Spine
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Single-center retrospective review. ⋯ 3.
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A retrospective cohort study at a single institution. ⋯ 3.
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Prospective chart review. ⋯ 2.
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A hospital-based retrospective epidemiological study. ⋯ 3.
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Delphi process with multiple iterative rounds using a nominal group technique. ⋯ 5.