Physical Activity Participation in a Multiethnic Population
Physical Activity Participation in a Multiethnic Population
The DHS is a longitudinal study of CV health in a probability based population sample of Dallas County adults aged 18 to 65 years. The DHS probability-based population was taken from a random sample constructed from 15,000 geocoded mailing addresses, representing 10 mutually exclusive geographic strata of different ethnic composition, which included each of the 405 Census Tracts in Dallas County. African Americans were intentionally oversampled to make up 50% of the study cohort. Full details of participant selection and study design have been published previously. Participants were enrolled from July 2000 to January 2002, and participant mortality was obtained through July 1, 2008, using the National Death Index. Deaths were classified as CV if they included International Statistical Classification of Diseases, 10th Revision, codes I10-I80.3.
Demographic information, including race/ethnicity, household income, educational level achieved, and medical history, was determined by self-report at study entry. Body mass index (BMI) was calculated based on measured height and weight. Hypertension was defined as one of the following: systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or the use of antihypertensive medication. Hypercholesterolemia was defined by self-report, by use of lipid-lowering medication, or by a fasting low-density lipoprotein ≥160 mg/dL. Diabetes mellitus was defined by self-report, by use of antihyperglycemic medication, or by fasting serum glucose ≥126 mg/dL.
At study entry, participants were asked about their PA participation and health beliefs as part of a detailed questionnaire. For PA, the question was asked, "During the past month, did you participate in any physical activities or exercises such as running, calisthenics, golf, gardening, or walking for exercise?" in a yes/no format in accordance with previous literature. Questions abstracted from the 1999 Behavioral Risk Factor Surveillance System were incorporated into the DHS survey instrument to assess beliefs about general health perceptions and health care access.8 Regarding health perceptions and exercise, "How effective do you think regular exercise is in preventing a heart attack?" was asked on a Likert scale.
Baseline characteristics were compared between PA participants and nonparticipants using the unpaired Student t test for continuous variables and the χ2 test for categorical variables. Logistic regression was used to quantify the association between race/ethnicity and PA participation. Multivariable Cox proportional hazards models were used to determine the association of PA with mortality after adjustment for age, sex, ethnicity, BMI, history of diabetes, history of hypertension, and income. All P values are 2 sided; P b .05 was considered statistically significant. Statistical analyses were performed using SAS version 9.2 (SAS Institute, Inc, Cary, NC).
Grant support for the Dallas Heart Study was provided by the Donald W. Reynolds Foundation at the University of Texas Southwestern Medical Center, Dallas, TX; the US Public Health Service General Clinical Research Center Grant M01-RR00633 from National Institutes of Health; National Center for Research Resources—Clinical Research; and the National Heart, Lung, and Blood Institute T35-HL086346. The authors are solely responsible for the design and conduct of this study, all study analyses, the drafting and editing of the manuscript, and its final contents.
Methods
The DHS is a longitudinal study of CV health in a probability based population sample of Dallas County adults aged 18 to 65 years. The DHS probability-based population was taken from a random sample constructed from 15,000 geocoded mailing addresses, representing 10 mutually exclusive geographic strata of different ethnic composition, which included each of the 405 Census Tracts in Dallas County. African Americans were intentionally oversampled to make up 50% of the study cohort. Full details of participant selection and study design have been published previously. Participants were enrolled from July 2000 to January 2002, and participant mortality was obtained through July 1, 2008, using the National Death Index. Deaths were classified as CV if they included International Statistical Classification of Diseases, 10th Revision, codes I10-I80.3.
Demographic information, including race/ethnicity, household income, educational level achieved, and medical history, was determined by self-report at study entry. Body mass index (BMI) was calculated based on measured height and weight. Hypertension was defined as one of the following: systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or the use of antihypertensive medication. Hypercholesterolemia was defined by self-report, by use of lipid-lowering medication, or by a fasting low-density lipoprotein ≥160 mg/dL. Diabetes mellitus was defined by self-report, by use of antihyperglycemic medication, or by fasting serum glucose ≥126 mg/dL.
At study entry, participants were asked about their PA participation and health beliefs as part of a detailed questionnaire. For PA, the question was asked, "During the past month, did you participate in any physical activities or exercises such as running, calisthenics, golf, gardening, or walking for exercise?" in a yes/no format in accordance with previous literature. Questions abstracted from the 1999 Behavioral Risk Factor Surveillance System were incorporated into the DHS survey instrument to assess beliefs about general health perceptions and health care access.8 Regarding health perceptions and exercise, "How effective do you think regular exercise is in preventing a heart attack?" was asked on a Likert scale.
Baseline characteristics were compared between PA participants and nonparticipants using the unpaired Student t test for continuous variables and the χ2 test for categorical variables. Logistic regression was used to quantify the association between race/ethnicity and PA participation. Multivariable Cox proportional hazards models were used to determine the association of PA with mortality after adjustment for age, sex, ethnicity, BMI, history of diabetes, history of hypertension, and income. All P values are 2 sided; P b .05 was considered statistically significant. Statistical analyses were performed using SAS version 9.2 (SAS Institute, Inc, Cary, NC).
Grant support for the Dallas Heart Study was provided by the Donald W. Reynolds Foundation at the University of Texas Southwestern Medical Center, Dallas, TX; the US Public Health Service General Clinical Research Center Grant M01-RR00633 from National Institutes of Health; National Center for Research Resources—Clinical Research; and the National Heart, Lung, and Blood Institute T35-HL086346. The authors are solely responsible for the design and conduct of this study, all study analyses, the drafting and editing of the manuscript, and its final contents.
