Table 4.

Difference-in-Differences Generalized Linear Model (GLM) Estimates of Health Care Spending between HSA and Traditional Plan Enrollees

Variables	Total Spending	Medical Spending	Pharmacy Spending
HSA×Post	−0.0459*	−0.0384	−0.0626***
	(0.0277)	(0.0370)	(0.0199)
Post	0.0956***	0.0930***	0.105***
	(0.0253)	(0.0339)	(0.0151)
HSA	−0.0676	−0.0398	−0.147***
	(0.0483)	(0.539)	(0.0481)
Year	0.0685***	0.0873***	0.0100
	(0.0130)	(0.0171)	(0.00988)
Region (Midwest reference)
Northeast	−0.0192	−0.0118	−0.0359
	(0.0475)	(0.0600)	(0.0386)
South	−0.0411	−0.0691*	0.0407
	(0.0305)	(0.0384)	(0.0311)
Unknown	−1.234***	−1.263***	−1.147***
	(0.0548)	(0.132)	(0.342)
West	−0.0541	−0.0378	−0.111**
	(0.0533)	(0.0634)	(0.0513)
Female	0.761***	0.901***	0.246***
	(0.0539)	(0.0601)	(0.0921)
Age	0.0379***	0.0378***	0.0384***
	(0.00138)	(0.00168)	(0.00161)
Female × Age	−0.0103***	−0.0127***	−0.00112
	(0.00127)	(0.00143)	(0.00182)
Firm size (100s)	0.000220	0.000197	0.000661
	(0.00142)	(0.00167)	(0.00181)
Type (Full replace reference)
Add-on (fully insured)	−0.111**	−0.0746	−0.210***
	(0.0461)	(0.0465)	(0.0616)
Add-on (ASO)	−0.0115	0.0517	−0.191**
	(0.0610)	(0.0620)	(0.0829)

Notes. N=228,930. Log-link used in GLM specification. Regressions also controls for 2005 plan type dummies (EPO, HMO, indemnity, POS, PPO) and 1-digit SIC dummies. Robust standard errors (clustered at firm level) in parentheses.

^***p<.01

^**p<.05

^*p<.1.

ASO, administrative services only; HSA, health savings account; HMO, health maintenance organization; POS, point of service; PPO, preferred provider organization.