Systematic Changes in the National Surgical Quality Improvement Program Database Over the Years Can Affect Comorbidity Indices Such as the Modified Frailty Index and Modified Charlson Comorbidity Index for Lumbar Fusion Studies
2020 ◽
Vol 231
(4)
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pp. e93
2018 ◽
Vol 18
(11)
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pp. 1982-1988
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2018 ◽
Vol 227
(4)
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pp. S28-S29