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Self-reported exercise and longitudinal outcomes in cystic fibrosis: a retrospective cohort study.

Collaco JM, Blackman SM, Raraigh KS, Morrow CB, Cutting GR, Paranjape SM - BMC Pulm Med (2014)

Bottom Line: Questionnaires, chart review, and U.S. CF Foundation Patient Registry data were used to track outcomes.Within the study sample 75% of subjects self-reported regular exercise.In adjusted mixed models, exercise was associated with both a reduced decline in FEV1 (p < 0.001) and BMI Z-score (p = 0.001) for adults, but not children aged 10-17 years old.

View Article: PubMed Central - PubMed

Affiliation: Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins Medical Institutions, David M, Rubenstein Building, 200 North Wolfe Street, 21287 Baltimore, MD, USA. mcollac1@jhmi.edu.

ABSTRACT

Background: Cystic fibrosis (CF) is characterized by recurrent respiratory infections and progressive lung disease. Whereas exercise may contribute to preserving lung function, its benefit is difficult to ascertain given the selection bias of healthier patients being more predisposed to exercise. Our objective was to examine the role of self-reported exercise with longitudinal lung function and body mass index (BMI) measures in CF.

Methods: A total of 1038 subjects with CF were recruited through the U.S. CF Twin-Sibling Study. Questionnaires were used to determine exercise habits. Questionnaires, chart review, and U.S. CF Foundation Patient Registry data were used to track outcomes.

Results: Within the study sample 75% of subjects self-reported regular exercise. Exercise was associated with an older age of diagnosis (p = 0.002), older age at the time of ascertainment (p < 0.001), and higher baseline FEV1 (p = 0.001), but not CFTR genotype (p = 0.64) or exocrine pancreatic function (p = 0.19). In adjusted mixed models, exercise was associated with both a reduced decline in FEV1 (p < 0.001) and BMI Z-score (p = 0.001) for adults, but not children aged 10-17 years old.

Conclusions: In our retrospective study, self-reported exercise was associated with improved longitudinal nutritional and pulmonary outcomes in cystic fibrosis for adults. Although prospective studies are needed to confirm these associations, programs to promote regular exercise among individuals with cystic fibrosis would be beneficial.

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Related in: MedlinePlus

Exercise participation vs. age. Lowess regression of percentage of subjects reporting specific types of exercise versus age at the time of ascertainment.
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Fig1: Exercise participation vs. age. Lowess regression of percentage of subjects reporting specific types of exercise versus age at the time of ascertainment.

Mentions: Differences in baseline characteristics and clinical outcomes were compared using T-tests for continuous variables and Pearson’s chi-square for categorical variables. To assess the effect of self-reported exercise on longitudinal changes in lung function while accounting for confounders, we employed mixed-effects regression modeling for longitudinal repeated measures with unstructured covariance and random effects for intercept and slope. For longitudinal effects, we only assessed subjects over the age of 10 years based on when rates of exercise participation stabilized (Figure 1). Baseline FEV1, sex, age of diagnosis, and age of questionnaire completion were included as potential confounders as these variables differed between those who reported exercising and those who did not (Table 1). All models used a dependent variable of FEV1 percent predicted consisting of all FEV1 measurements obtained over 5 years following the time of ascertainment of exercise status (t = 0). The independent variables were time since ascertainment, exercise status, and a time-exercise interaction term. Exercise status was defined as no exercise = 0 and any exercise = 1 for the any exercise models and as no competitive exercise = 0 and any competitive exercise = 1 for the competitive exercise models. All adjusted models included the covariates of baseline FEV1 percent predicted age at diagnosis, age at t = 0, and sex. We tested whether different subgroups of the study sample (females, adults, and subjects with reduced lung function) had different changes in lung function with exercise using time-exercise-sex, time-exercise-adult (adults being ≥18 years old), and time-exercise-reduced lung function (reduced lung function being baseline FEV1 < 80%) interaction terms. The interaction for sex (female = 1; male = 0) model included a time-exercise-sex interaction term. The interaction for age (≥18yo = 1; <18yo = 0) model included both the term dichotomous term for age and a time-exercise-dichotomous age interaction term. The interaction for baseline FEV1 (≥80% = 0; <80% = 1) model included both the term dichotomous term for baseline FEV1 and a time-exercise-dichotomous FEV1 interaction term. P values of less than 0.05 were considered statistically significant. Similar analyses were performed for BMI Z-scores, except both baseline BMI Z-score and baseline FEV1 were retained as covariates. In addition, the interaction term for time-exercise-reduced BMI Z-score was defined by reduced BMI-Z score < 0. All analyses were performed using Stata IC 11.0 (StataCorp LP, College Station, TX).Figure 1


Self-reported exercise and longitudinal outcomes in cystic fibrosis: a retrospective cohort study.

Collaco JM, Blackman SM, Raraigh KS, Morrow CB, Cutting GR, Paranjape SM - BMC Pulm Med (2014)

Exercise participation vs. age. Lowess regression of percentage of subjects reporting specific types of exercise versus age at the time of ascertainment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4195986&req=5

Fig1: Exercise participation vs. age. Lowess regression of percentage of subjects reporting specific types of exercise versus age at the time of ascertainment.
Mentions: Differences in baseline characteristics and clinical outcomes were compared using T-tests for continuous variables and Pearson’s chi-square for categorical variables. To assess the effect of self-reported exercise on longitudinal changes in lung function while accounting for confounders, we employed mixed-effects regression modeling for longitudinal repeated measures with unstructured covariance and random effects for intercept and slope. For longitudinal effects, we only assessed subjects over the age of 10 years based on when rates of exercise participation stabilized (Figure 1). Baseline FEV1, sex, age of diagnosis, and age of questionnaire completion were included as potential confounders as these variables differed between those who reported exercising and those who did not (Table 1). All models used a dependent variable of FEV1 percent predicted consisting of all FEV1 measurements obtained over 5 years following the time of ascertainment of exercise status (t = 0). The independent variables were time since ascertainment, exercise status, and a time-exercise interaction term. Exercise status was defined as no exercise = 0 and any exercise = 1 for the any exercise models and as no competitive exercise = 0 and any competitive exercise = 1 for the competitive exercise models. All adjusted models included the covariates of baseline FEV1 percent predicted age at diagnosis, age at t = 0, and sex. We tested whether different subgroups of the study sample (females, adults, and subjects with reduced lung function) had different changes in lung function with exercise using time-exercise-sex, time-exercise-adult (adults being ≥18 years old), and time-exercise-reduced lung function (reduced lung function being baseline FEV1 < 80%) interaction terms. The interaction for sex (female = 1; male = 0) model included a time-exercise-sex interaction term. The interaction for age (≥18yo = 1; <18yo = 0) model included both the term dichotomous term for age and a time-exercise-dichotomous age interaction term. The interaction for baseline FEV1 (≥80% = 0; <80% = 1) model included both the term dichotomous term for baseline FEV1 and a time-exercise-dichotomous FEV1 interaction term. P values of less than 0.05 were considered statistically significant. Similar analyses were performed for BMI Z-scores, except both baseline BMI Z-score and baseline FEV1 were retained as covariates. In addition, the interaction term for time-exercise-reduced BMI Z-score was defined by reduced BMI-Z score < 0. All analyses were performed using Stata IC 11.0 (StataCorp LP, College Station, TX).Figure 1

Bottom Line: Questionnaires, chart review, and U.S. CF Foundation Patient Registry data were used to track outcomes.Within the study sample 75% of subjects self-reported regular exercise.In adjusted mixed models, exercise was associated with both a reduced decline in FEV1 (p < 0.001) and BMI Z-score (p = 0.001) for adults, but not children aged 10-17 years old.

View Article: PubMed Central - PubMed

Affiliation: Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins Medical Institutions, David M, Rubenstein Building, 200 North Wolfe Street, 21287 Baltimore, MD, USA. mcollac1@jhmi.edu.

ABSTRACT

Background: Cystic fibrosis (CF) is characterized by recurrent respiratory infections and progressive lung disease. Whereas exercise may contribute to preserving lung function, its benefit is difficult to ascertain given the selection bias of healthier patients being more predisposed to exercise. Our objective was to examine the role of self-reported exercise with longitudinal lung function and body mass index (BMI) measures in CF.

Methods: A total of 1038 subjects with CF were recruited through the U.S. CF Twin-Sibling Study. Questionnaires were used to determine exercise habits. Questionnaires, chart review, and U.S. CF Foundation Patient Registry data were used to track outcomes.

Results: Within the study sample 75% of subjects self-reported regular exercise. Exercise was associated with an older age of diagnosis (p = 0.002), older age at the time of ascertainment (p < 0.001), and higher baseline FEV1 (p = 0.001), but not CFTR genotype (p = 0.64) or exocrine pancreatic function (p = 0.19). In adjusted mixed models, exercise was associated with both a reduced decline in FEV1 (p < 0.001) and BMI Z-score (p = 0.001) for adults, but not children aged 10-17 years old.

Conclusions: In our retrospective study, self-reported exercise was associated with improved longitudinal nutritional and pulmonary outcomes in cystic fibrosis for adults. Although prospective studies are needed to confirm these associations, programs to promote regular exercise among individuals with cystic fibrosis would be beneficial.

Show MeSH
Related in: MedlinePlus