Influence of admission hematocrit on inpatient rehabilitation outcomes after total knee and hip arthroplasty

Objective: To examine admission hematocrit (Hct) status on inpatient rehabilitation outcomes after total knee (TKA) and hip arthroplasty (THA). Design: This study was a retrospective, exploratory analysis, Patients (n = 400) were stratified by admission hematocrit levels: normal (Hct >= 36-41%, World Health Organization criteria for normal Hct in women and men), low (Hct between the operational 30% cutoff and 36-41%), and very low (Hct < 30%). Functional Independence Measure (FIM) scores and specific lower-body FIM motor scores, FIM efficiency, length of stay (LOS), and total hospital charges were analyzed. Results: Regardless of arthroplasty joint, all improved total FIM score, motor FIM score, and specific lower-body activity FIM scores (walking, wheelchair, dressing, transfers, stairs) by discharge (all P < 0.05). LOS was 28.9-31% longer in the TKA-very low Hct and THA-very low Hct groups than in the normal Hct groups (P = 0.026). Total hospital charges were 32.6-45.6% higher in the TKA-very low Hct and THA-very low Hct groups than in the normal Hct groups (P < 0.05). Hct was a significant contributor to the variance of linear regression models for LOS and total charges (P < 0.05). Conclusions: Although very low Hct at admission does not impede functional gains, it is related to longer LOS and greater hospital charges. Rehabilitation teams should consider this when preparing plans of care, rehabilitation goals, and plans for discharge.