Table 2. Risk factors for poor surgical outcome: multivariate logistic regression analysis.

Variable	OR (95% CI)	P-value
Age at operation (yr)	1.012 (0.949–1.079)	0.719
Preoperative MMT score	0.613 (0.321–1.171)	0.139
Atrophy type
Proximal type	1
Distal type	6.456 (1.938–21.508)	0.002
Duration of symptoms (mo)
<3	1
3–6	3.961 (1.203–13.039)	0.024
>6	18.724 (3.967–88.367)	<0.001
Compression type
VNR	1
AH	4.931 (1.457–16.685)	0.010
VNR + AH	5.538 (1.170–26.218)	0.031

MMT: manual muscle testing; AH: anterior horn; VNR: ventral nerve root; OR: odds ratio; CI: confidence interval; mo: month; yr: year.