Effect of Japanese Herbal Kampo Medicine Goreisan on Reoperation Rates after Burr-Hole Surgery for Chronic Subdural Hematoma: Analysis of a National Inpatient Database

Table 3

Relative risks, risk differences, and number needed to treat in reoperation rates comparing Goreisan users with nonusers.

	Relative risk	Risk difference	Number needed to treat
	(95% CI)	(95% CI)	(95% CI)
Propensity-score matching (,758)	0.78 (0.64; 0.93)	−1.4% (−2.4%; −0.38%)	72 (41; 265)
Instrumental-variable analysis (,836)	—	−2.2% (−3.8%; −0.67%)	45 (26; 148)

CI, confidence interval.