Table 1.

Comparison of confounders before PSM.

	Control group (n = 152)	Aspirin group (n = 118)	P value
Gender (female/male)	81/71	62/56	1.00
Age (year)	60.17 ± 10.56	64.31 ± 7.96	<0 . 001
LBP history (month)	40.98 ± 62.51	48.55 ± 65.15	0.333
Alcohol consumption	62	52	0.677
Smoking	64	52	0.842
BMI (kg/m2)	25.97 ± 3.54	25.79 ± 3.4	0.669
VAS	5.56 ± 1.76	6.08 ± 1.72	0.015
CCI	1.94 ± 0.97	2.19 ± 1.07	0.043

LBP, low back pain; BMI, body mass index; VAS, visual analogue scale; CCI, Charlson Comorbidity Index; PSM, Propensity Score Matching.

Italics indicate statistically significant differences.