National characteristics and trends in antiretroviral treatment in Australia can be accurately estimated using a large clinical cohort

Objectives: Cohort studies are often used as a national surveillance tool to monitor trends in HIV treatment and morbidity outcomes. However, there are limited studies validating the accuracy of using cohorts as a representation of the overall HIV-positive population. We compared data from a large Australian HIV-positive cohort study (Australian HIV Observational Database [AHOD]) and a 10% longitudinal sample from Australia's subsidized prescription medication scheme (Pharmaceutical Benefits Scheme [PBS]) to assess the use of cohorts for providing representative data for surveillance and monitoring purposes. Study Design and Setting: Basic demographics and treatment information from July 1, 2013, to March 31, 2016, were divided into half-yearly periods to compare HIV trends between AHOD (n = 2,488) and PBS (n = 18,409) patients. Results: In both data sets, most patients were men, aged above 50 years, and primarily resided in New South Wales. Both data sets revealed a significant shift toward the increased use of integrase strand transfer inhibitors and a gradual decline in the use of protease inhibitors and nonnucleoside reverse-transcriptase inhibitors among the treated population in Australia. Similarly, a substantial increase in the use of once daily, single-tablet, fixed-dose combination regimens was also observed. Conclusion: Our results show that observational cohort studies can serve as useful surrogate surveillance tools for monitoring patient characteristics and HIV treatment trends.