Elsevier

Progress in Cardiovascular Diseases

Volume 68, September–October 2021, Pages 19-24
Progress in Cardiovascular Diseases

Peak oxygen pulse and mortality risk in healthy women and men: The Ball State Adult Fitness Longitudinal Lifestyle Study (BALL ST)

https://doi.org/10.1016/j.pcad.2021.07.001Get rights and content

Abstract

Peak oxygen pulse (O2 pulsepeak) may have predictive utility for health outcomes yet, presently, has only been examined in men and only using a single baseline measure.

Purpose

The primary aim of this investigation was to evaluate the relationship between O2 pulsepeak and all-cause mortality in apparently healthy women and men. A secondary aim was to explore the relationship between longitudinal changes to O2 pulsepeak and mortality.

Methods

The sample included 3877 participants (43% women) for the primary aim and 759 participants (32% women) who performed two cardiopulmonary exercise tests ≥1 year apart for the secondary aim. Cox proportional hazard models were performed to determine the relationship between O2 pulsepeak and mortality. Prognostic peak oxygen consumption (VO2peak) and O2 pulsepeak models were compared using the concordance index and Akaike information criterion (AIC).

Results

In the assessment from baseline, there were 730 deaths over a 24.7 ± 11.8 year follow-up period. For men, a single measure of O2 pulsepeak was inversely associated with risk for mortality (P < 0.05). However, the concordance index and AIC indicated lower discrimination compared to VO2peak models and O2 pulsepeak did not provide complementary benefit to VO2peak models. For women, O2 pulsepeak was not associated with mortality risk. In the longitudinal analysis, there were 168 deaths over a follow-up of 20.1 ± 11.4 years. Changes to O2 pulsepeak were not significantly related to mortality in either sex.

Conclusions

Within an apparently healthy cohort, a single assessment of O2 pulsepeak is related to all-cause mortality in men but not women. Further, longitudinal changes to O2 pulsepeak are not predictive of mortality in either sex. These findings suggest O2 pulsepeak may have limited prognostic utility in healthy individuals, particularly within healthy women.

Introduction

Recommendations suggest the inclusion of cardiopulmonary exercise testing (CPX) in routine clinical practice to improve patient management and risk stratification.1 Of the numerous variables collected during CPX, the traditional variable of interest, which is the most commonly used as an indicator of health is maximum or peak oxygen consumption (VO2peak).1,2 Numerous studies indicate higher VO2peak levels are associated with decreased mortality along with a decreased risk for negative health outcomes such as diabetes, heart disease, pulmonary hypertension, and some forms of cancer.1, 2, 3, 4, 5, 6, 7 Peak heart rate (HR) during CPX is another important variable with higher peak HR values associated with a lower mortality risk.8,9 Other variables collected during CPX have received less attention but may also have prognostic utility, independently or in combination with VO2peak. One such CPX variable is peak oxygen pulse (O2 pulsepeak).

The O2 pulsepeak is determined by dividing VO2peak by peak HR obtained during CPX. Representing VO2 per heartbeat, O2 pulse is considered a marker of cardiovascular efficiency during exercise and, as such, is a proxy for stroke volume and peripheral oxygen extraction.10, 11, 12 Although these markers can be indicative of cardiovascular health, limited and conflicting data exist on the prognostic potential of O2 pulsepeak. Recent research has shown O2 pulsepeak is related to adverse outcomes in post-aortic dissection patients.13 Some research on men with cardiovascular disease has found that O2 pulsepeak is a significant predictor of mortality,10,14 while other research has found no relationship.15,16 More agreement is found with research on apparently healthy men, as multiple studies have reported that O2 pulsepeak is a significant predictor of mortality.10, 11, 12 However, there are conflicting findings regarding whether O2 pulsepeak complements VO2peak in predicting health outcomes; two studies suggest complementary improvements to risk prediction10,11 while one other suggests no benefit.12 To clarify the possible complementary benefit of O2 pulsepeak in risk prediction models for men, additional research is needed in other cohorts. Further, the research to date has only examined the prognostic potential of a single measure of O2 pulsepeak. Longitudinal changes to O2 pulsepeak have been reported17,18 and the next step is to determine if the degree of change predicts early mortality in a similar manner to longitudinal changes found with VO2peak.19,20

Considering the continued interest in understanding the prognostic potential of variables collected during CPX, more research is needed on O2 pulsepeak. Principally, previous research has only studied the relationship between O2 pulsepeak and mortality in apparently healthy men. Women typically have a lower O2 pulsepeak,18 which necessitates separate analyses. In addition, the relationship between VO2peak and mortality has been shown to differ between the sexes5,21 and a similar trend may occur with O2 pulsepeak. Thus, the primary aim of this study was to evaluate the relationship between O2 pulsepeak and all-cause mortality in a cohort of apparently healthy women and men. A secondary aim was to explore the relationship between longitudinal changes to O2 pulsepeak and all-cause mortality in apparently healthy women and men. We hypothesized that both a single measure of O2 pulsepeak as well as a measure of change in O2 pulsepeak would be significant predictors of mortality in women and men.

Section snippets

Methods

Data from the Ball State Adult Fitness Longitudinal Lifestyle Study (BALL ST) cohort were used for this study. The sample included apparently healthy adults aged 18–85 years old who performed at least one comprehensive health and fitness assessment between April 1, 1968 and December 31, 2016. For the analysis examining the prognostic potential of changes in O2 pulsepeak, the inclusion criteria were extended to include only those individuals who performed two comprehensive health and fitness

Results

Descriptive characteristics of the sample used for the analysis of a single measure of O2 pulsepeak are provided in Table 1. The sample included a total of 3877 participants (43% women) with an average age of 42.3 ± 12.0 years. Table 2 provides a comparison of the descriptive characteristics for participants identified as either living or deceased at the time of follow-up. A total of 730 participants (28% women) died during the follow-up period of 24.7 ± 11.8 years. The descriptive

Discussion

The present study examined the utility of single and longitudinal measures of O2 pulsepeak in apparently healthy women and men. A single measure of O2 pulsepeak was inversely related to all-cause mortality in men, similar to the findings from previous research.10, 11, 12 However, significant relationships between O2 pulsepeak and mortality were not observed in women following adjustments for potential confounders. Additionally, the concordance index and AIC values indicated that O2 pulsepeak

Financial support

Support for this project was provided, in part, from an American Heart Association Award #AIREA33930023 (M. Harber, PI).

Declaration of Competing Interest

The authors have no conflicts of interest to declare.

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