Extension of a pilot study: Impact from the cytochrome P450 2D6 polymorphism on outcome and costs associated with severe mental illness

The influence of cytochrome P450 2D6 (CYP2D6) genetic variability was exami ned in psychiatric inpatients by evaluating adverse drug events (ADEs), hos pital stays, and total costs over a 1-year period in an extension of at pre viously published brief report. One hundred consecutive psychiatric patient s from Eastern State Hospital in Lexington, Kentucky, were genotyped for CY P2D6 expression. ADEs mere evaluated by a neurologic rating scale, modified Udvalg for Kliniske Undersogelser Side Effect Rating Scale, or chart revie w. Information on total hospitalization days and total costs mere gathered for a 1-year period. Forty-five percent of the patients received medication s that were primarily dependent on the CYP2D6 enzyme for their elimination. When the analysis was restricted to just those patients in each group rece iving medication heavily dependent on the CYP2D6 enzyme, the following were observed: (1) a trend toward greater numbers of ADEs from medications as o ne moved from the group with ultrarapid CYP2D6 activity (UM) to the group w ith absent CYP2D6 activity (PM); (2) the cost of treating patients with ext remes in CYP2D6 activity (UM and PM) was on average $4,000 to $6,000 per ye ar greater than the cost of treating patients in the efficient metabolizer (EM) and intermediate metabolizer (IM) groups; and (3) total duration of ho spital stay was more pronounced for those in CYP2D6 PIM group. Variance of hospital stays and costs calculated from these preliminary data suggests th at 1,500 to 2,000 patients must be evaluated over at least a 1-year period to determine whether the CYP2D6 genetic variation significantly alters the duration of hospital stay and costs.