Spine
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This was a cross-sectional study. ⋯ 4.
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A retrospective study. ⋯ 4.
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A family-based study. ⋯ N/A.
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A retrospective cohort study of prospectively collected data. ⋯ 3.
This was a cross-sectional study. ⋯ 4.
A retrospective study. ⋯ 4.
A family-based study. ⋯ N/A.
A retrospective cohort study of prospectively collected data. ⋯ 3.