[1] Univ British Columbia, Dept Med, Vancouver, BC V5Z 1M9, Canada
[2] Occupat Hlth & Safety Agcy Healthcare, Vancouver, BC, Canada
[3] Univ Hawaii Manoa, John A Burns Sch Med, Dept Publ Hlth Sci, Honolulu, HI 96822 USA
[4] Univ Alberta, Sch Publ Hlth, Dept Publ Hlth Sci, Edmonton, AB T6G 2M7, Canada
[5] Univ Alberta, Sch Publ Hlth, Alberta Ctr Injury Control & Res, Edmonton, AB T6G 2M7, Canada
[6] Univ Calif Irvine, Dept Neurol, Irvine, CA 92717 USA
[7] Univ Calif Los Angeles, Sch Publ Hlth, Dept Epidemiol, Los Angeles, CA 90024 USA
[8] Univ Toronto, Dept Publ Hlth Sci, Toronto, ON M5S 1A1, Canada
[9] Univ Toronto, Dept Hlth Policy Management & Evaluat, Toronto, ON M5S 1A1, Canada
[10] Toronto Western Res Inst, Div Hlth Care & Outcomes Res, Toronto, ON, Canada
[11] Inst Work & Hlth, Toronto, ON, Canada
[12] Univ Hlth Network Rehabil Solut, Toronto Western Hosp, CREIDO, Toronto, ON, Canada
[13] Stanford Univ, Sch Med, Dept Orthopaed Surg, Stanford, CA 94305 USA
[14] Stanford Univ, Hosp & Clin, Orthopaed Spine Ctr, Stanford, CA 94305 USA
[15] Stanford Univ, Hosp & Clin, Spinal Surg Serv, Stanford, CA 94305 USA
[16] Merck & Co Inc, Rahway, NJ USA
[17] Karolinska Inst, Inst Environm Med, S-10401 Stockholm, Sweden
[18] CUNY, Sch Med, Dept Orthopaed, New York, NY USA
[19] CUNY, Grad Sch Arts & Sci, Dept Environm Med, Program Ergon & Biomech, New York, NY 10021 USA
[20] CUNY, Med Ctr, OIOC, New York, NY 10021 USA