Establishing a linked sentinel surveillance system for blood-borne viruses and sexually transmissible infections: methods, system attributes and early findings.

OBJECTIVE: To describe the attributes and key findings from implementation of a new blood-borne virus (BBV) and sexually transmissible infection (STI) sentinel surveillance system based on routine testing at clinical sites in Victoria, Australia.
METHODS: The Victorian Primary Care Network for Sentinel Surveillance (VPCNSS) on BBV and STI was established in 2006 at 17 sites. Target populations included men who have sex with men (MSM), young people and injecting drug users (IDU). Sites collected demographic and risk behaviour information electronically or using paper surveys from patients undergoing routine HIV or STI (syphilis, chlamydia (Chlamydia trachomatis)) or hepatitis C virus (HCV) testing. These data were linked with laboratory results.
RESULTS: Between April 2006 and June 2008, data were received for 67 466 tests and 52 042 questionnaires. In clinics providing electronic data, >90% of individuals tested for HIV, syphilis and chlamydia had risk behaviour information collected. In other clinics, survey response rates were >85% (HIV), 43.5% (syphilis), 42.7-66.5% (chlamydia) and <20% (HCV). Data completeness was >85% for most core variables. Over time, HIV, syphilis and chlamydia testing increased in MSM, and chlamydia testing declined in females (P = 0.05). The proportion of positive tests among MSM was 1.9% for HIV and 2.1% for syphilis. Among 16-24-year-olds, the proportion positive for chlamydia was 10.7% in males and 6.9% in females. Among IDU, 19.4% of HCV tests were antibody positive.
CONCLUSIONS: The VPCNSS has collected a large, rich dataset through which testing, risk behaviours and the proportion positive can be monitored in high-risk groups, offering a more comprehensive BBV and STI surveillance system for Victoria. Building system sustainability requires an ongoing focus.