[1] Rhode Isl Spine Ctr, Pawtucket, RI 02860 USA
[2] Brown Univ, Warren Alpert Med Sch, Dept Community Hlth, Providence, RI 02912 USA
[3] New York Chiropract Coll, Dept Res, Seneca Falls, NY USA
[4] Univ Hawaii, Dept Publ Hlth Sci & Epidemiol, John A Burns Sch Med, Manoa, HI USA