Weighted index explained more variance in physical function than an additively scored functional comorbidity scale

Objective1) examine association between the Functional Comorbidity Index (FCI) and discharge functional status (FS); 2) examine impact of FCI on FS when added to comprehensive models; and 3) compare additive FCI with weighted FCI and list of condition variables (list).Study Design and SettingPatients were drawn from Focus On Therapeutic Outcomes, Inc. (FOTO) database (1/1/06–12/31/07). FS collected using computer adaptive tests. Linear regression examined association between FCI and FS. Three methods of including functional comorbidities (FC) were compared.ResultsRelationship between FCI and FS varied by group (range, 0.02–0.9). Models with weighted index or list had similar R2. Weighted FCI or list increased R2 of crude models by <0.01 for cervical, shoulder, and lumbar; by 0.01 for wrist/hand, knee, and foot/ankle; by 0.02 for hip; by 0.03 for elbow; and by 0.08 for neurological. Addition of FCI to comprehensive models added <0.01 to R2 (all groups). Weighted FCI increased R2 by <0.01 for cervical, lumbar, and shoulder; by 0.01 for wrist/hand, hip, knee, and foot/ankle; by 0.02 for elbow; and by 0.04 for neurological; whereas list increased R2 by <0.01 for cervical, shoulder, and lumbar; by 0.01 for knee and foot/ankle; by 0.02 for elbow, wrist/hand, and hip; and by 0.05 for neurological.ConclusionList of comorbidities or weighted FCI is preferable to using additive FCI.