Specificity Monitoring
Specificity Monitoring and Kit Lot information is used to observe ongoing performances of test kits in Australia and to enable detection of assay and/or laboratory problems.
In addition to undergoing a pre-market evaluation, HIV and HCV assays registered on the Australian Register of Therapeutic Goods, under Schedule 3, must have their ongoing in-field performance monitored by the NRL. Similar monitoring is conducted for HTLV and HBsAg assays. For this purpose, data are collected from Australian Red Cross Blood Service and diagnostic and reference laboratories.
By monitoring the rate of false reactivity (specificity) in assays used for testing large numbers of samples (eg blood donor testing), both assay and laboratory problems may be detected. False reactivity is usually very small (<1%), but the accumulated data can be used to assess an assay's ongoing performance. A sudden increase in the rate of false reactivity may indicate a problem and cause increased blood wastage. Analyses of data from other NRL programmes can be performed and may elucidate assay, laboratory or batch problems.
Data Collection and Collation
All participants of the NRL Quality Assurance Programme are requested to enter the relevant data via the Internet (EDCNet). Laboratories are asked to record their specific run-related data and relay it to the NRL monthly for analysis.
For the Australian Red Cross Blood Service Laboratories the assay, batch, number of specimens tested, number of tests performed, numbers of repeat reactors and numbers of positive samples are collected. The resulting initial and repeat reactor rates are calculated after all confirmed positive results are removed from the data. For all other laboratories the assay(s) used, batches and number of specimens tested are collected.
Data from over 100 laboratories are collated for all approved anti-HIV and HCV assays.
Access to Reports
· Annual Reports
· NRL Web Site (Members section)
· Upon request to the NRL
Example of anti-HIV data collected through Specificity Monitoring for 2002Specimens: The number of specimens tested (only includes data sent to the NRL)
State 1 3 5 10 11 ARCBS Total 138
IRR: Initial Reactor Rate = percentage of negative specimens that are initially falsely reactive.
RRR: Repeat Reactor Rate = percentage of negative specimens that are repeatedly falsely reactive.
Specificity: The ability of a test to identify negative samples as negative. Specificity may be calculated as (100-RRR).