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. 2021 Feb 16;16(2):e0247070.
doi: 10.1371/journal.pone.0247070. eCollection 2021.

Albumin and the fibrinogen-to-albumin ratio: Biomarkers for the acute phase response following total knee arthroplasty

Emilie Amaro  1 , Stephanie N Moore-Lotridge  1   2 , Bronson Wessinger  3 , Michael A Benvenuti  1 , Thomas J An  3 , William K Oelsner  1 , Gregory G Polkowski  1 , Jonathan G Schoenecker  1   2   4   5   6
Affiliations

Albumin and the fibrinogen-to-albumin ratio: Biomarkers for the acute phase response following total knee arthroplasty

Emilie Amaro et al. PLoS One. .

Abstract

Purpose: Complications following total knee arthroplasty (TKA) lead to patient morbidity and cost. While acute phase reactants, such as c-reactive protein (CRP) and fibrinogen, have been used to predict complications following TKA, the extent and duration of changes in albumin levels following TKA are unknown. It is hypothesized that like CRP and fibrinogen, albumin, and the fibrinogen/albumin ratio (FAR) represent useful measures of the acute phase response (APR) following TKA. The purpose of this study was to describe the longitudinal course of albumin and FAR in healthy patients following TKA, relative to established biomarkers, and examine if the variance in albumin or FAR correlates with patient comorbidities.

Methods: This retrospective cohort study of patients undergoing TKA at a tertiary medical center. CRP, fibrinogen, and albumin values were collected pre- and post-operatively. An age-adjusted Charlson comorbidity index (CCI) was utilized as a measure of patient comorbidity status.

Results: The median preoperative albumin value was 4.3 g/dL, which dropped to 3.6 g/dL on postoperative day 1 following TKA. The albumin value returned to 93% of the baseline by postoperative week 2. The course of albumin inversely mirrored the course of CRP (r = -0.41). Median preoperative FAR was 0.087 g/L, which rose to 0.130 g/L by postoperative week 2 and returned to baseline by postoperative week 6. While preoperative FAR strongly correlated with postoperative week 2 values (r = 0.74), there was a weak positive correlation between age-adjusted CCI and pre-operative FAR (r = 0.24) in patients undergoing primary TKA.

Conclusion: Albumin levels follow a predictable postoperative decline that inversely correlates with CRP in healthy patients following TKA. Given the low cost and abundance of laboratories offering albumin levels, direct albumin levels and/or albumin ratios such as FAR may be underutilized biomarkers for monitoring the APR following TKA.

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Conflict of interest statement

The authors have read the journal’s policy and have the following competing interests: EA’s spouse works as a paid employee of Exsomed. GGP is a paid consultant for DJO Global and is a board member of the American Association of Hip and Knee Surgeons. JGS is a member of OrthoPediatrics surgeon’s advisory board and education advisory board, receives research support from OrthoPediatrics and PXE International, and receives pharmaceuticals related to research but not related to this submission from IONIS. This does not alter our adherence to PLOS ONE policies on sharing data and materials. There are no patents, products in development or marketed products associated with this research to declare.

Figures

Fig 1
Fig 1. Median circulating albumin (blue circle) and CRP (red square) following TKA. Y-error bars depict a CI of 95%. r = -0.41.
Fig 2
Fig 2
A) Median circulating albumin (blue circle) and fibrinogen (green square) following TKA. r = 0.29. B) Median fibrinogen/albumin ratio (FAR) following TKA. Y-error bars depict a CI of 95%.
Fig 3
Fig 3
A) Comparison of preoperative CRP and fibrinogen/albumin ratio (FAR) in included study patients (N = 157) and those excluded for rheumatoid arthritis (N = 9) or necessitating a revision TKA due to periprostatic infection (n = 32). Whiskers represent the range of data. Cohorts were compared using a non-parametric ANOVA (Kruskal Wallis test) given that data was nonnormally distributed, α = 0.05. B) Median circulating albumin (blue) and CRP (red) following TKA in a patient with cirrhosis who developed wound dehiscence at postoperative week 2. Y-error bars depict a CI of 95%.
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