Metabolic Syndrome Reduces the Survival Benefit of the Obesity Paradox after Infrainguinal Bypass

A Meta-Analysis to Derive Population-Based Quality Benchmarks of the Incidence of Surgical Site Infection after Lower Limb Revascularization Surgery

BACKGROUND

The reported incidence of surgical site infection (SSI) after lower limb revascularization surgery varies. We conducted a systematic review and meta-analysis of population-based studies reporting the incidence of SSI in adults who underwent these surgeries in high-income countries to derive SSI quality benchmarks.

METHODS

We searched MEDLINE, EMBASE, CENTRAL, and Evidence-Based Medicine Reviews (inception-to-April 28th, 2022) for population-based studies estimating the cumulative incidence of SSI among adults who underwent lower limb revascularization surgery for peripheral artery disease (PAD) in high-income countries. Two investigators independently screened abstracts and full-text articles, extracted data, and assessed risks of bias. We used random-effects models to pool data and GRADE to assess certainty.

RESULTS

Among 6,258 citations, we included 53 studies (n = 757,726 patients); 8 of which (n = 435,769 patients) reported nonoverlapping data that were meta-analyzed. The pooled cumulative incidence of any SSI was 6.0 in 100 patients [95% confidence interval (CI) = 4.3-8.0 in 100 patients; n = 8 studies; n = 435,769 patients; moderate certainty]. The cumulative incidence of Szilagyi grade I (cellulitis), grade II (subcutaneous tissue), and grade III (prosthetic graft) SSI was 6.5 in 100 patients (95% CI = 4.3-8.6 in 100 patients; n = 2 studies; n = 39,645 patients; low certainty), 2.1 in 100 patients (95% CI = 2.0-2.3 in 100 patients; n = 2 studies; low certainty), and 0.4 in 100 patients (95% CI = 0.4-0.4 in 100 patients; n = 1 study; n = 333,275 patients; low certainty), respectively. The pooled cumulative incidence of any early (in-hospital/≤30-days) and late (>30-days) SSI was 6.2 in 100 patients (95% CI = 4.4-8.0 in 100 patients; n = 7 studies; n = 431,273 patients; moderate certainty) and 3.7 in 100 patients (95% CI = 2.2-5.2 in 100 patients; n = 2 studies; n = 10,565 patients; low certainty), respectively.

CONCLUSIONS

This systematic review derived population-based benchmarks of the incidence of any SSI; Szilagyi I, II, and III SSI; and early and late SSI after lower limb revascularization surgery. These may be used by practicing surgeons and healthcare leaders/administrators to guide quality improvement efforts in the United States and perhaps other countries.

Risk Factors for Surgical Site Infection after Lower Limb Revascularisation Surgery: a Systematic Review and Meta-Analysis of Prognostic Studies

OBJECTIVE

To systematically review and meta-analyse adjusted risk factors for surgical site infection (SSI) after lower limb revascularisation surgery.

DATA SOURCES

MEDLINE, Embase, Evidence Based Medicine Reviews, and the Cochrane Central Register of Controlled Trials (inception to 28 April 2022).

REVIEW METHODS

Systematic review and meta-analysis conducted according to PRISMA guidelines. After protocol registration, databases were searched. Studies reporting adjusted risk factors for SSI in adults who underwent lower limb revascularisation surgery for peripheral artery disease were included. Adjusted odds ratios (ORs) were pooled using random effects models. GRADE was used to assess certainty.

RESULTS

Among 6 377 citations identified, 50 studies (n = 271 125 patients) were included. The cumulative incidence of SSI was 12 (95% confidence interval [CI] 10 - 13) per 100 patients. Studies reported 139 potential SSI risk factors adjusted for a median of 12 (range 1 - 69) potential confounding factors. Risk factors that increased the pooled adjusted odds of SSI included: female sex (pooled OR 1.41, 95% CI 1.20 - 1.64; high certainty); dependent functional status (pooled OR 1.18, 95% CI 1.03 - 1.35; low certainty); being overweight (pooled OR 1.82, 95% CI 1.29 - 2.56; moderate certainty), obese (pooled OR 2.20, 95% CI 1.44 - 3.36; high certainty), or morbidly obese (pooled OR 1.65, 95% CI 1.08 - 2.52; moderate certainty); chronic obstructive pulmonary disease (pooled OR 1.42, 95% CI 1.17 - 1.71; high certainty); chronic limb threatening ischaemia (pooled OR 1.67, 95% CI 1.22 - 2.29; moderate certainty); chronic kidney disease (pooled OR 2.13, 95% CI 1.18 - 3.83; moderate certainty); intra-operative (pooled OR 1.23, 95% CI 1.02 - 1.49), peri-operative (pooled OR 1.92, 95% CI 1.27 - 2.90), or post-operative (pooled OR 2.21, 95% CI 1.44 - 3.39) blood transfusion (moderate certainty for all); urgent or emergency surgery (pooled OR 2.12, 95% CI 1.22 - 3.70; moderate certainty); vein bypass and or patch instead of endarterectomy alone (pooled OR 1.86, 95% CI 1.33 - 2.59; moderate certainty); an operation lasting ≥ 3 hours (pooled OR 1.86, 95% CI 1.33 - 2.59; moderate certainty) or ≥ 5 hours (pooled OR 1.60, 95% CI 1.18 - 2.17; moderate certainty); and early or unplanned re-operation (pooled OR 4.50, 95% CI 2.18 - 9.32; low certainty).

CONCLUSION

This systematic review identified evidence informed SSI risk factors following lower limb revascularisation surgery. These may be used to develop improved SSI risk prediction tools and to identify patients who may benefit from evidence informed SSI prevention strategies.

Metabolic syndrome and surgical complications: a systematic review and meta-analysis of 13 million individuals

BACKGROUND

Metabolic syndrome (MetS) is characterised by the presence of at least three of the five following components: insulin resistance, obesity, chronic hypertension, elevated serum triglycerides, and decreased high-density lipoprotein cholesterol concentrations. It is estimated to affect 1 in 3 people around the globe and is reported to affect 46% of surgical patients. For people with MetS who undergo surgery, an emerging body of literature points to significantly poorer postoperative outcomes compared with nonaffected populations. The aim of this study is to review the current evidence on the risks of surgical complications in patients with MetS compared to those without MetS.

METHODS

Systematic review and meta-analysis using PRISMA and AMSTAR reporting guidelines.

RESULTS

The meta-analysis included 63 studies involving 1 919 347 patients with MetS and 11 248 114 patients without MetS. Compared to individuals without the condition, individuals with MetS were at an increased risk of mortality (OR 1.75 95% CI: 1.36-2.24; P <0.01); all surgical site infection types as well as dehiscence (OR 1.64 95% CI: 1.52-1.77; P <0.01); cardiovascular complications (OR 1.56 95% CI: 1.41-1.73; P <0.01) including myocardial infarction, stroke, cardiac arrest, cardiac arrythmias and deep vein thrombosis; increased length of hospital stay (MD 0.65 95% CI: 0.39-0.9; P <0.01); and hospital readmission (OR 1.55 95% CI: 1.41-1.71; P <0.01).

CONCLUSION

MetS is associated with a significantly increased risk of surgical complications including mortality, surgical site infection, cardiovascular complications, increased length of stay, and hospital readmission. Despite these risks and the high prevalence of MetS in surgical populations there is a lack of evidence on interventions for reducing surgical complications in patients with MetS. The authors suggest prioritising interventions across the surgical continuum that include (1) preoperative screening for MetS; (2) surgical prehabilitation; (3) intraoperative monitoring and management; and (4) postoperative rehabilitation and follow-up.

Surgical site infection after open lower extremity revascularization associated with doubled rate of major limb amputation

OBJECTIVE

Surgical site infection (SSI) after open lower extremity revascularization is a relatively common complication associated with increased hospital stays, graft infection, and in severe cases, graft loss. Although the short-term effects of SSI can be significant, it has not been considered a complication that increases major limb amputation. The purpose of this study was to determine the association of SSI with outcomes in patients undergoing surgical revascularization for peripheral arterial disease.

METHODS

We analyzed nationwide Vascular Quality Initiative (VQI) data from the infrainguinal bypass module from 2003 to 2017. The cohort included adults who underwent open lower extremity bypass for symptomatic peripheral arterial disease and had at least one follow-up record. Weighted Kaplan-Meier curves and Cox proportional hazards regression were used to assess the association between SSI and 1-year mortality and major limb amputation. Inverse-probability of treatment weights were used to account for differences in demographics and patient characteristics and allow for 'adjusted' Kaplan-Meier curves.

RESULTS

The analysis included 21,639 patients, and 1155 (5%) had a reported SSI within 30 days of surgery. Patients with SSI were more likely be obese (41% vs 30%), but there were no other clinically relevant differences between demographics, comorbidities, and bypass details. After weighting, patients with SSI were almost twice as likely to undergo major amputation by 6 months (hazard ratio, 1.84; 95% confidence interval, 1.07-3.17). The association with SSI and increased amputation rates persisted at 1 year. The association of SSI on amputation was no different based on preoperative Rutherford class (P = .91). The association between SSI and 1-year mortality rate was not statistically significant (hazard ratio, 1.15; 95% confidence interval, 0.91-1.46).

CONCLUSIONS

SSI is more common in obese patients, and patients who develop an SSI are observed to have a significantly increased rate of limb amputation after open lower extremity revascularization.

Metabolic Syndrome (MetS), Systemic Inflammatory Response Syndrome (SIRS), and Frailty: Is There any Room for Good Outcome in the Elderly Undergoing Emergency Surgery?

Background

Patients with MetS or SIRS experience higher rates of mortality and morbidity, across both cardiac and noncardiac surgery. Frailty assessment has acquired increasing importance in recent years as it predisposes elderly patients to a worse outcome. The aim of our study was to investigate the influence of MetS, SIRS, and with or without frailty on elderly patients undergoing emergency surgical procedures.

Methods

We analyzed data of all patients with nonmalignant diseases requiring an emergency surgical procedure from January 2017 to December 2020. The occurrence of MetS was identified using modified definition criteria used by the NCEP-ATP III Expert Panel: obesity, hypertension, diabetes, or if medication for high triglycerides or for low HDL cholesterol was taken. Systemic inflammatory response syndrome (SIRS) was evaluated according to the original consensus study (Sepsis-1). The frailty profile was investigated by the 5-modified Frailty Index (5-mFI) and the Emergency Surgery Frailty Index (EmSFI). Postoperative complications have been reported and categorized according to the Clavien-Dindo (C-D) classification system. Morbidity and mortality have been mainly considered as the 30-day standard period definition.

Results

Of the 2,318 patients included in this study, 1,010 (43.6%) fulfilled the criteria for MetS (MetsG group). Both 5-Items score and EmsFI showed greater fragility in patients with MetS. All patients with MetS showed more frequently a CACI index greater than 6. The occurrence of SIRS was higher in MetSG. LOS was longer in patients with MetS (MetSG 11.4 ± 12 days vs. n-MetSG 10.5 ± 10.2 days, p = 0.046). MetSG has a significantly higher rate of morbidity (353 (35.%) vs. 385 (29.4%), p = 0.005). The mortality rate in patients with MetS (98/1010, 10%) was similar to that in patients without it (129/1308, 10%). Considering patients with MetS who developed SIRS and those who had frailty or both, the occurrence of these conditions was associated with a higher rate of morbidity and mortality.

Conclusion

Impact of MetS and SIRS on elderly surgical patient outcomes has yet to be fully elucidated. The present study showed a 43.6% incidence of MetS in the elderly population. In conclusion, age per se should be not considered anymore as the main variable to estimate patient outcomes, while MetS and Frailty should have always a pivotal role.

The Association of Body Mass Index with Outcomes after Carotid Endarterectomy

BACKGROUND

Patients who are obese or underweight are traditionally at higher risk for perioperative morbidity and mortality. The effect of body mass index (BMI) on outcomes after carotid endarterectomy (CEA) is unclear. Our goal was to analyze the association of BMI with perioperative and long-term outcomes after elective CEA.

METHODS

The Vascular Quality Initiative (VQI) database was queried from 2003-2018 for patients undergoing elective CEAs. Patients were categorized into 5 BMI cohorts - underweight (UW, BMI < 18.5 kg/m²), normal weight (NW, BMI 18.5-24.9 kg/m²), overweight (OW, BMI 25-29.9 kg/m²), obese (OB, BMI 30-39.9 kg/m²), and morbidly obese (MO, BMI ≥ 40 kg/m²). Perioperative and long-term outcomes were assessed with univariable and multivariable analyses.

RESULTS

There were 89,079 patients included: 2% UW, 26% NW, 38.4% OW, 29.9% OB, and 3.6% MO. Overall, the mean age was 70.6 years, 60% were male, and 91.8% were of white race. There were significant differences among the BMI cohorts in regards to age, sex, smoking status, and comorbidities (all P < 0.05). For perioperative outcomes, the BMI cohorts differed significantly in reoperation for bleeding and 30-day mortality. On multivariable analysis, BMI was not associated with stroke or perioperative mortality. MO was associated with perioperative cardiac complications (Odds Ratios [OR] 1.26, 95% CI 1-1.57, P = 0.05). UW status was associated with increased return to the operating room (OR 1.89, 95% confidence interval [95% CI] 1.28-2.78, P = 0.001), 30-day mortality (OR 1.68, 95% CI 1-2.86, P =0.05), 1-year mortality (Hazard ratio [HR] 1.37, 95% CI 1.08-1.74, P = 0.01), and 5-year mortality (HR 1.22, 95% CI 1.06-1.41, P =0.005).

CONCLUSIONS

BMI status was not associated with perioperative stroke, cranial nerve injury, or surgical site infections. Patients with MO had higher perioperative cardiac complications. UW patients have lower short and long-term survival and should be a focus for long-term targeted risk factor stratification and modification.

Metabolic syndrome increases risk for perioperative outcomes following posterior lumbar interbody fusion

The present study is a retrospective cohort study. Metabolic syndrome (MetS) is a clustering of clinical findings that has been shown to increase the risk of the surgical outcomes. Our study aimed to evaluate whether MetS was a risk factor for increased perioperative outcomes in patients undergoing posterior lumbar interbody fusion (PLIF).We retrospectively analyzed patients over 18 years following elective posterior lumbar spine fusion from January 2014 to December 2018. Emergency procedures, infections, tumor, fracture, and revision surgeries were excluded. Patients were divided into 2 groups with and without MetS. The MetS was defined by having 3 of the following 4 criteria: obesity (body mass index ≥30 kg/m), dyslipidemia, hypertension, and diabetes. The follow-up period lasted up to 30 days after surgery. The outcomes of demographics, comorbidities, perioperative complications, and length of stay were compared between the 2 groups. Multivariate logistic regression analysis was used to identify perioperative outcomes that were independently associated with MetS.The overall prevalence of MetS was 12.5% (360/2880). Patients with MetS was a significantly higher risk factor for perioperative complications, and longer length of stay cmpared with patients without MetS (P < .05). The MetS group had a higher rate of cardiac complications (P = .019), pulmonary complication (P = .035), pneumonia (P = .026), cerebrovascular event (P = .023), urinary tract infection (P = .018), postoperative ICU admission (P = .02), and deep vein thrombosis (P = .029) than non-MetS group. The patients with MetS had longer hospital stays than the patients without MetS (22.16 vs 19.99 days, P < .001). Logistic regression analysis revealed that patients with MetS were more likely to experience perioperative complications (odds ratio [OR] 1.31; 95% confidence interval [CI]: 1.06-2.07; P < .001), and extend the length of stay (OR: 1.69; 95% CI: 1.25-2028; P = .001).The MetS is a significant risk factor for increased perioperative complications, and extend length of stay after PLIF. Strategies to minimize the adverse effect of MetS should be considered for these patients.

Can Patient Selection Explain the Obesity Paradox in Orthopaedic Hip Surgery? An Analysis of the ACS-NSQIP Registry

BACKGROUND

The "obesity paradox" is a phenomenon described in prior research in which patients who are obese have been shown to have lower postoperative mortality and morbidity compared with normal-weight individuals. The paradox is that clinical experience suggests that obesity is a risk factor for difficult wound healing and adverse cardiovascular outcomes. We suspect that the obesity paradox may reflect selection bias in which only the healthiest patients who are obese are offered surgery, whereas nonobese surgical patients are comprised of both healthy and unhealthy individuals. We questioned whether the obesity paradox (decreased mortality for patients who are obese) would be present in nonurgent hip surgery in which patients can be carefully selected for surgery but absent in urgent hip surgery where patient selection is minimized.

QUESTIONS/PURPOSES

(1) What is the association between obesity and postoperative mortality in urgent and nonurgent hip surgery? (2) How is obesity associated with individual postoperative complications in urgent and nonurgent hip surgery? (3) How is underweight status associated with postoperative mortality and complications in urgent and nonurgent hip surgery?

METHODS

We used 2011 to 2014 data from the American College of Surgeons National Surgical Quality Improvement Project (ACS-NSQIP) to identify all adults who underwent nonurgent hip surgery (n = 63,148) and urgent hip surgery (n = 29,047). We used logistic regression models, controlling for covariants including age, sex, anesthesia risk, and comorbidities, to examine the relationship between body mass _index (BMI) category (classified as underweight < 18.5 kg/m, normal 18.5-24.9 kg/m, overweight 25-29.9 kg/m, obese 30-39.9 kg/m, and morbidly obese > 40 kg/m) and adverse outcomes including 30-day mortality and surgical complications including wound complications and cardiovascular events.

RESULTS

For patients undergoing nonurgent hip surgery, regression models demonstrate that patients who are morbidly obese were less likely to die within 30 days after surgery (odds ratio [OR], 0.12; 95% confidence interval [CI], 0.01-0.57; p = 0.038) compared with patients with normal BMI, consistent with the obesity paradox. For patients undergoing urgent hip surgery, patients who are morbidly obese had similar odds of death within 30 days compared with patients with normal BMI (OR, 1.18; 95% CI, 0.76-1.76; p = 0.54). Patients who are morbidly obese had higher odds of wound complications in both nonurgent (OR, 4.93; 95% CI, 3.68-6.65; p < 0.001) and urgent cohorts (OR, 4.85; 95% CI, 3.27-7.01; p < 0.001) compared with normal-weight patients. Underweight patients were more likely to die within 30 days in both nonurgent (OR, 3.79; 95% CI, 1.10-9.97; p = 0.015) and urgent cohorts (OR, 1.47; 95% CI, 1.23-1.75; p < 0.001) compared with normal-weight patients.

CONCLUSIONS

Patients who are morbidly obese appear to have a reduced risk of death in 30 days after nonurgent hip surgery, but not for urgent hip surgery. Our results suggest that the obesity paradox may be an artifact of selection bias introduced by careful selection of the healthiest patients who are obese for elective hip surgery. Surgeons should continue to consider obesity a risk factor for postoperative mortality and complications such as wound infections for both urgent and nonurgent surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Metabolic Syndrome but not Obesity Adversely Affects Outcomes after Open Aortoiliac Bypass Surgery

BACKGROUND

Although the incident risk of peripheral artery disease increases in patients with metabolic syndrome, several authors report favorable outcomes in obese patients after arterial bypass surgery. We examine the effect of the so-called "obesity paradox" and metabolic syndrome on outcomes after open aortoiliac bypass surgery.

METHODS

We identified patients between 2004 and 2015 who had open surgical bypass for aortoiliac occlusive disease. We excluded patients with endovascular repair and those treated primarily for aneurysmal disease. Variables that were analyzed included preoperative medical history, Trans-Atlantic Inter-Society Consensus Document on Management of Peripheral Arterial Disease II classification, Rutherford classification, intra-operative, and postoperative outcomes. Metabolic syndrome was defined by World Health Organization criteria: diabetes and 2 or more of dyslipidemia, hypertension, and obesity (body mass index > 30 kg/m²). Data were analyzed by stratified Kaplan-Meier and multiple Cox regression for outcomes including long-term mortality and reintervention rate.

RESULTS

There were 154 open bypass surgery patients during the study period with a median age of 60 years (interquartile range [IQR] 53-68), median glomerular filtration rate 76.1 mL/min (IQR 54-102), and 58% female prevalence. In all, 53 patients had metabolic syndrome (4%), and 14 patients (9%) were obese but did not have metabolic syndrome. Primary bypass graft patency was 89.0 ± 2.7% at 1 year and 77.4 ± 4.1% at 5 years and was not significantly different between metabolic syndrome, obese, and nonmetabolic syndrome patients. Reintervention rate for the entire cohort was 25.3 ± 3.7% at 1 year and 40.6 ± 4.7% at 5 years. In those with and without metabolic syndrome, reintervention rate at 1 and 5 years was 33.0 ± 6.8% vs. 21.1 ± 4.2% and 56.1 ± 7.9% vs. 30.7 ± 5.4%, respectively (log-rank P = 0.003). In multivariable analyses, metabolic syndrome (hazard ratio [HR] 1.8, P = 0.036) and critical limb ischemia (CLI) (HR: 3.2, P = 0.001) were the only independent predictors of reintervention. Neither obesity nor the individual components comprising metabolic syndrome was a risk for reintervention. Multivariate analysis demonstrated age, female gender, CLI, and nonobesity as the independent risk factors for long-term mortality.

CONCLUSIONS

Our study supports the "obesity paradox" that obesity by itself is not a risk factor for reintervention and was a protective factor for mortality after open aortoiliac bypass surgery. Bypass graft patency and major amputation rates were not affected. Although the individual components do not predispose to worse outcome, metabolic syndrome is a constellation of factors that, together, are associated with adverse events.

The impact of metabolic syndrome and its components on perioperative outcomes after elective laparotomy - A prospective observational study

BACKGROUND

Metabolic syndrome (MetS) represents a constellation of risk factors, including central obesity, elevated fasting blood glucose, high blood pressure and atherogenic dyslipidemia. This prospective observational study aimed to assess the impact of MetS on perioperative outcomes of patients undergoing elective abdominal surgery with laparotomy.

METHODS

We included 105 consecutive non-diabetic patients undergoing elective abdominal surgery with laparotomy. Patients were divided into two groups based on MetS diagnosis. Perioperative adverse events were recorded according to the definitions of the European Perioperative Clinical Outcome guidelines.

RESULTS

The prevalence of MetS was 57.1%. The presence of MetS was associated with a 2.64 higher odds (95% CI 1.18-5.95, P = 0.019) for respiratory events and a 3.42 higher odds (95% CI 1.05-11.13, P = 0.041) for superficial surgical site infections. Furthermore, regarding MetS patients, all individual components of MetS were associated with worse outcomes in an independent manner.

CONCLUSIONS

MetS as an entity along with its individual components are associated with an increased risk of perioperative events in patients undergoing elective abdominal surgery with laparotomy.

[Management of complications after revascularization due to peripheral arterial occlusive disease : Prophylaxis and consistent adequate therapy after timely diagnostics]

BACKGROUND

Complications are a threat to successful revascularization for treatment of perpheral arterial occlusive disease (PAOD) and must, therefore, be either primarily prevented or effectively treated after having occurred.

OBJECTIVES

The aim of this article is to give a survey of possible complications after revascularization for treatment of PAOD and their management.

MATERIAL AND METHODS

A systematic literature review was performed in PubMed and Medline. The analysis mainly considered recent publications with a higher level of evidence.

RESULTS

Revascularization for treatment of PAOD can basically be performed by an open surgical approach, an endovascular approach or as a combination of both methods (hybrid operation). The spectrum of possible complications varies accordingly. A differentiation can be made between bleeding, ischemic and systemic complications as well as between vascular and non-vascular complications. Optimal management of complications begins with primary prophylaxis and further includes a timely diagnosis and treatment of established complications. The best prophylaxis consists of a high quality of indications and performance of revascularization.

CONCLUSION

Optimal management of complications is essential and of utmost importance for successful revascularization to treat PAOD.