PRELIMINARY COMPARISON OF PREDICTIVE AND EMPIRIC LITHIUM DOSING - IMPACT ON PATIENT OUTCOME

OBJECTIVE: To evaluate whether initiating lithium with predictive dosi ng compared with empiric dosing improves outcome in patients with mani c symptoms. DESIGN: The study was a randomized, single-blind design an d used the Modified Slattery predictive method. SETTING AND PARTICIPAN TS: Eighteen inpatients at an urban psychiatric hospital with a Mania Rating Scale (MRS) score greater than or equal to 24 were enrolled. OU TCOME MEASURES: The study endpoint was defined as an MRS rating less t han or equal to 14 or discharge from the hospital. Assessments (MRS, B rief Psychiatric Rating Scale, Clinical Global Impression, Systematic Assessment for Treatment of Emergent Events Scale, quality of life mea sures) were completed at baseline, on days 3 or 4 and 7 or 8, and week ly thereafter. RESULTS: The predictive group achieved a therapeutic co ncentration significantly sooner than did the empiric group (p=0.004); however, the mean serum lithium concentration at discharge did not di ffer between the groups. The predictive group was taking significantly higher dosages of antipsychotics in chlorpromazine equivalents on day 3 or 4 (p=0.05). Significantly fewer gastrointestinal/genitourinary a dverse effects on day 3 or 4 were reported by patients in the predicti ve group (p=0.04). No difference was found between groups with any rat ing scale or other pharmacokinetic or medication item. Even though the difference did not meet statistical significance, the predictive grou p's length of stay in the acute unit was three days shorter than that of the empiric group, which may represent significant cost savings. CO NCLUSIONS: The preliminary data do not suggest that patient outcome is improved by using Modified Slattery predictive dosing; however, the s uggestion of a shorter length of stay in a restrictive unit merits fur ther evaluation.