Abstract
Background:
Hypoalbuminemia has been associated with several medical complications following surgery in a variety of orthopedic procedures. Hypoalbuminemia has previously been shown to have an increased risk for transfusions, hospital stay longer than three days, and mortality following total shoulder arthroplasty (TSA). This study seeks to further assess the relationship between low serum albumin and morbidity to allow surgeons to both preoperatively optimize patients and assess the risk of surgery prior to TSA.
Methods:
The American College of Surgeons National Surgical Quality Improvement Program® database was queried to identify 14,494 TSA patients, 6,129 (42.23%) who met inclusion criteria. Patients who had shoulder hemiarthroplasty, revision TSA, or incomplete serum albumin data were excluded. Demographic factors, preoperative comorbidities, and acute complication rates were assessed between hypoalbuminemic (n=485; 7.91%) and a propensity-matched control cohort (n=485), controlling for differences in patient demographics and comorbidities. Multivariate propensity-adjusted logistic regression analyses were used to assess hypoalbuminemia as an independent risk factor for specific postoperative complications.
Results:
Hypoalbuminemic patients undergoing TSA demonstrated significantly higher rates of pulmonary complications (p=0.006), unplanned intubation (p=0.014), DVT/PE (p=0.014), cardiac complications (p=0.033), infectious complications (p=0.025), blood transfusions (p<0.001), reoperation (p=0.007), extended length of stay (> 4 days) (p=0.036), unplanned readmission (p=0.001), and mortality (p=0.025) in the 30-day postoperative period when compared to the propensity-matched control cohort. On multivariate regression analyses, hypoalbuminemia independently increased the risk for pulmonary complications (OR 9.678, p=0.031), blood transfusions (OR 2.539, p<0.001), reoperation (OR 5.461, p=0.032), and readmission (OR 2.607, p=0.007).
Conclusions:
Hypoalbuminemic patients undergoing TSA had increased rates of overall cardiac and pulmonary complications, unplanned intubations, DVT/PE’s, overall infectious complications, increased incidence of blood transfusions, reoperation, extended LOS (> 4 days), readmission, and death. Multivariate analyses demonstrated that low albumin was independently associated with increased risk for pulmonary complications, blood transfusions, reoperation, and readmission. Preoperative albumin levels in patients undergoing TSA may help with preoperative risk stratification and optimization.
Level of evidence: III
Keywords: reoperation, mortality, pulmonary, cardiac, albumin, hypoalbuminemia, total shoulder arthroplasty, readmission, blood transfusion, unplanned intubation, complication
Introduction
The use of total shoulder arthroplasty (TSA) for the treatment of osteoarthritis has increased significantly from an incidence rate of 6.1 per 100,000 patients in 2005 to 13.4 per 100,000 patients in 2013.1-3 As its popularity increases,4-5 surgeons must better be able to anticipate and manage complications associated with TSA.6 Though TSA has comparatively lower overall complication rates than hip and knee arthroplasty,7-8 these complications can drastically lower quality of life for patients and increase healthcare costs. Therefore, it is critical to identify and potentially modify risk factors in order to reduce such complications.
Hypoalbuminemia has previously been reported as a risk factor for various complications in orthopedic surgical patients, including infection and impaired wound healing.9-10 Hypoalbuminemia has numerous etiologies and is most commonly used as a marker of malnutrition, which has been previously associated with poor outcomes in orthopedic patients.11-13 Garcia et al. previously reported the effect of malnutrition in 1,681 TSA patients from 2005 to 2013 using the American College of Surgeons maintained National Surgical Quality Improvement Program (ACS-NSQIP) database, and demonstrated hypoalbuminemia to be an independent risk factor for blood transfusions, extended length of stay beyond 3 days, and increased mortality rate.14 Since then, the number of available TSA cases in the ACS-NSQIP database with complete albumin values has increased approximately four-fold. This expansion of data warrants an update to depict any existing association between hypoalbuminemia and surgical complications following TSA that may have not been previously reported.
The present study uses the ACS-NSQIP database to examine the effect of hypoalbuminemia on short-term perioperative and postoperative complications in patients undergoing primary TSA (both anatomic and reverse arthroplasty). Specifically, this study seeks to determine differences in patient characteristics for those with hypoalbuminemia and normal albumin levels, determine whether low albumin levels were associated with increased rates of certain complications, and further establish hypoalbuminemia as an independent risk factor for specific postoperative complications following TSA.
Methods
Patient Selection
The ACS-NSQIP database was queried for all patients who had undergone primary TSA (Current Procedure Terminology CPT code 23472) from 2005 to 2016.15 The study was exempt from Institutional Review Board approval as it utilized patient data from a publicly available, deidentified database maintained by the ACS. Patients at least 18 years of age who had complete serum albumin concentration levels were included in the study. Hypoalbuminemia was defined as a serum albumin level of less than 3.5 g/dL. Patients were stratified into two cohorts—those with normal albumin levels and those with low serum albumin. Patients who had undergone hemiarthroplasty procedures and revision shoulder arthroplasty procedures, corresponding to CPT codes 23470 and 23473/23474 respectively, were excluded from this study. Patients were also excluded if their serum albumin concentration was missing or unknown.
Variables
Demographic factors such as age, sex, race, and body mass index (BMI) were included for analysis. Preoperative comorbidities that were analyzed include smoking history, diabetes mellitus, dyspnea, chronic obstructive pulmonary disease (COPD), ascites, ventilator dependence, congestive heart failure (CHF), hypertension requiring medications, acute renal failure, dialysis, disseminated cancer, wound infections, steroid use for chronic conditions, weight loss of more than 10% of the patient’s body weight in the 6 months leading up to the surgery, hematologic disorders, preoperative blood transfusions, systemic sepsis, and preoperative functional status. Additionally, serum sodium levels, blood urea nitrogen, creatinine, albumin, white blood cell count, hematocrit level, and platelet count were included.
The following outcome variables were assessed: superficial incisional surgical site infections (SSI), deep incisional SSI, organ/space SSI, pneumonia, unplanned intubation, pulmonary embolism (PE), ventilator dependence for greater than 48 hours, progressive renal insufficiency, acute renal failure, urinary tract infection (UTI), stroke, cardiac arrest requiring cardiopulmonary resuscitation (CPR), deep venous thromboembolism (DVT), myocardial infarction (MI), blood transfusion requirements, systemic sepsis, septic shock, return to the operating room, extended LOS (length of stay) (≥ 4 days), unplanned readmission, and death. Variables where more than 10% of patients had missing information were excluded from analysis.
Statistical Analysis
Differences in demographics, preoperative comorbidities between hypoalbuminemic patients and those with normal albumin levels were assessed using Pearson’s chi-squared tests, Fischer’s exact tests, and one-way analysis of variance (ANOVA). Further analysis was completed by using propensity score matching without replacement to generate a matched control in a 1:1 manner with randomized case-drawing for comparison with the 485 hypoalbuminemic TSA patients. This matched control cohort of 485 patients with normal albumin levels, controlled for significant patient demographic factors and pre-operative comorbidities, was analyzed against hypoalbuminemic patients using Pearson’s Chi-Squared tests for categorical variables. ANOVA was used for continuous variables, such as age and laboratory values, to evaluate for differences in incidence rates and means, respectively, for each variable of interest. Multivariate propensity-adjusted logistic regression models were generated to assess hypoalbuminemia’s role as an independent risk factor for specific 30-day complications following primary TSA. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for each postoperative complication to quantify the risk association. An alpha of 0.05 was used to assess significance in univariate and multivariate analyses. All statistical analyses were performed using the IBM® SPSS® Statistics Version 25 software. (IBM Corp, Armonk, NY, USA)
Results
A total of 14,494 patients underwent TSA between 2005 and 2016. 6,129 patients met inclusion criteria for study, of which 485 patients (7.91%) had hypoalbuminemia as defined by a serum albumin concentration of less than 3.5 g/dL. A significantly higher proportion of females were found to have hypoalbuminemia (73.81%) compared to the normal albumin cohort (54.96%; p<0.001). Univariate analysis also yielded significant differences in race between the two cohorts (p=0.003; Table 1). The hypoalbuminemia cohort consisted of significantly more individuals who identified as “White” (88.45%) and African-American (7.63%) than the control cohort. Patients with hypoalbuminemia had higher rates of all comorbidities analyzed, with the exception of excessive recent weight loss. The mean serum albumin levels between the two cohorts were also significantly different; the low albumin patient cohort had a mean albumin level of 3.12 g/dL, while the normal cohort had a mean of 4.11 g/dL (p<0.001; Table 1).
Table 1.
Patient Demographics and Preoperative Comorbidities Stratified by Serum Albumin
| DEMOGRAPHICS | Normal Albumin | PM-Matched Control | Hypoalbuminemia | P-Value | P-PM Value | |||
|---|---|---|---|---|---|---|---|---|
| n=5644 (%) | n=485 (%) | n=485 (%) | ||||||
| Age (Mean ± SD)a | 68.86 ± 9.820 | 70.26 ± 9.442 | 71.24 ± 10.388 | <0.001 | 0.125 | |||
| Sex | <0.001 | 0.005 | ||||||
| Female | 3102 | 54.96% | 318 | 65.57% | 358 | 73.81% | ||
| Male | 2540 | 45.00% | 167 | 34.43% | 127 | 26.19% | ||
| Race | <0.001 | 0.179 | ||||||
| American Indian/Alaskan Native | 35 | 0.62% | 2 | 0.41% | 1 | 0.21% | ||
| Asian or Pacific Islander | 35 | 0.62% | 3 | 0.62% | 0 | 0.00% | ||
| Black or African American | 248 | 4.39% | 29 | 5.98% | 37 | 7.63% | ||
| Hispanic | 2 | 0.04% | 0 | 0.00% | 1 | 0.21% | ||
| White | 4965 | 87.97% | 424 | 87.42% | 429 | 88.45% | ||
| Unknown | 359 | 6.36% | 27 | 5.57% | 17 | 3.51% | ||
| PRE-OPERATIVE COMORBIDITIES | ||||||||
| Smoking History | 599 | 10.61% | 52 | 10.72% | 66 | 13.61% | 0.042 | 0.169 |
| Diabetes Mellitus | 1021 | 18.09% | 93 | 19.18% | 113 | 23.30% | 0.005 | 0.116 |
| Dyspnea | <0.001 | 0.012 | ||||||
| No Dyspnea | 5229 | 92.65% | 442 | 91.13% | 413 | 85.15% | ||
| At Rest | 19 | 0.34% | 1 | 0.21% | 4 | 0.82% | ||
| Moderate Exertion | 396 | 7.02% | 42 | 8.66% | 68 | 14.02% | ||
| COPD | 367 | 6.50% | 38 | 7.84% | 70 | 14.43% | <0.001 | 0.001 |
| Ascites | 1 | 0.02% | 0 | 0.00% | 1 | 0.21% | 0.152 | 1.000 |
| Congestive Heart Failure | 31 | 0.55% | 3 | 0.62% | 11 | 2.27% | <0.001 | 0.031 |
| Hypertension | 3840 | 68.04% | 335 | 69.07% | 354 | 72.99% | 0.024 | 0.179 |
| Acute Renal Failure | 3 | 0.05% | 0 | 0.00% | 2 | 0.41% | 0.053 | 0.499 |
| Disseminated Cancer | 16 | 0.28% | 4 | 0.82% | 5 | 1.03% | 0.021 | 1.000 |
| Wound Infection | 38 | 0.67% | 5 | 1.03% | 9 | 1.86% | 0.010 | 0.282 |
| Steroid Use | 317 | 5.62% | 38 | 7.84% | 56 | 11.55% | <0.001 | 0.051 |
| Bleeding Disorder | 158 | 2.80% | 25 | 5.15% | 24 | 4.95% | 0.007 | 0.883 |
| Blood Transfusions | 12 | 0.21% | 8 | 1.65% | 9 | 1.86% | <0.001 | 0.807 |
| Functional Status | <0.001 | <0.001 | ||||||
| Independent | 5456 | 96.67% | 465 | 95.88% | 436 | 89.90% | ||
| Partially Dependent | 127 | 2.25% | 13 | 2.68% | 42 | 8.66% | ||
| Totally Dependent | 6 | 0.11% | 1 | 0.21% | 5 | 1.03% | ||
| LABORATORY VALUESa | ||||||||
| Sodium (mEq/L) | 139.32 ± 3.073 | 139.21 ± 3.092 | 138.61 ± 3.776 | <0.001 | 0.007 | |||
| Blood Urea Nitrogen (mg/dL) | 18.47 ± 7.165 | 18.71 ± 7.810 | 19.15 ± 10.314 | 0.057 | 0.459 | |||
| Creatinine (mg/dL) | 0.96 ± 0.584 | 0.96 ± 0.545 | 1.06 ± 0.879 | <0.001 | 0.026 | |||
| Albumin (g/dL) | 4.11 ± 0.355 | 4.12 ± 0.349 | 3.12 ± 0.367 | <0.001 | <0.001 | |||
| White Blood Cells (103 c/mL) | 7.20 ± 2.524 | 7.35 ± 2.207 | 7.86 ± 2.609 | <0.001 | 0.001 | |||
| Hematocrit (%) | 40.63 ± 4.479 | 40.02 ± 4.495 | 36.37 ± 5.298 | <0.001 | <0.001 | |||
| Platelets (per mL) | 243.59 ± 69.043 | 243.63 ± 67.250 | 245.32 ± 96.123 | 0.614 | 0.753 | |||
PM: Propensity Matched; SD: standard deviation; COPD: chronic obstructive pulmonary disease;
Values expressed as Mean ± Standard Deviation.
All other values expressed as (%) and N.
Bold indicates statistical significance.
When comparing the propensity-matched control cohort and the hypoalbuminemic patients, the hypoalbuminemia cohort consisted of a significantly larger proportion of female patients (73.81% vs. 65.57%; p=0.005). The hypoalbuminemic TSA patients also demonstrated significantly higher rates of dyspnea (85.15% vs. 91.13%; p=0.012), COPD (14.43% vs. 7.84%; p=0.001), CHF (2.27% vs. 0.62%; p=0.031), and functional dependence (9.69% vs. 2.89%; p<0.001) in comparison to the matched control cohort (Table 1).
Hypoalbuminemic patients experienced a significantly longer mean LOS from operation to discharge (2.75 days vs. 2.20 days; p<0.001) and a significantly longer total length of hospital stay from admission to discharge (3.46 days vs. 2.26 days; p<0.001) than the matched control cohort. However, the mean number of days between admission and operation were not significantly different (p=0.894). The mean operative time (p=0.848) and time under anesthesia (p=0.921) were not significantly different between hypoalbuminemic patients and those with normal albumin levels (Table 2).
Table 2.
Perioperative Time Variables Stratified by Serum Albumin Levels
| OPERATIVE VARIABLES | PM-Generated Control Cohort | Hypoalbuminemia | PM P-Value |
|---|---|---|---|
| aAnesthesia Time Under (min) | 191.98 ± 62.688 | 193.39 ± 75.517 | 0.912 |
| a(Operative min) Time | 113.22 ± 44.736 | 113.75 ± 42.027 | 0.848 |
| aTotal Length of Hospital Stay (days) | 2.26 ± 1.981 | 3.46 ± 3.668 | <0.001 |
| afrom Days Admission to Operation | 0.81 ± 16.579 | 0.71 ± 2.112 | 0.894 |
| aDays to Discharge from Operation | 2.20 ± 1.889 | 2.75 ± 2.211 | <0.001 |
PM: Propensity-matched;
Values expressed as Mean ± Standard Deviation
Bold indicates statistical significance.
Patients with hypoalbuminemia had significantly higher rates of numerous 30-day postoperative complications. Hypoalbuminemic patients demonstrated higher rates of pulmonary complications (2.06% vs. 0.21%; p=0.006), unplanned intubation (1.24% vs. 0.00%; p=0.014), DVT/PE (1.24% vs. 0.00%; p=0.014), cardiac complications (1.44% vs. 0.21%; p=0.033), and infectious complications (1.03% vs. 0.00%; p=0.025). These patients also demonstrated significantly higher rates intraoperative/postoperative blood transfusions (14.43% vs. 5.36%; p<0.001), return to the operating room (2.47% vs. 0.41%; p=0.007), extended LOS (> 4 days) following the procedure (16.91% vs. 12.16%; p=0.036), unplanned readmission (6.80% vs. 2.47%; p=0.001), and mortality (1.03% vs. 0.00%; p=0.025; Table 3).
Table 3.
Adjusted 30-Day Postoperative Complication Analysis by Albumin Status
| POST-OPERATIVE COMPLICATION | PM-Control Cohort | Hypoalbuminemia | PM P-Value | ||
|---|---|---|---|---|---|
| n=485 | n=485 | ||||
| Pulmonary | 1 | 0.21% | 10 | 2.06% | 0.006 |
| Pneumonia | 1 | 0.21% | 6 | 1.24% | 0.058 |
| Unplanned Intubation | 0 | 0.00% | 6 | 1.24% | 0.014 |
| Ventilator Dependence (>48 hours) | 0 | 0.00% | 2 | 0.41% | 0.157 |
| Vascular | 2 | 0.41% | 7 | 1.44% | 0.094 |
| DVT/PE | 0 | 0.00% | 6 | 1.24% | 0.014 |
| CVA/Stroke | 2 | 0.41% | 1 | 0.21% | 0.563 |
| Cardiac | 1 | 0.21% | 7 | 1.44% | 0.033 |
| Cardiac Arrest | 0 | 0.00% | 2 | 0.41% | 0.157 |
| Myocardial Infarction | 1 | 0.21% | 5 | 1.03% | 0.101 |
| Infectious | 0 | 0.00% | 5 | 1.03% | 0.025 |
| Sepsis | 0 | 0.00% | 3 | 0.62% | 0.083 |
| Septic Shock | 0 | 0.00% | 1 | 0.21% | 0.317 |
| Surgical Site Infections | 0 | 0.00% | 1 | 0.21% | 0.317 |
| Renal | 6 | 1.24% | 9 | 1.86% | 0.435 |
| UTI | 6 | 1.24% | 8 | 1.65% | 0.590 |
| Renal Insufficiency | 0 | 0.00% | 1 | 0.21% | 0.317 |
| Blood Transfusionsa | 26 | 5.36% | 70 | 14.43% | <0.001 |
| Reoperation | 2 | 0.41% | 12 | 2.47% | 0.007 |
| Extended LOS (≥ 4 days) | 59 | 12.16% | 82 | 16.91% | 0.036 |
| Unplanned Readmission | 12 | 2.47% | 33 | 6.80% | 0.001 |
| Mortality | 0 | 0.00% | 5 | 1.03% | 0.025 |
PM: Propensity-matched; DVT: deep venous thromboembolism; PE: pulmonary embolism; CVA: cerebral vascular accident; UTI: urinary tract infection; LOS: length of stay;
Within 72 hours of starting operation
Bold indicates statistical significance.
Multivariate propensity-adjusted logistic regression analysis showed hypoalbuminemia to be independently associated with increased odds of pulmonary complications (OR 9.678, 95% CI 1.223-76.569, p=0.031), intraoperative/postoperative blood transfusions (OR 2.539, 95% CI 1.562-4.125, p<0.001), reoperation (OR 5.461, 95% CI 1.158-25.745, p=0.032), and unplanned readmission (OR 2.607, 95% CI 1.292-5.259, p=0.007). (Table 4)
Table 4.
Multivariable Propensity-Adjusted Logistic Regression Analyses Assessing Hypoalbuminemia as a Risk Factor for Postoperative Complications
| POST-OPERATIVE COMPLICATION | P-Value | Odds Ratio | 95% CI | |
|---|---|---|---|---|
| Pulmonary | 0.031 | 9.678 | 1.223 | 76.569 |
| Pneumonia | 0.102 | 5.922 | 0.704 | 49.811 |
| Unplanned Intubation* | 0.993 | >999.99 | 0.000 | - |
| Ventilator Dependence (>48 hours)* | 0.993 | >999.99 | 0.000 | - |
| Vascular | 0.133 | 3.41 | 0.687 | 16.920 |
| DVT/PE* | 0.992 | >999.99 | 0.000 | - |
| CVA/Stroke | 0.474 | 2.582 | 0.192 | 34.653 |
| Cardiac | 0.081 | 6.579 | 0.791 | 54.714 |
| Cardiac Arrest* | 0.993 | >999.99 | 0.000 | - |
| Myocardial Infarction | 0.203 | 4.159 | 0.464 | 37.304 |
| Infectious* | 0.992 | >999.99 | 0.000 | - |
| Sepsis* | 0.993 | >999.99 | 0.000 | - |
| Septic Shock* | 0.992 | >999.99 | 0.000 | - |
| Surgical Site Infections* | 0.992 | >999.99 | 0.000 | - |
| Renal | 0.683 | 1.251 | 0.427 | 3.662 |
| UTI | 0.889 | 1.082 | 0.358 | 3.267 |
| Renal Insufficiency | 0.993 | >999.99 | 0.000 | - |
| Blood Transfusionsa | <0.001 | 2.539 | 1.562 | 4.125 |
| Reoperation | 0.032 | 5.461 | 1.158 | 25.745 |
| Extended LOS (≥ 4 days) | 0.250 | 1.246 | 0.857 | 1.812 |
| Unplanned Readmission | 0.007 | 2.607 | 1.292 | 5.259 |
| Mortality | 0.993 | >999.99 | 0.000 | |
CI: Confidence Interval; DVT: deep venous thromboembolism; PE: pulmonary embolism; CVA: cerebral vascular accident; UTI: urinary tract infection; LOS: length of stay;
Had an incidence rate of 0.00% in the PM-generated control cohort (Table 3)
Within 72 hours of starting operation
Bold indicates statistical significance.
Discussion
This study demonstrated increased rates of overall cardiac and pulmonary complications, unplanned intubations, DVT/PE’s, overall infectious complications, increased incidence of blood transfusions, reoperation, extended LOS (> 4 days), readmission, and death in patients with hypoalbuminemia. Given these potential complications, a thorough evaluation of patients found to have low serum albumin is warranted. Patients should be appropriately referred to nutritional services for preoperative optimization if the hypoalbuminemia is secondary to nutritional deficiencies prior to TSA.
Albumin comprises more than 50% of whole blood and has been shown to carry out numerous responsibilities. Recent literature has shown albumin’s role to extend beyond that of a carrier protein with its anticoagulant properties. While the mechanism is incompletely understood, low albumin can lead to a hypercoagulable state, potentially causing increased rates of DVT and subsequent PE.16-20 In this study, low albumin was associated with an increased rate of DVT/PE, which has not been demonstrated in previous analyses of TSA..14
This study found increased rates of required blood transfusion in TSA patients intraoperatively and postoperatively in patients with low serum albumin. These results support previous studies on transfusion rates in hypoalbuminemic patients undergoing TSA and revision total knee arthroplasty (TKA).10-14 Hypoalbuminemia can serve as a surrogate marker for chronic kidney disease and chronic inflammatory states, both of which have the potential to cause preoperative anemia and subsequently, higher rates of transfusion.21-23 The need for blood transfusions is likely multifactorial and individual to each patient, necessitating further research to clarify the relationship between anemia requiring transfusions and low albumin levels.
Low albumin has often been used as a surrogate marker for overall poorer health. Similar to Garcia et al., this study also found increased rates of pulmonary complications in hypoalbuminemic patients undergoing primary TSA.14 This study additionally found an increased rate of unplanned intubation in the hypoalbuminemic group as well.14 This finding is in line with other reports of increased rates of unplanned intubation in hypoalbuminemic patients undergoing surgical treatment for geriatric hip fractures and revision TKA.10,24 Albumin helps maintain intravascular volume, prevents fluid extravasation, and supports the vascular endothelial surface.25-26 It is plausible that decreased albumin levels could perturb a tenacious fluid homeostasis, potentially leading to adverse clinical complications.
Reports in the cardiac literature indicate that hypoalbuminemia is strongly associated with increased rates of coronary disease, MI, and other cardiac events in the general population.27-30 This study found increased rates of cardiac complications in patients with low albumin, an association previously unreported in patients undergoing TSA.14 The exact mechanism behind hypoalbuminemia’s role in causing various cardiac complications, such as MI or heart failure is, as of yet, incompletely understood. However, the results of this study indicate that low albumin level may be useful as an indicator or screening tool for further work up or preoperative optimization to help mitigate the effects of cardiac postoperative complications.
This current study found an overall increase in infectious complications in the low albumin cohort. Hypoalbuminemia has been reported to be associated with increased infection rates in a broad spectrum of clinical settings.31,32 Similar to this study, a recent meta-analysis analyzed patients with albumin levels <3.5 g/dL and demonstrated a nearly 2.5-fold increased risk of SSI in orthopedic procedures.33 This study also found increased rates of extended LOS, reoperation, readmission, and mortality in patients with low albumin. Low albumin levels have been well associated with poor healing reserves in the literature, likely secondary to poor nutritional status.34 This poor healing capability may contribute to the increased infection and reoperation rates. A limitation inherent to this study is that the ACS-NSQIP database does not delineate the reason for readmissions. Albumin levels as a surrogate marker for nutritional status may be overutilized as tools such as the Mini Nutritional Assessment and Subjective Global Assessment have proven to be effective in evaluating nutritional status.35,36 However, as the results of the current study demonstrate, the importance of low albumin levels as a potential marker for an arduous postoperative course in primary TSA cannot be overlooked. Wilson et al. suggest that obtaining an albumin level at admission may prove beneficial in orthopedic lower extremity trauma patients due to the high rate of readmission, reoperation, and overall postoperative complications.37
Similar to Garcia et al.,14 our study demonstrated that patients with hypoalbuminemia were at increased risk of blood transfusions in the multivariate logistic regression models. Our study did not demonstrate hypoalbuminemia to be an independent risk factor for mortality and extended LOS (> 4 days) in the postoperative period following TSA.14 We also additionally report hypoalbuminemia to be an independent risk factor for reoperation, readmission, and pulmonary complications – relationships previously unidentified in TSA patients.14 Further work investigating the role of hypoalbuminemia and its potential role in increased risk of mortality following TSA is warranted to better risk-stratify patients preoperatively.
The current study has several limitations. Only variables that were recorded for more than 85% of the patients were included in this study. A limitation inherent to all clinical registries is the lack of verification of data entries that may influence analyses. The ACS-NSQIP database only reports outcomes within a 30-day surveillance period. Recording adverse events and complications for a longer time can provide further insight into longer term outcomes. Another limitation of this study lies in the exclusion of variables that did not have at least a 90% reporting rate. For example, pneumonia and angina were excluded. While the exclusion helps the analyses presented in the study remain as accurate as possible, excluding such variables may lead to unidentified relationships that may be in fact significant. A dependence on CPT/ICD-9 codes is another limitation as these codes were not originally designed for data analysis and could be subject to coding bias with financial incentives or coding errors.38 Despite propensity-score matching and multivariate analysis, the effect of confounding cannot be excluded given the large number of variables that may increase risk of complications in TSA. Finally, all patients who had undergone TSA were included in this retrospective study. The present study did not distinguish patients based on their need for an anatomic total shoulder arthroplasty versus a reverse design as the CPT code is the same for both procedures.
Conclusions
Hypoalbuminemic TSA patients had increased rates of overall cardiac and pulmonary complications, unplanned intubations, DVT/PE’s, overall infectious complications, increased incidence of blood transfusions, reoperation, extended LOS (> 4 days), readmission, and death. Multivariate analyses demonstrated low albumin to independently increase the risk for pulmonary complications, blood transfusions, reoperation, and readmission. Shoulder surgeons may wish to proceed with caution when deciding on elective TSA for hypoalbuminemic patients and defer treatment until medical or nutritional status are optimizated. Future research into identifying a minimum serum albumin level could prove useful in establishing guidelines in pre-operative counseling in this specific population of patients suffering from degenerative shoulder disease requiring TSA.
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