Association of systemic inflammation response index with postoperative clinical outcomes among operated patients with aortic dissection: a systematic review with meta-analysis

Introduction

Aortic dissection (AD) is a life-threatening cardiovascular emergency characterized by the formation of a false lumen within the aortic wall, with an estimated annual incidence of 2–4 cases per 100,000 individuals and a persistently high mortality rate if left untreated (1,2). Despite substantial advances in diagnostic techniques, surgical strategies, and perioperative management, AD remains associated with considerable early and long-term morbidity and mortality, particularly in patients requiring operative intervention (3-5). Surgical repair, including open surgery and endovascular techniques, is currently the cornerstone of treatment for both type A and selected type B AD; however, postoperative adverse outcomes such as aorta-related adverse events (ARAEs), acute kidney injury (AKI), neurological dysfunction, infection, and organ failure remain common and significantly affect prognosis and quality of life (6,7). Therefore, identifying patients at high risk of unfavorable postoperative outcomes is of great clinical importance for optimizing perioperative management and improving long-term outcomes in this population.

At present, however, risk stratification and prognostic assessment for postoperative outcomes in AD patients remain suboptimal. Although several clinical characteristics, imaging findings, and intraoperative factors have been reported to be associated with adverse outcomes, reliable and easily accessible preoperative biomarkers for predicting postoperative prognosis are still limited, and existing evidence is often inconsistent or derived from small, single-center studies (7,8). In recent years, increasing attention has been paid to systemic inflammation as a key contributor to perioperative organ dysfunction and adverse outcomes following major cardiovascular and surgical procedures. The systemic inflammation response index (SIRI), calculated from peripheral neutrophil, monocyte, and lymphocyte counts, has emerged as a novel inflammatory biomarker and has been shown to be predictive of postoperative complications and mortality in various surgical settings, including cardiovascular surgery, gastrointestinal surgery, and oncologic surgery (9-12). Nevertheless, the prognostic value of preoperative SIRI for postoperative clinical outcomes in patients with AD remains unclear, and available evidence is fragmented.

Therefore, we conducted the present meta-analysis to systematically evaluate the association between preoperative SIRI and postoperative clinical outcomes in operated AD patients, aiming to clarify its potential role in perioperative risk stratification and clinical decision-making. We present this article in accordance with the PRISMA reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1-0423/rc) (13).

Methods

Literature search

PubMed, Chinese National Knowledge Infrastructure (CNKI) and Web of Science databases were searched up to February 9, 2026 with following terms: systemic inflammation response index, SIRI, aortic dissection and dissection of aorta. The specific search strategy in the PubMed was presented in Figure S1. MeSH terms and free texts were applied.

Study selection

Studies met following criteria were included: (I) patients were diagnosed with AD by CT angiography; (II) patients received the operation due to the AD; (III) SIRI was evaluated before the surgery according to the formula: monocyte count * neutrophil count/lymphocyte count; (IV) the association of preoperative with postoperative clinical outcomes was explored providing relevant data; (V) full texts were available; (VI) studies were published in English or Chinese.

Studies met following criteria were excluded: (I) insufficient or duplicated data; and (II) letters, editorials, reviews, case reports, animal studies or conference abstracts.

Two reviewers independently screened the titles and abstracts of all retrieved records and then assessed the full texts of potentially eligible studies for final inclusion. Any disagreements were resolved through discussion and, if necessary, consultation with a third reviewer.

Data collection

Following data were extracted: the first author, year, country, sample size, type of AD, age, cutoff value of SIRI, endpoint, clinical outcomes, relative risk (RR) and 95% confidence interval (CI).

In this meta-analysis, primary outcomes included the risk of ARAE, major adverse event (MAE) and in-hospital mortality. Secondary outcomes included the AKI, prolonged intubation, stroke, renal failure, infection, reoperation for bleeding, acute hepatic disfunction (AHD), permanent neurological dysfunction (PND), low cardiac output syndrome (LCOS), gastrointestinal bleeding, distal aortic negative remodeling (DANR), pericardial effusion drainage, severe acute respiratory distress syndrome (SARDS), and sepsis.

Data extraction was independently performed by two reviewers using a standardized form. Any discrepancies were resolved by discussion and consensus.

Quality assessment

Methodological quality was assessed by the Newcastle-Ottawa Scale (NOS), which evaluates studies across three domains, including selection, comparability, and outcome/exposure assessment. Studies with NOS scores ≥6 were defined as high-quality studies (14).

Statistical analysis

All analyses were conducted by STATA version 17.0 software. Heterogeneity between studies was calculated by Q test and I² statistic. If significant heterogeneity was detected, represented as I²>50% and/or P<0.1, the random effects model was used; otherwise, the fixed effects model was applied (15). However, given that the number of included studies for each individual outcome was limited (no more than four studies per endpoint), statistical tests for heterogeneity such as Cochran’s Q test and I² statistic may have low power and yield imprecise estimates. Under such circumstances, a random-effects model is generally recommended to account for potential between-study variability and to provide more conservative pooled estimates, even when statistical heterogeneity is not formally significant. Therefore, random-effects models were applied for all outcome analyses in this meta-analysis (16,17). RRs with 95% CIs were combined to assess the association of preoperative SIRI with primary and secondary outcomes in operated AD patients. Subgroup analysis by the type of AD for the ARAE was further performed. Considering the important differences in pathophysiology, treatment strategies, and prognosis between Stanford type A and type B AD, subgroup analysis according to dissection type was performed whenever relevant data were available, and the pooled findings should be interpreted cautiously.

Results

Literature search and selection

Sixty-nine records were searched from databases and nine duplicated publications were removed. After reviewing title, abstracts and then full texts, eight available studies were eventually included (Figure 1) (18-25).

Figure 1 PRISMA flow diagram of this meta-analysis.

Basic characteristics

All eight included studies were retrospective and from China. A total of 2,404 patients were enrolled with 1,295 patients with type A AD and 1,109 patients with type B AD. The cutoff values of preoperative SIRI ranged from 2.33 to 15.112 and all studies were with high-quality (Table 1). Detailed scores for each NOS domain are presented in Table S1.

Association of preoperative SIRI with primary outcomes in operated AD patients

Four studies explored the relationship between preoperative SIRI and risk of postoperative ARAE among AD patients. Pooled results demonstrated that higher SIRI was significantly related to increased risk of ARAE (RR =2.80, 95% CI: 2.12–3.69, P<0.001; I²=1.9%, P=0.38) (Figure 2). Furthermore, subgroup analysis by the type of AD showed similar results (type A: RR =2.25, 95% CI: 1.05–4.81, P=0.04; type B: RR =2.94, 95% CI: 2.05–4.21, P<0.001) (Figure S2; Table 2).

Figure 2 Association of systemic inflammation response index with risk of postoperative aorta-related adverse event among patients with aortic dissection undergoing the surgery. CI, confidence interval; RR, relative risk.

However, no significant relationship between preoperative SIRI and risk of MAE (RR =1.86, 95% CI: 0.74–4.67, P=0.19) (Figure 3) or in-hospital mortality (RR =2.38, 95% CI: 0.39–14.42, P=0.34) (Figure 4) was observed (Table 2).

Figure 3 Association of systemic inflammation response index with risk of postoperative major adverse event among patients with aortic dissection undergoing the surgery. CI, confidence interval; RR, relative risk.

Figure 4 Association of systemic inflammation response index with risk of postoperative in-hospital mortality among patients with aortic dissection undergoing the surgery. CI, confidence interval; RR, relative risk.

Association of preoperative SIRI with secondary outcomes in operated AD patients

For secondary outcomes, meta-analysis was performed only when data from more than one study were available. Outcomes reported by a single study were summarized descriptively as part of the systematic review. After combining available data, it was manifested that preoperative SIRI was associated with the risk of postoperative AKI (RR =2.82, 95% CI: 2.07–3.85, P<0.001) (Figure S3), renal failure (RR =3.895, 95% CI: 2.376–6.385, P<0.001), infection (RR =1.780, 95% CI: 1.110–2.856, P=0.02), AHD (RR =8.919, 95% CI: 1.220–65.226, P=0.002), PND (RR =2.180, 95% CI: 1.244–3.820, P=0.005), LCOS (RR =2.812, 95% CI: 1.299–6.088, P=0.006), gastrointestinal bleeding (RR =4.339, 95% CI: 1.895–9.935, P<0.001) and DANR (RR =1.39, 95% CI: 1.09–1.81, P=0.01) (Table 3).

However, it was revealed that SIRI was not significantly related to the risk of postoperative prolonged intubation (RR =1.64, 95% CI: 0.82–3.26, P=0.16) (Figure S4), stroke (RR =0.81, 95% CI: 0.29–2.22, P=0.68) (Figure S5), reoperation for bleeding (RR =1.461, 95% CI: 0.664–3.210, P=0.356), pericardial effusion drainage (RR =0.944, 95% CI: 0.689–1.293, P=0.72), SARDS (RR =1.622, 95% CI: 0.318–8.257, P=0.87) or sepsis (RR =5.062, 95% CI: 0.569–45.059, P=0.11) (Table 3).

Discussion

In the present meta-analysis, we systematically evaluated the association between preoperative SIRI and postoperative clinical outcomes in operated patients with AD. Based on pooled data from eight retrospective studies involving 2404 patients, elevated preoperative SIRI was significantly associated with an increased risk of ARAE, as well as multiple postoperative complications including AKI, renal failure, infection, AHD, PND, LCOS, gastrointestinal bleeding, and DANR. These associations were consistent across subgroups stratified by dissection type for ARAE. In contrast, no statistically significant relationship was observed between SIRI and MAE or in-hospital mortality. Collectively, these findings suggest that preoperative SIRI may serve as a useful indicator of postoperative morbidity rather than short-term mortality in patients undergoing surgical treatment for AD. Nevertheless, because Stanford type A and type B AD differ substantially in underlying disease characteristics, operative strategies, and prognosis, the pooled results based on a mixed AD population should be interpreted with caution.

The observed associations between elevated preoperative SIRI and adverse postoperative outcomes may be explained by the central role of systemic inflammation in the pathophysiology of AD and perioperative organ dysfunction. AD is increasingly recognized as an inflammation-driven disease, characterized by intense activation of neutrophils and monocytes, endothelial injury, and immune dysregulation, which contribute to aortic wall destruction, malperfusion, and postoperative complications (1,5). SIRI integrates neutrophil and monocyte counts, which reflect innate immune activation, and lymphocyte counts, which represent immune regulatory capacity. A higher SIRI therefore indicates an exaggerated inflammatory response combined with relative immunosuppression. This inflammatory imbalance may predispose patients to postoperative organ injury, particularly AKI, hepatic dysfunction, and neurological complications, through mechanisms such as microvascular dysfunction, ischemia–reperfusion injury, and cytokine-mediated tissue damage (26-28). In addition, systemic inflammation has been shown to promote adverse aortic remodeling and impair vascular healing, providing a plausible biological explanation for the observed association between elevated SIRI and DANR (7,8).

From a clinical perspective, the present findings suggest that preoperative SIRI may have potential value in perioperative risk stratification and postoperative management of patients with AD. As SIRI is easily calculated from routine blood tests, it could be used preoperatively to identify patients at higher risk of postoperative complications. In patients with elevated SIRI, intensified perioperative monitoring, early renal-protective strategies, strict hemodynamic control, and closer surveillance for infectious and neurological complications may be warranted. Furthermore, these patients may benefit from individualized postoperative management strategies, such as optimized fluid management, early mobilization, and closer follow-up imaging to monitor aortic remodeling. Although direct evidence supporting inflammation-targeted interventions in AD is still limited, the identification of high inflammatory burden preoperatively may help clinicians allocate resources more effectively and tailor perioperative care to reduce complication rates.

It is also noteworthy that all studies included in the present meta-analysis were conducted in China. This may reflect where this line of research has been most actively explored in AD rather than indicating that SIRI is a region-specific biomarker. In fact, SIRI has also been investigated in non-Chinese populations, including a large U.S. population-based study and recent cardiovascular surgical research from Türkiye, suggesting that its potential applicability is not limited to China (29). Because SIRI can be calculated easily from routine complete blood counts, it has practical advantages in terms of accessibility, simplicity, and low cost (30). However, broader adoption of SIRI in other healthcare systems is likely limited by several factors, including the lack of standardized cutoff values, the non-specific nature of this inflammatory marker, and the current predominance of retrospective single-center studies without sufficient prospective external validation. Therefore, although wider clinical evaluation of SIRI appears warranted, especially as an adjunct tool for perioperative risk stratification, additional multicenter prospective studies from different geographic regions are still needed before this biomarker can be more broadly implemented in routine practice (31).

Nevertheless, several issues limit the immediate clinical application of our findings and highlight directions for future research. The evidence supporting the association between SIRI and certain postoperative outcomes remains limited, as some endpoints were derived from only one or two studies, raising concerns regarding the robustness and reproducibility of these results. Future large-scale, multicenter prospective studies are needed to validate the predictive value of SIRI for specific postoperative complications and to determine optimal cutoff values across different populations. In addition, studies incorporating individual patient data are required to explore potential interactions between SIRI and key clinical variables such as age, surgical approach, extent of aortic repair, and perioperative management strategies. Finally, mechanistic studies are warranted to further elucidate the biological pathways linking systemic inflammation, immune dysregulation, and postoperative outcomes in AD, which may ultimately facilitate the development of targeted anti-inflammatory or immunomodulatory interventions to improve patient prognosis.

Another issue that merits consideration is the substantial variation in SIRI cutoff values across the included studies, which ranged from 2.33 to 15.112. At present, the available evidence is insufficient to support a single optimal cutoff value for all operated patients with AD, because the included studies differed in patient characteristics, dissection type, clinical setting, and methods used to determine cutoff values. It is also possible that different cutoff values may be more appropriate for different clinical subgroups, such as Stanford type A versus type B AD, or acute versus chronic AD, given their differences in inflammatory status, disease severity, treatment strategy, and prognosis. Therefore, a unified threshold for clinical use cannot yet be recommended, and future large-scale prospective studies are needed to determine and validate the most appropriate cutoff values in different AD populations. Nevertheless, the present findings still suggest that elevated preoperative SIRI may help identify patients with a higher inflammatory burden who are at increased risk of postoperative adverse outcomes. In clinical practice, preoperative recognition of elevated SIRI levels may contribute to risk stratification and support more individualized perioperative management, including closer monitoring, earlier organ-protective strategies, stricter control of perioperative hemodynamics, and more intensive surveillance for complications such as AKI, infection, and neurological dysfunction.

Several limitations of this meta-analysis should be acknowledged. First, all included studies were conducted in China and the overall sample size was relatively small, which may limit the generalizability of the findings to other populations and healthcare settings. Second, the number of studies available for each individual outcome was limited, and for some postoperative endpoints only one or two studies provided data. Therefore, the pooled estimates for these outcomes may be less stable and should be interpreted cautiously. Future studies are needed to improve the reproducibility and robustness of these findings. Third, due to the small number of eligible studies, sensitivity analyses and formal assessments of publication bias could not be performed, which may affect the robustness and credibility of the overall conclusions. Four, the lack of access to individual patient data precluded further subgroup analyses based on important clinical factors such as age, surgical approach, or perioperative management strategies. Five, both Stanford type A and type B AD were included, and although subgroup analysis was performed for ARAE, not all outcomes could be stratified by dissection type because of limited data. Six, the cutoff values of SIRI varied substantially across the included studies, which may have contributed to between-study heterogeneity and reduced the comparability of the pooled results. This issue should be taken into account when interpreting the findings. In addition, significant heterogeneity was observed for some outcomes, such as MAE, in-hospital mortality, and prolonged intubation, which may be related to differences in patient characteristics, dissection type, surgical interventions, timing of SIRI measurement, and cutoff definitions across studies.

Conclusions

Based on current available evidence, it was indicated that elevated preoperative SIRI was associated with worse postoperative clinical outcomes such as the ARAE and AKI in AD patients and might contribute to postoperative risk assessment and clinical management of patients with AD. However, more relevant studies are needed to further verify the association of preoperative SIRI with postoperative outcomes in AD patients due to the limitations existed in this meta-analysis and included studies.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the PRISMA reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1-0423/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1-0423/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1-0423/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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