[1] Inst Work & Hlth, Toronto, ON M5G 2E9, Canada
[2] Univ Toronto, Dept Publ Hlth Sci, Toronto, ON, Canada
[3] Univ Toronto, Dept Hlth Policy Management & Evaluat, Toronto, ON, Canada
[4] Toronto Western Res Inst, Div Hlth Care & Outcomes Res, Toronto, ON, Canada
[5] Toronto Western Hosp, Univ Hlth Network Rehabil Solut, Ctr Res Expertise Improved Disabil Outcomes, Toronto, ON M5T 2S8, Canada
[6] Univ Alberta, Sch Publ Hlth, Dept Publ Hlth Sci, Edmonton, AB, Canada
[7] Univ Alberta, Sch Publ Hlth, Alberta Ctr Injury Control & Res, Edmonton, AB, Canada
[8] Karolinska Inst, Inst Environm Med, S-10401 Stockholm, Sweden
[9] Univ British Columbia, Dept Med, Vancouver, BC V5Z 1M9, Canada
[10] Univ Calif Irvine, Dept Neurol, Irvine, CA 92717 USA
[11] Univ Calif Los Angeles, Sch Publ Hlth, Dept Epidemiol, Los Angeles, CA 90024 USA
[12] Stanford Univ, Sch Med, Dept Orthoped Surg, Stanford, CA 94305 USA
[13] Stanford Univ Hosp & Clin, Orthoped Spine Ctr, Stanford, CA USA
[14] Stanford Univ Hosp & Clin, Spinal Surg Serv, Stanford, CA USA
[15] Univ Hawaii Manoa, John A Burns Sch Med, Dept Publ Hlth Sci, Honolulu, HI 96822 USA
[16] CUNY, Dept Orthoped, New York, NY 10021 USA
[17] CUNY, Dept Environm Med, New York, NY 10021 USA
[18] CUNY, Sch Med, Program Ergon & Biomech, New York, NY 10031 USA
[19] CUNY, Grad Sch Arts & Sci, New York, NY 10031 USA
[20] CUNY, Med Ctr, Occupat & Ind Orthoped Ctr, New York, NY 10031 USA
[21] Merck & Co Inc, Rahway, NJ 07065 USA