Preoperative Serum Albumin and Inflammatory Markers as Predictors of Postoperative Outcomes in Patients Undergoing Major Abdominal Surgery: A Prospective Observational Study.

Major abdominal surgery is associated with substantial physiological stress and may result in postoperative complications despite improvements in surgical techniques, anesthesia, antimicrobial prophylaxis, and perioperative care. Surgical site infection (SSI), wound dehiscence, respiratory complications, sepsis, and delayed recovery remain important causes of prolonged hospitalization and postoperative morbidity.

 

Several patient-related factors influence postoperative outcomes, including age, nutritional status, diabetes mellitus, anemia, systemic inflammation, underlying malignancy, and the urgency and magnitude of surgery. Identification of modifiable risk factors before surgery may allow appropriate interventions and improve postoperative recovery.

albumin has traditionally been used as a biochemical indicator associated with nutritional and inflammatory status. Although albumin concentration is influenced by several factors and should not be interpreted as an isolated measure of nutritional intake, low preoperative serum albumin has consistently been associated with increased postoperative morbidity and mortality.

 

The inflammatory response also has an important role in surgical outcomes. C-reactive protein is an acute-phase protein synthesized predominantly by hepatocytes in response to inflammatory cytokines. Similarly, the neutrophil-to-lymphocyte ratio, derived from a routine complete blood count, provides an inexpensive indicator of systemic inflammation. Elevated inflammatory markers may identify patients with increased physiological stress or underlying inflammatory disease.

 

Combining clinical assessment with readily available biochemical and hematological parameters could therefore provide a practical approach to perioperative risk assessment. The present study was undertaken to evaluate the relationship between preoperative serum albumin, CRP, and NLR and postoperative outcomes among patients undergoing major abdominal surgery.

 

AIM AND OBJECTIVES

Aim

To assess the association between preoperative biochemical and inflammatory markers and postoperative outcomes in patients undergoing major abdominal surgery.

 

Objectives

1.        To determine preoperative serum albumin, CRP, and NLR among patients undergoing major abdominal surgery.

2.        To determine the frequency of postoperative complications in the study population.

3.        To compare biochemical and inflammatory parameters between patients with and without postoperative complications.

4.        To evaluate the association of hypoalbuminemia with surgical site infection and duration of hospital stay.

5.        To identify clinical and laboratory predictors of adverse postoperative outcomes.

Study Design

Prospective observational study.

 

Study Setting

The study was conducted among patients admitted under the Department of General Surgery at a tertiary care teaching hospital in Raipur, Chhattisgarh, India, with clinical and biochemical evaluation performed in collaboration with the Departments of General Medicine and Biochemistry.

 

Study Duration

The study was conducted over a period of 12 months.

 

Study Population

Adult patients undergoing major abdominal surgical procedures during the study period were considered for inclusion.

 

Sample Size

A total of 150 patients fulfilling the eligibility criteria were included.

 

Inclusion Criteria

Patients aged ≥18 years undergoing major elective or emergency abdominal surgery and willing to participate in the study

were included.

 

Exclusion Criteria

Patients with established chronic liver failure, nephrotic syndrome, severe immunodeficiency, long-term corticosteroid therapy, pregnancy, or incomplete laboratory or postoperative follow-up data were excluded.

 

Clinical Assessment

A detailed clinical history was obtained with particular attention to age, sex, diabetes mellitus, hypertension, smoking, underlying diagnosis, presence of malignancy, and whether surgery was elective or emergency.

Patients underwent routine preoperative evaluation according to institutional protocols.

 

Laboratory Investigations

Venous blood samples were collected before surgery. The following parameters were assessed:

·         Hemoglobin

·         Total leukocyte count

·         Differential leukocyte count

·         Serum albumin

·         Serum total protein

·         C-reactive protein

·         Serum creatinine

·         Blood glucose

The neutrophil-to-lymphocyte ratio was calculated by dividing the absolute neutrophil count by the absolute lymphocyte count.

For the present analysis, serum albumin <3.5 g/dL was considered hypoalbuminemia.

 

Postoperative Assessment

Patients were monitored throughout hospitalization for:

·         Surgical site infection

·         Wound dehiscence

·         Respiratory complications

·         Sepsis

·         Requirement for re-intervention

·         Intensive care requirement

·         Duration of postoperative hospitalization

·         In-hospital mortality

Surgical site infection was assessed according to standard clinical criteria.

 

Ethical Considerations

The study protocol should be reviewed and approved by the Institutional Ethics Committee before initiation. Written informed consent should be obtained from all participants. Patient confidentiality should be maintained throughout the study.

 

Statistical Analysis

Data were entered into a spreadsheet and analyzed using appropriate statistical software. Continuous variables were expressed as mean ± standard deviation or median with interquartile range, depending on data distribution. Categorical variables were expressed as frequencies and percentages.

 

Student's t-test or Mann-Whitney U test was used for continuous variables, while the chi-square test or Fisher's exact test was used for categorical variables. Multivariable logistic regression was used to identify independent predictors of postoperative complications. A p-value <0.05 was considered statistically significant.

Baseline Characteristics

A total of 150 patients undergoing major abdominal surgery were included. The mean age was 48.7 ± 15.2 years, and 91 (60.7%) were males. Emergency procedures accounted for 58 (38.7%) cases, while 92 (61.3%) underwent elective surgery. Diabetes mellitus was present in 34 (22.7%) patients and hypertension in 39 (26.0%). Preoperative hypoalbuminemia was identified in 56 (37.3%) patients.

 

Table 1. Baseline Characteristics of Study Participants

 

Postoperative Complications

Forty-two patients (28.0%) developed at least one postoperative complication. Surgical site infection was the most common complication and occurred in 22 patients (14.7%). Respiratory complications occurred in 12 (8.0%), wound dehiscence in 8 (5.3%), and postoperative sepsis in 7 (4.7%) patients. Some patients experienced more than one complication.

 

Table 2. Distribution of Postoperative Complications

 

Comparison According to Postoperative Complications

Patients developing postoperative complications had significantly lower serum albumin and higher CRP and NLR than patients with an uncomplicated postoperative course.

 

Table 3. Laboratory Parameters According to Postoperative Outcome

Hypoalbuminemia was present in 29 of 42 (69.0%) patients who developed complications compared with 27 of 108 (25.0%) patients without complications (p<0.001).

 

Serum Albumin and Surgical Site Infection

Among 56 patients with serum albumin <3.5 g/dL, 16 (28.6%) developed SSI compared with 6 of 94 (6.4%) patients with serum albumin ≥3.5 g/dL.

 

Table 4. Association Between Serum Albumin and Surgical Site Infection

p<0.001

Duration of Hospital Stay

Patients with hypoalbuminemia experienced significantly longer postoperative hospitalization than patients with serum albumin ≥3.5 g/dL.

Mean postoperative hospital stay was 10.8 ± 4.7 days in patients with hypoalbuminemia compared with 6.9 ± 3.1 days among patients with normal albumin levels (p<0.001).

 

Predictors of Postoperative Complications

On multivariable logistic regression analysis, hypoalbuminemia, elevated preoperative CRP, emergency surgery, and diabetes mellitus remained independently associated with postoperative complications.

 

 

 

 

 

Table 5. Multivariable Analysis of Factors Associated with Postoperative Complications

 

The present study demonstrates an association between preoperative biochemical and inflammatory abnormalities and postoperative complications among patients undergoing major abdominal surgery. Patients who developed complications had significantly lower serum albumin and higher CRP and NLR than those with an uncomplicated postoperative course.

 

Hypoalbuminemia was particularly important. Approximately two-thirds of patients who developed postoperative complications had preoperative serum albumin below 3.5 g/dL. In addition, patients with hypoalbuminemia experienced a greater frequency of SSI and longer postoperative hospitalization.

 

The relationship between hypoalbuminemia and adverse surgical outcomes has been recognized for several decades. Gibbs et al. demonstrated that preoperative serum albumin was strongly associated with operative morbidity and mortality in a large surgical cohort. Low serum albumin may reflect a combination of inadequate nutritional reserves, systemic inflammation, chronic illness, and increased physiological vulnerability.

 

The association between albumin and SSI observed in the present study is clinically relevant. Adequate protein status contributes to collagen synthesis, tissue repair, immune function, and wound healing. However, serum albumin is also a negative acute-phase reactant, and low concentrations may represent the severity of systemic inflammation rather than nutritional deficiency alone. Therefore, albumin should be interpreted alongside clinical and inflammatory parameters.

The significantly higher CRP concentration in patients developing complications supports the role of systemic inflammation in perioperative risk. CRP is inexpensive and widely available and may complement routine preoperative clinical assessment.

 

Similarly, NLR was significantly elevated among patients with postoperative complications. NLR integrates changes in circulating neutrophils and lymphocytes during systemic inflammation and physiological stress. Because it is calculated from routine blood counts, it does not require an additional laboratory investigation.

 

Emergency surgery was another independent predictor of postoperative complications. Emergency surgical patients frequently present with acute infection, perforation, obstruction, dehydration, metabolic disturbances, or inadequate opportunity for preoperative optimization. These factors may contribute to increased postoperative morbidity.

 

Diabetes mellitus was also associated with adverse postoperative outcomes. Hyperglycemia and impaired immune responses can interfere with wound healing and increase susceptibility to infection. Appropriate perioperative glycemic management therefore remains an important component of surgical care.

 

The findings suggest that a combination of clinical variables and inexpensive laboratory markers could assist surgeons and physicians in identifying high-risk patients. Patients with hypoalbuminemia or significant inflammatory abnormalities may benefit from further assessment, correction of reversible metabolic abnormalities, appropriate nutritional support when clinically indicated, optimization of comorbidities, and closer postoperative surveillance.

 

LIMITATIONS

This was a single-center observational study with a relatively modest sample size. Serum albumin can be influenced by inflammation, hydration, hepatic function, renal disease, and other clinical factors and therefore cannot be regarded as a specific nutritional marker. Long-term postoperative outcomes were not evaluated. Larger multicenter prospective studies are required to validate appropriate cut-off values and develop clinically applicable risk-prediction models.

Preoperative hypoalbuminemia, elevated CRP, and increased NLR are associated with postoperative complications following major abdominal surgery. Low serum albumin was particularly associated with surgical site infection and prolonged hospitalization.

Routine assessment of serum albumin together with clinical risk factors and inflammatory markers may provide a simple and cost-effective approach for perioperative risk stratification. Identification of high-risk patients before surgery may facilitate medical optimization, nutritional assessment, and enhanced postoperative monitoring.

 

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