Objective: To assess the sensitivity and specificity of linkage of HIV/AIDS diagnoses in Australia to the National Death Index (NDI).
Methods: An aggregated file containing 19,772 matched HIV/AIDS diagnoses reported to the national HIV/AIDS databases from 1980 to 30 June 2004 was linked to the NDI using probabilistic linkage methods based on the namecode, date of birth, and sex as identifiers. Based on the 6,900 HIV/AIDS known deaths reported by 1 January 2003 and 1,455 known non-deaths with an active follow-up beyond 1 January 2003, the different combinations of weights assigned to matched pairs were examined to obtain maximum sensitivity and specificity.
Results: The trade-off between sensitivity and specificity was used to obtain an optimal linkage. The optimal linkage was found to link 5,658 of the 6,900 HIV/AIDS known deaths (a sensitivity of 82%), and 116 false positives of the 1,455 known not deaths (specificity of 92%). Causes of deaths were recorded for 86.5% of deaths that were linked to the NDI.
Conclusions: This is a feasible method for conducting linkage studies if both the identifying deaths and non-deaths are available. The relatively poor sensitivity could be due to limited identifiers available for linkage on the HIV/AIDS databases.