Serum Albumin Predicts Survival and Postoperative Course Following Surgery for Geriatric Hip Fracture
Authors: Bohl Daniel D. , Shen Mary R. , Hannon Charles P. , Fillingham Yale A. , Darrith Brian , Della Valle Craig J. 
Published: December 2017

Update
This article was updated on February 8, 2018, because of a previous error. On page 2111, in the Statistical Analysis section, the sentence that had read “Unfortunately, for rare outcomes (classically defined as those occurring at a rate of <10%), odds ratios become exaggeratedly large compared with relative risks.” now reads “Odds ratios and relative risk approximate each other when the outcome is rare (classically defined as an outcome occurring at a rate of <10%), but become increasingly divergent as the outcome becomes more common.”
An erratum has been published: J Bone Joint Surg Am. 2018 Mar 21;100(6):e41.

Background:
Serum albumin level is the most well-established serum marker of malnutrition, with a serum albumin concentration <3.5 g/dL considered to be suggestive of malnutrition. The purpose of this study was to test if serum albumin level is associated with death, specific postoperative complications (e.g., pneumonia), length of hospital stay, and readmission following a surgical procedure for geriatric hip fracture.

Methods:
A retrospective cohort study of geriatric patients (≥65 years of age) undergoing a hip fracture surgical procedure as part of the American College of Surgeons National Surgical Quality Improvement Program was conducted. Outcomes were compared between patients with and without hypoalbuminemia. All comparisons were adjusted for baseline and procedural differences between populations, and patients with missing serum albumin concentration were included in analyses using a missing data indicator.

Results:
There were 29,377 geriatric patients undergoing a hip fracture surgical procedure who met inclusion criteria; of these patients, 17,651 (60.1%) had serum albumin available for analysis. The prevalence of hypoalbuminemia was 45.9%. Following adjustment for baseline and procedural characteristics, the risk of death was inversely associated with serum albumin concentration as a continuous variable (adjusted relative risk, 0.59 [95% confidence interval (CI), 0.53 to 0.65]; p < 0.001). In comparison with patients with normal albumin concentration, patients with hypoalbuminemia had higher rates of death (9.94% compared with 5.53% [adjusted relative risk, 1.52 (95% CI, 1.37 to 1.70); p < 0.001]), sepsis (1.19% compared with 0.53% [adjusted relative risk, 1.92 (95% CI, 1.36 to 2.72); p < 0.001]), and unplanned intubation (2.64% compared with 1.47% [adjusted relative risk, 1.51 (95% CI, 1.21 to 1.88); p < 0.001]). The mean length of stay (and standard deviation) was longer among patients with hypoalbuminemia at 5.67 ± 4.68 days compared with those without hypoalbuminemia at 4.99 ± 3.95 days; the adjusted difference was 0.50 day (95% CI, 0.38 to 0.63 day; p < 0.001). However, the rate of readmission did not differ (p = 0.054) between patients with hypoalbuminemia (10.91%) and those without hypoalbuminemia (9.03%); the adjusted relative risk was 1.10 (95% CI, 1.00 to 1.21).

Conclusions:
Hypoalbuminemia is a powerful independent risk factor for mortality following a surgical procedure for geriatric hip fracture. These data suggest that further investigation into postoperative nutritional supplementation is warranted to decrease the risk of complications.

Level of Evidence:
Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.