Table 4.

Drug and health services utilization among non-switchers and switchers to authorized generic vs. generic

Utilization	Non-Switchers	Switchers by Type		AG vs. Generic P-value
		Brand to AG	Brand to Generic
Annual number of all-cause outpatient visits (mean, 95% CI)	20.8 (18.4-23.6)	17.5 (16.6-18.5)	17.4 (16.9-17.9)	0.819
Annual number of all-cause urgent care visits (mean, 95% CI)	11.4 (8.2-15.8)	0.6 (0.5-0.7)	0.5 (0.5-0.6)	0.140
Annual all-cause emergency department visits
Any visit (%, 95% CI)	32.2 (23.8-41.9)	27.6 (24.5-30.8)	22.8 (21.3-24.3)	0.006
Number per year (mean, 95% CI)	0.7 (0.4-1.0)	0.5 (0.4-0.6)	0.4 (0.4-0.5)	0.074
Annual all-cause hospitalizations
Any visit (%, 95% CI)	26.0 (18.1-35.8)	17.7 (15.1-20.6)	17.7 (16.4-19.1)	0.997
Number per year (mean, 95% CI)	2.5 (1.4-4.6)	1.4 (1.0-1.8)	1.5 (1.3-1.7)	0.641
Medication discontinuation (%, 95% CI)	99.4 (99.2-99.6)	35.2 (32.0-38.5)	34.8 (33.2-36.5)	0.854

The mean observation time was 78 days for non-switchers, 220 days for switchers to AG, and 276 days for switchers to generic. Because of these differences in observation time the occurrence and number of outpatient, urgent care, emergency department, and hospital visits was estimated on an annual basis using univariate negative binomial regression for count variables and logistic regression for binary variables without adjusting for covariates. The difference in utilization between switchers to AG and switchers to generic was assessed via rate ratios for the negative binomial models and odds ratios for the logistic models, with statistical significance reflected by P<0.05.

AG = authorized generic; “Generic” refers to all other independent generics filed under an Abbreviated New Drug Application (ANDA)