Blood must be stored at room temperature (do not refrigerate or freeze) and shipped to the laboratory to arrive within 24 hours of blood draw.The UMDNJ stuff reads a bit like an advertorial;
T-SPOT.TB has proven to be the most accurate TB screening test available with 95% sensitivity in culture positive TB patients and 97% specificity in low risk healthy individuals (2).The study referred to (2) was partly authored by the CEO from the manufacturer, Oxford Immunotec Limited.
Quoted specificity and sensitivity roughly matches those in the FDA approved package insert however to add to the confusion is Oxford's "International" site which has a slightly different version
Specificity of 99%*The * refers to the US package insert in which borderline results are excluded. The US package insert insists that if borderline results persists
other diagnostic tests and/or epidemiologic information should be used to help determine TB infection status of the patientIn addition the US package insert gives a further two equal estimates for specificity
If all the borderline (equivocal) results are considered all positive or all negative, the estimated specificity of T-SPOT.TB was either 94.8% or 99.0% respectively.Similarly with sensitivity
If all the borderline (equivocal) results are considered all positive or all negative, the estimated sensitivity of T-SPOT.TB was either 96.2% or 90.7%, respectively.Oxford are offering various values for specificity and sensitivity with at least one being the most accurate. It is interesting to compare their approach to that of the QFT-GIT insert
As there is no definitive standard for confirming or excluding the diagnosis of LTBI, an estimate of sensitivity and specificity for QuantiFERON®-TB Gold IT cannot be practically evaluated
