Validating Procedures used to Identify Duplicate Reports in Haiti's National HIV/AIDS Case Surveillance System

Valid deduplication of human immunodeficiency virus (HIV) case reports is critical to the utility of these data to inform HIV programs. The Haitian Ministry of Health (MSPP) and partners operate a case-based, national HIV/AIDS surveillance system (HASS), using deterministic and probabilistic procedures to identify duplicate records. These procedures are described and validated based on expert classifications.

Two samples of HASS records identified as duplicates were selected: 100 pairs from deterministic and 100 pairs from probabilistic matching procedures (total: 200 pairs, 400 case reports). Clinical data from the national electronic medical record (iSanté) were reviewed and consensus gold-standard determinations on the status of duplications were made. False positive rates (FPR) were estimated by reviewing these records, while false negative rates were calculated (FNR) by using LinkPlus™ probabilistic linkage software. The effect of deduplication on total HIV case counts was demonstrated.

Review of deterministic matches yielded 99 true positives and 1 false positive (FPR, 1 per 100; 95% CI, 0.71-5.4). Review of probabilistic matches yielded a FPR of 6 per 100 (95% CI, 2.7-12.4). LinkPlus identified 1,491 probable matches among 68,393 records, representing a FNR of 2 per 100 (95% CI, 0.55-7.0). After adjustment, the estimated unique count of reported HIV patients in HASS was 211,885 (95% CI, 207, 293-213, 232) as of December 2013.

Based on application of the established procedures, HASS conforms to the duplication performance standard recommended by the Centers for Disease Control and Prevention for HIV surveillance.