Measuring impact of Medex using third-party payer claims

The financial impact of the Medex, as measured by charges made to a third-party payer, was consistently positive. Although the Medex practices studied billed more services for a greater amount to a third-party payer (Blue Cross and Blue Shield) during the two years before the arrival of a Medex, they displayed a still greater increase in both the number and amounts charged for lab/X-ray services and outpatient/office and inpatient (non-surgery) charges after his arrival. This increase in outpatient/office and inpatient (non-surgery) volume and charges can be interpreted as a natural consequence of the role that was defined for the physician's assistant. The 394% increase in lab/X-ray services is far greater than the simple doubling one would expect if the Medex were only seeing an additional number of patients equal to the physician's. Other studies on many of these same practices have shown that the Medex is more likely than his preceptor to order diagnostic laboratory and X-ray services, perhaps as a consequence of his more recent training in the university. The physicians who had a Medex also increase their use of laboratory and X-ray services after the arrival of the Medex, perhaps as another indirect result of his university influence. The difference in total charges to one third-party payer would certainly indicate a practice revenue sufficient to offset the cost of adding a Medex. The use of third-party payer data in the evaluation of programs such as this has important methodological implications. One of the most prevalent problems in health care evaluation is assessing the consequences from establishing new programs.