[1] Stanford Univ, Sch Med, Dept Orthopaed Surg, Stanford, CA 94305 USA
[2] Stanford Univ Hosp & Clin, Orthopaed Spine Ctr, Stanford, CA USA
[3] Stanford Univ Hosp & Clin, Spinal Surg Serv, Stanford, CA USA
[4] Univ Hawaii Manoa, John A Burns Sch Med, Dept Publ Hlth Sci, Honolulu, HI 96822 USA
[5] Univ Alberta, Sch Publ Hlth, Dept Publ Hlth Sci, Edmonton, AB T6G 2M7, Canada
[6] Univ Alberta, Sch Publ Hlth, Alberta Ctr Injury Control & Res, Edmonton, AB T6G 2M7, Canada
[7] CUNY, Dept Orthopaed, New York, NY USA
[8] CUNY, Dept Environm Med, New York, NY USA
[9] CUNY, Sch Med, Program Ergon & Biomech, New York, NY USA
[10] CUNY, Grad Sch Arts & Sci, New York, NY USA
[11] CUNY, Grad Sch Arts & Sci, New York, NY USA
[12] CUNY, Med Ctr, Occupat & Ind Orthopaed Ctr, New York, NY 10021 USA
[13] Univ British Columbia, Dept Med, Vancouver, BC V5Z 1M9, Canada
[14] Merck & Co Inc, Rahway, NJ 07065 USA
[15] Karolinska Inst, Inst Environm Med, S-10401 Stockholm, Sweden
[16] Univ Toronto, Dept Publ Hlth Sci, Toronto, ON, Canada
[17] Univ Toronto, Dept Hlth Policy Management & Evaluat, Toronto, ON, Canada
[18] Toronto Western Hosp, Univ Hlth Netwoirk Rehabil Solut, Ctr Res Expertise Improved Disabil Outcomes, Toronto, ON, Canada
[19] Inst Work & Hlth, Toronto, ON, Canada
[20] Univ Toronto, Dept Publ Hlth Sci, Toronto, ON, Canada
[21] Toronto Western Res Inst, Div Hlth Care & Outcomes Res, Toronto, ON, Canada
[22] Toronto Western Res Inst, Univ Hlth Network, Div Hlth Care & Outcomes Res, Toronto, ON, Canada
[23] Univ Calif Irvine, Dept Neurol, Irvine, CA 92717 USA
[24] Univ Calif Los Angeles, Sch Publ Hlth, Dept Epidemiol, Los Angeles, CA 90024 USA