Preoperative Exercise Testing and Perioperative Outcomes

Submaximal Cardiopulmonary Exercise Testing in Adults Presenting for Moderate- to High-risk Surgery and Perioperative Outcomes (SAMPO) is a single-center prospective observational cohort repository with a retrospective validation component designed to evaluate whether measures derived from brief, clinically integrated submaximal cardiopulmonary exercise testing (smCPET) are associated with perioperative outcomes in adults undergoing moderate- to high-risk noncardiac surgery. The repository is being developed in the Yale New Haven Hospital Pre-Surgical Evaluation Clinic to support systematic collection, curation, and analysis of exercise-derived physiologic data obtained during routine preoperative care, together with clinical, perioperative, and postoperative outcome data. The overall purpose is to determine whether smCPET variables can improve perioperative risk stratification, identify patients at increased risk for postoperative complications, and generate a scalable framework for future perioperative risk modeling and implementation studies.

Perioperative complications remain common after major noncardiac surgery and are associated with increased morbidity, prolonged recovery, higher readmission rates, greater resource use, and higher health care costs. Current preoperative risk assessment often relies on history, comorbidity burden, procedural risk classification, and subjective estimates of functional capacity. Although formal cardiopulmonary exercise testing has demonstrated value for perioperative prognostication, broad adoption has been limited by the time, personnel, technical, and infrastructure requirements of conventional maximal testing. A brief submaximal approach may offer a more pragmatic alternative in the preoperative clinic setting. Early implementation work by the investigators suggests that rapid smCPET can be integrated into routine workflow, produces technically usable data in a high proportion of patients, and may yield physiologic measures associated with early postoperative morbidity. This repository is intended to extend that work by creating a structured dataset that allows more rigorous assessment of the relationship between preoperative smCPET findings and clinically meaningful postoperative outcomes.

The central scientific premise of the repository is that preoperative physiologic response to submaximal exercise reflects cardiopulmonary reserve and integrative functional capacity in ways not fully captured by routine clinical history or conventional screening instruments. Variables such as peak oxygen uptake achieved during submaximal effort, anaerobic threshold, ventilatory efficiency, heart rate response, and slope-based exercise measures may identify latent vulnerability before surgery. If those measures show meaningful associations with early and later postoperative complications, they may support more objective risk assessment, perioperative triage, allocation of optimization resources, and selection of patients for enhanced monitoring or future interventional studies. The repository is therefore designed not merely as a passive data storage effort, but as an analytic infrastructure for validating clinically feasible physiologic markers in the perioperative setting.

The study includes a prospective component and a retrospective component. In the prospective component, adult participants undergoing routine preoperative evaluation in the Yale Pre-Surgical Evaluation Clinic who are referred for or complete smCPET as part of clinical care are approached for consent for inclusion in the repository. smCPET is not performed for research purposes; rather, the study captures data already generated during standard clinical assessment and links those data to perioperative and postoperative outcomes. The planned initial enrollment period is 36 months with follow-up extending through the perioperative period and including later outcome ascertainment. The protocol also describes an overall study duration of 48 months and a single study site.

The retrospective component consists of historical data from the period before clinical implementation of smCPET, including approximately 24 months of historical control data to support validation, comparison, matched cohort analyses, and evaluation of outcomes, costs, and resource utilization patterns. This aspect of the study is intended to contextualize the prospective findings and allow comparison between patients evaluated in the era of smCPET-enabled preoperative assessment and an earlier period without routine smCPET integration. Together, the two components create a hybrid repository structure: a prospective observational cohort of clinically evaluated patients supplemented by retrospective clinical data for validation and comparison.

This is an observational study. No experimental intervention is assigned by the investigators, no treatment is randomized, and no additional clinical procedures are mandated solely for research participation. All smCPET procedures included in the repository are performed as part of standard preoperative clinical care and surgical planning. Research participation pertains to collection, storage, linkage, de-identification, and analysis of clinical and outcome data. Accordingly, the study is intended to characterize associations and predictive relationships rather than test efficacy of an intervention.

The target population consists of adults older than 45 years who are presenting for moderate- to high-risk noncardiac surgery and who undergo evaluation in the Yale Pre-Surgical Evaluation Clinic. Patients are identified through routine clinic screening workflows, including triage processes, clinic screening tools, and clinician referral pathways based on clinical concern for elevated perioperative risk or impaired functional capacity. The protocol describes referral and screening criteria that include low estimated activity capacity and selected high-risk cardiovascular features within the broader context of moderate- to high-risk surgery. Participants are recruited from the future pool of preoperative smCPET patients at the Yale Pre-Surgical Evaluation Clinic. Because the study draws from a real-world clinical population evaluated in routine care, the repository is intended to reflect pragmatic perioperative practice rather than an artificially selected experimental cohort.

Screening for clinical smCPET occurs through the standard Yale Pre-Surgical Evaluation Clinic process. Primary screening may be conducted by triage nursing using the clinic screening tool or by referral using predefined criteria related to surgical risk, functional capacity assessment, or high-risk clinical features. Enrollment into the repository occurs after the smCPET and preoperative evaluation appointment. Potential participants are first introduced to the study by the clinical care team during the routine clinic visit, after which a study team member provides a brief explanation of the repository and consent process. This approach is intended to preserve separation between clinical care decisions and research participation. Enrollment discussions are conducted privately, bilingual interpretation is available when needed, and study personnel use a structured consent process that includes verification of understanding. Participants are informed that participation is voluntary and that a decision about repository enrollment will not affect clinical care.

The repository uses a dual-track consent approach. Prospective participants undergoing clinical smCPET are asked to provide written informed consent for inclusion in the repository and associated follow-up data collection. The consent process addresses storage of clinical and outcome data, future analysis within the repository framework, and the protections used for confidentiality and secure handling of identifiable information. For data elements that require access to the medical record for outcome ascertainment, identifiers may be temporarily retained under the authority of the principal investigator until outcome linkage is complete. Once the required linkage and validation steps are finished, identifiers are removed and replaced with a unique study code. De-identified data are stored in a secure encrypted REDCap database or other institutionally approved system. Access to identified information is limited to authorized study personnel, and any external sharing of de-identified data requires principal investigator and institutional review oversight as applicable.

Data collected in the repository are broad and designed to support both primary and secondary analyses. The core exposure domain includes physiologic variables derived from submaximal cardiopulmonary exercise testing performed in routine clinical care. These may include peak oxygen uptake achieved during the submaximal test, anaerobic threshold, ventilatory efficiency metrics, oxygen uptake efficiency and slope-based exercise measures, heart rate and blood pressure response, oxygen saturation trends, and related respiratory or metabolic parameters available from the clinical test platform. The specific smCPET variables available for analysis may evolve as the clinical program matures, but the repository is designed to preserve standardized capture of variables judged clinically and scientifically relevant for perioperative risk stratification.

In addition to smCPET variables, the repository captures demographic data and baseline clinical characteristics relevant to perioperative risk. These include age, sex, body mass index, comorbidity burden, and selected information from preoperative evaluation such as serum chemistries, hematologic data, echocardiography findings, radiographic data, and other clinically obtained investigations. The perioperative data structure also includes physiological variables such as heart rate, blood pressure, oxygen saturation, and pulse-related measures, along with procedure-related descriptors and other perioperative characteristics available in the medical record. Because the repository is built around routine clinical care, the exact distribution of covariates will reflect real-world practice patterns and clinical documentation.

Outcome ascertainment is a major purpose of the repository. The study is designed to examine both early postoperative morbidity and later complications after surgery. Early postoperative complications include events recorded using the Postoperative Morbidity Survey framework and related complication domains during the immediate postoperative period. These domains include pulmonary, infectious, renal, gastrointestinal, cardiovascular, neurological, hematological, wound, and pain-related complications, assessed at designated postoperative time points such as days 1, 3, and 5 when available. The repository also captures later postoperative events, including 30-day and 60-day complications and mortality outcomes. Examples of later complications listed in the protocol include myocardial infarction, angina, stroke, atrial fibrillation, surgical site infection, postoperative pneumonia, and other organ-specific complications identified through readmission records, postoperative follow-up, or clinical documentation. Length of stay and resource utilization measures are also included to support broader health services analyses.

The primary objective of the repository is to evaluate the association between established clinical smCPET measures and postoperative outcomes in patients who undergo preoperative smCPET as part of standard care. A key aim is to determine whether smCPET-derived variables can identify thresholds or patterns associated with increased risk of early postoperative complications and clinically important later adverse events. The repository is also intended to support development and refinement of predictive models using clinically available exercise-derived physiologic data. By identifying thresholds or multivariable patterns associated with increased risk, the study aims to provide evidence supporting the use of smCPET as an objective adjunct to existing perioperative evaluation strategies.

Secondary aims include validation of preliminary observations from earlier implementation work, subgroup analyses in clinically relevant patient subsets, comparison of smCPET-era patients with historical controls, and exploratory evaluation of cost-effectiveness, quality metrics, and resource utilization. The retrospective validation component enables comparison between contemporary patients assessed with smCPET-integrated workflows and historical cohorts from the period before smCPET implementation. This may help clarify whether the addition of structured physiologic assessment is associated with differences in triage, outcome profiles, or resource use, although causal interpretation will remain limited by the observational design. The repository may also support future studies evaluating whether smCPET variables can assist in identifying candidates for perioperative optimization, enhanced surveillance, or targeted prehabilitation strategies.

The planned analytic framework includes threshold determination for candidate smCPET measures, prediction modeling for postoperative outcomes, and comparative analyses involving the historical control cohort. Statistical work will focus on the strength and consistency of associations between smCPET variables and outcomes after accounting for relevant clinical covariates. The study is expected to use descriptive statistics to characterize the cohort, univariable and multivariable methods to evaluate associations, and model performance approaches appropriate for risk prediction analyses. Depending on the available sample and event rates, analyses may examine discrimination, calibration, and incremental prognostic value beyond routinely available clinical variables. Subgroup analyses may explore heterogeneity according to surgical risk, comorbidity burden, or other clinically meaningful strata. Because the study is repository-based and observational, all analyses will be interpreted in light of potential confounding, selection effects, and missing data.

The repository is expected to enroll approximately 1,500 participants. This sample size is intended to support evaluation of associations across a range of minor and major perioperative outcomes, though the effective sample for specific analyses will depend on event frequencies, completeness of testing, and availability of follow-up. The study is conducted at a single center, which supports consistency in testing workflow and outcome capture but may limit generalizability to other institutions with different patient populations or perioperative practices. Nonetheless, the pragmatic real-world setting is an important strength because it allows evaluation of smCPET within the actual environment in which it may ultimately be used.

The design has several anticipated strengths. First, smCPET data are derived from routine clinical care rather than an artificial research-only protocol, enhancing practical relevance. Second, the repository links physiologic testing to detailed perioperative outcomes, allowing evaluation across early morbidity, later complications, length of stay, and mortality. Third, the prospective data collection structure combined with retrospective validation data provides a richer framework than either approach alone. Fourth, the single-site workflow may improve internal consistency in screening, test conduct, data handling, and follow-up. Finally, the repository may generate reusable infrastructure and de-identified datasets that support future methodologic and translational perioperative research.

The study also has expected limitations. Because there is no randomization and no investigator-assigned intervention, analyses can identify associations but cannot by themselves establish that smCPET-guided care improves outcomes. Patients referred for clinical smCPET are a selected subgroup of the broader surgical population and may differ systematically from patients not tested. Historical comparisons may be influenced by secular changes in practice, case mix, perioperative management, and documentation quality. As with any clinical repository, missing data and variability in routine-care measurement may affect some analyses. The investigators therefore intend to treat this repository as a platform for careful prognostic evaluation and hypothesis generation, not as definitive proof of causal benefit.

Data security and confidentiality are central operational features of the repository. Identifiable clinical information needed for linkage and follow-up is handled under the supervision of the principal investigator and authorized study staff. Electronic data are maintained in encrypted REDCap or comparable secure systems, and paper materials, when applicable, are stored in locked locations with restricted access. Once linkage is complete, data are coded and de-identified for long-term storage and analysis. The protocol states that digital storage may be indefinite, subject to institutional oversight. External use of repository data requires appropriate approval, and any shared data will be de-identified, limited to the minimum necessary variables, and governed by data use expectations designed to prevent unauthorized redistribution or attempts at re-identification.

Monitoring and data quality procedures are included to support integrity of the repository. The protocol describes systematic data quality assurance processes, screening and eligibility documentation, controlled access to records, internal monitoring by the repository director or principal investigator, and periodic oversight of data requests and protocol modifications. These procedures are intended to align with Good Clinical Practice principles applicable to a repository study, even though the project is noninterventional. The repository structure also allows documentation of withdrawals, administrative removals, incomplete testing, and other circumstances that may affect analytic eligibility.

Participants may be removed from the repository for voluntary withdrawal, administrative reasons, or clinical circumstances. Voluntary withdrawal can occur at any time without penalty and without impact on clinical care. Administrative removal may occur if ongoing consent cannot be maintained or other repository conditions are no longer met. Clinical removal may occur in cases such as inability to complete smCPET, inadequate test quality, or change in surgical status. The study team documents removal status and determines the extent to which already collected data may be retained or withdrawn in accordance with consent, institutional policy, and regulatory requirements.

The broader long-term significance of SAMPO is to establish whether a brief, scalable physiologic assessment performed during routine preoperative care can contribute meaningful prognostic information for adults facing moderate- to high-risk noncardiac surgery. If smCPET measures demonstrate reproducible associations with early postoperative morbidity, major complications, and later outcomes, the findings may support wider perioperative adoption of brief objective exercise testing, more efficient identification of higher-risk patients, and better targeting of perioperative resources. The repository is also intended to create a foundation for future external validation studies, clinical prediction tool development, implementation evaluations, and eventually interventional trials testing whether smCPET-informed care pathways can improve outcomes.

In summary, SAMPO is a single-center observational repository study that captures routine-care preoperative submaximal cardiopulmonary exercise testing data and links those data to detailed perioperative and postoperative outcomes in adults undergoing moderate- to high-risk noncardiac surgery. The study combines prospective enrollment of clinically evaluated patients with retrospective historical comparison data, uses secure repository methods for data storage and de-identification, and focuses on validating feasible physiologic markers of perioperative risk. Through this work, the investigators seek to improve objective preoperative risk assessment and build a practical evidence base for integrating brief cardiopulmonary exercise measures into surgical evaluation pathways.