Table 2. Multiple Linear Regression Analysis of Factors Associated with the Tariff-Actual Cost Gap .

Variables		B	SE	[95% CI]	P
Age		1.05	0.15	[1.35 to 0.76]	< 0.001
Length of stay		81.2	1.86	[84.8 to 77.5]	< 0.001
Gender	Male (Ref)
	Female	26.7	5.71	[37.9 to 15.5]	< 0.001
Hospital type	Teaching (Ref)
	Non-teaching	2.4	8.51	[-12.8 to 19.1]	0.771
Surgeon practice	Full time (Ref)
	Part time	67.3	5.22	[56.9 to 77.5]	< 0.001
Insurance type	Social security (Ref)
	Iranian health insurance	5.0	5.73	[-5.7 to 16.7]	0.334
	Relief committee	-9.5	19.2	[- 47.2 to 28.2]	0.625
	Armed forces	-9.3	13.8	[- 36.3 to 17.7]	0.501
Surgical specialty	Orthopedics (Ref)
	Urology	186.3	12.6	[161.7 to 210.1]	< 0.001
	General surgery	147.4	9.12	[129.5 to 165.3]	< 0.001
	Ophthalmic	158.6	12.4	[134.3 to 182.8]	< 0.001
	Obstetrics and Gynecology	71.3	12.8	[46.2 to 96.3]	< 0.001
	Neurosurgery	346.9	67.6	[214.3 to 479.5]	< 0.001

Note. CI: Confidence interval; SE: Standard error.