Table 1.

Characteristics of lumbar surgery patients with and without postoperative pain (PPP) before and after selecting propensity score matched control group

	Before matching			After matching
	No PPP	PPP	p Value	No PPP	PPP	p Value
	n=8460	n=1756		n=1756	n=1756
Age at surgery (years), mean (SD)	53.6 (16.0)	52.9 (15.5)	0.044	52.1 (16.0)	52.9 (15.5)	0.16
Male, %	50.7	43.3	<0.001	43.0	43.3	0.86
Charlson Comorbidity Index, mean (SD)	1.1 (2.0)	1.2 (2.0)	0.002	1.1 (1.8)	1.2 (2.0)	0.06

p Values were based on Fisher's exact tests for categorical and Wilcoxon tests for continuous variables.