Participants ( N = 35 ) were 51.8 9.7 years old , 80 percent female with CLBP for 14.2 10.1 years , treated with opioids for 7.9 5.7 years , with severe disability ( Oswestry Disability Index score : 66.7 11.4 ) , and average pain score of 5.6 1.5 ( 0-10 rating scale ) .