Correlation of Preoperative Prognostic Laboratory Markers with Bariatric Surgery-Related Complications

Abstract

Introduction:

Bariatric surgery is defined as the best long-term treatment for morbid obesity and this leads massive increase in bariatric surgeries worldwide. However, these procedures are associated with severe morbidities and mortalities. And the clarification of preoperative predictors is still unclear today.

Materials and Methods:

We collected all clinical and laboratory findings of the patients retrospectively who underwent elective bariatric surgery at our hospital (2018–2021). We evaluated the parameters in terms of predictors of early complications.

Results:

From January 2018 to August 2021, 325 patients underwent bariatric surgery (sleeve: 172–bypass: 153). In total, 24 patients had early postbariatric complications (11 leak, 10 bleeding, and 3 pulmonary embolism). After evaluation of the data, preoperative laboratory markers and ratios were not found to be significantly associated with major complications. Only “asthma” as a comorbidity was a significant predictor of postbariatric surgery complications.

Conclusion:

The preoperative laboratory markers and ratios are potential prognostic factors for postoperative morbidities and mortalities in patients undergoing bariatric surgery. Our clinical findings do not correlate with major complications. More prospective studies and larger number of patients are needed to shed light on the potential importance of these parameters. Clinical trial Registration number: 2021/09-17.

Introduction

Bariatric surgery is defined as the best long-term treatment for morbid obesity. Compared with the medical management, bariatric surgery has been shown to be an effective way to allow sustained weight loss and reduction of obesity-related comorbidities such as type 2 diabetes mellitus (DM), hypertension (HT), hyperlipidemia, sleep apnea, and malignancy.^1,2 The dramatic increase in obesity has led to a massive increase in bariatric surgeries worldwide.

Despite their benefits, these elective surgeries carry potential risks for considerable morbidity and mortality raging from 0.1% to 2%.³ Reliable preoperative detection of high-risk patients before bariatric surgery would allow appropriate preoperative care and operation selection, early diagnosis, and optimization of treatment for possible complications in the perioperative period.⁴

Obesity is characterized by expanded adipose tissue mass that closely associated with the production of main proinflammatory markers such as interleukin-6 and tumor necrosis factor-alpha. An increase in circulating levels of these factors leads to the formation of a chronic low-grade inflammatory state,⁵ and consequently the levels of inflammatory markers used as a prognostic marker in various major diseases.

In recent years, some researchers have reported on the predictive value of laboratory markers for inflammation such as white blood cell count, neutrophil/lymphocyte ratio (NLR), platelet count, platelet/lymphocyte ratio (PLR), serum total bilirubin level, C reactive protein level, serum sodium (Na), aspartate aminotranferase (AST), and alanine aminotransferase (ALT), which can be used as diagnostic parameters in the perioperative predictor of diagnosis, morbidity and mortality.^6–9

The aim of this study was to evaluate our clinical experience with bariatric surgery and assess retrospectively the clinical relevance of preoperative laboratory markers in predicting postoperative complications in patients with morbid obesity.

Materials and Methods

This retrospective study design was based on medical records of patients who were admitted to our hospital and underwent bariatric (sleeve gastrectomy [SG] or Roux-en-Y gastric bypass [RYGB]) surgeries. The criteria for surgical treatment at our clinic are either body mass index [BMI] >40 kg/m² or BMI >35 kg/m² with associated comorbidities, including DM, HT, and obstructive sleep apnea. Exclusion criteria are lack of necessary data, previous abdominal surgeries (including bariatric surgery), and hematological diseases.

Medical records of patients were reviewed and the following parameters were collected: demographics (age and gender), BMI, medical history, type of surgery performed, and laboratory findings (complete blood count, neutrophils, lymphocytes, NLR, PLR, serum total bilirubin levels, Na, AST, ALT, and albumin). Early major postoperative complications (bleeding, leak, etc.) and mortality rates were also evaluated. This study was approved by the Clinical Research Ethics Committee of Bursa Yüksek İhtisas Training and Research Hospital (date: August 9, 2021 number: 2021/09-17).

Statistical analysis

The Shapiro–Wilk test was used to evaluate the conformity of continuous variables to the normal distribution. Continuous variables are expressed as mean ± standard deviation if the data followed the normal distribution and median (25th percentage–75th percentage) values if the data did not follow the normal distribution. The Mann–Whitney U test and independent samples t-test were used to compare groups for continuous variables. Fisher's exact test and the chi-square test compared the categorical variables between the groups.

Factors that may affect the development of complications were examined by logistic regression analysis. SPSS (IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0.; IBM Corp., Armonk, NY) program was used for statistical analysis, and the type I error rate was set at 5%.

Results

A total of 325 patients who underwent bariatric surgery between January 2018 and August 2021 were included. There was no significant difference in the comparison of the age, gender, and comorbidities of the patients according to the type of surgery.

It was determined that there was no statistical difference according to age between patients who had RYGB and SG (p = 0.812). There was no difference between patients who underwent RYGB and SG according to gender distribution (p = 0.981).

In our study, HT (24.80% vs. 14%; p = 0.013), DM (19% vs. 5.20%; <0.001), and asthma (9.20% vs. 3.50; p = 0.034) were the most common comorbidities. All of these medical conditions were significantly higher in the RYGB group. There was no significant difference in the comparison of complication rate, length of hospital stay, and mortality according to the type of surgery.

Early postoperative major complications were found in 24 patients (11 leak, 10 bleeding, and 3 pulmonary embolism). It was determined that the complication rates were not statistically different according to the type of operation (p = 0.581). Complications were observed in 6.5% of patients who underwent RYGB, whereas this rate was 8.10% in the group of patients who underwent SG. There was no difference between the surgical procedures with respect to hospital stay (p = 0.702). The median hospital stay was 5 days for both types of operations. There was no difference between the groups in terms of mortality rates (p = 0.603).

Comparison of patients with and without complications according to age, gender, and comorbidities is given in Table 1. There was no difference in terms of these conditions between the patient groups with and without complications (p = 0.502, p = 0.275, and p = 0.976, respectively). Moreover, in our study, the rates of HT and DM, which are the most common comorbidities, were not statistically different between the groups (p = 0.178 and p = 0.191, respectively), whereas the rate of asthma was found to be significantly higher in patients with complications (p = 0.026). Although asthma was detected in 16.70% of patients with complications, this rate was determined as 5.30% in the patient group without complications.

Table 1.

Comparison of Age, Gender, and Comorbidities Between Patients With and Without Complications

	Complication		p
	(+) (n = 24), n (%)	(−) (n = 301), n (%)	p
Age (years)	40.50 (29.75–50.50)	43 (33–50)	0.502^a
Gender (female/male)	22/2	245/55	0.275^c
Comorbidities	11 (45.80)	135 (44.90)	0.926^b
HT	5 (20.80)	33 (11)	0.178^c
DM	7 (29.20)	55 (18.30)	0.191^b
Asthma	4 (16.70)	16 (5.30)	0.026^c

Bold value indicates statistically significant results.

Data are presented as median (25th percentile–75th percentile) and n %.

Mann–Whitney U test.

Chi-square test.

Fisher's exact test.

DM, diabetes mellitus; HT, hypertension.

The comparison of laboratory parameters between patient groups with and without complication is given in Table 2. There was no difference between the patient groups according to laboratory results. Logistic regression analysis was performed to determine the risk factors thought to be effective on the complications (Table 3). In the evaluation of the table, variables matching the p < 0.25 criterion as a result of univariable analysis, multivariable logistic regression analysis, were applied.

Table 2.

Comparison of Laboratory Values and Ratios Between Patients With and Without Complications

	Complication		p
	(+) (n = 24)	(−) (n = 301)	p
Leukocytes	8800 (7720–10922.50)	8520 (7030–9985)	0.240^a
Neutrophil	5375 (4290–7040)	5120 (4135–6270)	0.253^a
Lymphocyte	2630 (2217.50–3112.50)	2550 (2100–3135)	0.740^a
Platelets (10³)	305 (256–349)	292 (247–341)	0.483^a
Total bilirubin	0.39 (0.29–0.64)	0.42 (0.30–0.55)	0.766^a
AST	18 (15–27.50)	20 (16–28)	0.557^a
ALT	21 (17.25–34.75)	24 (16–35)	0.944^a
Sodium	139 (137–141.75)	139 (138–142)	0.640^a
Albumin	42.78 ± 5.53	43.78 ± 3.23	0.389^b
NLR	2.09 (1.59–2.67)	1.97 (1.65–2.51)	0.535^a
PLR	113.84 (102.53–139.10)	116.42 (92.27–141.75)	0.935^a

Data are presented as median (25th percentile–75th percentile) and mean ± standard deviation.

Mann–Whitney U test.

Independent samples t-test.

ALT, alanine aminotransferase; AST, aspartate aminotransferase; NLR, neutrophil/lymphocyte ratio; PLR, platelet/lymphocyte ratio.

Table 3.

Identification of Risk Factors Associated with Complications

	Univariable model			Multivariable model
	Wald	OR (95% CI)	p	Wald	OR (95% CI)	p
Age	0.32	0.99 (0.95–1.03)	0.570
Gender (female)	1.44	2.47 (0.56–10.81)	0.230	0.67	1.98 (0.39–10.13)	0.410
Comorbidity	0.01	1.04 (0.45–2.40)	0.926
DM (+)	2.01	2.14 (0.75–6.10)	0.156	0.22	1.84 (0.14–24.14)	0.643
HT (+)	1.67	1.84 (0.73–4.66)	0.197	0.18	0.61 (0.06–5.91)	0.669
Asthma (+)	44.66	3.56 (1.09–11.66)	0.036	0.60	1.96 (0.36–10.68)	0.437
Sleeve gastrectomy	0.30	1.27 (0.55–2.94)	0.582
Leukocytes	1.01	1 (1–1)	0.316
Neutrophil	1.48	1 (1–1)	0.224	1.68	1 (1–1)	0.194
Lymphocyte	0.01	1 (0.99–1.01)	0.968
Platelets (10³)	0.18	1 (1–1)	0.670
Total bilirubin	0.27	0.58 (0.07–4.54)	0.604
AST	0.02	1.01 (0.97–1.04)	0.887
ALT	0.07	0.99 (0.97–1.02)	0.799
Sodium	0.43	0.95 (0.83–1.10)	0.953
Albumin	1.88	0.92 (0.82–1.04)	0.170	0.39	1.05 (0.90–1.22)	0.531
NLR	1.17	1.27 (0.82–1.96)	0.280
PLR	0.02	0.99 (0.98–1.01)	0.896

Bold values met the p < 0.25 criterion as a result of univariable analysis were included in the multivariable logistic regression analysis.

CI, confidence interval; OR, odds ratio.

It was determined that the multivariable logistic regression model was significant (p < 0.001) and was compatible with the data set (p = 0.466). It was determined that the variables given in the multivariable analysis section of Table 3 were not effective on the development of complications (p > 0.05).

Discussion

It is the basic request of surgeons to reveal the determinants of complications, especially before elective bariatric surgeries. Suitable markers can be helpful in the correct timing of intervention to reduce the complication rate and improve benefits of the procedure. Postoperative complications in bariatric surgery may lead to functional defects or worse mortality for the patient. In addition, this situation may also cause a serious increase in medical costs due to the prolongation of the hospital stay. The primary aim of our study was to evaluate the relationship between simple, inexpensive, and routinely obtained laboratory markers (in the preoperative period) with major complications associated with postoperative bariatric surgery.

Cancer constitutes a high inflammatory state similar to obesity. Therefore, most studies evaluate inflammatory markers in the context of malignancy. Since similar inflammatory markers have already been confirmed in patients undergoing gastrointestinal surgery, we chose to test these markers specifically for major postoperative complications in a bariatric population.^10,11

Previous studies have shown that inflammatory markers have an important prognostic role in diseases such as diverticulitis, appendicitis, and various gastrointestinal cancers. Da Silva et al.¹² used postoperative day 1 NLR to predict complications after bariatric surgery, Aykota et al.¹³ evaluated the effects of SG on PLR, Katzke et al.¹⁴ studied AST and ALT levels in lung and colorectal cancer, Cao et al.¹⁵ used serum bilirubin levels for survival prediction in colorectal cancer, and Yang et al.¹⁶ evaluated serum sodium levels in prediction of acute perforated appendicitis in children.

We analyzed and compared the laboratory values and rates between groups with and without complications. In our results, we assessed that the above markers did not differ statistically significant between these two groups.

Similar to our study, Mari et al. showed that the NLR ratio of the patients before bariatric surgery was statistically significant in predicting early postoperative complications.¹⁷ However, unlike our study, they also included minor complications such as wound infection or gastroesophageal reflux disease. Therefore, we think that this statistical difference is due to the width of the complications examined.

Surprisingly, when the comorbidities of the patients between the groups were compared, we found that asthma created a significant difference as a risk factor affecting the development of complications. The clinical relationship between asthma and obesity is very close. Most of our patients with asthma or asthmatic bronchitis were patients requiring oral or inhaled glucocorticoids. Glucocorticoids are used in the treatment of asthma because of their immunosuppressive and anti-inflammatory effects.¹⁸ However, these drugs can cause various complications such as weight gain, HT, hyperglycemia, sleep disturbance, inhibition of wound repair, and increased risk of infection.¹⁹

Therefore, such medications may lead to an increase in complications in the postoperative period. However, there is no clear consensus that asthma is a risk factor for major complications in bariatric surgery. There are no specific instructions about optimal time when glucocorticoids should be stopped before surgery or when treatment should be resumed after surgery to help prevent major complications.

Conclusion

In our retrospective study, our findings demonstrated that preoperative laboratory markers or ratios have no effect on prediction of early postbariatric surgery-related major complications and, in contrast, “asthma” was the most important complication predictor among other characteristics. Although our total number of patients were statistically sufficient, the small number of patients with complications and the retrospective nature of our study were the limitations. More prospective studies and number of patients are needed to shed light on the potential importance of laboratory markers and obesity-related diseases evaluated preoperatively in the pathophysiology and prevention of complications associated with bariatric surgery.

Footnotes

Author Disclosure Statement

The authors have no conflicts of interest to declare.

Funding Information

The authors have no financial support to declare.

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