Table 4.

Time series regression model for the monthly change in the proportion of Bone Morphogenetic Protein use with lumbar and cervical fusion in the United States in relationship to the FDA Public Health Notification

	Lumbar fusion	Cervical fusion
Change in % monthly BMP use
Post FDA trend	−0.978***	−0.231
	(−3.96)	(−1.66)
Change in percent female	7.089	−1.469
	(0.57)	(−0.31)
Change in mean age	−0.597*	−0.0844
	(−2.01)	(−0.35)
Change in mean charlson score	1.113	−7.402
	(0.13)	(−1.75)
Constant	0.658***	0.167*
	(3.83)	(2.28)
ARMA
time lag (1 month)	−0.344***	−0.319***
	(−3.80)	(−3.68)
Sigma
Constant	1.646***	0.870***
	(19.28)	(16.71)
Pre vs. post trend p-value	0.000***	0.035*
Number of months	123	123

t statistics in parentheses

Estimates based on weighted sample from the Nationwide Inpatient Sample

^*p < 0.05,

^**p < 0.01,

^***p < 0.001