Table 2.

Association of a Change in Vertical Integration Status on Nurse Practitioner (NP) Employment by Practice Specialty Type Using Linear Probability Models and Event Studies: 2008–2015.

	Primary care		Nonprimary care		Multispecialty
	(1)	(2)	(3)	(4)	(5)	(6)
Vertical	0.013** (0.003)	—	0.013*** (0.002)	—	0.0003 (0.004)	—
Vertical (t – 3+)		−0.011** (0.004)		−0.013*** (0.003)		−0.010 (0.006)
Vertical (t – 2)	—	−0.005 (0.003)	—	−0.004 (0.002)	—	−0.004 (0.004)
Vertical (t + 0)	—	0.004 (0.003)	—	0.005* (0.002)	—	0.001 (0.005)
Vertical (t + 1)	—	0.007 (0.004)	—	0.012*** (0.003)	—	0.001 (0.006)
Vertical (t + 2)	—	0.008 (0.005)	—	0.009* (0.004)	—	−0.007 (0.007)
Vertical (t + 3+)	—	0.027*** (0.006)	—	0.021*** (0.005)	—	−0.005 (0.009)
Year FEs	Yes	Yes	Yes	Yes	Yes	Yes
Practice FEs	Yes	Yes	Yes	Yes	Yes	Yes
Covariates	Yes	Yes	Yes	Yes	Yes	Yes
Observations	405,060	405,060	614,184	614,176	135,048	135,048
Unique practices	50,635	50,635	76,773	76,772	16,881	16,881
Sample mean	0.22	0.22	0.14	0.14	0.31	031

Note. Data are from SK&A and include practices present for all eight years. “Vertical” practices report hospital/health system ownership (i.e., hospital–physician integration). Outcome is binary indicator for employing at least one NP. Event study reference category is the year prior to vertical integration (i.e., t − 1). Covariates include the following: number of physicians in the practice, a dummy for full independence for NP scope of practice, and county-level demographics. Standard errors clustered at the practice level. FEs = fixed effects.

^*p < .05.

^**p < .01.

^***p < .001.