Comparative effectiveness of amitriptyline vs duloxetine in the treatment of chronic low back pain: An observational study

Table 1 Changes of outcome measures at different time points

Outcome measures	Groups	Mean	SD	P value
VAS at baseline	Amitriptyline	7.9213	0.5579	< 0.0001
	Duloxetine	8.4646	0.7948
VAS at 1 week	Amitriptyline	0.9145	0.6375	< 0.0001
	Duloxetine	4.0394	1.2306
VAS at 4 weeks	Amitriptyline	1.0000	0.9913	< 0.0001
	Duloxetine	1.5984	0.9450
VAS at 12 weeks	Amitriptyline	1.8740	1.7182	< 0.0001
	Duloxetine	0.9213	0.7828
BPI at baseline	Amitriptyline	8.5118	1.1606	0.1156
	Duloxetine	8.2913	1.0624
BPI at 1 week	Amitriptyline	6.4016	1.2036	0.8234
	Duloxetine	6.3701	1.0374
BPI at 4 weeks	Amitriptyline	4.4409	0.7309	0.7319
	Duloxetine	4.4724	0.7328
BPI at 12 weeks	Amitriptyline	0.1803	0.7109	0.1803
	Duloxetine	2.0157	0.6899

VAS: Visual analog scale; BPI: Brief pain inventory; SD: Standard deviation.