Applying current normative data to prognosis in heart failure: The Fitness Registry and the Importance of Exercise National Database (FRIEND)

Adherence to long-term telemonitoring-supported physical activity in patients with chronic heart failure

Chronic heart failure (CHF) is one of the most common diseases with a prevalence of 1-2% in adults, disproportionately affecting the elderly. Despite consistent drug therapy, physical activity (PA) is an integral part of current guidelines. Yet adherence to regular PA and exercise interventions is poor and potential predictors and barriers to PA remain elusive. We examined the effects of a telemonitoring-based exercise intervention in 699 CHF patients in a prospective, randomized-controlled (1:1), multicenter trial. The study was registered in the German Clinical Trials Register under DRKS00019022 on 28.05.2020. For both, the exercise and control group, self-reported PA (MET*h/week) increased and sedentary behavior declined during the 12-month intervention period. In the exercise group, daily step count as analyzed via activity trackers remained stable (pre: 6459 [4016] steps/day, post: 6532 [3858] steps/day; p = 0.621). The average number of completed exercise instruction videos provided via an online application was 1.50 [1.44] videos/week at the beginning and gradually decreased to 1.00 [1.50] videos/week; p < 0.001). Multivariate regression model revealed that exercise-related PA (MET*h/week) and exercise capacity (Wmax) at baseline, CHF severity, atrial fibrillation and age predicted changes in self-reported exercise-related PA (R2 = 0.396). Furthermore, the BMI and the average number of completed videos per week at baseline were associated with the change in completed videos over the course of the study (R2 = 0.251). Our results show the influence of certain baseline characteristics as barriers and predictors of PA progression. Therefore, exercise programs should pay attention to patients' individual conditions to set achievable goals, and eventually affect the adherence and sustainability of exercise-focused interventions.

Quantifying assumptions underlying peak oxygen consumption equations across the body mass spectrum

The goal of this study is to quantify the assumptions associated with the Wasserman-Hansen (WH) and Fitness Registry and the Importance of Exercise: A National Database (FRIEND) predictive peak oxygen consumption (pVO2) equations across body mass index (BMI). Assumptions in pVO2 for both equations were first determined using a simulation and then evaluated using exercise data from the Stanford Exercise Testing registry. We calculated percent-predicted VO2 (ppVO2) values for both equations and compared them using the Bland-Altman method. Assumptions associated with pVO2 across BMI categories were quantified by comparing the slopes of age-adjusted VO2 ratios (pVO2/pre-exercise VO2) and ppVO2 values for different BMI categories. The simulation revealed lower predicted fitness among adults with obesity using the FRIEND equation compared to the WH equations. In the clinical cohort, we evaluated 2471 patients (56.9% male, 22% with BMI >30 kg/m2, pVO2 26.8 mlO2/kg/min). The Bland-Altman plot revealed an average relative difference of -1.7% (95% CI: -2.1 to -1.2%) between WH and FRIEND ppVO2 values with greater differences among those with obesity. Analysis of the VO2 ratio to ppVO2 slopes across the BMI spectrum confirmed the assumption of lower fitness in those with obesity, and this trend was more pronounced using the FRIEND equation. Peak VO2 estimations between the WH and FRIEND equations differed significantly among individuals with obesity. The FRIEND equation resulted in a greater attributable reduction in pVO2 associated with obesity relative to the WH equations. The outlined relationships between BMI and predicted VO2 may better inform the clinical interpretation of ppVO2 values during cardiopulmonary exercise test evaluations.

2023 update: The importance of cardiorespiratory fitness in the United States

The American Heart Association issued a Policy Statement in 2013 that characterized the importance of cardiorespiratory fitness (CRF) as an essential marker of health outcomes and specifically the need for increased assessment of CRF. This statement summarized the evidence demonstrating that CRF is "one of the most important correlates of overall health status and a potent predictor of an individual's future risk of cardiovascular disease." Subsequently, this Policy Statement led to the development of a National Registry for CRF (Fitness Registry and the Importance of Exercise: A National Data Base [FRIEND]) which established normative reference values for CRF for adults in the United States (US). This review provides an overview of the progress made in the past decade to further our understanding of the importance of CRF, specifically related to prevention and for clinical populations. Additionally, this review overviews the evolvement and additional uses of FRIEND and summarizes a hierarchy of assessment methods for CRF. In summary, continued efforts are needed to expand the representation of data from across the US, and to include data from pediatric populations, to further develop the CRF Reference Standards for the US as well as further develop Global CRF Reference Standards.

Validity of Estimated Cardiorespiratory Fitness in Patients With Primary Breast Cancer

Background

Estimated peak oxygen consumption (Vo₂peak) is widely used in oncology; however, estimated Vo₂peak equations were developed in noncancer settings.

Objectives

The aim of this study was to evaluate the validity of estimated Vo₂peak in women with primary breast cancer and to develop oncology-specific estimated Vo₂peak equations.

Methods

Vo₂peak was directly measured (TrueOne 2400, Parvo Medics) during 380 cardiopulmonary exercise tests in women previously treated for breast cancer (mean age: 59 ± 10 years; 3.1 ± 1.2 years post-therapy). The American College of Sports Medicine (ACSM), the Fitness Registry and the Importance of Exercise National Database (FRIEND), and heart failure (HF)-FRIEND equations were used to estimate Vo₂peak. New equations were developed using patient and peak (Onc_peak) or submaximal (Onc_sub) exercise test characteristics.

Results

The median differences between measured and estimated Vo₂peak were 7.0 mL O₂·kg⁻¹·min⁻¹, 3.9 mL O₂·kg⁻¹·min⁻¹, and −0.2 mL O₂·kg⁻¹·min⁻¹ for ACSM, FRIEND, and HF-FRIEND, respectively. The number of estimated Vo₂peak values within ±3.5 mL O₂·kg⁻¹·min⁻¹ of the measured values was 70 (18%), 164 (43%), and 306 (81%) for ACSM, FRIEND, and HF-FRIEND, respectively. The Onc_peak and Onc_Sub models included body mass index, age, a history of chemotherapy or radiation, the peak measured heart rate, and the treadmill grade and/or speed. The median differences between measured and estimated Vo₂peak were 0.02 mL O₂·kg⁻¹·min⁻¹ (Onc_peak) and −0.2 mL O₂·kg⁻¹·min⁻¹ (Onc_sub). Eighty-six percent (n = 325) and 76% (n = 283) estimated Vo₂peak values were within ±3.5 mL O₂·kg⁻¹·min⁻¹ of the measured Vo₂peak values for Onc_peak and Onc_sub, respectively.

Conclusions

HF-FRIEND or oncology-specific equations could be applied to estimate Vo₂peak in patients previously treated for breast cancer in settings where cardiopulmonary exercise tests are not available. (Trial Comparing the Effects of Linear Versus Nonlinear Aerobic Training in Women With Operable Breast Cancer [EXCITE]; NCT01186367

Comparison of the FRIEND and Wasserman-Hansen Equations in Predicting Outcomes in Heart Failure

Background

Percentage of age‐predicted peak oxygen uptake (VO₂) achieved (ppVO₂) has been widely used to stratify risk in patients with heart failure. However, there are limitations to traditional normal standards. We compared the recently derived FRIEND (Fitness Registry and the Importance of Exercise: A National Data Base) equation to the widely used Wasserman‐Hansen (WH) ppVO₂ equation to predict outcomes in patients with heart failure.

Methods and Results

A subgroup of 4055 heart failure patients from the FRIEND registry (mean age 53±15 years) was followed for a mean of 28±16 months. The FRIEND and WH equations along with measured peak VO₂ expressed in mL/kg⁻¹ per min⁻¹ were compared for mortality and composite cardiovascular events. ppVO₂ was higher for the FRIEND versus the WH equation (66±30% versus 58±25%; P<0.001). The areas under the receiver operating characteristic curves were slightly but significantly higher for the FRIEND equation for mortality (0.74 versus 0.72; P=0.03) and cardiac events (0.70 versus 0.68; P=0.008). Area under the receiver operating characteristic curve for measured peak VO₂ was 0.70 (P<0.001) for mortality and 0.73 (P<0.001) for cardiovascular events. For each 1‐SD higher ppVO₂ for the FRIEND equation, mortality was reduced by 18% (hazard ratio, 0.82; 95% CI, 0.69–0.97; P<0.02); for each 1‐SD higher ppVO₂ for the WH equation, the mortality was reduced by 17% (hazard ratio, 0.83; 95% CI, 0.71–0.97; P=0.02). The corresponding reductions in risk per 1 SD for cardiovascular events for the FRIEND and WH equations were 23 and 21%, respectively (both P<0.001).

Conclusions

Peak VO₂ expressed as percentage of an age‐predicted standard strongly predicts mortality and major cardiovascular events in patients with heart failure. The FRIEND registry equation exhibited test characteristics slightly superior to the commonly used WH equation.

The V˙E/V˙co2 Slope During Maximal Treadmill Cardiopulmonary Exercise Testing: REFERENCE STANDARDS FROM FRIEND (FITNESS REGISTRY AND THE IMPORTANCE OF EXERCISE: A NATIONAL DATABASE)

PURPOSE

Cardiopulmonary exercise testing (CPX) is the gold standard approach for the assessment of cardiorespiratory fitness (CRF). The primary aim of the current study was to determine reference standards for the minute ventilation/carbon dioxide production (V˙E/V˙co2) slope in a cohort from the "Fitness Registry and the Importance of Exercise: A National Database" (FRIEND) Registry.

METHODS

The current analysis included 2512 tests from 10 CPX laboratories in the United States. Inclusion criteria included CPX data on apparently healthy men and women: (1) age ≥20 yr; and (2) with a symptom-limited exercise test performed on a treadmill. Ventilation and V˙co2 data, from the initiation of exercise to peak, were used to calculate the V˙E/V˙co2 slope via least-squares linear regression. Reference values were determined for men and women by decade of life.

RESULTS

On average, V˙E/V˙co2 slope values were lower in men and increased with age independent of sex. Fiftieth percentile values increased from 27.1 in the second decade to 33.9 in the eighth decade in men and from 28.5 in the second decade to 33.7 in the eighth decade in women. In the overall group, correlations with baseline characteristics and the V˙E/V˙co2 slope were statistically significant (P < .05) although generally weak, particularly for age and body mass index.

CONCLUSION

The results of the current study establish reference values for the V˙E/V˙co2 slope when treadmill testing is performed, and all exercise data are used for the slope calculation. These results may prove useful in enhancing the interpretation of CPX results when assessing CRF.

Determinants of Cardiorespiratory Fitness in Patients with Heart Failure Across a Wide Range of Ejection Fractions

Impaired cardiorespiratory fitness (CRF) in heart failure (HF) is influenced by a complex array of cardiac and extracardiac factors. The study aimed to identify clinical determinants of CRF measured as peak oxygen consumption (peak VO₂) in HF patients, and to determine a peak VO₂ prediction model using regression equations. Retrospective analysis of 200 HF patients who completed treadmill cardiopulmonary exercise testing and underwent Doppler echocardiography and/or biomarker analysis on the same day was performed. After univariate linear regression analysis, a multivariate peak VO₂ prediction model was developed using significant variables in a stepwise linear regression analysis. In subjects with repeated testing, Pearson's correlation was used to assess correlations between measured and predicted change in peak VO₂ (Δpeak VO₂) over time. Mean age was 57 years, with 55% being male. Stepwise linear regression was used to generate a weighted model for peak VO₂: 30.895 + (-0.112•age[years]) + (0.296•hemoglobin [g/dl]) + (-0.101•E/e'[unit change]) + (-0.202• body mass index [kg/m²]) + (-0.593• N-terminal pro-brain natriuretic peptide [log_N pg/ml])) + (-1.349•CRP [log mg/L]). Predicted peak VO₂ correlated strongly with measured peak VO₂ in HF with reduced ejection fraction and HF with preserved ejection fraction patients (r = +0.63, p <0.001; r = +0.64, p <0.001, respectively). Predicted Δpeak VO₂ correlated with measured Δpeak VO₂ (r = +0.23, p <0.001). In conclusion, in patients with HF across a wide range of left ventricular ejection fraction, age, systemic inflammation, oxygen carrying capacity, obesity, and elevated filling pressures are the strongest predictors of impaired CRF. The proposed CRF model allows prediction of peak VO₂ in HF patients and may be used to estimate peak VO₂ changes over time.

Prognostic comparison of the FRIEND and Wasserman/Hansen peak VO2 equations applied to a submaximal walking test in outpatients with cardiovascular disease

AIMS

The aim of this study was to determine the ability to predict all-cause mortality using established per cent-predicted (%PRED) equations for peak oxygen consumption (VO2peak) estimated by a submaximal walk test in outpatients with cardiovascular disease.

METHODS

Male patients (N = 1491) aged 62 ± 10 years at baseline underwent a moderate and perceptually regulated (11-13 on the 6-20 Borg scale) 1-km treadmill-walking test to estimate VO2peak. %PRED was derived from the Fitness Registry and the Importance of Exercise: A National Data Base (FRIEND) and the Wasserman/Hansen equations.

RESULTS

There were 215 deaths during a median 9.4-year follow-up. The FRIEND prediction equation provided better prognostic information with receiver operating curve analysis showing significantly different areas under the curve (0.72 and 0.69 for the FRIEND and the Wasserman/Hansen equations respectively, p = 0.001). Overall mortality rate was higher across decreasing tertiles of %PRED using FRIEND, with 26%, 11% and 5% for the least fit, intermediate and high fit tertiles, respectively (p for trend < 0.0001). Compared with the least fit tertile, the adjusted hazard ratios for the second and third tertiles were 0.54 (95% confidence interval 0.34-0.87, p = 0.01) and 0.45 (95% confidence interval 0.25-0.81, p = 0.008), respectively. Each 1% increase in %PRED conferred a 3% improvement in survival (p = 0.0004).

CONCLUSION

Low %PRED VO2peak in cardiac outpatients determined by the FRIEND equation was associated with a high mortality rate independent of traditional cardiovascular risk factors and clinical history. The FRIEND equation may provide a suitable normal standard when applied to clinically stable outpatients with cardiovascular disease.

A longitudinal big data approach for precision health

Precision health relies on the ability to assess disease risk at an individual level, detect early preclinical conditions and initiate preventive strategies. Recent technological advances in omics and wearable monitoring enable deep molecular and physiological profiling and may provide important tools for precision health. We explored the ability of deep longitudinal profiling to make health-related discoveries, identify clinically relevant molecular pathways and affect behavior in a prospective longitudinal cohort (n = 109) enriched for risk of type 2 diabetes mellitus. The cohort underwent integrative personalized omics profiling from samples collected quarterly for up to 8 years (median, 2.8 years) using clinical measures and emerging technologies including genome, immunome, transcriptome, proteome, metabolome, microbiome and wearable monitoring. We discovered more than 67 clinically actionable health discoveries and identified multiple molecular pathways associated with metabolic, cardiovascular and oncologic pathophysiology. We developed prediction models for insulin resistance by using omics measurements, illustrating their potential to replace burdensome tests. Finally, study participation led the majority of participants to implement diet and exercise changes. Altogether, we conclude that deep longitudinal profiling can lead to actionable health discoveries and provide relevant information for precision health.