TABLE 5.

SSM Function Analysis

Mixed-effects	Effects			P
	Estimate	2.5%	97.5%
Intercept	1.719	1.544	1.894	<0.001
FMI of paraspinal muscles (Goutallier grade ≥2)	0.162	0.063	0.262	0.002
Degeneration score total	−0.005	−0.028	0.018	0.699
Age	0.005	−0.001	0.010	0.136
Female	0.178	0.086	0.269	<0.001
BMI	0.022	0.013	0.031	<0.001
Duration of symptoms>6 mo	0.020	−0.080	0.120	0.702
CIRS	0.012	0.001	0.024	0.033
Problem getting worse in the last 3 mo before inclusion into study	0.250	0.148	0.353	<0.001
HADS	0.372	0.251	0.493	<0.001
Study visit at 12 mo	−0.413	−0.534	−0.292	<0.001
Study visit at 24 mo	−0.424	−0.544	−0.303	<0.001
Study visit at 36 mo	−0.366	−0.486	−0.246	<0.001
Surgery	0.017	−0.118	0.152	0.810
Study visit at 12 mo: surgery	−0.341	−0.484	−0.198	<0.001
Study visit at 24 mo: surgery	−0.300	−0.442	−0.158	<0.001
Study visit at 36 mo: surgery	−0.323	−0.464	−0.181	<0.001

Bold values indicate statistical significance.

SSM function ranges 1 to 4, best to worst; minimal clinically important difference=0.52.

BMI indicates body mass index; CIRS, Cumulative Illness Rating Scale; FMI, fatty muscle infiltration; HADS, Hospital Anxiety and Depression Scale; SSM, Spinal Stenosis Measure.