Table 3.

% of patients experiencing improvements in frequency and severity of back pain and limitation of activities.

Improvement (% of patients)	3 months	6 months	12 months	18 months
Frequency of back pain	69.8%*	77.3%*	79.9%*	76.9%*
Severity of back pain	54.3%*	65.4%*	69.8%*	71.6%*
Limitation of activities	53.1%*	66.4%*	68.7%*	65.1%*

*Sign test, change from baseline, P < 0.001.