CONSTRAINTS ON ANTIDEPRESSANT PRESCRIBING AND PRINCIPLES OF COST-EFFECTIVE ANTIDEPRESSANT USE .2. COST-EFFECTIVENESS ANALYSES

Cost-effectiveness studies are a useful tool in drug-choice decisions. They are appropriate when alternative therapies have different levels of effectiveness, as with antidepressants. The calculation of cost ef fectiveness is similar to that used by some authors to determine wheth er a drug should be included in a formulary, so it clearly has immedia te practical application and potential acceptability. However, the act ual acceptability of cost-effectiveness studies has been hampered by a lack of conformity over study objectives, methodology and use of avai lable data, and this significantly affects results. Studies that focus on the same location and setting, and conducted at the same time, fre quently provide different results in their conclusions, depending on t he assumptions and viewpoints, and the effects of sampling error. For example. dosage can affect purchase price calculations, but also compl iance and efficacy, which are important considerations. Moreover, conc lusions based on cost disadvantages of new drugs are not appropriate f or planning fur the future, since a drug's market price tends to fail with time and increasing demand. Appropriate use of outcome measures i s important, and treatment failures, as well as successes, should be c onsidered. Cost-effectiveness analysis has been used to demonstrate an important point: even when the appropriate use of antidepressants and speciality care increases medical costs, it improves value for money. A variety of drugs for one indication should be available to the pres criber, as the most cost-effective one may differ between patient subp opulations.Many costs of morbidity, adverse effects and secondary effe cts of antidepressants remain to be properly quantified, but are likel y to have an important influence on cost effectiveness. These costs ar e likely to be higher fur tricyclic antidepressants than the newer rev ersible inhibitors of monoamine oxidase and selective serotonin (5-hyd roxytryptamine: 5-HT) reuptake inhibitors. Costing in some areas of he alth is relatively straightforward. Depression is among the most diffi cult areas to cost because of its gradation in severity, its chronic a nd recurrent nature, and its subtle effects on working capacity. Quant ification of differences resulting from the use of different drugs has many pitfalls. Until now, each cost analysis of depression has differ ed from the last, and most have placed excessive reliance on poorly su bstantiated and hypothetical assumptions. More in-depth studies are re quired to define the most cost-effective policies for recommendation t o healthcare decision-makers and antidepressant drug prescribers. Comp liance, adverse effects, and safety in overdose are important factors. The impact uf indirect costs also needs to be addressed.