Article	Risk of Bias	Inconsistency	Indirectness	Imprecision	Publication Bias	Overall
Beaton et al., 2023 [11]	Low: Randomized, double-blind, placebo-controlled design with proper randomization, blinding, and allocation concealment. Minimal risk of bias from study design and execution.	Low: There is no indication of inconsistency. Outcomes are measured systematically using standardized scales (e.g., NPRS) at predefined time points.	Low: The study directly addresses the population, intervention, and outcomes relevant to postsurgical pain in abdominoplasty.	Moderate: While the sample size is well-powered for the primary endpoint (SPI24), the lower power for SPI48 (66%) raises slight concerns about precision for secondary outcomes.	Low: The study was registered on ClinicalTrials.gov, and the design reduces the likelihood of publication bias.	High Quality The study exhibits a low risk of bias, direct applicability to the research question, and strong consistency in methodology. While there is some imprecision for the secondary outcomes, this is not sufficient to downgrade the overall quality, resulting in a high-quality rating.
Abo-Zeid et al., 2018 [12]	Low: Prospective, double-blinded, and randomized design reduces bias, but the randomization is via a closed envelope method. Minimal risk of bias from study design and execution.	Low: No evidence of unexplained variability between groups or within study outcomes, as appropriate statistical tests (ANOVA, Kruskal–Wallis) were used for analysis.	Low: The study directly addresses the population of interest (patients undergoing abdominoplasty) and interventions (TAP-B, RSB, and SCI) relevant to the research question.	Low: Sample size is adequately powered for primary outcomes, and the statistical methodology is sound, giving confidence in the precision of the results.	Low: Registered trial with an IRB approval and clinical trial registration (NCT03077581) reduces the likelihood of publication bias.	High Quality The study has a strong design and execution with low risk in most domains.
Edwards et al., 2015 [13]	Moderate: This is an observational study, which inherently has a higher risk of bias compared to randomized trials. Although the study followed Good Clinical Practice guidelines and had IRB approval, there is no control group.	Low: The study seems to have consistent methodology across multiple sites with similar treatments and data collection methods, reducing inconsistency risks.	Low: The study directly addresses the relevant population (patients undergoing breast and/or abdominoplasty surgeries) and the intervention (liposome bupivacaine), making it applicable to the research question.	Moderate: Some imprecision arises from the observational design, which limits the ability to draw causal inferences. However, the study appears to include a reasonable sample size and appropriate outcome measures.	Low: A multicenter study with adherence to Good Clinical Practice and detailed outcome reporting reduces the likelihood of publication bias.	Moderate Quality The observational nature and lack of a control group introduces some bias, but the study is well conducted and follows rigorous standards, making it a moderate-quality study.
Gardner et al., 2019 [14]	Moderate: The study is randomized, which reduces bias; however, there is no mention of blinding, which could affect the results and reporting of pain and narcotic consumption.	Low: The results appear consistent within the study; statistical significance is noted between the two groups for both time points, suggesting reliable outcomes.	Low: The study directly addresses the population undergoing abdominoplasty and the specific intervention (TAP-B), making it relevant to the research question.	Moderate: While statistically significant differences were found, the sample size (20 participants) is small, which may limit the generalizability of the results.	Low: The study presents clear data, and its design as a prospective comparative study reduces concerns about publication bias.	Moderate Quality The randomized design supports quality, but the lack of blinding and small sample size introduces limitations. The significant findings still suggest valuable insights.
Fiala 2015 [15]	Moderate: The study design includes random assignment of patients to either the TAP block or standard treatment, but there is no mention of blinding, which may introduce bias in pain reporting.	Low: The results are consistent across both groups, with statistically significant differences noted in narcotic use and time to first request for pain medication.	Low: The study directly addresses patients undergoing abdominoplasty and evaluates a specific intervention (TAP block) relevant to post-surgical pain management.	Moderate: While the sample size (32 patients) is reasonable for a pilot study, the findings, though statistically significant, should be interpreted cautiously due to this size.	Low: The study presents clear and relevant data, with a focus on a specific clinical question, reducing concerns about publication bias.	Moderate Quality The pilot study design shows potential efficacy of the TAP block but is limited by the lack of blinding and relatively small sample size, which could affect reliability.
Minkowitz et al., 2020 [6]	Low: The study is a multicenter, randomized, double-blind trial, which minimizes bias and enhances the reliability of the findings.	Low: The study design is consistent in methodology across multiple centers, and the results are expected to be reliable due to the controlled design.	Low: The study directly addresses the population of interest (patients undergoing abdominoplasty) and compares relevant treatment options (IV tramadol vs. morphine vs. placebo).	Moderate: While the planned sample size of 360 patients enhances power, the actual results may vary, and the specific outcomes need to be interpreted with caution until completed.	Low: The study’s registration and adherence to ethical guidelines reduce concerns about publication bias, ensuring transparency and accountability.	High Quality The phase 3 design, randomization, blinding, and multicenter approach strengthen the overall quality of evidence. The study aims to evaluate both efficacy and safety comprehensively.
Morales Jr et al., 2013 [16]	Moderate: The study is retrospective and relies on case record reviews, which introduces potential biases in data collection and reporting.	Low: The use of standardized methods for administering liposomal bupivacaine and consistent evaluation criteria across patients helps maintain consistency in the results.	Low: The study directly investigates the efficacy of liposomal bupivacaine in postoperative pain management for patients undergoing abdominoplasty, aligning with the objective.	Moderate: While average pain scores and medication usage provide some insight, variability in individual responses may limit the robustness of findings, requiring further validation.	Low: The findings are likely to contribute valuable information to the existing literature on postoperative pain management, indicating a low risk of publication bias.	Moderate Quality The study provides important data on the effectiveness of liposomal bupivacaine for pain management, but the retrospective nature and small sample size limit its overall quality.
Price et al., 2023 [7]	Moderate: Although the study has institutional review board approval and includes a clear inclusion criterion, it is retrospective and may have biases in data collection and patient selection.	Low: The study employs standardized protocols for pain management across both groups, contributing to consistent outcomes.	Low: The study directly addresses the impact of a multimodal approach to pain management in abdominoplasty patients, aligning with the stated objective.	Moderate: The sample size of 80 patients is adequate, but potential variability in responses to pain management protocols may affect the precision of the findings.	Low: The study’s findings are likely to fill a gap in literature regarding multimodal pain management in surgical settings, indicating a low risk of publication bias.	Moderate Quality The study contributes valuable insights into multimodal pain management in abdominoplasty; however, the retrospective nature and potential biases in data collection limit its overall quality.
Mentz et al., 2005 [17]	Moderate: The study employs a randomized design, which reduces bias, but with a small sample size (20 patients), there may still be concerns regarding the potential selection and reporting bias.	Low: The intervention and control groups were clearly defined, with a consistent method of pain assessment and a standardized protocol for administering treatments.	Low: The study directly investigates the use of a Stryker Pain Pump versus standard pain management, addressing the research question without any indirect measures.	High: With only 20 patients, the sample size is small, increasing the likelihood of variability in results and decreasing statistical power, contributing to imprecision.	Low: Given the novelty of the use of a Stryker Pain Pump in postoperative pain management for abdominoplasty, there is no clear indication of publication bias.	Moderate Quality The study presents an innovative approach to pain management with well-documented methodology, but the small sample size and potential biases limit the overall confidence in the results.
Singla et al., 2018 [18]	Low: This is a randomized, double-blind, placebo-controlled, multicenter trial with well-defined protocols, reducing the likelihood of selection and performance bias. Adherence to Good Clinical Practices further minimizes bias.	Low: The study uses a standardized surgical procedure and pain assessment method across multiple clinical sites, with consistent endpoints, reducing potential inconsistency in outcomes.	Low: The study directly investigates the effect of IV meloxicam on postoperative pain control, addressing the research question without indirect or surrogate measures.	Moderate: The sample size is powered at >80%, which is strong, but the assumption of an effect size of 0.40 may affect generalizability to broader populations. Exact patient numbers are not provided, affecting the precision.	Low: As a phase 3 trial for a well-established drug (meloxicam), there is low risk of publication bias. The trial follows standardized protocols, decreasing selective reporting risks.	High Quality The study design is robust with a clear methodology, randomization, double-blind structure, and appropriate statistical analyses, providing high confidence in the reliability of the results.
Bjelland et al., 2019 [19]	Low: The study is a triple-blinded RCT with randomization conducted using a concealed computerized block algorithm, reducing bias. Blinding was maintained for patients, personnel, and analysts. However, a single surgeon performed the procedures, which could introduce performance bias, though steps were taken to standardize techniques.	Low: There is no mention of significant variability in the outcomes. Pain and opioid consumption were measured at multiple time points, and consistent methods of assessment (NRS, PCA, etc.) were used across the study. Variability in results was controlled through the use of well-defined protocols and statistical methods, but no external replication was reported.	Moderate: The population (post-bariatric patients undergoing abdominoplasty) and interventions (ropivacaine vs placebo for pain control) are highly specific to this clinical setting. While generalizable within this context, broader applicability to other populations or procedures may be limited.	Moderate: The sample size of 50 patients was relatively small, though justified by power analysis. While confidence intervals were reported, the relatively small sample may limit the precision of the results, especially in detecting smaller effect sizes. However, a sample size of 23 per group was calculated to be sufficient to detect clinically relevant differences.	Low: There is no indication of selective outcome reporting. The study was pre-registered with EudraCT and clinicaltrials.gov, minimizing the risk of publication bias. However, the absence of multiple independent studies reduces the ability to fully assess publication bias.	Moderate Quality The evidence quality is strong due to the robust design (RCT), triple blinding, and use of appropriate statistical analyses. Some limitations exist, such as small sample size and indirectness to broader populations, but the study was conducted with high methodological rigor.
Ali et al., 2020 [20]	Low: The study was randomized with a computer-generated number table. Treatment allocation was concealed. Double-blinded design, with patients and the anesthetist recording the data blinded to group assignment. Adequate blinding of data collectors and outcome assessors.	Low: No conflicting or heterogeneous results across groups were reported. The study used standard statistical methods (unpaired t-test, Chi-square) without notable variability in outcomes.	Moderate: The study population is relatively specific (ASA I and II, ages 18–50, undergoing elective abdominoplasty), which may limit the applicability to other populations or surgeries. The interventions (ketamine vs. morphine) are widely used in clinical practice.	Low: Power analysis was appropriately conducted, requiring 71 patients per group to achieve sufficient power. A total of 160 patients were enrolled to account for dropouts. Statistical analysis methods were adequately applied with sufficient patient numbers.	Low: The study was registered (NCT03664622), followed transparent procedures, and reported conventional outcomes for pain management trials.	High Quality
Giordano et al., 2020 [21]	High: As a retrospective study with no randomization, there is a higher risk of bias. The reliance on existing records and potential unmeasured confounders also increases bias.	Low: The results were consistent across groups, with clear differences in opioid use and LOS, and similar complication rates. No notable variability was observed.	Moderate: The population and interventions are relevant, but the small sample size and single-center design limit the generalizability to broader populations.	Moderate: Despite significant findings, the small sample size and wide standard deviations introduce imprecision, reducing the reliability of the results.	Low: There is no strong evidence of publication bias, as both significant and non-significant outcomes were reported.	Low Quality This is due to the retrospective design and imprecision from the small sample size. However, the results are consistent and directly relevant to the study population.
Shauly et al., 2022 [22]	High: The study is retrospective with no control group or randomization, increasing the likelihood of bias, particularly selection and reporting bias. Additionally, all surgeries were performed by a single surgeon, which could introduce performance bias.	Moderate: There is no clear mention of results variability or heterogeneity across patients, but the uniform protocol may reduce variability, indicating consistent outcomes. However, without comparative data, it is difficult to fully assess this.	Moderate: The study population and interventions are relevant, but the highly specific surgical protocol and single-surgeon setting limit the generalizability to other contexts or surgeons.	Moderate: The relatively small sample size of 80 patients and reliance on subjective pain scores without long-term follow-up data introduce imprecision in the estimates of effectiveness and safety outcomes.	Low: There is no evidence of selective reporting, but the retrospective design and inclusion of a single surgeon’s patients may raise concerns about unpublished negative outcomes.	Low Quality This is due to the retrospective, non-randomized design and moderate imprecision due to the small sample size and subjective outcome measures. While the outcomes are directly relevant, the highly specific surgical setting and protocol further reduce the generalizability of the findings.
Varas et al., 2020 [23]	Moderate: The study was randomized and double-blind, reducing selection and performance bias. However, the abandonment of the primary outcome after recruiting 25 patients raises concerns about reporting bias.	Low: The methods for randomization and blinding were clearly outlined, and the interventions were well-defined, suggesting consistency. Additional analyses using both linear and nonlinear models further support robustness.	Low: The study’s population (adults undergoing abdominoplasty/liposuction) and interventions (ketamine and magnesium) are relevant to clinical practice, limiting indirectness.	Moderate: While a sample size calculation was performed, the outcome of interest was changed midway through the trial, which may lead to uncertainties in the findings related to morphine consumption.	High: The study adhered to ethical guidelines and Good Clinical Practice. It was registered, ensuring transparency. The careful monitoring of adverse effects adds to the overall quality.	Low Quality The randomized and double-blind design strengthens the study but concerns regarding the changes in the primary outcome and potential biases affect the overall confidence in the results.
Silva Filho et al., 2021 [24]	Moderate: The results indicate that the trial followed the CONSORT guidelines, which helps to ensure transparency in reporting participant flow. However, there were some missing blood concentration measurements due to sample mishandling, reducing the completeness of the dataset.	Low: The study involves a single population with consistent methodology, inconsistency is unlikely	Low: The findings for systolic blood pressure and secondary outcomes, such as fentanyl and ephedrine consumption, are consistent and follow logical trends between the two groups	Moderate: There are some concerns regarding the precision of certain results. For instance, the study’s statistical significance was noted in certain comparisons (e.g., systolic blood pressure over time) with moderate effect sizes. However, the confidence intervals, especially for blood pressure post-intubation, were relatively wide.	Low: There is no strong indication of publication bias based on the available data. The study appears to have been designed and reported transparently, without selective reporting of outcomes that would raise concerns of bias.	Moderate Quality The evidence is reliable, though there are some concerns about sample size and imprecision in certain measures. However, the results appear consistent and relevant, providing useful insights into the effects of remifentanil and magnesium sulfate.
Bray Jr et al., 2007 [25]	High: The study is retrospective in nature, which inherently carries a risk of bias due to non-randomized group allocation. This can introduce selection bias, as patients may have been chosen based on factors not controlled for. Additionally, there was no blinding of patients or assessors, which could influence outcomes like pain reporting.	Low: The outcomes showed small, non-statistically significant differences in all key measures, including pain medication use, pain scores, and hospital stay length. The direction of these small differences was consistent, suggesting that there is little unexplained variability between study results.	Low: The population (abdominoplasty patients) and interventions (use of pain pumps) are directly relevant to the clinical question. There is no indirectness in terms of population, intervention, or outcomes that would limit the applicability of the results to similar clinical settings.	Serious: The results did not achieve statistical significance for any outcomes, which limits the precision of the effect estimates. Additionally, the relatively small sample size (38 with pain pumps and 35 without) means that the study may not have had enough power to detect clinically meaningful differences.	Moderate: As this is a single study, the risk of bias cannot be completely ruled out without evidence from other similar studies.	Low Quality While the study addresses a relevant clinical question, the retrospective design, lack of blinding, and imprecision of results reduce confidence in the findings. The evidence provided is of low quality, meaning that further research is likely to impact the confidence in the estimate of effect and may change the findings.
Chavez-Abraham et al., 2011 [10]	Serious: This was a consecutive case series comparing patients before and after the use of an elastomeric continuous infusion pump (ECIP), without randomization. Lack of randomization and blinding raises the risk of bias, as the study groups were historical controls rather than being directly randomized. Postoperative pain and narcotic use are subjective, and the absence of blinding could lead to bias in reporting.	Moderate: The study does not report significant variability across the different outcomes (pain scores and narcotic use), but without detailed statistical analysis, it is unclear whether the results are consistent across various subgroups or across different outcome measures. As the data are observational, some inconsistency could arise.	Low: The population (augmentation mammaplasty and abdominoplasty patients) and the intervention (ECIP with lidocaine) are directly applicable to the research question on postoperative pain management in plastic surgery. The outcomes of interest (pain scores and narcotic use) are also clinically relevant.	Moderate: The study involves a large number of patients (675 augmentation mammaplasty patients and 200 abdominoplasty patients in the control group; 690 and 215 in the intervention group). However, the results for pain scores and narcotic use are not reported with enough detail (e.g., confidence intervals or p-values) to fully assess precision. Given the large sample size, imprecision is likely not a significant concern.	Moderate: The study does not directly provide evidence of publication bias, but publication bias could be a concern, particularly in observational studies where positive or favorable results are more likely to be published. Additionally, given the widespread interest in pain management innovations like ECIP, there may be a tendency to publish studies that report positive outcomes, even when the findings are not robust. However, there is no specific indication from the study design itself to suggest selective reporting or significant bias.	Low Quality While the study includes a large sample size and directly relevant patient population, the lack of randomization and blinding introduces bias. Additionally, the results are not presented with sufficient statistical rigor to assess precision fully, though the sample size somewhat mitigates this concern.
Singla et al., 2019 [26]	Low: The study was a phase III, multicenter, randomized, double-blind, placebo- and active-controlled trial, which is a robust and high-quality design for clinical trials. Randomization and blinding were performed, and the use of placebo and active comparators strengthens internal validity.	Moderate: The use of clinician-administered doses and the possibility of protocol deviations during the study may introduce some performance bias. In addition, while pain intensity and respiratory events were measured objectively, the interpretation of some outcomes (like respiratory safety events) may be subject to observer bias, as they depend on clinical judgment. Overall, though, the risk of bias appears minimal.	Low: The population and interventions are well-aligned with the clinical question of interest: pain management in post-surgical patients undergoing abdominoplasty. There are no significant issues with indirectness, as the study used appropriate comparators (morphine and placebo) and measured clinically relevant outcomes (pain intensity, respiratory safety). The study is directly applicable to the clinical scenario it seeks to address.	Low: The sample size (375 patients) was calculated to provide high statistical power (>88%) for key endpoints, such as superiority to placebo and noninferiority to morphine. The study design and power calculations suggest that imprecision is not a significant concern, as sufficient numbers were included to detect meaningful differences.	Low: As the study is part of a well-documented clinical trial with publicly available registration (NCT02820324) and conducted in a rigorous phase III setting, there is no evidence to suggest publication bias. However, as always with industry-sponsored trials, there is a potential risk that negative results from similar trials may not be published. Nonetheless, no direct evidence of publication bias is indicated here.	High Quality This study design and conduct were strong, with minimal risks of bias, indirectness, and imprecision. The high level of evidence suggests reliable conclusions can be drawn from the study’s findings.
Elsawy et al., 2021 [27]	Moderate: The study is single-blinded, which may introduce bias in patient-reported outcomes. Randomization was present, but allocation concealment was not clearly mentioned.	Low: The results showed consistent findings with significantly lower VAS scores and prolonged analgesic effects in the ESP group across multiple time points.	Low: The population, intervention, and outcomes are directly relevant to the clinical question. The study population was specifically patients undergoing abdominoplasty.	Moderate: While the results are statistically significant, the sample size (51 patients) may not provide robust generalizability, and confidence intervals around the estimates were not reported.	Low: There is no indication of publication bias based on the outcomes; however, this cannot be definitively assessed without a systematic review of all available literature.	Moderate Quality Given the moderate risk of bias, moderate imprecision, and strong consistency in results, the overall quality of evidence is rated as moderate.
Mansour et al., 2021 [28]	Low: The study is double-blinded and randomized, reducing the risk of bias significantly. The randomization process was clearly described, and informed consent was obtained.	Low: The outcomes were consistent across different time points and groups, with clear comparisons between the TAP and LK groups, showing statistically significant differences.	Low: The study population and interventions are directly relevant to the research question regarding pain management in abdominoplasty patients, with appropriate outcomes measured.	Moderate: While the sample size was adequate (50 patients), confidence intervals and specific p-values were not reported, which could affect the reliability of the results.	Low: There are no apparent indicators of publication bias, and the study’s outcomes seem to have been reported transparently.	High Quality The overall quality of evidence is moderate, reflecting low risk of bias, low inconsistency, and low indirectness, but moderate imprecision due to lack of detailed statistical reporting.
Salama et al., 2018 [29]	Moderate: The study employed randomization and blinding for patients and outcome assessors, which helps reduce bias. However, the lack of blinding for the surgeon performing the procedure introduces potential bias in treatment administration and outcome assessment.	Low: The study appears consistent in its methodology and outcomes across the three groups. There were clear protocols for each intervention, and the outcomes measured (morphine consumption, NRS scores, etc.) are well-defined and comparable.	Low: The study population and interventions are directly relevant to the clinical question being addressed (pain management in patients undergoing abdominoplasty). The inclusion criteria ensure a focused patient group, minimizing indirectness in the applicability of results.	Moderate: While the sample size of 90 patients is reasonable for detecting differences, some outcomes may have wide confidence intervals due to variability in individual patient responses. Further details on the specific effect sizes and confidence intervals would enhance precision.	Low: The study does not indicate signs of publication bias, and prospective randomization suggests a lower likelihood of selective reporting. However, the assessment is limited due to the absence of systematic searches for unpublished studies or protocols to evaluate bias thoroughly.	Moderate Quality The overall quality of evidence is moderate, given the sound methodology, reasonable sample size, and clear outcomes. However, the potential for risk of bias from the unblinded surgical procedure and some concerns regarding imprecision may affect the robustness of the conclusions drawn from the study.
Alotaibi et al., 2020 [30]	Low: The study is a randomized controlled trial with proper blinding and handling of dropouts and withdrawals	Low: The findings are consistent within the study. The outcomes indicate a clear distinction in pain management between the two groups, with a significant difference in opioid consumption and VAS scores. There is no indication of variability that would suggest inconsistency across similar studies.	Low: The study directly addresses the population of interest (patients undergoing lipoabdominoplasty) and the intervention (ultrasound-guided TAP block). This makes the evidence highly relevant and minimizes concerns about indirectness.	Moderate: While the sample size of 60 patients is reasonable, the findings regarding opioid consumption and pain scores could be subject to variability, especially if confidence intervals and effect sizes are not provided. This indicates a moderate level of imprecision in the estimates of the treatment effect.	Low: There is no indication of publication bias, as the study addresses a relevant clinical question and reports significant findings.	High Quality
Farahat et al., 2023 [31]	Moderate: The study likely involved random allocation of patients to groups. However, potential biases in allocation concealment or blinding may exist, affecting the validity of results.	Low: Results between the groups (ESP-B and TAP-B vs. control) are consistent in terms of reduced opioid consumption and improved analgesia duration, suggesting low inconsistency.	Low: The study directly addresses the analgesic efficacy in the specific population (females undergoing abdominoplasty) and relevant interventions (ESP-B and TAP-B).	Moderate: While the study presents clear results, the sample size of 69 may limit the precision of the estimates, especially regarding rare events or specific outcomes.	Low: There is no indication of publication bias, as the study reports outcomes clearly and is likely to be part of the ongoing literature on multimodal analgesia.	Moderate Quality Considering the moderate risk of bias and imprecision, the overall quality of evidence is rated as moderate, indicating that further studies may be necessary to strengthen the findings.
Kakagia et al., 2007 [32]	Low: The study uses appropriate randomization and blinding	Low: The results from different groups (saline, ropivacaine, levobupivacaine) seem consistent, assuming that the comparisons made are appropriate. No significant discrepancies in findings were mentioned.	Low: The study population appears directly relevant to the clinical question, as all patients underwent mini abdominoplasty, which is the focus of the investigation.	Moderate: While the sample size of 46 patients is reasonable, results could be imprecise if the confidence intervals of the outcomes are wide or not reported.	Low: No indication of publication bias is provided. The study seems to report its findings transparently. However, further data about the availability of studies could provide a clearer picture.	High Quality The study provides relevant insights into postoperative analgesia following mini abdominoplasty
Sun et al., 2008 [33]	Low: The study has a well-defined randomization process and blinding for participants and staff	Low: The study appears consistent in its findings across treatment groups, with no conflicting results reported within the design or outcomes assessed.	Low: The study population is relevant to the research question, focusing on patients undergoing major plastic surgeries, which aligns well with the objectives of the study.	Low: The sample size is adequately large, with 120 participants in total	Low: There are no indications of publication bias in the methods or findings reported. The study seems to transparently report all relevant outcomes.	High Quality The methods employed are generally sound and appropriate for the study objectives.
Michaels et al., 2009 [34]	Moderate: While the study involves a retrospective review of cases with a defined senior author, there is no mention of randomization and potential selection bias in grouping patients may affect the reliability of results.	Low: The outcomes reported for rib blocks versus general anesthesia show consistent results across the measures assessed (recovery room time, narcotics, nausea/vomiting, pain), with significant differences noted.	Low: The study population is relevant to the surgical context being examined, focusing specifically on abdominoplasty patients, allowing for direct application of findings.	Moderate: The sample sizes (39 in group 1 and 29 in group 2) are relatively small, which could affect the precision of the estimates. Detailed confidence intervals for the significant results were not provided, limiting interpretability.	Low: There is no indication of publication bias. The results appear to be reported transparently, with no selective outcome reporting evident.	Moderate Quality The overall quality is moderate, as the study employs a clear methodology and demonstrates significant findings; however, limitations in study design and sample size warrant cautious interpretation.
Gravante et al., 2011 [35]	Moderate: The retrospective design introduces a potential for bias, particularly in patient selection and matching. While efforts were made to match groups for age and sex, residual confounding may still be present due to the nature of retrospective data.	Low: The study provides consistent results regarding postoperative pain management across the two groups, with clear outcomes related to analgesic requirements.	Low: The study population is relevant to the research question, focusing specifically on patients undergoing abdominoplasty with TAP blocks, allowing direct applicability of findings.	Moderate: The sample size of 51 patients is relatively small, which can reduce the precision of the results	Low: There are no indications of publication bias, as the study reports outcomes comprehensively and focuses on relevant measures.	Moderate Overall quality remains moderate due to the retrospective nature of the study and potential biases, but the clarity and consistency of results strengthen the findings.
Meouchy et al., 2021 [36]	Low: The study used random allocation to assign patients to groups, which minimizes selection bias.	Low: The results are consistent, with significant differences noted in multiple outcomes (morphine and tramadol consumption, pain severity, and quality of recovery) between the two groups.	Low: The study’s population and interventions are directly relevant to the question posed, focusing on postoperative analgesia in patients receiving quadratus lumborum blocks.	Low: Results are statistically significant, with clear mean values and confidence in the measured outcomes, indicating low variability in the data.	Low: There are no indications of publication bias, as the study presents clear and relevant outcomes, and there are no conflicts of interest mentioned.	High Quality The overall quality of the evidence is high due to the low risk of bias, consistency, and clear outcomes measured.
Sforza et al., 2024 [37]	Low: The study design is randomized and double-blind, reducing the risk of selection and performance bias. All participants had similar characteristics, and allocation concealment appears well-managed.	Low: The results are consistent across multiple time points, showing significant differences in pain scores and morphine requirements between the PECS and no-PECS groups.	Low: The study population and intervention are directly relevant to the research question regarding analgesia in breast augmentation surgery.	Low: Results are statistically significant with precise mean values and standard deviations provided for primary outcomes, indicating low variability in the findings.	Low: There are no indications of publication bias, as the study reports clear and relevant outcomes, and the protocol was approved by an ethical board.	High Quality The overall quality of evidence is high, with low risk of bias, consistency, directness, and precision in the findings.
Feng 2010 [3]	Moderate: The study is retrospective and lacks randomization, which introduces potential selection bias. However, it uses a control group and evaluates a large sample size, which partially mitigates this concern.	Low: The results are consistent across different severity classes, showing significantly less pain and reduced narcotic use in the treatment group compared to the control group.	Low: The patient population and intervention are directly relevant to the question of pain management in abdominoplasty procedures.	Moderate: While the treatment effects are significant, the lack of detailed statistical analysis on variability (e.g., confidence intervals) limits the precision of the findings.	Low: There is no indication of publication bias, as the outcomes are clear and relevant, with a focus on clinical efficacy based on patient questionnaires.	Moderate Quality Overall, the study provides moderate-quality evidence due to the retrospective design and potential biases, despite strong findings regarding pain reduction and recovery.
Araco et al., 2010 [38]	Moderate: The study is observational with potential for selection bias based on classification into TAP+ and TAP- groups.	Low: The results show consistent findings, with TAP+ patients significantly requiring less analgesia, indicating no significant variation in outcomes across the study population.	Low: The patient population and interventions evaluated directly address the question of TAP block efficacy in postoperative pain management after surgery.	Moderate: While the results indicate a significant reduction in analgesic requirements, the lack of detailed statistical measures (e.g., confidence intervals) limits the precision of the findings.	Low: There is no clear indication of publication bias as the outcomes reported are straightforward and based on clear clinical efficacy measures.	Moderate Quality The evidence suggests a positive impact of TAP blocks on reducing analgesia requirements postoperatively, but the observational nature and potential biases warrant a moderate quality rating.
Wu et al., 2019 [39]	Low: The study is randomized and double-blinded, which minimizes selection and performance bias. Clear inclusion and exclusion criteria are well defined, enhancing the validity of the findings.	Low: The results are consistent across the different groups, with no significant differences in VAS scores and consumption of dezocine, supporting the reliability of the outcomes.	Low: The population, interventions, and outcomes directly relate to the research question. The study design is appropriate for assessing the efficacy of pain management techniques in LC.	Low: The sample size of 180 patients provides a robust data set, and outcomes are clearly reported. There are no indications of wide confidence intervals or uncertain estimates affecting the results.	Low: The study design and outcomes are straightforward and relevant to the clinical question, with no apparent indication of selective reporting or publication bias.	High Quality Given the low risk of bias, low inconsistency, low indirectness, low imprecision, and low publication bias, the overall quality of the evidence is high, indicating strong support for the study’s conclusions.
Metry et al., 2019 [40]	Moderate: The study is randomized, but the blinding of participants and assessors is not explicitly stated. Selection bias is minimized through randomization, but without clear details on blinding, risk remains moderate. The exclusion criteria were also broad, which could introduce bias.	Low: Results appear consistent across outcomes measured, with similar patterns of pain scores and recovery times reported in both groups. No significant variability in the results is noted.	Low: The study directly addresses the clinical question of pain management techniques in abdominoplasty, using relevant outcomes such as VAS scores, total analgesic consumption, and patient satisfaction. The population is appropriate for the study’s aims.	Moderate: The sample size of 200 patients provides a reasonable power for detecting differences; however, specific confidence intervals or standard deviations for key outcomes were not provided, making precise interpretations challenging.	Low: The study is registered with a clinical trials registry, indicating an intent to publish, and reducing concerns about selective reporting. The outcomes seem to align with the registered protocol.	Moderate Quality Given the moderate risk of bias, low inconsistency, low indirectness, moderate imprecision, and low publication bias, the overall quality of evidence is moderate, suggesting the findings can be considered reliable but with some caution.
Türkoglu et al., 2022 [41]	Moderate: The study design appears to involve randomization, but details about allocation concealment and blinding of participants and assessors are not provided, leaving potential for bias. The reporting of patient selection and any exclusions is also unclear, impacting the assessment of bias.	Low: The results show consistent findings regarding pain control across the three groups, with significant differences in VAS scores and analgesic consumption. No discrepancies in outcomes are noted, suggesting low inconsistency.	Low: The study directly addresses the clinical question of postoperative pain management in abdominoplasty patients, making the findings applicable to the target population and relevant outcomes.	Moderate: While the study provides significant results with clear differences in pain scores and opioid consumption, specific confidence intervals or standard deviations for the key outcomes are not mentioned, which can hinder precise interpretation.	Low: The study presents results with clear outcomes, and there is no indication of selective reporting. Given the straightforward nature of the intervention and outcomes, publication bias is unlikely.	Moderate Quality The overall quality of evidence is moderate, considering the moderate risk of bias, low inconsistency, low indirectness, moderate imprecision, and low publication bias.