Clin Orthop Surg.  2018 Dec;10(4):398-406. 10.4055/cios.2018.10.4.398.

Preoperative Serum Albumin Levels Predict Treatment Cost in Total Hip and Knee Arthroplasty

• Rudasill S
• Ng A
• Kamath AF

• KMID: 2426523
• DOI: http://doi.org/10.4055/cios.2018.10.4.398

Abstract

BACKGROUND
Hypoalbuminemia (serum albumin < 3.5 g/dL) is associated with increased morbidity and mortality in patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, costs associated with hypoalbuminemia remain unknown. This study investigated the effect of serum albumin on direct treatment costs, length of stay (LOS), and readmissions for primary and revision THA and TKA patients.
METHODS
All adult patients at a single institution undergoing primary or revision THA or TKA between January 2014 and December 2016 were retrospectively reviewed. Patients were stratified by preoperative serum albumin level. The primary outcome was total direct costs at index hospitalization. Secondary outcomes included LOS and readmission within 30 days. Multivariable regressions were utilized to adjust for demographics and comorbidities.
RESULTS
Of 3,785 patients, 114 (3.0%) had hypoalbuminemia. After adjustment, hypoalbuminemia was associated with a 16.2% increase in costs (β = 0.162; 95% confidence interval [CI], 0.112 to 0.213; p < 0.001), representing an average cost increase of $3,383 (95% CI, $2,281 to $4,485) relative to costs for serum albumin > 4.5 g/dL. The increased total costs were significantly higher in revision ($4,322, p = 0.034) than in primary ($3,446, p < 0.001) procedures. In adjusted regression, each 1.0 g/dL increase in serum albumin yielded a 6.6% reduction in costs (β = −0.066; 95% CI, −0.090 to −0.042]; p < 0.001), for average savings of $1,282 (95% CI, $759 to $1,806) per unit albumin. Adjusted regressions demonstrated that a 1-point increase in serum albumin reduced readmissions by 53% (odds ratio, 0.47; 95% CI, 0.31-0.73; p = 0.001) and LOS by 0.6 days (β = −0.60; 95% CI, −0.76 to −0.44; p < 0.001).
CONCLUSIONS
Hypoalbuminemia is associated with increased total direct costs, LOS, and readmissions following primary and revision THA and TKA. Future efforts to predict and address total costs should take into consideration the patient's preoperative serum albumin levels.

Keyword

Hip replacement arthroplasty; Knee replacement arthroplasty; Cost; Hypoalbuminemia; Length of stay

MeSH Terms

Adult
Arthroplasty, Replacement, Hip
Arthroplasty, Replacement, Knee*
Comorbidity
Demography
Health Care Costs*
Hip*
Hospitalization
Humans
Hypoalbuminemia
Income
Knee*
Length of Stay
Mortality
Retrospective Studies
Serum Albumin*
Serum Albumin

Figure

• 

  Fig. 1 Patient selection criteria. Of 4,763 initial patients, 3,785 (79.5%) met selection criteria. TKA: total knee arthroplasty, THA: total hip arthroplasty, BMI: body mass index, Hb: hemoglobin.

• 

  Fig. 2 Total direct costs by primary (A) and revision (B) total hip arthroplasty (THA) and total knee arthroplasty (TKA). At a level of *p < 0.05, hypoalbuminemia was associated with significantly increased costs for primary THA ($17,735 vs. $14,031, p < 0.001) and primary TKA ($17,815 vs. $13,184, p < 0.001) relative to those with serum albumin > 4.5 g/dL. This trend persisted for revision procedures, as those with hypoalbuminemia had higher costs for revision THA ($32,275 vs. $19,818, p < 0.001) and revision TKA ($23,640 vs. $18,704, p < 0.001). A serum albumin level of 3.5–4.0 g/dL also had significantly higher costs relative to serum albumin > 4.5 g/dL for both primary and revision THA procedures, as well as revision TKA procedures.

• 

  Fig. 3 Additional cost of each serum albumin category by primary or revision procedure relative to serum albumin > 4.5 g/dL. Multivariable regressions for both primary and revision procedures accounted for age, body mass index, hemoglobin, glomerular filtration rate, and joint (hip or knee). At a level of *p < 0.05, hypoalbuminemia was associated with significantly increased costs for both primary (average, $3,446; p < 0.001) and revision (average, $4,322; p = 0.034) procedures. Furthermore, serum albumin 3.5–4.0 g/dL was also associated with an average cost increase of $3,787 (p = 0.008) relative to those with serum albumin > 4.5 g/dL.

• 

  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.

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