The effect of pharmacogenetic testing for CYP450 2D6 and 2C19 on treatment costs have not yet been documented. This study used Danish patient registers to calculate healthcare costs of treating patients with diagnoses within the schizophrenic spectrum for 1 year with or without pharmacogenetic testing for polymorphisms in the genes for the CYP2D6 and CYP2C19 enzymes. In a randomized, controlled trial, stratified with respect to metabolizer genotype, 104 patients were assigned to treatment based on pharmacogenetic testing and 103 patients to treatment as usual. Random exclusion of extensive and intermediate metabolizers was used to increase the frequency of extreme metabolizers (poor metabolizers and ultrarapid metabolizers for CYP2D6) to 20% in both groups. Cost differences were analysed at several levels including (i) overall healthcare expenditure, (ii) psychiatric hospital cost (iii) nonpsychiatric hospital cost, (iv) primary care spending and (v) pharmaceuticals. Statistically significant differences in costs of psychiatric care dependent on metabolizer status were found between intervention groups. Pharmacogenetic testing significantly reduced costs among the extreme metabolizers (poor metabolizers and ultrarapid metabolizers) to 28%. Use of primary care services and pharmaceuticals was also affected by the intervention.This study confirms earlier findings that extreme metabolizers (poor and ultrarapid metabolizers) incur higher costs than similar patients with a normal metabolizer genotype. However, this study shows that these excess costs can be reduced by pharmacogenetic testing. Pharmacogenetic testing for CYP2D6 and CYP2C19 could thus be considered as a means of curtailing high psychiatric treatment costs among extreme metabolizers.Limited healthcare budgets and cost-containment challenge payers and providers of health care worldwide. New technologies and treatments are compared with existing ones to maximize health gain. Pharmacogenetic testing (PGx) is one among these new technologies. In psychiatry, several attempts have been made to estimate whether PGx for polymorphisms (genetic changes) in different genes provides a cost-effective alternative to treatment based on clinical dose titration or therapeutic [1][2][3][4][5].Psychiatric treatment is characterized by problems of adverse drug reactions and lack of effect. This leads to compliance problems, frequent shifts in medicine and high costs [6][7][8]. PGx was expected to ease some of these problems. The fundamental hypothesis being that knowledge regarding patients' genotype could guide the treating clinician in the choice of pharmaceutical and/or dosage. This could potentially individualize treatment and reduce the time from initiation of pharmaceutical therapy until an acceptable medical response occurs, thus leading to improved patient treatment, care and outcome.Pharmacogenetic testing for changes in the CYP2D6 and CYP2C19 enzymes is one candidate for the use of PGx in psychiatry. Numerous antipsychotics and antidepressants are metab...

Patients value reductions in shifts in antidepressants and price when choosing between genetic screening and no screening. They do not focus on how the reductions are provided, nor do they value the genetic information the test provides irrespective of its effect on outcome. Given, that the test is able to provide a reduction of one shift in the number of antidepressant shifts with a probability of 5 percent, WTP for the test exceeds its cost.

If diagnosed with depression, peoples' WTP for pharmacogenetic testing appears to exceed its price as long as there is a reasonable probability for improvements in treatment (in the present case 10%). Utility is associated with outcomes only. Hence, other modes of provision of similar improvements in treatment may be valued equally highly. WTP estimates and the associated policy implications appear to be robust because they were unaffected by estimation model.

Based on this natural experiment we were not able to document statistically significant differences in total costs between treatment sites that had guidelines recommending pharmacogenetic testing, relative to sites without such guidelines, over a period of one year. However, guidelines of pharmacogenetic testing and possibly also therapeutic drug monitoring seem to lead to reductions in costs for primary care services. In the case of the former, reductions do, however, seem to be outweighed by increases in costs for psychiatric and non-psychiatric inpatient stays. In conclusion, no statistically significant differences in total direct costs across sites with different treatment strategies were found.