Assessing the clinical and cost impact of on-demand immunoassay testing for the diagnosis of heparin induced thrombocytopenia.

BACKGROUND: The diagnostic work-up for heparin induced thrombocytopenia (HIT) can take several days. Consequently patients may be speculatively switched onto replacement anticoagulant therapy before a diagnosis is confirmed. On-demand immunoassay diagnostic testing enables timely treatment decisions, based on test results. OBJECTIVE: To estimate the clinical and cost impact of the use of on-demand versus batched diagnostic tests for HIT. METHODS: Literature was reviewed to identify test performance, clinical and cost data. Semi-structured interviews (n=4) and a survey (n=90) provided insights into current practice and challenges. Flow diagram models were developed to estimate the potential impact of on-demand testing. RESULTS: Modelling estimated more HIT-related outcomes for patients maintained on heparin whilst awaiting test results and patients switched onto replacement anticoagulant therapy awaiting test results, compared with on-demand testing and treatment based on the results. The budget impact model estimated that on-demand testing reduced replacement anticoagulant therapy costs from $39,616 to $12,799 per patient. There are limitations to the data available to inform modelling and the estimates should be treated with caution. CONCLUSIONS: Using on-demand testing may drive positive effects on clinical and cost outcomes.

The structure of pigeon multiple-class same-different learning.

Three experiments examined the structure of the decision framework used by pigeons in learning a multiple-class same-different task. Using a same-different choice task requiring the discrimination of odd-item different displays (one or more of the display's component elements differed) from same displays (all display components identical), pigeons were concurrently trained with sets of four discriminable display types. In each experiment, the consistent group was tested such that the same and different displays of four display types were consistently mapped onto their choice alternatives. The inconsistent group received a conflicting mapping of the same and different displays and the choice alternatives that differed across the four display types but were consistent within a display type. Experiment 1 tested experienced pigeons, and Experiment 2 tested naive pigeons. In both experiments, the consistent group learned their discrimination faster and to a higher level of choice accuracy than did the inconsistent group, which performed poorly in general. Only in the consistent group was the discrimination transferred to novel stimuli, indicative of concept formation in that group. A third experiment documented that the different display classes were discriminable from one another. These results suggest that pigeons attempt to generate a single discriminative rule when learning this type of task, and that this general rule can cover a large variety of stimulus elements and organizations, consistent with previous evidence suggesting that pigeons may be capable of learning relatively unbounded relational same-different concepts.