Outpatient use of major antipsychotic drugs in ambulatory care settings in the United States, 1997-2000.
OBJECTIVE
To describe the prescription of antipsychotic agents in the United States and to investigate the association between demographic characteristics, clinical diagnosis, and antipsychotic prescribed.


METHODS
Four years (1997-2000) of data from the National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Care Survey (NHAMCS) were combined for analysis. Distributions for patient age, race, gender, primary diagnosis, and provider's medical specialty were assessed. Logistic regression models were developed to estimate the probability of receiving either (1) a second-generation vs a first-generation antipsychotic, or (2) olanzapine vs risperidone, given differences in gender, race, age, and primary diagnosis.


RESULTS
Nearly 35.9 million ambulatory healthcare visits resulted in antipsychotic prescription during 1997-2000, or nearly 1% of all healthcare visits for the period. Nearly 30% of these visits were to nonpsychiatric physicians. The use of first-generation antipsychotics declined during this period, while the use of second-generation antipsychotics increased. Risperidone and olanzapine accounted for the majority of second-generation antipsychotic use. While the mean ages of patients using risperidone and olanzapine were similar, the age distributions differed, with risperidone showing more frequent use among the young (< 18 years) and the old (> 65 years). Patients of nonwhite race were more likely to receive olanzapine than risperidone.


CONCLUSIONS
Results from this national survey indicate that second-generation antipsychotics are being used with increasing frequency and are widely used outside of the psychiatric specialty. Differences in age distribution, racial representation, and diagnostic representation are associated with drug selection, reinforcing the importance of accounting for case-mix factors when researching these antipsychotics in observational studies.
Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA. dvb@lilly.com
David L
DL
Van Brunt
P Joseph
PJ
Gibson
Janet L
JL
Ramsey
Robert
R
Obenchain
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000639:trends*; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016013:Likelihood Functions; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010045:Outpatients / Q000706:statistics & numerical data; D011237:Predictive Value of Tests; D014481:United States
D014150:Antipsychotic Agents