Previous studies have shown female sex, impaired pulmonary function, older age, malnutrition, and... more Previous studies have shown female sex, impaired pulmonary function, older age, malnutrition, and colonization of the respiratory tract with Pseudomonas cepacia to be associated with a poor prognosis in patients with cystic fibrosis. We sought to determine the prognostic value of exercise testing in addition to the other prognostic factors. A total of 109 patients with cystic fibrosis, 7 to 35 years old, underwent pulmonary-function and exercise testing in the late 1970s. They were followed for eight years to determine the factors associated with subsequent mortality. Survival rates were calculated with standard life-table methods. Cox proportional-hazards regression models were used to determine crude relative risks of mortality and relative risks adjusted for age, sex, body-mass index, forced expiratory volume in one second (FEV1) end-tidal partial pressure of carbon dioxide (PCO2) at peak exercise, and oxygen consumption at peak exercise (VO2 peak). Patients with the highest levels of aerobic fitness (VO2 peak, > or = 82 percent of predicted) had a survival rate of 83 percent at eight years, as compared with rates of 51 percent and 28 percent for patients with middle (VO2 peak, 59 to 81 percent of predicted) and lowest (VO2 peak, < or = 58 percent of predicted) levels of fitness, respectively. After adjustment for other risk factors, patients with higher levels of aerobic fitness were more than three times as likely to survive than patients with lower levels of fitness. Colonization with P. cepacia was associated with a risk of dying that was increased fivefold. Age, sex, body-mass index, FEV1, and end-tidal PCO2 at peak exercise were not independently correlated with mortality. Higher levels of aerobic fitness in patients with cystic fibrosis are associated with a significantly lower risk of dying. Although better aerobic fitness may simply be a marker for less severe illness, measurement of VO2 peak appears to be valuable for predicting prognosis. Further research is warranted to determine whether improving aerobic fitness through exercise programs will result in a better prognosis.
This study was conducted to: 1) measure total physical activity levels, including the intensities... more This study was conducted to: 1) measure total physical activity levels, including the intensities of the various types of activities, in children and adolescents with CF compared with non-CF healthy control subjects; and 2) determine whether vigorous activity level was related to aerobic fitness and disease status in patients with CF. Thirty patients with CF (18 male, 12 female) and 30 control subjects (17 male, 13 female), 7-17 yr old, participated in this study. Habitual physical activity was measured using Kriska's Modifiable Activity Questionnaire (MAQ) and the past year's average of total hours, MET-hours, and vigorous (VIG) hours (>6 METs) of activity per week were determined. Aerobic fitness was determined from peak oxygen uptake (VO2peak) obtained via maximal exercise testing on a cycle ergometer. Standard spirometry was used to measure pulmonary function. Body mass index (BMI) was determined from height and weight measurements. The CF and control groups were similar in age and gender distribution, but the patients were smaller (BMI, 98 vs 112% of predicted) and less aerobically fit (36.5 vs 41.4 mL x kg(-1) x min(-1)). Total and MET-hours of physical activity did not differ between groups; however, the CF group participated in significantly fewer hours of vigorous activities than the control group (2 vs 3.7 h x wk(-1)). In patients with worse lung disease, VIG-h x wk(-1) were significantly related to VO2peak (r = 0.83). These results suggest that children with CF engage in less vigorous physical activities than their healthy non-CF peers, despite having good lung function. In view of the progressive nature of the disease, and the association between aerobic fitness and vigorous activity, patients should be encouraged to engage in more vigorous activities that promote aerobic fitness and may ultimately have an impact on survival.
To compare serum uric acid levels in adolescents born prematurely and adolescents born at term an... more To compare serum uric acid levels in adolescents born prematurely and adolescents born at term and to assess the correlation between serum uric acid and blood pressure (BP) in those born prematurely. In this observational cohort study, 124 adolescents born prematurely and 44 adolescents born at term were studied at 14 years of age. Multivariate analyses were used to describe the relationship of premature birth to serum uric acid while adjusting for confounding variables. Pearson correlation was used to describe the relationship between uric acid and systolic BP among those born prematurely. Adjusting for race, sex, maternal hypertension, and fetal growth, we found that preterm adolescents had greater serum uric acid levels than adolescents born at term (adjusted mean difference 0.46, 95% CI 0.10-0.81 mg/dL; 27.4, 6-48.2 μmol/L; P = .012). Among those born prematurely, uric acid was positively correlated with systolic BP (Pearson correlation coefficient: 0.29, 0.12-0.44; P = .0013). ...
Previous studies have shown female sex, impaired pulmonary function, older age, malnutrition, and... more Previous studies have shown female sex, impaired pulmonary function, older age, malnutrition, and colonization of the respiratory tract with Pseudomonas cepacia to be associated with a poor prognosis in patients with cystic fibrosis. We sought to determine the prognostic value of exercise testing in addition to the other prognostic factors. A total of 109 patients with cystic fibrosis, 7 to 35 years old, underwent pulmonary-function and exercise testing in the late 1970s. They were followed for eight years to determine the factors associated with subsequent mortality. Survival rates were calculated with standard life-table methods. Cox proportional-hazards regression models were used to determine crude relative risks of mortality and relative risks adjusted for age, sex, body-mass index, forced expiratory volume in one second (FEV1) end-tidal partial pressure of carbon dioxide (PCO2) at peak exercise, and oxygen consumption at peak exercise (VO2 peak). Patients with the highest levels of aerobic fitness (VO2 peak, > or = 82 percent of predicted) had a survival rate of 83 percent at eight years, as compared with rates of 51 percent and 28 percent for patients with middle (VO2 peak, 59 to 81 percent of predicted) and lowest (VO2 peak, < or = 58 percent of predicted) levels of fitness, respectively. After adjustment for other risk factors, patients with higher levels of aerobic fitness were more than three times as likely to survive than patients with lower levels of fitness. Colonization with P. cepacia was associated with a risk of dying that was increased fivefold. Age, sex, body-mass index, FEV1, and end-tidal PCO2 at peak exercise were not independently correlated with mortality. Higher levels of aerobic fitness in patients with cystic fibrosis are associated with a significantly lower risk of dying. Although better aerobic fitness may simply be a marker for less severe illness, measurement of VO2 peak appears to be valuable for predicting prognosis. Further research is warranted to determine whether improving aerobic fitness through exercise programs will result in a better prognosis.
This study was conducted to: 1) measure total physical activity levels, including the intensities... more This study was conducted to: 1) measure total physical activity levels, including the intensities of the various types of activities, in children and adolescents with CF compared with non-CF healthy control subjects; and 2) determine whether vigorous activity level was related to aerobic fitness and disease status in patients with CF. Thirty patients with CF (18 male, 12 female) and 30 control subjects (17 male, 13 female), 7-17 yr old, participated in this study. Habitual physical activity was measured using Kriska's Modifiable Activity Questionnaire (MAQ) and the past year's average of total hours, MET-hours, and vigorous (VIG) hours (>6 METs) of activity per week were determined. Aerobic fitness was determined from peak oxygen uptake (VO2peak) obtained via maximal exercise testing on a cycle ergometer. Standard spirometry was used to measure pulmonary function. Body mass index (BMI) was determined from height and weight measurements. The CF and control groups were similar in age and gender distribution, but the patients were smaller (BMI, 98 vs 112% of predicted) and less aerobically fit (36.5 vs 41.4 mL x kg(-1) x min(-1)). Total and MET-hours of physical activity did not differ between groups; however, the CF group participated in significantly fewer hours of vigorous activities than the control group (2 vs 3.7 h x wk(-1)). In patients with worse lung disease, VIG-h x wk(-1) were significantly related to VO2peak (r = 0.83). These results suggest that children with CF engage in less vigorous physical activities than their healthy non-CF peers, despite having good lung function. In view of the progressive nature of the disease, and the association between aerobic fitness and vigorous activity, patients should be encouraged to engage in more vigorous activities that promote aerobic fitness and may ultimately have an impact on survival.
To compare serum uric acid levels in adolescents born prematurely and adolescents born at term an... more To compare serum uric acid levels in adolescents born prematurely and adolescents born at term and to assess the correlation between serum uric acid and blood pressure (BP) in those born prematurely. In this observational cohort study, 124 adolescents born prematurely and 44 adolescents born at term were studied at 14 years of age. Multivariate analyses were used to describe the relationship of premature birth to serum uric acid while adjusting for confounding variables. Pearson correlation was used to describe the relationship between uric acid and systolic BP among those born prematurely. Adjusting for race, sex, maternal hypertension, and fetal growth, we found that preterm adolescents had greater serum uric acid levels than adolescents born at term (adjusted mean difference 0.46, 95% CI 0.10-0.81 mg/dL; 27.4, 6-48.2 μmol/L; P = .012). Among those born prematurely, uric acid was positively correlated with systolic BP (Pearson correlation coefficient: 0.29, 0.12-0.44; P = .0013). ...
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