Fig. 4. Length of stay (LOS) by total hip arthroplasty (THA) and total knee arthroplasty (TKA). (A) At a level of ^*p < 0.05, hypoalbuminemia was associated with significantly increased LOS for primary THA (4.0 vs. 2.6 days, p < 0.001) and primary TKA (4.2 vs. 2.8 days, p < 0.001) relative to those with serum albumin > 4.5 g/dL. (B) This trend persisted for revision procedures, as those with hypoalbuminemia had higher LOS for revision THA (7.3 vs. 3.6 days, p < 0.001) and revision TKA (4.3 vs. 2.7 days, p < 0.001). For both THA and TKA primary procedures, all serum albumin classes lower than serum albumin > 4.5 g/dL were associated with significantly longer lengths of stay. For TKA revision procedures, both serum albumin 3.5–4.0 g/dL and 4.0–4.5 g/dL were associated with significantly increased LOS.