Abstract
Objectives: The purpose of this study was to externally validate the prognostic value of age- and gender-based nomograms and categorical definitions of impaired exercise capacity (EC). Background: Exercise capacity predicts death, but its use in routine clinical practice is hampered by its close correlation with age and gender. Methods: For a median of 5 years, we followed 22,275 patients without known heart disease who underwent symptom-limited stress testing. Models for predicted or impaired EC were identified by literature search. Gender-specific multivariable proportional hazards models were constructed. Four methods were used to assess validity: Akaike Information Criterion (AIC), right-censored c-index in 100 out-of-bootstrap samples, the Nagelkerke Index R2, and calculation of calibration error in 100 bootstrap samples. Results: There were 646 and 430 deaths in 13,098 men and 9,177 women, respectively. Of the 7 models tested in men, a model based on a Veterans Affairs cohort (predicted metabolic equivalents [METs] = 18 - [0.15 × age]) had the highest AIC and R2. In women, a model based on the St. James Take Heart Project (predicted METs = 14.7 - [0.13 × age]) performed best. Categorical definitions of fitness performed less well. Even after accounting for age and gender, there was still an important interaction with age, whereby predicted EC was a weaker predictor in older subjects (p for interaction <0.001 in men and 0.003 in women). Conclusions: Several methods describe EC accounting for age and gender-related differences, but their ability to predict mortality differ. Simple cutoff values fail to fully describe EC's strong predictive value.
| Original language | English |
|---|---|
| Pages (from-to) | 1867-1875 |
| Number of pages | 9 |
| Journal | Journal of the American College of Cardiology |
| Volume | 50 |
| Issue number | 19 |
| DOIs | |
| State | Published - Nov 6 2007 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Nursing(all)
Cite this
External Prognostic Validations and Comparisons of Age- and Gender-Adjusted Exercise Capacity Predictions. / Kim, Esther S H; Ishwaran, Hemant; Blackstone, Eugene; Lauer, Michael S.
In: Journal of the American College of Cardiology, Vol. 50, No. 19, 06.11.2007, p. 1867-1875.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - External Prognostic Validations and Comparisons of Age- and Gender-Adjusted Exercise Capacity Predictions
AU - Kim, Esther S H
AU - Ishwaran, Hemant
AU - Blackstone, Eugene
AU - Lauer, Michael S.
PY - 2007/11/6
Y1 - 2007/11/6
N2 - Objectives: The purpose of this study was to externally validate the prognostic value of age- and gender-based nomograms and categorical definitions of impaired exercise capacity (EC). Background: Exercise capacity predicts death, but its use in routine clinical practice is hampered by its close correlation with age and gender. Methods: For a median of 5 years, we followed 22,275 patients without known heart disease who underwent symptom-limited stress testing. Models for predicted or impaired EC were identified by literature search. Gender-specific multivariable proportional hazards models were constructed. Four methods were used to assess validity: Akaike Information Criterion (AIC), right-censored c-index in 100 out-of-bootstrap samples, the Nagelkerke Index R2, and calculation of calibration error in 100 bootstrap samples. Results: There were 646 and 430 deaths in 13,098 men and 9,177 women, respectively. Of the 7 models tested in men, a model based on a Veterans Affairs cohort (predicted metabolic equivalents [METs] = 18 - [0.15 × age]) had the highest AIC and R2. In women, a model based on the St. James Take Heart Project (predicted METs = 14.7 - [0.13 × age]) performed best. Categorical definitions of fitness performed less well. Even after accounting for age and gender, there was still an important interaction with age, whereby predicted EC was a weaker predictor in older subjects (p for interaction <0.001 in men and 0.003 in women). Conclusions: Several methods describe EC accounting for age and gender-related differences, but their ability to predict mortality differ. Simple cutoff values fail to fully describe EC's strong predictive value.
AB - Objectives: The purpose of this study was to externally validate the prognostic value of age- and gender-based nomograms and categorical definitions of impaired exercise capacity (EC). Background: Exercise capacity predicts death, but its use in routine clinical practice is hampered by its close correlation with age and gender. Methods: For a median of 5 years, we followed 22,275 patients without known heart disease who underwent symptom-limited stress testing. Models for predicted or impaired EC were identified by literature search. Gender-specific multivariable proportional hazards models were constructed. Four methods were used to assess validity: Akaike Information Criterion (AIC), right-censored c-index in 100 out-of-bootstrap samples, the Nagelkerke Index R2, and calculation of calibration error in 100 bootstrap samples. Results: There were 646 and 430 deaths in 13,098 men and 9,177 women, respectively. Of the 7 models tested in men, a model based on a Veterans Affairs cohort (predicted metabolic equivalents [METs] = 18 - [0.15 × age]) had the highest AIC and R2. In women, a model based on the St. James Take Heart Project (predicted METs = 14.7 - [0.13 × age]) performed best. Categorical definitions of fitness performed less well. Even after accounting for age and gender, there was still an important interaction with age, whereby predicted EC was a weaker predictor in older subjects (p for interaction <0.001 in men and 0.003 in women). Conclusions: Several methods describe EC accounting for age and gender-related differences, but their ability to predict mortality differ. Simple cutoff values fail to fully describe EC's strong predictive value.
UR - http://www.scopus.com/inward/record.url?scp=35548988391&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=35548988391&partnerID=8YFLogxK
U2 - 10.1016/j.jacc.2007.08.003
DO - 10.1016/j.jacc.2007.08.003
M3 - Article
C2 - 17980254
AN - SCOPUS:35548988391
VL - 50
SP - 1867
EP - 1875
JO - Journal of the American College of Cardiology
JF - Journal of the American College of Cardiology
SN - 0735-1097
IS - 19
ER -