TABLE III.

Change from Baseline in Primary Outcome Measures for Operatively and Nonoperatively Managed Patients, According to Duration of Symptoms, at One, Two, Three, and Four Years of Follow-up^*

	Change from Baseline
	1 Year	2 Years	3 Years	4 Years
Operative treatment group
SF-36 bodily pain
Patients with symptoms for ≤6 months	46.3 ± 1.1	45.7 ± 1.1	46.5 ± 1.2	48.3 ± 1.2
Patients with symptoms for >6 months	40.2 ± 1.4	39.2 ± 1.4	40 ± 1.5	41.9 ± 1.5
P value	<0.001	<0.001	<0.001	<0.001
SF-36 physical function
Patients with symptoms for ≤6 months	48.3 ± 1.1	47.1 ± 1.1	47.1 ± 1.1	47.7 ± 1.1
Patients with symptoms for >6 months	39 ± 1.4	39.1 ± 1.3	40.7 ± 1.4	41.2 ± 1.4
P value	<0.001	<0.001	<0.001	<0.001
Oswestry Disability Index
Patients with symptoms for ≤6 months	–40.3 ± 0.9	–39.9 ± 0.9	–40.4 ± 0.9	–41.1 ± 0.9
Patients with symptoms for >6 months	–34.5 ± 1.1	–34.1 ± 1.1	–34 ± 1.1	–34.6 ± 1.2
P value	<0.001	<0.001	<0.001	<0.001
Nonoperative treatment group
SF-36 bodily pain
Patients with symptoms for ≤6 months	30.7 ± 1.3	32.9 ± 1.3	32.9 ± 1.4	31.8 ± 1.4
Patients with symptoms for >6 months	22.7 ± 2.4	21.5 ± 2.5	22 ± 2.7	21.4 ± 2.8
P value	0.003	<0.001	<0.001	<0.001
SF-36 physical function
Patients with symptoms for ≤6 months	28.2 ± 1.2	30.3 ± 1.3	30.4 ± 1.3	29.5 ± 1.3
Patients with symptoms for >6 months	22 ± 2.3	22.8 ± 2.4	24.1 ± 2.6	22.6 ± 2.6
P value	0.013	0.005	0.025	0.015
Oswestry Disability Index
Patients with symptoms for ≤6 months	–23.1 ± 1	–24.9 ± 1	–25.4 ± 1.1	–24.9 ± 1.1
Patients with symptoms for >6 months	–16.4 ± 1.9	–17.4 ± 2	–17.1 ± 2.1	–18.5 ± 2.1
P value	0.001	<0.001	<0.001	0.006

^*The values are given as the mean and the standard deviation.