TABLE 1.

Results of univariate and multivariate linear regression illustrating the relationship between different factors and crossover (MIS to open surgery)

Univariate linear regression model	Coefficients		p-Valuea	95% CI for B		Collinearity statistics
	B	SE		Lower bound	Upper bound	Variance inflation factor
No. of centers	− 0.279	0.138	0.136	− 0.717	0.159	6.436
Pretrial surgeon volume	3.844	1.133	0.047	0.546	12.142	19.073
Sample size	0.010	0.004	0.070	− 0.002	0.023	4.075
Composite quality score	− 9.992	1.733	0.010	− 15.505	− 4.478	3.235
Year of publication	0.219	0.121	0.367	− 0.165	0.603	28.403
Site of tumor (upper vs. lower GI cancer)	− 23.031	6.224	0.034	− 42.837	− 3.224	9.073
ASA score (3 + 4 versus 1 + 2)	0.795	0.270	0.049	0.013	1.653	12.534
Disease stage (III + IV versus I + II)	0.239	0.070	0.042	0.015	0.462	11.279
Dependent variable: MIS to open crossover (%)

Multivariate linear regression model	Coefficients		p-Valuea	95% CI for B
	B	SE		Lower bound	Upper bound
Pretrial surgeon volume	− 2.344	0.323	0.037	0.546	1.142
Composite quality score	− 7.594	1.984	0.014	− 15.505	− 4.478
Site of tumor (upper vs. lower GI cancer)	− 12.031	3.387	0.021	− 22.376	− 2.340
ASA score (3 + 4 vs. 1 + 2)	0.895	0.279	0.050	0.001	1.253
Disease stage (III + IV vs. I + II)	0.239	1.070	0.122	− 0.789	1.462
Dependent variable: MIS to open crossover (%)

^a Boldface denotes statistical significance

SE standard error, CI confidence interval, MIS minimally invasive surgery, GI gastrointestinal, ASA American Society of Anesthesiologists