Independent risk factors for major respiratory symptoms, lung diseases, and obstruction were then determined using logistic regression models. The stepwise method was used with a p value <0.01 to enter and p>0.05 to remove a variable. Participants with a physician-diagnosed lung disease (asthma, chronic bronchitis, or emphysema) were excluded from the model for airways obstruction.
All of the following variables were offered for entry into each logistic regression model: gender, age, height, weight, waist and hip circumference, race, education completed, annual income, clinic location, cigarette smoking status (current, former, never), pack-years of smoking, InFEVi, InFVC (ln=natural log), and obstruction. Log transformation of the FEVi and FVC resulted in better model fits and enabled a simple statistical test to determine if the ratio of FEVi/FVC, when substituted for the FEVi and FVC variables, would significantly improve the fit of each model. This was never true. Responses to all of the ATS questions regarding respiratory symptoms listed in Table 1 were entered into the lung disease models. Two cardiovascular variables were also allowed to enter into each model: CHD=a history of coronary heart disease (myocardial infarction, angina pectoris, or cardiac bypass surgery); and CHF=a definite history of congestive heart failure.
A total of 5,201 participants were enrolled from May 1989 to June 1990 into the CHS study; 45 percent were men and 4 percent were nonwhite. Participants were recruited in roughly equal numbers from the four communities (1,275 to 1,318 each). Table 2 shows their age distribution: 13 percent were 80 years or older. The majority were married (69 percent), 23 percent were widowed, 4.1 percent were never married, and only 3.3 percent were divorced More info canadian family pharmacy online. They were relatively well educated: 34 percent had at least some college education and an additional 37 percent were high school graduates. A detailed description of the cohort is published elsewhere.
Table 1—Respiratory Symptom and Lung Disease Prevalence by Smoking Status and Gender
|Frequent cough (7B)||8.2||6.1||8.6||7.6||25.1||27.7||10.0|
|Cough day and night (7D)||9.1||5.7||8.6||8.1||24.3||27.7||10.5|
|Cough >3 mo (7E)||7.4||5.7||7.5||7.6||22.8||24.2||9.2|
|Frequent phlegm (8B)||8.0||12.5||10.3||15.4||27.7||38.1||13.8|
|Phlegm day and night (8D)||7.4||11.4||8.6||14.5||25.1||32.0||12.4|
|Phlegm >3 mo (8E)||7.9||11.5||9.9||16.0||23.8||31.1||13.1|
|Wheeze day and night (10A3)||4.1||3.2||4.5||5.7||10.7||18.6||5.6|
|Wheeze and dyspnea (11 A)||6.9||6.0||9.8||7.2||10.2||9.5||7.7|
|Wheezing requiring medication (11D)||5.2||4.2||6.5||4.9||8.1||5.2||5.5|
|Dyspnea grade 3 (13C)||10.0||6.4||12.5||9.6||11.5||12.6||10.1|
|Chronic bronchitis (18C)||5.2||2.4||8.2||4.4||7.9||6.5||5.4|
|Acute bronchitis (17-IB)||23.6||13.1||30.9||17.2||34.6||19.9||22.5|
|Hay fever (17-3)||12.2||14.1||14.6||9.3||15.2||6.9||12.2|
Table 2—Demographic Characteristics of CHS Participants
|Age distribution, yr|
|Pack-years, mean (SD)|