Table 1. Comparison of clinical outcomes between gravity-drain and closed-suction groups.

Variable	Gravity-drain group	Closed-suction group	P value
Transfusion rates (%)	38	63	0.001
Median postoperative drain output (mL)	350	499	0.01
Number of symptomatic spinal epidural hematomas	0	1	–
Median drain indwelling time (days)	2	2	0.55
Median length of hospital stay (days)	3	3	0.37
Number of bedside wound aspirations	0	0