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Measurement of Exercise Tolerance before Surgery (METS) study: a protocol for an international multicentre prospective cohort study of cardiopulmonary exercise testing prior to major non-cardiac surgery.

ABSTRACT: Preoperative functional capacity is considered an important risk factor for cardiovascular and other complications of major non-cardiac surgery. Nonetheless, the usual approach for estimating preoperative functional capacity, namely doctors' subjective assessment, may not accurately predict postoperative morbidity or mortality. 3 possible alternatives are cardiopulmonary exercise testing; the Duke Activity Status Index, a standardised questionnaire for estimating functional capacity; and the serum concentration of N-terminal pro-B-type natriuretic peptide (NT pro-BNP), a biomarker for heart failure and cardiac ischaemia.The Measurement of Exercise Tolerance before Surgery (METS) Study is a multicentre prospective cohort study of patients undergoing major elective non-cardiac surgery at 25 participating study sites in Australia, Canada, New Zealand and the UK. We aim to recruit 1723 participants. Prior to surgery, participants undergo symptom-limited cardiopulmonary exercise testing on a cycle ergometer, complete the Duke Activity Status Index questionnaire, undergo blood sampling to measure serum NT pro-BNP concentration and have their functional capacity subjectively assessed by their responsible doctors. Participants are followed for 1 year after surgery to assess vital status, postoperative complications and general health utilities. The primary outcome is all-cause death or non-fatal myocardial infarction within 30 days after surgery, and the secondary outcome is all-cause death within 1 year after surgery. Both receiver-operating-characteristic curve methods and risk reclassification table methods will be used to compare the prognostic accuracy of preoperative subjective assessment, peak oxygen consumption during cardiopulmonary exercise testing, Duke Activity Status Index scores and serum NT pro-BNP concentration.The METS Study has received research ethics board approval at all sites. Participant recruitment began in March 2013, and 1-year follow-up is expected to finish in 2016. Publication of the results of the METS Study is anticipated to occur in 2017.

SUBMITTER: Wijeysundera DN

PROVIDER: S-EPMC4800144 | biostudies-other | 2016 Mar

REPOSITORIES: biostudies-other

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Project description:BackgroundPreoperative anaemia is associated with elevated risks of postoperative complications. This association may be explained by confounding related to poor cardiopulmonary fitness. We conducted a pre-specified substudy of the Measurement of Exercise Tolerance before Surgery (METS) study to examine the associations of preoperative haemoglobin concentration with preoperative cardiopulmonary exercise testing performance (peak oxygen consumption, anaerobic threshold) and postoperative complications.MethodsThe substudy included a nested cross-sectional analysis and nested cohort analysis. In the cross-sectional study (1279 participants), multivariate linear regression modelling was used to determine the adjusted association of haemoglobin concentration with peak oxygen consumption and anaerobic threshold. In the nested cohort study (1256 participants), multivariable logistic regression modelling was used to determine the adjusted association of haemoglobin concentration, peak oxygen consumption, and anaerobic threshold with the primary endpoint (composite outcome of death, cardiovascular complications, acute kidney injury, or surgical site infection) and secondary endpoint (moderate or severe complications).ResultsHaemoglobin concentration explained 3.8% of the variation in peak oxygen consumption and anaerobic threshold (P<0.001). Although not associated with the primary endpoint, haemoglobin concentration was associated with moderate or severe complications after adjustment for peak oxygen consumption (odds ratio=0.86 per 10 g L-1 increase; 95% confidence interval, 0.77-0.96) or anaerobic threshold (odds ratio=0.86; 95% confidence interval, 0.77-0.97). Lower peak oxygen consumption was associated with moderate or severe complications without effect modification by haemoglobin concentration (P=0.12).ConclusionHaemoglobin concentration explains a small proportion of variation in exercise capacity. Both anaemia and poor functional capacity are associated with postoperative complications and may therefore be modifiable targets for preoperative optimisation.

Project description:AimsIn this multicentre study, we compared cardio-pulmonary exercise test (CPET) parameters between heart failure (HF) patients classified as New York Heart Association (NYHA) class I and II to assess NYHA performance and prognostic role in mild HF.Methods and resultsWe included consecutive HF patients in NYHA class I or II who underwent CPET in three Brazilian centres. We analysed the overlap between kernel density estimations for the per cent-predicted peak oxygen consumption (VO2 ), minute ventilation/carbon dioxide production (VE/VCO2 ) slope, and oxygen uptake efficiency slope (OUES) by NYHA class. Area under the receiver-operating characteristic curve (AUC) was used to assess the capacity of per cent-predicted peak VO2 to discriminate between NYHA class I and II. For prognostication, time to all-cause death was used to produce Kaplan-Meier estimates. Of 688 patients included in this study, 42% were classified as NYHA I and 58% as NYHA II, 55% were men, and mean age was 56 years. Median global per cent-predicted peak VO2 was 66.8% (IQR 56-80), VE/VCO2 slope was 36.9 (31.6-43.3), and mean OUES was 1.51 (±0.59). Kernel density overlap between NYHA class I and II was 86% for per cent-predicted peak VO2 , 89% for VE/VCO2 slope, and 84% for OUES. Receiving-operating curve analysis showed a significant, albeit limited performance of per cent-predicted peak VO2 alone to discriminate between NYHA class I vs. II (AUC 0.55, 95% CI 0.51-0.59, P = 0.005). Model accuracy for probability of being classified as NYHA class I (vs. NYHA class II) across the spectrum of the per cent-predicted peak VO2 was limited, with an absolute probability increment of 13% when per cent-predicted peak VO2 increased from 50% to 100%. Overall mortality in NYHA class I and II was not significantly different (P = 0.41), whereas NYHA class III patients displayed a distinctively higher death rate (P < 0.001).ConclusionsPatients with chronic HF classified as NYHA I overlapped substantially with those classified as NYHA II in objective physiological measures and prognosis. NYHA classification may represent a poor discriminator of cardiopulmonary capacity in patients with mild HF.

Project description:INTRODUCTION:Cardiopulmonary exercise testing (CPET) is widely used within the United Kingdom for preoperative risk stratification. Despite this, CPET's performance in predicting adverse events has not been systematically evaluated within the framework of classifier performance. METHODS:After prospective registration on PROSPERO (CRD42018095508) we systematically identified studies where CPET was used to aid in the prognostication of mortality, cardiorespiratory complications, and unplanned intensive care unit (ICU) admission in individuals undergoing non-cardiopulmonary surgery. For all included studies we extracted or calculated measures of predictive performance whilst identifying and critiquing predictive models encompassing CPET derived variables. RESULTS:We identified 36 studies for qualitative review, from 27 of which measures of classifier performance could be calculated. We found studies to be highly heterogeneous in methodology and quality with high potential for bias and confounding. We found seven studies that presented risk prediction models for outcomes of interest. Of these, only four studies outlined a clear process of model development; assessment of discrimination and calibration were performed in only two and only one study undertook internal validation. No scores were externally validated. Systematically identified and calculated measures of test performance for CPET demonstrated mixed performance. Data was most complete for anaerobic threshold (AT) based predictions: calculated sensitivities ranged from 20-100% when used for predicting risk of mortality with high negative predictive values (96-100%). In contrast, positive predictive value (PPV) was poor (2.9-42.1%). PPV appeared to be generally higher for cardiorespiratory complications, with similar sensitivities. Similar patterns were seen for the association of Peak VO2 (sensitivity 85.7-100%, PPV 2.7-5.9%) and VE/VCO2 (Sensitivity 27.8%-100%, PPV 3.4-7.1%) with mortality. CONCLUSIONS:In general CPET's 'rule-out' capability appears better than its ability to 'rule-in' complications. Poor PPV may reflect the frequency of complications in studied populations. Our calculated estimates of classifier performance suggest the need for a balanced interpretation of the pros and cons of CPET guided pre-operative risk stratification.

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Measurement of Exercise Tolerance before Surgery (METS) study: a protocol for an international multicentre prospective cohort study of cardiopulmonary exercise testing prior to major non-cardiac surgery.

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