Li Y, Zheng KY, Liu ZL, Yu TM, Zhang WJ, Zhong MW, Hu SY. Perirenal fat area is a preoperative predictor of hypertension resolution after laparoscopic sleeve gastrectomy: Generalized additive models. World J Gastroenterol 2025; 31(12): 104952 [PMID: 40182591 DOI: 10.3748/wjg.v31.i12.104952]
Corresponding Author of This Article
San-Yuan Hu, MD, Chief Physician, Professor, Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, No. 107 West Wenhua Road, Jinan 250012, Shandong Province, China. husanyuan1962@hotmail.com
Research Domain of This Article
Gastroenterology & Hepatology
Article-Type of This Article
Retrospective Study
Open-Access Policy of This Article
This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Yue Li, Zeng-Lin Liu, Department of General Surgery, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250014, Shandong Province, China
Kai-Yuan Zheng, Wen-Jie Zhang, Ming-Wei Zhong, Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University and Shandong Provincial Qianfoshan Hospital, Jinan 250014, Shandong Province, China
Tian-Ming Yu, San-Yuan Hu, Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250012, Shandong Province, China
Author contributions: Li Y, Zhang WJ, and Hu SY participated in the conception and design of the study and were involved in the acquisition, analysis, or interpretation of data; Li Y wrote the manuscript; Zheng KY, Liu ZL, Yu TM, and Zhang WJ accessed and verified the study data. All authors critically reviewed and provided final approval of the manuscript; and all authors were responsible for the decision to submit the manuscript for publication.
Supported by the National Natural Science Foundation of China, No. 82270914 and No. 82401043.
Institutional review board statement: This investigation was approved by the Institutional Ethics Committee of Shandong Qianfoshan Hospital, No. 2025(S002).
Informed consent statement: The need for patient consent was waived due to the retrospective nature of the study.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: No additional data are available.
Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: San-Yuan Hu, MD, Chief Physician, Professor, Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, No. 107 West Wenhua Road, Jinan 250012, Shandong Province, China. husanyuan1962@hotmail.com
Received: January 10, 2025 Revised: February 16, 2025 Accepted: February 28, 2025 Published online: March 28, 2025 Processing time: 75 Days and 0.8 Hours
Abstract
BACKGROUND
Laparoscopic sleeve gastrectomy (LSG) can lead to complete resolution of hypertension in most patients with obesity within one year. However, the preoperative factors related to this resolution are still unclear.
AIM
To clarify the impact of relevant factors, particularly perirenal fat, on postoperative hypertension resolution.
METHODS
In this retrospective single-center study, a total of 138 patients with obesity and hypertension were included, all of whom underwent LSG in the hospital and were followed up for one year. Multivariate logistic regression models were used to identify independent risk factors for postoperative hypertension resolution. Generalized additive models were employed to clarify the nonlinear relationships between these factors and hypertension resolution, and their predictive values were compared using fivefold cross-validation.
RESULTS
After LSG, 107 patients (77.5%) experienced hypertension resolution, while 31 patients (22.5%) did not achieve resolution. Both the preoperative perirenal fat area (PrFA) and perirenal fat thickness were independent risk factors for postoperative hypertension resolution (P < 0.001 vs P = 0.002). These factors are curvilinearly correlated with the hypertension resolution rate, but PrFA has a better predictive value than perirenal fat thickness dose (area under the curve = 0.846 vs 0.809). Compared with those with PrFA ≥ 18 cm2, patients with PrFA < 18 cm2 had a higher hypertension resolution rate [87% vs 68.1%; odds ratio (95% confidence interval) = 3.513 (1.367-9.902), P = 0.012].
CONCLUSION
PrFA is a preoperative predictor of postoperative hypertension resolution. It is curvilinearly associated with the resolution rate, and patients with PrFA < 18 cm² have better hypertension resolution outcomes after LSG.
Core Tip: In this retrospective single-center study, we found that the preoperative perirenal fat area (PrFA), an important factor linking obesity and hypertension, is an independent predictor of hypertension resolution after laparoscopic sleeve gastrectomy. Particularly, PrFA could achieve an accuracy of approximately 85% in predicting resolution using the generalized additive model. Based on the curvilinear correlation between PrFA and resolution rate, we set 18 cm2 as the cutoff value for PrFA and found that patients with PrFA < 18 cm2 had a higher hypertension resolution rate than those with PrFA ≥ 18 cm2 [87% vs 68.1%; odds ratio (95% confidence interval) = 3.513 (1.367-9.902), P = 0.012].
Citation: Li Y, Zheng KY, Liu ZL, Yu TM, Zhang WJ, Zhong MW, Hu SY. Perirenal fat area is a preoperative predictor of hypertension resolution after laparoscopic sleeve gastrectomy: Generalized additive models. World J Gastroenterol 2025; 31(12): 104952
The prevalence of obesity has increased worldwide and the World Health Organization has declared it a global epidemic[1]. Obesity promotes the incidence of conditions such as type 2 diabetes mellitus (T2DM), hypertension, dyslipidemia and other metabolic-related diseases, increases the risk of cardiovascular diseases[2-4]. Epidemiological studies indicate that 65%-75% of the risk for primary hypertension is due to overweight or obesity, and changes in body mass index (BMI) in patients with obesity are related to the improvement in hypertension[5-7]. However, BMI is not the only indicator associated with hypertension.
Visceral fat accumulation is recognized as a risk factor of the development of cardiac metabolic complications, and it is often assessed based on the visceral fat area[8,9]. As an important component of visceral fat, perirenal adipose tissue (PRAT) is a retroperitoneal fat pad located in the anatomical space behind the peritoneum, between the renal capsule and fascia, surrounding the kidneys and adrenal glands. It can directly affect kidney function and might play a unique role in the occurrence and development of obesity and metabolic diseases[10,11]. Increasing evidence suggests that the PRAT contributes to the occurrence and progression of hypertension in the association analysis[12]. This effect might be caused by physical pressure leading to changes in renal hemodynamics and activation of the renin-angiotensin-aldosterone system, the secretion of various adipokines and cytokines by adipose tissue to alter metabolism and inflammatory status, and the promotion of sympathetic nervous system excitation[13]. Compared with normotensive individuals, patients with hypertension exhibit greater PRAT mass, and their PRAT mass is positively correlated with increased blood pressure[12,14].
Bariatric surgery is an effective method for reducing the weight of patients with obesity, especially when the optimal drug treatment cannot achieve the treatment goal. Among these procedures, laparoscopic sleeve gastrectomy (LSG) has gradually become the mainstream surgical option worldwide[15]. Increasing evidence shows that bariatric surgery can effectively alleviate obesity-related diseases such as T2DM and hypertension[16]. Studies have indicated that the average resolution rate of hypertension at 1 year after LSG is 58%, ranging from 10% to 93%[17].
However, the exact mechanism by which LSG improves hypertension remains unclear, and some patients do not experience resolved hypertension postoperatively. Additionally, it is unknown whether a relationship exists between PRAT and the resolution of hypertension in patients with obesity after LSG. This uncertainty also hinders the application of bariatric surgery in patients with obesity and hypertension, especially those whose weight has not yet reached the current surgical standards. Therefore, we conducted this study to identify the factors influencing postoperative hypertension resolution.
MATERIALS AND METHODS
Participants
The study included 138 patients with obesity and hypertension who underwent LSG in Shandong Qianfoshan Hospital from July 2019 to September 2023. The inclusion criteria: (1) BMI ≥ 27.5 kg/m²; (2) A history of hypertension prior to hospitalization or a diagnosis of hypertension at admission; and (3) Follow-up records available at 1 year post-LSG. The exclusion criteria: (1) Secondary hypertension caused by diseases or medications; and (2) Severe postoperative complications such as gastric leaks, massive bleeding or obstruction. This study was approved by the ethics committee.
Preoperative indicators, such as sex, age, BMI, waist circumference, hip circumference, blood pressure, history of obesity and hypertension (defined as blood pressure ≥ 140/90 mmHg or taking antihypertensive drugs)[18], were collected. In addition, complications, including hyperlipidemia, T2DM, and obstructive sleep apnea-hypopnea syndrome, and test reports, including blood routine, liver and kidney function, blood biochemistry, glucose metabolism, lipid metabolism, thyroid function, sex hormone levels, renin-angiotensin-aldosterone system levels, and urine routine, were recorded. These data were all obtained from clinical records. The improvement of hypertension at 1 year after surgery was retrieved from the follow-up database.
Measurement of preoperative renal fat area and thickness
Patients with obesity routinely undergo computed tomography (CT) examinations before LSG to exclude contraindications. CT scans (GE health care, United States) were obtained from clinical data and analyzed using ImageJ software (Fiji) for measurements. At the level of the left renal vein, the CT window width was adjusted to 150 HU, and the window level was adjusted to -120 HU to clearly delineate the boundaries of the renal fascia[19]. The perirenal fat area (PrFA) was calculated by subtracting the renal area from the total area within the renal fascia[20,21]. The length from the posterior part of the renal capsule to the posterior renal fascia at the level of the left renal vein was defined as the perirenal fat thickness (PrFT)[22]. The schematic is shown in Figure 1. The blue line represents the boundary line of PrFA, and the yellow line denotes the length of PrFT.
Figure 1 The schematic diagram for measuring the perirenal fat area and perirenal fat thickness.
A: At the level of the left renal vein, the computed tomography window width was adjusted to 150 HU, and the window level was adjusted to -120 HU; B: The blue line represents the boundary line of perirenal fat area, and the yellow line represents the length of perirenal fat thickness.
LSG procedure
The surgical procedure used in this study was LSG, as described in previous research[23]. All surgeries were performed by the same surgeon. A specially designed guiding tube was used to ensure a fixed residual stomach volume. An incision was made 5 cm from the proximal end of the pylorus toward the His angle, and the effect of the cutting closure device was reinforced with sutures.
Measurement of blood pressure
Blood pressure was measured using an Omron HBP-1300 blood pressure monitor (Omron Health care, Japan) while the patient sat quietly in a room for at least 5 minutes, with the bladder emptied and the arm at heart level. Three blood pressure readings were taken at 1-minute intervals, and the average of the 2nd and 3rd readings was used for analysis. The criteria for diagnosing hypertension included current use of antihypertensive medication and/or a systolic blood pressure (SBP) > 140 mmHg and/or a diastolic blood pressure (DBP) > 90 mmHg. The definition of hypertension resolution is blood pressure remaining at normal levels (SBP < 140 mmHg and DBP < 90 mmHg) without the use of antihypertensive medications.
Statistical analysis
Analyses were performed using R version 3.5.1. Univariate and multivariate logistic regression models were constructed using the glm R package to identify related factors or independent influencing factors for the hypertension resolution rate. Generalized additive models (GAMs) were built using the mgcv R package to describe the relationship between the PrFA or PrFT and the resolution rate. The ggplot2 R package was used to visualize the models. Fivefold cross-validation and the pROC R package were employed to evaluate the prediction accuracies of different GAMs.
After performing a normality test, the quantitative data were found to follow a normal distribution and were analyzed using the t test. Categorical variables were analyzed by the χ2 test or Fisher’s exact test. Multivariate logistic regression models, including covariates such as BMI, were used to clarify the relationships between PrFA and hypertension resolution and blood pressure changes via the glm R package. A P value less than 0.05 was considered significant.
RESULTS
A total of 138 patients were included in the study (Figure 2), including 74 (53.6%) males and 64 (46.4%) females. Among them, 80 (58.0%) patients had a history of hypertension prior to hospitalization, whereas 58 (42.0%) patients were diagnosed with hypertension at admission. At one year post-surgery, the hypertension of 107 (77.5%) patients had resolved, and 31 (22.5%) patients had not achieved complete resolution.
Figure 2 Flowchart of study participants.
LSG: Laparoscopic sleeve gastrectomy.
Preoperative SBP, waist circumference, aspartate aminotransferase (AST)/alanine aminotransferase (ALT) levels, uric acid levels, sodium levels, total cholesterol levels, low-density lipoprotein cholesterol levels, PrFT, PrFA and visceral fat area at the corresponding plane were associated with resolution (P < 0.05; Table 1). BMI, waist-to-hip ratio and DBP were not associated with postoperative resolution. SBP, AST/ALT levels, sodium levels and PrFT (or PrFA) were recognized as independent risk factors for hypertension resolution by multivariable logistic regression models including PrFT or PrFA (Table 2).
Table 1 Baseline characteristics of patients and their correlation with hypertension resolution, n (%).
Basic information
Resolved
Unresolved
OR (95%CI)
P value
Age (years)
33.1 ± 9.3
35.3 ± 8.1
0.973 (0.931-1.017)
0.226
Gender
1.785 (0.792-4.197)
0.170
Male
54 (50.5)
20 (64.5)
Female
53 (49.5)
11 (35.5)
Obesity duration (years)
6.3 ± 6.9
9.1 ± 7.3
0.951 (0.898-1.002)
0.063
Related diseases
T2DM
58 (54.2)
21 (67.7)
0.564 (0.234-1.285)
0.183
Hyperlipidemia
50 (46.7)
19 (61.3)
0.554 (0.24-1.241)
0.156
NAFLD
97 (90.7)
28 (90.3)
1.039 (0.222-3.675)
0.956
OSAHS
77 (72.0)
23 (74.2)
0.893 (0.343-2.15)
0.807
Hyperuricemia
52 (48.6)
20 (64.5)
0.52 (0.221-1.172)
0.121
Physical examination
SBP (mmHg)
152.7 ± 11.7
158 ± 13.3
0.966 (0.935-0.998)
0.038
DBP (mmHg)
94.9 ± 12.7
97.9 ± 13.3
0.982 (0.95-1.013)
0.260
BMI (kg/m2)
42.2 ± 7
45.1 ± 8.8
0.951 (0.902-1.002)
0.060
Waist circumference (cm)
127.7 ± 15.1
134.5 ± 17.5
0.974 (0.949-0.999)
0.040
Hip circumference (cm)
130.9 ± 13.8
136 ± 17
0.977 (0.95-1.004)
0.089
Waist-to-hip ratio
1 ± 0.1
1 ± 0.1
0.051 (0-21.548)
0.338
Blood tests
HbA1c (%)
6.7 ± 1.3
6.8 ± 1.3
0.908 (0.683-1.232)
0.512
HOMA-IR
11.9 ± 8.1
13.8 ± 10.3
0.977 (0.936-1.022)
0.286
ALT (U/L)
51.2 ± 41.6
48.6 ± 43.6
1.002 (0.992-1.013)
0.761
AST (U/L)
28.5 ± 17.9
34.7 ± 25.6
0.986 (0.968-1.005)
0.136
AST/ALT
0.6 ± 0.2
0.8 ± 0.4
0.058 (0.008-0.307)
0.002
Creatinine (μmol/L)
66.2 ± 23.4
67.8 ± 18.6
0.997 (0.98-1.015)
0.719
eGFR
116.1 ± 33.2
118.6 ± 19
0.997 (0.981-1.01)
0.694
Uric acid (μmol/L)
391.6 ± 152
454.9 ± 102.4
0.997 (0.993-1)
0.034
Sodium (mmol/L)
136.3 ± 13.6
140.5 ± 2.5
0.81 (0.66-0.958)
0.033
Triglyceride (mmol/L)
2.3 ± 2.1
2.5 ± 2.8
0.972 (0.832-1.182)
0.730
Total cholesterol (mmol/L)
4.5 ± 1.2
5 ± 0.9
0.641 (0.412-0.947)
0.035
HDL-CH (mmol/L)
1.1 ± 0.4
1 ± 0.2
2.721 (0.747-15.931)
0.198
LDL-CH (mmol/L)
2.8 ± 1
3.2 ± 0.8
0.562 (0.325-0.913)
0.028
ApoA1:ApoB
3.7 ± 11
1 ± 0.5
2.445 (1.147-9.909)
0.172
ApoE (mg/L)
50 ± 17.9
50.8 ± 11.6
0.997 (0.974-1.022)
0.819
Homocysteine (μmol/L)
13.7 ± 8.5
17.4 ± 9.8
0.96 (0.919-1.001)
0.053
FT3 (pmol/L)
5.8 ± 2.6
5.4 ± 0.9
1.299 (0.924-2.24)
0.323
FT4 (pmol/L)
19.2 ± 14.4
17.8 ± 2.3
1.018 (0.979-1.166)
0.658
Renin
36.8 ± 60.6
42.2 ± 90.5
0.999 (0.994-1.005)
0.699
Angiotensin II
43.5 ± 21.3
39.9 ± 17.4
1.009 (0.989-1.032)
0.388
Aldosterone
11.8 ± 7.6
13.9 ± 11.3
0.975 (0.934-1.019)
0.239
ACTH (pg/mL)
36.1 ± 24.1
32.3 ± 22.5
1.007 (0.99-1.028)
0.432
Cortisol at 8:00 am (nmol/L)
309.8 ± 131.6
356.3 ± 115.8
0.997 (0.994-1)
0.080
CT measurements
PrFA (cm2)
19 ± 10.5
30.5 ± 16
0.934 (0.901-0.965)
< 0.001
PrFT (cm)
1.4 ± 0.9
2.1 ± 1.3
0.551 (0.369-0.802)
0.002
Visceral fat area (cm2)
198.4 ± 89.7
262.6 ± 105.8
0.993 (0.989-0.997)
0.002
Total fat area (cm2)
576.4 ± 175.1
645.7 ± 178.3
0.998 (0.996-1)
0.058
Table 2 Both perirenal fat area and perirenal fat thickness are independent predictors of hypertension resolution after surgery.
PrFA and PrFT showed a nonlinear correlation with the postoperative hypertension resolution rate (P < 0.001 vs P = 0.002; Figure 3) after adjusting for covariates such as preoperative SBP using GAMs. Compared with PrFT, PrFA had better predictive accuracy (area under the curve = 0.846 vs 0.809; Table 3). Compared with those with ≥ 18 cm2, patients with a PrFA < 18 cm2 had a higher hypertension resolution rate [87% vs 68.1%; odds ratio (95% confidence interval) = 3.513 (1.367 to 9.902), P = 0.012; Table 4] after adjusting for covariates such as preoperative SBP using a multivariate logistic regression model.
Figure 3 Perirenal fat area and perirenal fat thickness were correlated with the curve of postoperative hypertension resolution rates.
Preoperative blood pressure and other factors were used as covariates, with perirenal fat area or perirenal fat thickness as independent variables and resolution rate as the outcome variable to construct a generalized additive model. The solid line represents the fitted values, and the shaded area indicates the 95% confidence interval. A: Using perirenal fat area as the independent variable; B: Using perirenal fat thickness as the independent variable. PrFA: Perirenal fat area; PrFT: Perirenal fat thickness.
Table 3 The predictive value of perirenal fat area is superior to that of perirenal fat thickness.
Fold
GAM (PrFA)
GAM (PrFT)
1
0.835 (0.669-1.000)
0.918 (0.817-1.000)
2
0.694 (0.443-0.945)
0.646 (0.371-0.922)
3
0.979 (0.932-1.000)
0.896 (0.771-1.000)
4
0.806 (0.547-1.000)
0.736 (0.554-0.918)
5
0.918 (0.792-1.000)
0.850 (0.704-0.997)
Mean
0.846 (0.676-0.989)
0.809 (0.643-0.967)
Table 4 Patients with lower perirenal fat area have higher rates of hypertension resolution after surgery, n (%).
PrFA < 18 cm2
PrFA ≥ 18 cm2
P value
adjOR (95%CI)
adjP value
Patients number
69
69
Age
33.2 ± 10.1
33.9 ± 7.9
0.673
Gender
Male
23.2 (16)
84.1 (58)
Female
76.8 (53)
15.9 (11)
< 0.001
Obesity duration (years)
7.8 ± 8
5.9 ± 5.9
0.114
NAFLD
61 (88.4)
64 (92.8)
0.382
OSAHS
49 (71)
51 (73.9)
0.703
SBP (mmHg)
154.3 ± 12.4
153.5 ± 12.1
0.709
DBP (mmHg)
95.5 ± 12.9
95.7 ± 12.9
0.937
BMI (kg/m2)
40.8 ± 7.3
44.9 ± 7.2
0.001
Waist circumference (cm)
123.4 ± 14.8
135.1 ± 14.8
< 0.001
Hip circumference (cm)
129.7 ± 13.9
134.3 ± 15.2
0.064
Waist-to-hip ratio
0.952 ± 0.064
1.008 ± 0.057
< 0.001
HbA1c (%)
6.8 ± 1.5
6.6 ± 1.1
0.520
HOMA-IR
11.7 ± 8.3
12.9 ± 9
0.425
ALT/AST
0.7 ± 0.3
0.6 ± 0.2
0.058
Creatinine (μmol/L)
62.2 ± 22.9
70.9 ± 21
0.021
Uric acid (μmol/L)
373.6 ± 146
438.1 ± 136.5
0.008
Sodium (mmol/L)
137.4 ± 9
137.2 ± 14.6
0.924
Triglyceride (mmol/L)
2.4 ± 2.5
2.3 ± 2.1
0.809
Total cholesterol (mmol/L)
4.6 ± 1.3
4.7 ± 1
0.643
HDL-CH (mmol/L)
1.1 ± 0.4
1.1 ± 0.3
0.311
LDL-CH (mmol/L)
2.8 ± 1
3 ± 0.8
0.204
Renin
40.4 ± 72.7
35.6 ± 63.6
0.677
Angiotensin II
47.1 ± 24
38.3 ± 15.3
0.011
Aldosterone
11.8 ± 8
12.8 ± 9.1
0.476
Cortisol at 8:00 am (nmol/L)
320.9 ± 140.7
319.5 ± 117.9
0.949
PrFA (cm2)
11.6 ± 4
31.5 ± 10.8
< 0.001
Visceral fat area (cm2)
149.5 ± 57.4
276.2 ± 86.6
< 0.001
Total fat area (cm2)
528.3 ± 183.3
655.6 ± 147.2
< 0.001
Postoperative resolution of hypertension
60 (87)
47 (68.1)
0.008
3.513 (1.367-9.902)
0.012
DISCUSSION
To our knowledge, this is the first study assessing the correlation between preoperative visceral fat evaluation indicators and postoperative hypertension resolution in patients with obesity and hypertension undergoing LSG. The study revealed that PrFA is an excellent independent predictor of hypertension resolution 1 year after LSG, with a prediction accuracy of 0.85 for resolution, surpassing that of PrFT. On the basis of their curve, we classified patients using the median PrFA and found that patients with PrFA < 18 cm2 had a significantly higher resolution rate than those with high PrFA.
Research has reported that the hypertension resolution rates after LSG at 1 year, 3 years, and 5 years are comparable[24]. One year of postoperative follow-up is sufficient for assessing hypertension resolution. The resolution rate of hypertension reached 78.3% in our study, similar to the meta-analysis results of Sarkhosh et al[17]. With respect to influencing factors, some studies have shown that BMI, waist circumference, hip circumference, and the waist-to-hip ratio are associated with the risk of hypertension[25,26], but we found no correlation between them and postoperative hypertension resolution, which is consistent with the findings reported by Benaiges et al[27]. Although sex may influence fat distribution[28], our study revealed no significant correlation between patient sex and hypertension resolution (P = 0.17). Consequently, sex was not included as a covariate in the multivariable logistic regression model. Moreover, the unreported results indicate that the postoperative resolution rates for the male/female subgroups are as follows: PrFA < 18 cm² vs ≥ 18 cm² = 93.8% vs 67.2%/84.9% vs 72.7%, which is consistent with the overall trend. In addition, postoperative changes in BMI, percentage of total weight loss, and hypertension resolution are all surgical outcomes. For temporal reasons, postoperative BMI and percentage of total weight loss cannot be included as covariates in the preoperative predictive model study and cannot replace the predictive role of preoperative PrFA. A study by Diemieszczyk et al[29] involving 305 participants showed no correlation between weight loss induced by LSG and improved postoperative hypertension. This finding might suggest that the resolution of postoperative hypertension may be unrelated to preoperative generalized obesity, while PRAT has unique characteristics compared with other visceral fat and may play a distinct role in the development of obesity and metabolic diseases[11].
PrFA and PrFT are important indicators for measuring perirenal fat mass, obesity and visceral fat accumulation[21,30,31]. These factors can also be utilized in the analysis of factors related to obesity-associated hypertension[9,14]. CT scans, considered the ideal standard for quantifying visceral fat mass, offer greater reliability than ultrasound examinations by minimizing subjective operator influence[32]. Many studies have employed CT to measure PrFA or PrFT in assessing visceral fat and metabolic status[33,34]. Furthermore, patients with obesity scheduled for LSG are required to undergo CT scans to clarify their abdominal conditions, allowing for the early identification of structural abnormalities or secondary obesity due to adrenal-related diseases[35]. On the basis of these findings, PrFA and PrFT can be measured without additional examinations to predict postoperative hypertension resolution.
Currently, no published research indicates whether PrFA or PrFT serve as independent predictors of hypertension resolution following LSG. Given a significant correlation between PrFA and PrFT, we analyzed them separately in conjunction with other indicators to determine each one’s predictive value. Overall, both PrFA and PrFT exhibited independent predictive value (P < 0.001 vs 0.002). Through fivefold cross-validation, we found that PrFA has a superior predictive value compared with PrFT (0.846 vs 0.809). This result may be attributed to the superior accuracy and precision of the measurement of PrFA compared to PrFT. PrFA offers a more comprehensive assessment of adipose distribution in the perirenal region, thereby circumventing the limitations of single-site thickness measurements and providing a more accurate reflection of perirenal fat volume. Further evidence is required to substantiate this finding. After adjusting for confounding factors, it was found that when the PrFA was less than 18 cm2, there was a better postoperative hypertension resolution rate, providing an effective classification method for clinical decision-making. Considering the collinear relationship between PrFA and PrFT, the inclusion of both PrFA and PrFT in the model necessitates the use of kernel ridge regression, which is relatively complex and poses challenges for clinical application. Importantly, the predictive accuracy of PrFA has reached 85%. Taking into account both accuracy and convenience, PrFA remains the optimal indicator for predicting hypertension resolution.
In contrast to Ricci et al’s findings[12], our results indicate that patients experiencing postoperative hypertension resolution have lower preoperative perirenal fat mass, possibly because those with less perirenal fat mass suffer less metabolic damage and are thus more likely to achieve recovery[19,36,37]. For example, greater preoperative perirenal fat mass may compress renal tissue, reducing renal blood flow and resulting in kidney damage[38]. Additionally, the accumulation of lipids around the kidneys may exert an additional “lipotoxic” effect, damaging renal function through increased oxidative stress, mitochondrial dysfunction, and endoplasmic reticulum stress[39], as evidenced by blood creatinine levels (PrFA < 18 cm2vs PrFA ≥ 18 cm2 = 62.2 vs 70.9, P = 0.021). Impaired renal function typically leads to the development of resistant hypertension and makes it difficult for hypertension patients to remit with weight loss[40,41].
Furthermore, this study revealed that the AST/ALT ratio is also an independent predictor of postoperative hypertension resolution. It is commonly used to assess the severity of non-alcoholic fatty liver disease and liver fibrosis[42], and is also associated with the incidence of hypertension and other cardiovascular events[43,44]. A study reported a relationship between the AST/ALT ratio and peripheral arterial stiffness[45], potentially explaining the correlation between the AST/ALT ratio and postoperative hypertension resolution.
This study has several limitations. Owing to ethical constraints, we lack CT scans taken 1 year after LSG, which prevents us from observing changes in perirenal fat and better correlates these changes with postoperative hypertension resolution to further elucidate the underlying mechanisms. Additionally, the number of patients included in this study was limited, and most LSG patients were approximately 30 years old, data on older LSG patients are lacking, and further validation and analysis on a larger scale are needed. Additionally, prospective studies are needed to further validate our findings, as well as basic research to clarify the specific mechanisms involved.
In summary, our research introduces a new indicator based on a more comprehensive data analysis, which can accurately classify patients with obesity and hypertension. This helps identify those who might benefit more from bariatric surgery and provides additional references for clinical decision-making. This finding also explains, to some extent, why LSG only alleviates hypertension in a portion of patients, offering a new potential direction for studying the mechanisms by which LSG relieves hypertension. Further in-depth research may assist in the development of effective intervention measures for a larger population of patients with hypertension.
CONCLUSION
The PrFA serves as a preoperative predictor for hypertension resolution following LSG, with its curvilinear correlation to resolution rates not only providing a quantitative basis for clinical stratification but also advancing the development of imaging-based prognostic models. Future investigations should prioritize multicenter prospective cohort studies to validate the generalizability of this biomarker, coupled with mechanistic research to elucidate its role in blood pressure modulation. These endeavors will ultimately enable the creation of personalized treatment algorithms for surgical candidate selection, thereby pioneering precision medicine approaches in obesity-associated hypertension management.
Footnotes
Provenance and peer review: Unsolicited article; Externally peer reviewed.
Peer-review model: Single blind
Specialty type: Gastroenterology and hepatology
Country of origin: China
Peer-review report’s classification
Scientific Quality: Grade B, Grade B
Novelty: Grade B, Grade C
Creativity or Innovation: Grade C, Grade C
Scientific Significance: Grade B, Grade C
P-Reviewer: Bazhenova L; George ST S-Editor: Wang JJ L-Editor: A P-Editor: Zheng XM
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