. Author manuscript; available in PMC: 2014 Apr 1.

Published in final edited form as: Psychiatr Serv. 2013 Apr 1;64(4):324–330. doi: 10.1176/appi.ps.201200186

Table 3.

Results from Cox Model Regression Analyses of Time to Adoption for Four Original Second-Generation Antipsychotic Formulations

Variables	Olanzapine Hazard ratio	P- Value	Quetiapine Hazard ratio	P- Value	Ziprasidone Hazard ratio	P- Value	Aripiprazole Hazard ratio	P- Value
Sex
Female	.84	<.001	.86	<.001	.87	<.001	.91	.001
Male	Reference		Reference		Reference		Reference
Age
<30	1.07	.545	1.48	<.001	1.52	<.001	1.43	<.001
30–39	1.33	<.001	1.45	<.001	1.47	<.001	1.45	<.001
40–49	1.33	<.001	1.38	<.001	1.34	<.001	1.34	<.001
50+	Reference		Reference		Reference		Reference
Specialty
General Practice	.28	<.001	.35	<.001	.18	<.001	.22	<.001
Pediatrics	.24	<.001	.25	<.001	.21	<.001	.38	<.001
Neurology	.33	<.001	.54	<.001	.16	<.001	.16	<.001
Psychiatrist	Reference		Reference		Reference		Reference
Practice Setting
Solo	.89	<.001	.86	<.001	.95	.087	.96	.167
Other	.88	.003	.81	<.001	.88	.001	.90	.003
No Classification	.78	<.001	.83	<.001	.84	<.001	.83	<.001
Group	Reference		Reference		Reference		Reference
Any Hospital Practice
Yes	1.04	.072	1.08	.001	.97	.272	.99	.664
No	Reference		Reference		Reference		Reference
Antipsychotic Volume
1^st quartile	.34	<.001	.39	<.001	.33	<.001	.28	<.001
2^nd quartile	.40	<.001	.46	<.001	.38	<.001	.35	<.001
3^rd quartile	.51	<.001	.55	<.001	.52	<.001	.47	<.001
4^th quartile	Reference		Reference		Reference		Reference
Top 25 Medical School
Yes	.94	.082	.94	.055	.87	.001	.98	.628
No	Reference		Reference		Reference		Reference
Foreign Medical Graduate
Yes	1.13	<.001	1.13	<.001	1.09	.005	1.15	<.001
No	Reference		Reference		Reference		Reference

Note: These data were obtained from IMS Health, Xponent™, 1996–2008. Hazard ratios are presented in this table, with p-values provided in parentheses. A hazard ratio greater than 1.00 suggests that a physician with that characteristic was faster to adopt the drug on average relative to the reference group (and adjusting for the other variables in the model), while a hazard ratio less than 1.00 suggests that a physician with that characteristic was slower to adopt the drug on average relative to the reference group. These models also include for state fixed effects and variables characterizing the population residing in the zip code of the physician’s practice using data from the 2002 Area Resource File (percent black, percent Hispanic, percent enrolled in an HMO, percent who have completed high school, and percent 65 years or older).