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Peri-Operative Stroke Risk During Major Surgery

Peri-Operative Stroke Risk During Major Surgery


This study delves into the incidence and risk factors associated with peri-operative stroke, a rare yet significant complication of surgery. Drawing on retrospective register data from 23 hospitals in Sweden spanning 2007 to 2014, the research aimed to identify independent risk factors influencing stroke occurrence within 30 days post-surgery. The analysis encompassed over 300,000 patients undergoing major noncardiovascular, non-neurosurgical, and non-ambulatory procedures.


Among the key findings, 687 patients (0.22%) experienced a stroke within the designated timeframe. Strongly correlated risk factors included increasing ASA-class and age, with notable odds ratios associated with ASA classes 2, 3, and 4, as well as age groups ranging from 45 to over 90 years. Non-elective procedures, male gender, and a history of cerebrovascular disease also emerged as significant risk factors. Patients who suffered peri-operative stroke exhibited elevated mortality rates and reduced days alive and at home within 30 days post-surgery.


The study underscores the critical importance of detailed pre-operative risk assessment and personalized peri-operative management to mitigate stroke risk and enhance patient-centered outcomes. By identifying high-risk individuals based on factors like age, ASA class, and medical history, clinicians can tailor interventions to optimize patient care. These insights hold implications for public health, highlighting the potential benefits of targeted strategies to reduce peri-operative stroke incidence and improve overall surgical outcomes. Moreover, the study sheds light on the need for further research to elucidate the impact of anesthesiological management on peri-operative stroke risk, contributing valuable data to inform future investigations in this domain.


Despite the considerable progress in medical science, stroke remains a significant global health concern, standing as the second leading cause of death worldwide in 2010. Within the context of surgical procedures, the occurrence of stroke can lead to devastating outcomes, often associated with higher mortality rates compared to strokes that occur outside of surgical settings. While peri-operative stroke incidents are relatively infrequent among low-risk patients and procedures, constituting only around 0.1% of cases, the risk escalates significantly in higher-risk patients, reaching approximately 1.9%, even in seemingly low-risk surgical interventions. 


Recent research, exemplified by the NeuroVISION trial, has unveiled an unexpectedly high incidence of covert stroke—clinically unrecognized ischemia detected through magnetic resonance imaging—in relatively low-risk surgical populations. This revelation underscores the potentially profound long-term impact of even covert strokes on cognitive function and cerebrovascular risk. These findings underscore the urgent need for concerted efforts aimed at reducing the incidence of peri-operative stroke to yield substantial public health benefits.


A multitude of pre- and intra-operative factors have been identified as contributors to the risk of stroke. Notably, advanced age, particularly exceeding 61 years, emerged as the most robust independent risk factor. This is closely followed by recent myocardial infarction, acute renal failure requiring dialysis, prior stroke or transient ischemic attack, hypertension, chronic obstructive pulmonary disease, and smoking. These findings are consistent with earlier studies and are further supported by additional risk factors such as diabetes mellitus, hyperglycemia, atrial fibrillation, congestive heart failure, valvular heart disease, renal disease, coronary artery disease, cancer, patent foramen ovale, and migraine. 


The impact of pre-existing medications, including statins and acetylsalicylic acid, on peri-operative stroke risk remains a subject of ongoing investigation, with current evidence yielding inconclusive results. Similarly, the influence of intra-operative management strategies on stroke risk lacks clear-cut evidence of superiority.


In summary, while several potentially modifiable pre- and intra-operative risk factors for peri-operative stroke have been identified, a lack of robust evidence hinders the formulation of definitive clinical guidelines. Our study aimed to address this gap by assessing the incidence and risk factors for peri-operative stroke in a large cohort of Swedish patients. By shedding light on these factors, we aim to pave the way for future research endeavors focused on optimizing peri-operative management to reduce peri-operative morbidity and its associated socio-economic burdens.


The study conducted a comprehensive retrospective analysis across 23 hospitals in Sweden to investigate the occurrence of perioperative stroke and other critical outcomes among patients undergoing surgery between 2007 and 2014. By leveraging a variety of data sources, including the Swedish personal identification number, information was meticulously gathered and cross-referenced to ensure accuracy and reliability.


Participants in the study were individuals aged 18 years and older who had undergone surgery during the specified timeframe. Exclusions were made for certain types of surgeries and cases with incomplete data. Pre-existing medical conditions, particularly diabetes, were carefully identified through medical records and prescription data, providing a robust understanding of patients’ health profiles prior to surgery.


The primary focus of the study was to assess the occurrence of perioperative stroke within 30 days of the index surgery. This was meticulously tracked using the ‘Riksstroke’ database, which provided high-resolution data on stroke cases. Secondary outcomes, such as mortality rates at various intervals and the composite measure of ‘days alive and at home within 30 days after surgery’ (DAH 30), offered additional insights into postoperative recovery and overall patient well-being.


Ethical considerations were paramount throughout the study, with approval obtained from the Regional Ethics Committee of Stockholm. Due to the retrospective nature of the research and the de-identified nature of the data, the need for informed consent was appropriately waived, ensuring adherence to ethical guidelines.


The findings of this study provide valuable insights into the risks associated with surgery, particularly regarding perioperative stroke, mortality rates, and postoperative recovery. By shedding light on these critical aspects, healthcare providers can better understand and mitigate risks, ultimately improving patient care and outcomes.

Statistical Analysis

The study conducted statistical analysis to assess the incidence and impact of peri-operative stroke, employing various methods to investigate pre-operative characteristics’ contribution to stroke risk and its implications on patient outcomes. Initial analysis involved χ2 tests and Mann–Whitney U tests to compare categorical and continuous variables, respectively. Subsequently, logistic regression models were constructed, initially using univariate approaches and later incorporating significant variables into a full multivariable model. Model testing included backward stepwise regression and penalized logistic regression.


Data were presented using a forest plot, and the effect of peri-operative stroke on the composite outcome DAH 30 was assessed using proportional odds logistic regression. Interaction terms influencing stroke risk were integrated into the model, with diagnostic assessment ensuring the assumption of proportional odds was met. Mortality estimates were derived using a multivariable logistic regression model, adjusting for identified covariates.


Due to data quality issues, detailed temporal mortality analysis using Cox-regression modeling was precluded. Attempts to analyze mortality beyond 30 days post-operation were hindered by violations of proportional hazards assumptions. All statistical analyses were conducted using R Statistics version 4.2.2 via RStudio.


In this study, a comprehensive analysis was conducted on a large cohort of surgical cases, excluding those involving neurologic, cardiac, and major vascular surgeries, resulting in a dataset of 318,017 cases. Detailed examination revealed that the incidence of postoperative stroke within 30 days following surgery was 0.216%. 


Key demographic and procedural factors were found to influence the occurrence of peri-operative stroke. These included gender, age, procedure type (elective vs. non-elective), and ASA Physical Status, with older age and higher ASA classification correlating strongly with elevated risk. Notably, a history of cerebrovascular disease emerged as a significant predictor, underlining the importance of pre-existing health conditions in assessing surgical risk. Moreover, male gender and non-elective surgery were identified as additional risk factors contributing to the likelihood of peri-operative stroke.


Furthermore, specific comorbidities were scrutinized as independent predictors, shedding light on their role in surgical outcomes. This thorough investigation allowed for a nuanced understanding of the multifactorial nature of peri-operative stroke risk, encompassing both patient-related factors and procedural characteristics.


The impact of peri-operative stroke on patient outcomes was extensively evaluated. Analyses revealed that patients who experienced a stroke during the peri-operative period were more likely to suffer from adverse health outcomes, as evidenced by a lower composite outcome score (DAH 30). This underscores the substantial impact of peri-operative stroke on morbidity, highlighting the need for vigilant monitoring and proactive management strategies in these cases.


Furthermore, the study delved into the association between peri-operative stroke and mortality. Results indicated a statistically significant increase in adjusted odds of mortality among patients who suffered a stroke following surgery, even after accounting for demographic and procedural variables. This underscores the grave implications of peri-operative stroke on patient survival and emphasizes the importance of early detection and intervention to mitigate adverse outcomes.


Overall, the findings of this study underscore the complex interplay of factors influencing peri-operative stroke risk and its profound implications for patient morbidity and mortality. By elucidating these factors, clinicians can better identify high-risk patients, tailor interventions, and implement preventive measures to enhance surgical safety and improve patient outcomes.


This study investigated the incidence of peri-operative stroke and its pre-operative risk factors in a substantial cohort of non-cardiovascular, non-neurologic patients over the period from 2007 to 2014. The reported incidence of approximately 0.22% underscores the continued significance of stroke as a peri-operative complication, aligning with prior research and emphasizing its importance in patient care. Notably, even covert strokes, with a higher incidence than overt strokes, have been shown to detrimentally affect patient outcomes.


In our multivariable logistic regression analysis, ASA Physical Status emerged as one of the strongest pre-operative risk factors for peri-operative stroke, with a striking tenfold increase in odds from ASA 1 to ASA 4. This finding underscores the potential for tailored peri-operative management strategies based on individual risk profiles, consistent with previous research indicating elevated stroke risk in higher-risk patients.


Furthermore, our study revealed that peri-operative stroke significantly impacts both short- and long-term mortality, as well as decreases in the composite outcome of DAH 30, highlighting its adverse effects on patient outcomes. These findings underscore the imperative to reduce the incidence of peri-operative stroke through targeted interventions.


While acknowledging the limitations inherent in the study, including the use of data collected over a decade ago and potential developments in medical practices since then, our results remain consistent with both older and more recent estimates of peri-operative stroke incidence. Additionally, the study’s reliance on data from multiple centers across Sweden, along with its large cohort size and robust methodology, enhances the validity and generalizability of our findings.


In conclusion, our study underscores the association between increasing ASA class and age with heightened peri-operative stroke risk, and the subsequent impact on morbidity and mortality. Detailed pre-operative risk assessment and personalized peri-operative management strategies hold promise for improving patient outcomes and advancing public health initiatives. Further research into intra-operative risk factors is warranted to better understand and mitigate the risk of peri-operative stroke.

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