The formularies used by health care payers is changing from a list of approved drugs that can be reimbursed to a list of preferred drugs that will be reimbursed automatically without question or paperwork. Rarely is reimbursement denied for a non-formulary drug if the consumer or provider is persistent. However, the extent to which this "hassle factor" prevents consumers or providers petitioning for off-formulary coverage is unknown.
This change in the character of formularies has been possible as many drug classes have several competing agents that offer arguably similar mechanisms of action. Therefore, for example, some formularies include a choice of only one or two SSRIs for automatic reimbursement based on the argument that all SSRIs "are the same." This argument is applied to numerous other drug classes as well, although the differential efficacy of particular agents within other drug classes is often more clear-cut.
It is commonly asserted that response to psychotherapeutics by an individual is idiosyncratic and there is no way of predicting a priori whether any one agent from a class is more likely to work in a particular individual than is another. If this assertion is true, then the interpretation and policy implications will differ depending on the perspective considered. From one perspective the use of preferred drug lists is likely to compromise the quality of mental health care because the preferred agent will not work in all eligible populations. From another perspective, use of a preferred drug list is justified because it is impossible to know whether the preferred agent will be effective in a particular patient until it is tried. Nonetheless, given that there is at least some evidence that restriction of therapeutic options to only one preferred agent is detrimental to outcomes in the treatment of depression, this formulary effect (independent of specific agent) is fertile ground for further rigorous research.13