Spine
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Prospective cohort study. ⋯ 2.
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A retrospective case-control study. ⋯ 3.
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Secondary analysis of a national survey. ⋯ 3.
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Systematic review. ⋯ 4.
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Case report. ⋯ 5.
Prospective cohort study. ⋯ 2.
A retrospective case-control study. ⋯ 3.
Secondary analysis of a national survey. ⋯ 3.
Systematic review. ⋯ 4.
Case report. ⋯ 5.