Body Mass Index or Serum Albumin Levels: Which is further Prognostic following Cardiac Surgery?

Preoperative Serum Albumin as Predictor of Outcomes After Thyroidectomy

Objective

Albumin is considered to be a surrogate marker for inflammation and nutritional status. Levels usually decrease after surgery but little is known about the predictive value of preoperative albumin levels in patients undergoing thyroidectomy. This study aimed to investigate the 30-day incidence of postoperative outcomes in thyroidectomy patients with and without preoperative hypoalbuminemia.

Study Design

Retrospective cohort study.

Setting

TriNetX Database.

Methods

TriNetX, a federated deidentified database, was retrospectively queried to identify patients who underwent thyroidectomy. Postoperative outcomes within 30 days of thyroidectomy, based on International Classification of Disease, 10th Revision and Current Procedural Terminology codes, in patients with preoperative hypoalbuminemia (≤3.4 g/dL) (cohort 1) were analyzed and compared to patients without hypoalbuminemia (cohort 2).

Results

After propensity score matching, 2398 patients were identified in each cohort. Hypoalbuminemia patients were more likely to have postoperative pneumonia (odds ratio, OR: 3.472, 95% confidence interval, CI [2.016-5.978]), acute renal failure (OR: 3.872, 95% CI [2.412-6.217]), venous thromboembolism (OR: 1.766, 95% CI [1.016-2.819]), and surgical site infection (OR: 2.353, 95% CI [1.282-4.32]). Rates of recurrent laryngeal nerve injury were comparable between cohorts.

Conclusion

Patients undergoing thyroidectomy with preoperative hypoalbuminemia have a higher prevalence of postoperative complications compared to patients without preoperative hypoalbuminemia. While not routinely assessed, preoperative evaluation of serum albumin levels may help guide expectations and optimal management of thyroidectomy patients.

The Relationship Between Body Mass Index and In-Hospital Mortality in Patients Following Coronary Artery Bypass Grafting Surgery

Background: The association between Body Mass Index (BMI) and clinical outcomes following coronary artery bypass grafting (CABG) remains controversial. Our objective was to investigate the real-world relationship between BMI and in-hospital clinical course and mortality, in patients who underwent CABG. Methods: A sampled cohort of patients who underwent CABG between October 2015 and December 2016 was identified in the National Inpatient Sample (NIS) database. Outcomes of interest included in-hospital mortality, peri-procedural complications and length of stay. Patients were divided into 6 BMI (kg/m²) subgroups; (1) under-weight ≤19, (2) normal-weight 20-25, (3) over-weight 26-30, (4) obese I 31-35, (5) obese II 36-39, and (6) extremely obese ≥40. Multivariable logistic regression model was used to identify predictors of in-hospital mortality. Linear regression model was used to identify predictors of length of stay (LOS). Results: An estimated total of 48,710 hospitalizations for CABG across the U.S. were analyzed. The crude data showed a U-shaped relationship between BMI and study population outcomes with higher mortality and longer LOS in patients with BMI ≤ 19 kg/m² and in patients with BMI ≥40 kg/m² compared to patients with BMI 20-39 kg/m². In the multivariable regression model, BMI subgroups of ≤19 kg/m² and ≥40 kg/m² were found to be independent predictors of mortality. Conclusions: A complex, U-shaped relationship between BMI and mortality was documented, confirming the "obesity paradox" in the real-world setting, in patients hospitalized for CABG.

Physical Features and Vital Signs Predict Serum Albumin and Globulin Concentrations Using Machine Learning

OBJECTIVE

Serum protein concentrations are diagnostically and prognostically valuable in cancer and other diseases, but their measurement via blood test is uncomfortable, inconvenient, and costly. This study investigates the possibility of predicting albumin, globulin, and albumin-globulin ratio from easily accessible physical characteristics (height, weight, Body Mass Index, age, gender) and vital signs (systolic blood pressure, diastolic blood pressure, mean arterial pressure, pulse pressure, pulse) using advanced machine learning techniques.

METHODS

We obtained albumin concentration, globulin concentration, albumin-globulin ratio and predictor information (physical characteristics, vital signs) from physical exam records of 46,951 healthy adult participants in Hangzhou, China. We trained a computational model to predict each serum protein concentration from the predictors and then evaluated the predictive accuracy of each model on an independent portion of the dataset that was not used in model training. We also determined the relative importance of each feature within the model.

RESULTS

Prediction accuracies were r=0.540 (95% CI: 0.539-0.540; Pearson r) for albumin, r=0.250 (95% CI: 0.249-0.251) for globulin, and r=0.373 (95% CI: 0.372-0.374) for albumin-globulin ratio. The most important predictive features were age (100% ± 0.0%; mean ± 95% CI of normalized importance), gender (34.4% ± 0.7%), pulse (25.6% ± 1.3%) and Body Mass Index (24.4% ± 2.3%) for albumin, pulse (83.7% ± 3.8%) for globulin, and age (99.2% ± 1.0%), gender (59.2% ± 1.7%), Body Mass Index (46.1% ± 4.2%) and height (40.0% ± 3.8%) for albumin-globulin ratio.

CONCLUSIONS

Our models predicted serum protein concentrations with appreciable accuracy showing the promise of this approach. Such models could serve to augment existing tools for identifying "at-risk" individuals for follow-up with a blood test.

The influence of postoperative albumin levels on the outcome of cardiac surgery

BACKGROUND

The prognostic role of low postoperative serum albumin levels (SAL) after cardiac surgery (CS) remains unclear in patients with normal preoperative SAL. Our aim was to evaluate the influence of SAL on the outcome of CS.

METHODS

Prospective observational study. Patients undergoing CS with normal preoperative SAL and nutritional status were included and classified into different subgroups based on SAL at 24 h after CS. We assessed outcomes (i.e., in-hospital mortality, postoperative complications and long-term survival) and results were analyzed among the different subgroups of SAL.

RESULTS

We included 2818 patients. Mean age was 64.5 ± 11.6 years and body mass index 28.0 ± 4.3Kg·m^- 2. 5.8%(n = 162) of the patients had normal SAL levels(≥35 g·L^- 1), 32.8%(n = 924) low deficit (30-34.9 g·L^- 1), 44.3%(n = 1249) moderate deficit (25-29.9 g·L^- 1), and 17.1%(n = 483) severe deficit(< 25 g·L^- 1). Higher SAL after CS was associated with reduced in-hospital (OR:0.84;95% CI:0.80-0.84; P = 0.007) and long-term mortality (HR:0.85;95% CI:0.82-0.87;P < 0.001). Subgroups of patients with lower SAL showed worst long-term survival (5-year mortality:94.3% normal subgroup, 87.4% low, 83.1% moderate and 72.4% severe;P < 0.001). Multivariable analysis showed higher in-hospital mortality, sepsis, hemorrhage related complications, and ICU stay in subgroups of patients with lower SAL. Predictors of moderate and severe hypoalbuminemia were preoperative chronic kidney disease, previous CS, and longer cardiopulmonary bypass time.

CONCLUSIONS

The presence of postoperative hypoalbuminemia after CS is frequent and the degree of hypoalbuminemia may be associated with worst outcomes, even in the long-term scenario.

Serum Proteins Alteration in Association with Body Mass Index in Human Volunteers

INTRODUCTION

Serum proteins are an important indicator of the nutritional status in an individual. There is a worldwide prevalence of both undernourishment and obesity. It has been suggested that low Body Mass Index (BMI) is associated with a decrease in serum protein levels predisposing them to other illnesses. Overweight and obese individuals carry risk for various other non-communicable diseases.

AIM

To compare the serum protein levels in underweight, overweight and obese individuals with that of normal body mass index individuals.

MATERIALS AND METHODS

This prospective study was conducted in subjects who attended the master health checkup clinic of PSG hospitals. Subjects in the age group of 20-50 years were selected. Their serum proteins and BMI was measured. Twenty subjects each of underweight, normal, overweight and obese individuals were selected, categorized and compared.

RESULTS

The serum protein level of normal individuals (Group I) was compared with underweight (Group II), overweight (Group III) and obese subjects (Group IV) by one-way ANOVA analysis. The mean serum total proteins in gm/dl in group I controls was 7.555±0.37 compared to Group II (underweight) which was 7.295±0.419. Low BMI was found to be associated with a decrease in serum protein level which was not statistically significant. Elevated BMI as in overweight and obese subjects showed no significant alterations in serum protein levels with p >0.05 and the changes were found to be independent of the body mass index.

CONCLUSION

Underweight individuals showed a decrease in serum protein levels whereas there were no significant changes in the serum protein levels in overweight and obese individuals.

Serum albumin perturbations in cyanotics after cardiac surgery: Patterns and predictions

INTRODUCTION

Hypoalbuminemia is a well-recognized predictor of general surgical risk and frequently occurs in patients with cyanotic congenital heart disease (CCHD). Moreover, cardiopulmonary bypass (CPB)-induced an inflammatory response, and the overall surgical stress can effect albumin concentration greatly. The objective of his study was to track CPB-induced changes in albumin concentration in patients with CCHD and to determine the effect of hypoalbuminemia on postoperative outcomes.

MATERIALS AND METHODS

Prospective observational study conducted in 150 patients, Group 1 ≤18 years (n = 75) and Group 2 >18 years (n = 75) of age. Albumin levels were measured preoperatively (T1), after termination of CPB (T2) and 48 h post-CPB (T3). Primary parameters (mortality, duration of postoperative ventilation, duration of inotropes and duration of Intensive Care Unit [ICU] stay) and secondary parameters (urine output, oliguria, arrhythmias, and hemodynamic parameters) were recorded.

RESULTS

The albumin levels in Group 1 at T1, T2, and T3 were 3.8 ± 0.48, 3.2 ± 0.45 and 2.6 ± 0.71 mg/dL; and in Group 2 were 3.7 ± 0.50, 3.2 ± 0.49 and 2.7 ± 0.62 mg/dL respectively. All patients showed a significant decrease in albumin concentration 48 h after surgery (P < 0.01). Analysis between the groups, however, showed no statistical difference. Eleven patients expired during the study period, and nonsurvivors showed significantly lower serum albumin concentration 48 h after surgery 2.3 ± 0.62 mg/dL versus 3.7 ± 0.56 mg/dL in the survivors (P < 0.05). Receiver operating characteristic curve showed that a baseline albumin cut-off value of 3.3 g/dL predicts mortality with a positive predictive value 47.6% and a negative predictive value of 99.2% (P < 0.05). A strong correlation was seen between albumin levels at 48 h with duration of CPB (r2 = 0.6321), ICU stay (r2 = 0.7447) and incidence of oliguria (r2 = 0.8803).

CONCLUSIONS

The study demonstrated similar fall in albumin concentration in cyanotic patients (both adult and pediatric) in response to CPB. Low preoperative serum albumin concentrations (<3.3 g/dL) can be used to identify and prognosticate subset of cyanotics predisposed to additional surgical risk.

Impact of Body Mass Index on Outcomes in Cardiac Surgery

OBJECTIVES

Body mass index (BMI) commonly is used in obesity classification as a surrogate measure, and obesity is associated with a cluster of risk factors for cardiovascular disease. The aim of this study was to investigate the impact of BMI on short-term outcomes after cardiac surgery.

DESIGN

A retrospective cohort study.

SETTING

University teaching hospital, 2 centers.

PARTICIPANTS

The study comprised 4,740 patients who underwent cardiac surgery at 2 hospitals-from July 1, 2001, to June 30, 2013, in 1 hospital and from September 1, 2003, to August 31, 2014, in a second hospital.

INTERVENTIONS

No changes to standard practice were required.

MEASUREMENTS AND MAIN RESULTS

Patients were assigned into 6 BMI groups as follows: underweight (BMI<18.5 kg/m(2)), normal weight (≥18.5 to<25 kg/m(2)), overweight (≥25 to<30 kg/m(2)), class I obese (≥30 to<35 kg/m(2)), class II obese (≥35 to<40 kg/m(2)), and class III obese (BMI≥40 kg/m(2)). Short-term major postoperative complications (postoperative stroke, cardiac arrest, new atrial fibrillation/flutter, permanent rhythm device insertion, deep sternal infection, sepsis, prolonged ventilation, pneumonia, renal dialysis, renal failure, intensive care unit readmission, total intensive care unit hours, and readmission in 30 days, and mortalities (in-hospital mortality, 30-day mortality, surgical mortality) were compared among various BMI groups after cardiac surgery. Age, sex, surgery type, family history of coronary artery disease, diabetes, hypertension, heart failure, and lipid-lowering medication were the risk factors for early outcomes. Multiple logistic regression analysis indicated that the underweight and class III obese BMI groups demonstrated significant, adverse differences in some short-term outcomes, including deep sternal infection, prolonged ventilation, new atrial fibrillation/flutter, and renal failure. However, being in the overweight or class I obese group demonstrated a positive effect on discharge and surgical mortality.

CONCLUSIONS

The results of this study demonstrated that extreme obesity and underweight were significantly associated with early major adverse clinical outcomes. However, there was an "obese paradox" in short-term mortality after cardiac surgery.