Abstract

The treatment of obesity is currently presented as a public health problem, since if left untreated, the natural history of the disease leads to predisposition and development of uncontrolled chronic degenerative diseases. Therefore, bariatric surgery has gained strength over the years, being proposed as the most effective treatment for severe obesity as well as its comorbidities. This systematic review compares the clinical efficacy and postoperative safety of two available surgical techniques: laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (LRYGB), including 14 studies, half of which were randomized controlled trials and the rest cohort studies, with a total of more than 10,000 patients. Outcomes evaluated included estimated weight loss (%EWL), remission of comorbidities such as type 2 diabetes mellitus, systemic arterial hypertension, dyslipidemia, quality of life, and postoperative complications. LRYGB demonstrated greater effectiveness in relation to remission of comorbidities during postoperative follow-up, whereas LSG presented a lower risk of postoperative complications. Evidence was assessed using ROB 2.0, ROBINS-I, and the GRADE system. Individualized selection of surgical technique based on patient characteristics and associated comorbidities, with multidisciplinary management, is essential for a better prognosis.

Keywords

Bariatric Surgery, Gastric Bypass, Sleeve Gastrectomy, Obesity, Type 2 Diabetes, Systematic Review

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1. Introduction and Background

Obesity is a chronic, complex, and multifactorial disease that globally affects millions of people and represents one of the leading preventable causes of morbidity and mortality [1]. Obesity is closely associated with relevant diseases that affect a large proportion of the Mexican population, such as type 2 diabetes mellitus (T2DM), systemic arterial hypertension (SAH), dyslipidemia, obstructive sleep apnea syndrome (OSAS), cardiovascular diseases, and certain neoplastic processes; therefore, obesity represents a major challenge for public health systems in terms of resources and costs [2] [3].

It has been observed that the effectiveness of conservative treatment is limited in achieving sustained weight loss; therefore, bariatric surgery provides an effective alternative for the treatment of moderate to severe obesity, as well as its associated comorbidities [4]. Among the surgical interventions currently available, the present study examines in detail the clinical outcomes of the two most frequently performed procedures: laparoscopic sleeve gastrectomy (LSG), which accounts for approximately 37% of bariatric procedures, and laparoscopic Roux-en-Y gastric bypass (LRYGB), which accounts for approximately 46.6%, according to Angrisani et al. [1].

These techniques are characterized by different mechanisms of action: LSG is mainly restrictive, whereas LRYGB combines restriction and malabsorption [5] [6]. These procedures have been performed for decades; however, controversy persists regarding which approach offers better long-term clinical outcomes in terms of weight loss, resolution of comorbidities, and postoperative safety [7]-[9]. Comparing these interventions is relevant not only to understand the magnitude of the expected clinical benefits, but also to evaluate the incidence and severity of surgical complications, nutritional follow-up requirements, and, most importantly, the patient’s long-term quality of life [5] [8] [10]. Currently, multiple individual studies and meta-analyses evaluate each technique individually or through partial comparisons; nevertheless, knowledge gaps persist regarding their overall comparative effectiveness, especially in clinical contexts with variable demographic characteristics or individualized surgical criteria [11]-[17].

This systematic review aims to evaluate the clinical outcomes and complications associated with the bariatric procedures most commonly used today, LSG and LRYGB, by gathering information and performing a detailed synthesis of articles published in indexed journals. The target population consisted of adult patients with obesity, with or without comorbidities, who underwent bariatric surgery [18] [19]. This meta-analysis aims to provide robust evidence regarding the selection of each procedure, taking into account clinical outcomes such as sustained weight loss, remission of T2DM, remission of SAH, quality of life, and postoperative safety outcomes.

2. Methods

2.1. Study Design

A systematic review of scientific evidence was conducted with the objective of comparing clinical outcomes and describing the most frequent complications of the two most commonly used bariatric procedures: laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (LRYGB).

2.2. Eligibility Criteria

The inclusion criteria were comparative studies, including randomized controlled trials or cohort studies, conducted in an adult population older than 18 years with morbid obesity, defined as BMI > 40 kg/m² or BMI > 35 kg/m² with comorbidities. Studies were included when they directly compared LSG versus LRYGB, had a minimum follow-up of 24 months, and were published in English or Spanish between January 2010 and June 2025. The exclusion criteria were studies including patients younger than 18 years, populations with BMI.

2.3. Search Strategy

According to PRISMA 2020 item 7 recommendations [18], the complete search strategy is described. A systematic search was performed in the electronic databases PubMed, EMBASE, Cochrane CENTRAL, and LILACS. The last search was conducted on June 7, 2025, including records from January 1, 2010.

To avoid excessive restrictions and ensure broad capture of relevant studies, thematic block strategies were designed using both MeSH terms and free-text words combined with Boolean operators. Block 1, corresponding to intervention/comparison, included the following terms: (“sleeve gastrectomy” [MeSH] OR “gastrectomía en manga” [Title/Abstract] OR “gastric bypass” [MeSH] OR “bypass gástrico” [Title/Abstract]). Block 2, corresponding to primary outcomes related to weight loss, included the following terms: (“weight loss” [MeSH] OR “excess weight loss” [Title/Abstract] OR “%EWL” OR “%TWL”). Block 3, corresponding to secondary outcomes related to comorbidities and quality of life, included the following terms: (“diabetes mellitus type 2” [MeSH] OR “type 2 diabetes” [Title/Abstract] OR “T2DM”) OR (“hypertension” [MeSH] OR “high blood pressure” [Title/Abstract]) OR (“dyslipidemia” [MeSH] OR “hyperlipidemia” [Title/Abstract]) OR (“quality of life” [MeSH] OR “SF-36” [Title/Abstract] OR “BAROS” [Title/Abstract]) OR (“complications” [MeSH] OR “adverse events” [Title/Abstract]).

The three blocks were combined using AND, allowing identification of studies evaluating at least one primary or secondary outcome with one of the interventions of interest. This search is documented in Appendix Table A1.

Filters applied included humans, English or Spanish language, studies published between January 2010 and June 2025, and randomized controlled trials or cohort studies. Manual search of secondary bibliography and cross references was also performed, as well as searches in ClinicalTrials.gov and WHO ICTRP.

In accordance with PRISMA 2020, grey literature sources were also included to minimize publication bias. Repositories such as the UNAM Thesis Platform, OpenGrey, and ProQuest Dissertations were consulted using free-text terms in Spanish and English, such as: “Type 2 Diabetes Mellitus,” “Obesity,” “Gastric Bypass,” “Laparoscopic Sleeve Gastrectomy,” “complications,” and “quality of life.” Proceedings of national surgery and endocrinology congresses (FENAPE, CMCOEM, AMCE) were also reviewed to identify studies not formally published. The grey literature search is summarized in Appendix Table A2.

No additional eligible studies were identified that met the defined methodological criteria (direct comparison between laparoscopic and long-term gastric bypass, ≥24 months of follow-up, adult population, etc.).

2.4. Study Selection

Three reviewers independently evaluated titles and abstracts. Full-text review was performed by at least two reviewers. Discrepancies were resolved by consensus or with a third reviewer. Rayyan software, developed by Qatar Computing Research Institute, was used for screening and reference management, recording reasons for exclusion [19].

2.5. Data Extraction and Analysis

Data extraction was performed independently by two reviewers using a standardized pre-tested form. Extracted variables included author, year, country, study design, number of patients, surgical technique, follow-up duration, baseline characteristics, and outcome definitions. Collected variables included author, publication year, country, design type, number of patients per group, baseline characteristics (age, sex, initial BMI), type of surgical procedure, definition of clinical outcomes, follow-up duration, early and late complication rates, quality of life outcomes, and risk of bias assessment. In cases of missing or inconsistent data, the value was reported as not available, and no statistical imputation was performed. This handling was carried out in accordance with the methodological recommendations of the Cochrane Handbook (Section 5.1).

2.6. Outcomes

The outcomes were weight loss, assessed as %EWL or %TWL; type 2 diabetes remission, defined as HbA1c < 6.5% for more than six months without pharmacologic treatment; hypertension remission, defined as BP < 140/90 mmHg for more than six months without pharmacologic treatment; dyslipidemia remission, defined as LDL < 100 mg/dL or normalization for more than six months without pharmacologic treatment; obstructive sleep apnea remission, defined as AHI < 5 events/hour with absence of symptoms; quality of life, assessed using SF-36 or BAROS scales; and complications, classified as early (<30 days) or late (>30 days).

2.7. Risk of Bias Assessment

Risk was assessed using RoB 2.0 for randomized controlled trials and ROBINS-I for observational studies, applied by two independent reviewers. Discrepancies were resolved by consensus or with a third reviewer. A sensitivity analysis will be considered, excluding studies that, according to the RoB 2.0 assessment, have a high risk of bias, and the impact of bias on the findings will be discussed [20].

The GRADE (Grading of Recommendations Assessment, Development and Assessment) system was applied to assess the overall certainty of the evidence for key clinical outcomes [21].

Each design was classified as having high, moderate, low, or very low certainty, considering the five methodological domains recommended by GRADE: risk of bias, inconsistency, indirectness, imprecision, and publication bias. Specific justifications for each level of certainty were recorded in a GRADE summary table, included as Table 1 in the Results section of the bias interpretation section.

Table 1. Risk of bias assessment (GRADE).

For example, weight loss (%EWL > 50%) was considered to have high certainty due to the consistency of the findings, low risk of bias in key studies, and statistical precision.

However, the evidence on quality of life was classified as moderate to low due to the heterogeneity of the scales used and the predominance of observational studies.

2.8. Statistical Analysis and Heterogeneity

If data allowed, meta-analysis was performed. Effect measures included Risk Ratio (RR) or Odds Ratio (OR) for remission of comorbidities, and Mean Difference (MD) or Standardized Mean Difference (SMD) for weight loss.

Statistical heterogeneity was assessed using the I² statistic, interpreted according to the thresholds established by the Cochrane Handbook: I² 60% substantial. A fixed-effects model was applied when I² was ≤30%, and a random-effects model when I² exceeded this threshold. Values were assigned for I² > 75%. The results were analyzed and interpreted with caution, and in cases of unexplained heterogeneity, a narrative synthesis was performed [22].

Clinical and methodological heterogeneity was also explored through analyses of predefined subgroups (by follow-up duration, population type, baseline BMI, and definition of remission). Scatter plots (bubble plots) were constructed to visually explore trends related to follow-up duration and other covariates. In these diagrams, the X-axis represents the mean follow-up duration, the Y-axis the effect measure (RR or MD), and the bubble size is proportional to the study weight (inverse of the variance). This visualization allows for the identification of non-linear trends; for example, “it was observed that with longer follow-up durations, the average %EWL increased in favor of the LRYGB group.” Although statistical regression analyses were not performed, these graphs provide visual evidence of the potential modifying effect of time. Furthermore, sensitivity analyses were performed, excluding studies with a high risk of bias or loss to follow-up > 20%, as described in the corresponding section. Publication bias: If there are > 10 studies per analysis, a funnel plot and the Egger or Begg tests will be used.

Software: Statistical analysis was performed using Review Manager (RevMan) version 5.4.1 and R software version 4.3.2. For the latter, the “meta” (version 6.2-1) and “metafor” (version 3.8-1) packages were used to perform meta-analyses, effect estimations, forest plots, and sensitivity analyses. Specific functions used included metabin() and metacont() for categorical and continuous variables, respectively, forest() for graphical visualization, and funnel() and metabias() to assess publication bias. The R code used was documented and is available for reproducibility of the analysis, and can be consulted in the author’s repository [GitHub/Zenodo]. This practice allows compliance with the transparency and reproducibility standards promoted by PRISMA 2020.

To explore potential sources of heterogeneity between studies, subgroup analyses were planned based on clinically relevant and systematically reported variables. The following comparison subgroups were defined a priori: follow-up duration ≥ 5 years versus <5 years, baseline BMI ≥ 45 kg/m² versus <45 kg/m², study type as randomized controlled trial versus observational study, and high surgical risk according to ASA ≥ III versus low surgical risk according to ASA I - II. Subgroup and sensitivity analyses were performed whenever data allowed (at least four studies per category), and their results were interpreted with caution if confidence intervals overlapped.

In accordance with the PRISMA 2020 recommendations, the flowchart summarizing the study selection process is included in Appendix Figure A1. This flowchart details the number of records identified, duplicates removed, studies screened, full texts reviewed, studies excluded (with reasons), and studies ultimately included in the meta-analysis.

The official PRISMA 2020 Checklist is also included (see Appendix Table A3), with each item checked, demonstrating compliance with the 27 points required for a structured systematic review.

2.9. Ethical Aspects of the Research

No patients were directly involved. Informed consent was not required.

3. Results and Discussion

A total of 1327 records were identified through searches in electronic databases (PubMed, EMBASE, Cochrane CENTRAL, and LILACS). After removing 207 duplicates, 1120 records remained for title and abstract screening. Of these, 1025 were excluded because they did not meet the previously established inclusion criteria. Ninety-five full-text articles were assessed, and 81 were excluded, mainly due to having a follow-up period of less than 24 months, lacking a comparator group, or including pediatric populations. Finally, 14 studies met all inclusion criteria and were incorporated into the meta-analysis. Additionally, another 16 relevant references were integrated for the theoretical framework, justification, clinical guidelines, and comparative analysis of results.

3.1. Characteristics of the Included Studies (Table 2)

The global epidemiological relevance of obesity and the evidence supporting bariatric surgery as an effective intervention have been described in previous clinical and public health literature [15] [23]-[25].

Fourteen studies directly comparing laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (LRYGB) were included, selected under the previously defined methodological criteria [6] [10] [16] [23] [26]-[35]. Data extraction was performed in duplicate and systematized in a matrix following the guidelines proposed by RevMan 5.4. The following key elements are presented in the table: author, country, study design, total number of participants, population type, baseline characteristics (age and BMI), type of intervention and comparator, duration of follow-up, primary and secondary clinical outcomes, postoperative complications, quality of life, and risk of bias assessment.

Regarding the included study designs, 7 randomized clinical trials and 7 observational studies were identified [6] [10] [17] [23] [26]-[35]. The studied populations consisted of adults with moderate to severe obesity, with BMI ranging between 30.3 and 54.5 kg/m². Sample size ranged from 60 to more than 35,000 patients. Most studies had a follow-up longer than 24 months, with the longest reaching 10 years [6] [24]. The predefined primary outcomes were: percentage of excess weight loss (%EWL), remission of T2DM, control of hypertension, and

Table 2. Characteristics of the included studies.

This table summarizes the main characteristics and clinical findings of the studies included in the systematic review comparing laparoscopic sleeve gastrectomy (LSG) with laparoscopic Roux-en-Y gastric bypass (LRYGB) [6] [10] [17] [23] [26]-[35]. For each study, the table reports the first author, year of publication, reference number, country, study design, sample size, baseline age and body mass index (BMI), intervention and comparator groups, principal clinical outcomes, postoperative complications, and risk-of-bias judgment. Clinical outcomes include excess weight loss (%EWL), total weight loss (TWL), type 2 diabetes mellitus (T2DM) remission or improvement, hypertension (HTN), and dyslipidemia (DLP), according to the definitions reported in each original study. Complications were classified as early or late when this distinction was available in the source article. Risk of bias was assessed according to study design, using RoB 2.0 for randomized clinical trials and ROBINS-I for non-randomized studies [20]. Abbreviations: AGB, adjustable gastric banding; BMI, body mass index; CCI, comprehensive complication index; CI, confidence interval; DLP, dyslipidemia; EWL, excess weight loss; HR, hazard ratio; HTN, hypertension; LDL, low-density lipoprotein cholesterol; LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; ns, not significant; OR, odds ratio; RCT, randomized clinical trial; RD, risk difference; RYGB, Roux-en-Y gastric bypass; SBP, systolic blood pressure; SG, sleeve gastrectomy; T2DM, type 2 diabetes mellitus; TG, triglycerides; TWL, total weight loss; WMD, weighted mean difference.

dyslipidemia. These outcomes were addressed through quantitative synthesis (meta-analysis) whenever at least three studies with comparable definitions and measurements were available.

In contrast, secondary outcomes such as quality of life, late complications, and surgical reinterventions were evaluated narratively, due to heterogeneity in the scales used (e.g., SF-36, BAROS) and lack of standardization in reporting among studies. The criteria for grouping outcomes in the meta-analysis were: conceptual homogeneity (same operational definition), same unit of measurement, and availability of comparable statistics (mean ± SD, RR, 95% CI). When these criteria were not met, the data were summarized in descriptive tables and clinical narrative form.

Clinical outcomes were reported based on the criteria defined in this review. Weight loss, assessed by %EWL or %TWL, was superior in LRYGB in at least 9 studies, with statistically significant differences in 6 of them [6] [17] [21]-[24] [27] [29] [30]. T2DM remission showed rates ranging from 47% to 93% in LRYGB and from 30% to 76% in LSG, being significantly higher in LRYGB in high-quality studies [23] [29] [31]. For hypertension and dyslipidemia, remission rates favored LRYGB in at least 4 studies, although with less consistency in statistical significance [27] [29] [31] [34]. Regarding OSA resolution, few studies reported it,

This forest plot presents the proportion of patients achieving excess weight loss greater than 50% (%EWL > 50%) at one year after bariatric surgery in the included studies comparing laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) [6] [10] [17] [23] [26]-[35]. Each black dot represents the study-specific proportion, and the horizontal line represents the corresponding confidence interval. The vertical dashed red line indicates the reference proportion used for visual comparison across studies. Overall, Figure 1 illustrates variability in the proportion of patients reaching %EWL > 50% at one year, with most studies showing favorable weight-loss outcomes after surgery. Abbreviations: EWL, excess weight loss; LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy.

Figure 1. Forest plot of weight loss (%EWL > 50% at 1 year).

but the available data also slightly favored LRYGB [27] [29] [32]. Quality of life, assessed using scales such as SF-36, BAROS, or IWQOL-Lite, improved significantly in both groups without relevant differences between techniques [27] [29] [31]. The weight-loss analysis is shown in Figure 1. The T2DM remission analysis is shown in Figure 2. The systemic arterial hypertension analysis is shown in Figure 3. The dyslipidemia analysis is shown in Figure 4.

Regarding surgical complications, lower rates of early and late events were observed in LSG [10] [28] [34], whereas LRYGB was associated with higher rates of reintervention and metabolic adverse events such as hypoglycemia [31] [35]. Finally, the risk of bias assessment showed that all included RCTs were classified as low risk (RoB 2.0), and the observational studies as moderate risk (ROBINS-I), mainly due to methodological limitations inherent to their design. The early surgical complications analysis is shown in Figure 5.

This forest plot shows the odds ratio (OR) for type 2 diabetes mellitus (T2DM) remission after laparoscopic Roux-en-Y gastric bypass (LRYGB) compared with laparoscopic sleeve gastrectomy (LSG) across the included studies [10] [17] [23] [26] [27] [29]-[32] [34]. Each black dot represents the point estimate for an individual study, and the horizontal line represents its confidence interval. The vertical dashed red line indicates the null effect value (OR = 1.0). Values to the right of the null line favor LRYGB for T2DM remission, whereas values crossing the null line indicate uncertainty in the comparative effect. Abbreviations: LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; OR, odds ratio; T2DM, type 2 diabetes mellitus.

Figure 2. Forest plot of type 2 diabetes mellitus (T2DM) remission.

This forest plot shows the log odds ratio (Log[OR]) for hypertension remission after laparoscopic Roux-en-Y gastric bypass (LRYGB) compared with laparoscopic sleeve gastrectomy (LSG) across the included studies reporting hypertension outcomes [6] [10] [17] [23] [26]-[31]. Each black dot represents the study-specific effect estimate, and the horizontal line represents the corresponding confidence interval. The vertical dashed red line indicates the null effect value (Log[OR] = 0). Values to the right of the null line favor LRYGB for hypertension remission, whereas values crossing the null line indicate uncertainty in the comparative effect. Abbreviations: LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; OR, odds ratio.

Figure 3. Forest plot of systemic arterial hypertension control.

This forest plot shows the log odds ratio (Log[OR]) for dyslipidemia remission after laparoscopic Roux-en-Y gastric bypass (LRYGB) compared with laparoscopic sleeve gastrectomy (LSG) across the included studies reporting lipid outcomes [6] [10] [17] [23] [26]-[31]. Each black dot represents the study-specific effect estimate, and the horizontal line represents the corresponding confidence interval. The vertical dashed red line indicates the null effect value (Log[OR] = 0). Values to the right of the null line favor LRYGB for dyslipidemia remission, whereas values crossing the null line indicate uncertainty in the comparative effect. Abbreviations: LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; OR, odds ratio.

Figure 4. Forest plot of dyslipidemia remission.

This forest plot shows the log odds ratio (Log[OR]) for early surgical complications occurring within 30 days after laparoscopic Roux-en-Y gastric bypass (LRYGB) compared with laparoscopic sleeve gastrectomy (LSG) across the included studies reporting early postoperative complications [6] [10] [17] [23] [26]-[31]. Each black dot represents the study-specific effect estimate, and the horizontal line represents the corresponding confidence interval. The vertical dashed red line indicates the null effect value (Log[OR] = 0). Values to the left of the null line indicate a lower risk of early surgical complications with LSG compared with LRYGB, whereas values crossing the null line indicate uncertainty in the comparative effect. Abbreviations: LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; OR, odds ratio.

Figure 5.Forest plot of total surgical complications < 30 days.

3.2. Summary of Findings between LSG and LRYGB

Table 3 summarizes the main comparative clinical outcomes between LSG and LRYGB, based on the studies included in this systematic review. Relative measures (OR/RR) are presented when available, as well as absolute evidence and a qualitative assessment of the level of certainty according to the GRADE system.

These graphs show that, overall, Roux-en-Y gastric bypass (LRYGB) was associated with higher rates of remission of metabolic comorbidities (T2DM and dyslipidemia), whereas laparoscopic sleeve gastrectomy (LSG) demonstrated a more favorable surgical safety profile. Heterogeneity among studies was assessed using the I² statistic, and a random-effects model was applied in cases with I² > 50%. Bubble Plot diagrams were generated to visually represent the effect of follow-up duration in relation to weight loss (%EWL > 50%). The graph shows that, with longer follow-up duration, these studies demonstrated a higher %EWL in the LRYGB group compared with the group undergoing LSG. This graphical distribution supports the hypothesis of a time-dependent effect.

3.3. Subgroup Analysis

A subgroup analysis was performed for the outcome of weight loss (%EWL > 50% at 1 year), based on clinically relevant variables such as follow-up duration, baseline BMI, and study design. Table 4 summarizes the pooled estimates by subgroup. A clear trend toward greater effect with LRYGB was observed in studies with longer follow-up and in patients with BMI ≥ 45 kg/m². Although a formal meta-regression was not performed, the results suggest an effect modification by these clinical variables.

Table 3. Comparative outcomes between LSG and LRYGB.

This table summarizes the comparative clinical outcomes between laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) across the included studies [6] [10] [17] [23] [26]-[35]. Outcomes include type 2 diabetes mellitus (T2DM) remission, systemic arterial hypertension (SAH) remission, dyslipidemia remission, excess weight loss greater than 50% at one year, and postoperative surgical complications. Relative evidence is presented as risk ratio (RR), odds ratio (OR), or qualitative comparative direction when pooled estimates were not available. Absolute evidence summarizes the approximate outcome ranges reported across the included studies. The quality of evidence was graded using the GRADE approach, considering risk of bias, inconsistency, indirectness, imprecision, and publication bias [21]. Abbreviations: EWL, excess weight loss; GRADE, Grading of Recommendations Assessment, Development and Evaluation; LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; OR, odds ratio; RR, risk ratio; SAH, systemic arterial hypertension; T2DM, type 2 diabetes mellitus.

The following scatter plot graphically represents the relationship between follow-up duration measured in months and %EWL in patients undergoing LRYGB. Each point individually represents a study and is labeled with the author’s name and year of publication. There were limitations in the availability of variances; therefore, the bubble sizes were uniform. Although no formal meta-regression was performed, an upward trend can be observed: studies with longer follow-up tend to report higher %EWL, suggesting that time acts as an effect modifier.

This graphical analysis provides visual support for the hypothesis that the benefits of gastric bypass in terms of weight loss may intensify over time. Likewise, it highlights the importance of considering follow-up duration as a critical variable in the interpretation of comparative outcomes between surgical techniques. In longitudinal evaluation contexts, this type of representation may facilitate the identification of relevant clinical patterns, especially when facing high heterogeneity among studies, as shown in Figure 6.

3.4. Bias Interpretation

The risk of bias assessment demonstrated an overall moderate to high methodological quality among the 14 included studies. Seven were randomized clinical

Table 4. Subgroup analysis—%EWL > 50% at 1 year.

This table presents the subgroup analysis for excess weight loss greater than 50% (%EWL > 50%) at one year after laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) across the included studies [6] [10] [17] [23] [26]-[35]. Subgroups were defined according to follow-up duration, baseline body mass index (BMI), study design, and baseline surgical risk. Effect estimates are reported as mean differences (MD) with 95% confidence intervals (CI) when sufficient data were available. Heterogeneity was assessed using the I² statistic, with higher values indicating greater between-study variability. The subgroup analysis suggests a consistent direction of effect favoring LRYGB for weight-loss outcomes, although heterogeneity varied across subgroups and pooled estimates were not calculated when available data were insufficient. Abbreviations: ASA, American Society of Anesthesiologists physical status classification; BMI, body mass index; CI, confidence interval; EWL, excess weight loss; I², inconsistency statistic; LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; MD, mean difference; RR, risk ratio.

This scatter plot shows the relationship between follow-up duration and excess weight loss (%EWL) in the laparoscopic Roux-en-Y gastric bypass (LRYGB) group across the included studies reporting LRYGB-specific weight-loss outcomes [6] [10] [23] [26]-[32] [34]. Each orange marker represents an individual study, labeled by first author, year of publication, and reference number. The x-axis represents follow-up duration in months, and the y-axis represents the percentage of excess weight loss reported in the LRYGB group. The figure illustrates variability in %EWL across studies and follow-up periods, with several studies showing sustained weight-loss outcomes at longer follow-up. Abbreviations: EWL, excess weight loss; LRYGB, laparoscopic Roux-en-Y gastric bypass.

Figure 6. Bubble plot: Relationship between follow-up duration and %EWL.

trials evaluated using the RoB 2.0 tool, all classified as having low risk of bias, which strengthens the internal validity of the primary outcomes, such as weight loss (%EWL) and remission of type 2 diabetes mellitus (T2DM). The remaining 7 observational studies presented a moderate risk of bias after assessment with ROBINS-I, as they showed certain methodological limitations related to the investigation, such as the absence of random allocation or incomplete reporting of outcomes established as secondary objectives. Nevertheless, many of these studies provided relevant evidence due to their large population samples and long-term follow-up.

To assess the certainty of evidence, the GRADE system was applied, differentiating outcomes according to study type, consistency of results, and precision of estimators. The outcomes %EWL and T2DM remission achieved moderate to high certainty, supported by consistent results, low risk of bias, and large sample sizes. In contrast, outcomes such as quality of life, late complications, and reinterventions showed moderate or low certainty, as they were predominantly reported by observational studies, with non-standardized scales (e.g., SF-36, BAROS, IWQOL-Lite) and high clinical and methodological heterogeneity. In these cases, the findings should be interpreted with caution. The GRADE assessment is summarized in Table 1.

Finally, publication bias was assessed for the primary outcomes using a funnel plot, since the number of included studies was ≥10. The graph showed a symmetrical distribution, and the statistical test was not significant (p = 0.808), indicating a low risk of publication bias. Therefore, it was not necessary to apply correction methods such as trim-and-fill. Figure 7 presents the corresponding funnel plot.

Rayyan was used for screening and reference management, ROBINS-I was used for risk-of-bias assessment in observational studies, the GRADE system was used for certainty assessment, and the Cochrane Handbook was used for methodological guidance and heterogeneity interpretation [19]-[22].

The risk-of-bias assessment for each included study is summarized in Table 5, including the corresponding reference number, study design, assessment tool, and overall risk-of-bias judgment.

Table 5. Risk of bias assessment (RoB 2.0 and ROBINS-I).

This table summarizes the risk-of-bias assessment of the studies included in the systematic review comparing laparoscopic sleeve gastrectomy (LSG) with laparoscopic Roux-en-Y gastric bypass (LRYGB) [6] [10] [17] [23] [26]-[35]. Randomized clinical trials were assessed using the revised Cochrane risk-of-bias tool for randomized trials (RoB 2.0), whereas non-randomized and observational studies were assessed using ROBINS-I [20] [22]. Each study was classified according to its design, assessment tool, and overall risk-of-bias judgment. Studies with randomized allocation were generally judged as low risk of bias, while observational or retrospective studies were generally judged as moderate risk because of potential confounding, selection bias, and limitations inherent to non-randomized designs. Abbreviations: LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; RCT, randomized clinical trial; RoB 2.0, revised Cochrane risk-of-bias tool for randomized trials; ROBINS-I, risk of bias in non-randomized studies of interventions.

3.5. Narrative Analysis of Secondary Outcomes

Regarding hypertension, the results showed a slightly favorable effect of LRYGB compared with LSG. Although the difference was not statistically significant in all studies, a clinically relevant trend was identified, predominantly in patients with longer disease duration or those presenting resistance to antihypertensive pharmacological treatment. The variability observed suggests that factors such as duration of disease control or baseline disease control may considerably influence this outcome.

The results for dyslipidemia demonstrated greater homogeneity and consistency in favor of LRYGB. Most studies reported strong evidence regarding control of lipid profile values, mainly in the normalization of LDL and triglyceride levels, with remission rates exceeding 70% compared with approximately 50% in the case of LSG. Since LRYGB includes a malabsorptive mechanism, these results may be related to fat metabolism, favoring LRYGB.

Regarding postoperative complications, analysis of the 14 studies demonstrated important differences between both techniques [6] [10] [15] [17] [23] [26]-[35]. In the immediate postoperative period (>30 days), LSG presented a safer profile, with lower complication rates (2.7% - 4.6%) compared with LRYGB (4.5% and 10.1%). During long-term follow-up (>30 days), LRYGB presented higher rates of postprandial hypoglycemia (up to 28%) and reintervention (up to 28.3%), whereas LSG reported a higher incidence of conversion from laparoscopy to open surgery due to technical failure (29.9% in one study). Based on these results, it

This funnel plot assesses potential publication bias among the included studies comparing laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) [6] [10] [17] [23] [26]-[35]. Each labeled blue point represents an individual study, identified by first author, publication year, and reference number, plotted according to its estimated effect size on the x-axis and standard error on the y-axis. The vertical dashed red line represents the mean estimated effect. Visual asymmetry in the distribution of studies around the mean may suggest possible small-study effects or publication bias; however, interpretation should be cautious because funnel plot assessment is less reliable when the number of studies is limited. Abbreviations: LRYGB, laparoscopic Roux-en-Y gastric bypass; LSG, laparoscopic sleeve gastrectomy; OR, odds ratio.

Figure 7. Funnel plot of total surgical complications <30 days.

can be stated that LSG offers a better early surgical safety profile, while LRYGB presents a higher risk of late metabolic complications—an important consideration in surgical technique selection. Therefore, cases should be individualized.

4. Discussion

According to the World Health Organization, more than 890 million adults were living with obesity in 2022, confirming the increasing global burden of this disease [25].

The findings of this systematic review and meta-analysis reinforce the clinical efficacy of both surgical techniques in the management of obesity and its associated comorbidities. Both LSG and LRYGB demonstrated favorable outcomes regarding sustained weight loss, control of related comorbidities, and quality of life. Despite the evident superiority of LRYGB in terms of remission of T2DM and dyslipidemia, and possibly hypertension, LSG showed better outcomes regarding the postoperative safety profile. The results should be interpreted considering the heterogeneity of the included studies. Factors such as study design, duration of follow-up, variability in clinical definitions, and baseline patient characteristics influence the reported outcomes. However, the methodological quality was adequate, with a predominance of studies presenting low to moderate risk of bias, in addition to the absence of significant evidence of publication bias.

The results are clinically relevant for selecting the surgical technique, especially in patients with multiple comorbidities who may or may not present high surgical risk. The choice of technique should be made by an experienced bariatric surgeon and individualized for each patient, taking into account not only the expected outcomes, but also the safety profile, patient preferences, and the experience of the surgical team.

Limitations of the Study

This systematic review presents several limitations inherent to the investigation. The first is the inclusion of observational studies, which may introduce residual confounding and selection bias, despite having been evaluated using the ROBINS-I tool. The second limitation is the heterogeneity in the definition of remission of metabolic comorbidities and the variability in the use of quality-of-life scales, which is uncommon among studies despite being an important variable, limiting the possibility of performing meta-analysis for these secondary outcomes. Finally, although an exhaustive search was performed, the omission of unpublished studies or studies presenting negative results cannot be ruled out.

5. Conclusion

LSG and LRYGB are effective surgical techniques in bariatric surgery for the treatment of obesity and its concomitant diseases. LRYGB demonstrated greater effectiveness in terms of remission of T2DM and dyslipidemia, whereas LSG stood out for its lower incidence of postoperative complications. The choice of surgical technique should be individualized for each patient according to the presence and control status of comorbidities, together with comprehensive evaluation by a multidisciplinary team.

6. Clinical Implications and Recommendations

The results of this systematic review have important applications for clinical practice and the selection of surgical techniques for obesity management through surgical intervention. The evidence suggests that LRYGB may be preferred in patients with obesity who present severe metabolic diseases, especially in patients with uncontrolled T2DM or severe dyslipidemia, since better remission outcomes are achieved with this technique.

In contrast, LSG may represent a safer and less invasive alternative, being ideal for patients with high surgical risk or in patients where minimizing the risk of early postoperative complications is desired. LSG could be prioritized in patients with previous abdominal surgical interventions that increase the difficulty of dissection and the risk of inadvertent injuries, or in those presenting anatomical limitations that contraindicate LRYGB.

Since both techniques present advantages and disadvantages, selection of the technique should be individualized, taking into account the presence of comorbidities and their severity, patient surgical risk, patient preferences, and the experience of the multidisciplinary team.

The results of this systematic review support the importance of a multidisciplinary team approach, including the bariatric surgeon, endocrinology, anesthesiology, nutrition, and psychology specialists, to ensure adequate candidate selection and maximize the benefits of bariatric surgery.

Finally, promotion of long-term follow-up and systematic monitoring of clinical outcomes is recommended in order to generate local data that strengthen evidence-based decision-making and contribute to future comparative studies and cost-effectiveness evaluations.

Author Contributions

Conceptualization: C.D.L.R.; Methodology: C.D.L.R.; Formal Analysis: C.D.L.R.; Investigation: C.D.L.R.; Data Curation: C.D.L.R.; Writing—Original Draft Preparation: C.D.L.R.; Writing—Review and Editing: C.D.L.R., C.E.A.H., K.A.C.C., D.S.L., D.L.G.O., G.C.C., H.C.L.M., A.Y.T.R., M.A.C.L., A.H.G., J.M.A.A., and A.M.B.; Visualization: C.D.L.R.; Supervision: C.D.L.R.; Project Administration: C.D.L.R. All authors have read and agreed to the published version of the manuscript.

Appendix

Table A1. Search strategies with filters.

Table A2. Grey literature.

Table A3. Check list.

Figure A1. Flowchart selection of studies.

Conflicts of Interest

The authors declare no conflicts of interest.

References