The cost is greatly increased and samples are not likely to be representative. Many types of variations in medical practice need to be systematically analyzed to determine the cost-benefits of the alternatives. For example, one HMO in Boston has decided to use specially trained nurses as gatekeepers. Obviously such a policy greatly reduces the gatekeeper cost over having family practice specialists as gatekeepers. The impact of such a move on the health of the customers would require systematic analysis of patient records in the two alternative medical delivery systems over an extended time period.
Much research needs to be performed on the systematic analysis of risk adjusted outcomes.
Given the various risk factors such as age, general health, and stage of an illness, how effective was the treatment. How is information to be obtained. First, there is no need for labels which provides for privacy. However, the data must be carefully handled so that individual identities can not be inferred from the records. Analysis could be done at the sites of the medical records and only summary information sent forward.