrative databases and unconfirmed case definitions based on combinations of diagnosis and procedure codes.

METHODS

We developed and validated an AGW case definition using a combination of diagnosis codes and other information available in the electronic medical record (provider type, laboratory testing). We calculated the positive predictive value (PPV) of this case definition compared with manual medical record review in a random sample of 250 cases. Using this case definition, we calculated the annual age- and sex-stratified prevalence of AGW among individuals 11 through 30 years of age from 2000 through 2005.

RESULTS

We identified 2730 individuals who met the case definition. The PPV of the case definition was 82%, and the average annual prevalence was 4.16 per 1000. Prevalence of AGW was higher in females compared with males in every age group, with the exception of the 27- to 30-year-olds. Among females, prevalence peaked in the 19- to 22-year-olds, and among males, the peak was observed in 23- to 26-year-olds.

CONCLUSIONS

The case definition developed in this study is the first to be validated with medical record review and has a good PPV for the detection of AGW. The prevalence rates observed in this study were higher than other published rates, but the age- and sex-specific patterns observed were consistent with previous reports.