CRYSTAL CITY, VA. — The combination of smoking and an active lifestyle was associated with significantly worse lung function than was the combination of nonsmoking and a sedentary lifestyle in blacks, on the basis of data from more than 3,000 participants in the Jackson Heart Study.
Previous studies have shown that the poor lung function associated with a sedentary lifestyle can significantly predict cardiovascular problems, said Brenda Campbell Jenkins, Ph.D., and her colleagues at Jackson (Miss.) State University. Additional research suggests that blacks might be especially vulnerable to lung damage from smoking, they noted.
But no study has examined the combined effects of smoking and sedentary lifestyle and their effects on lung function, Dr. Campbell Jenkins said in an interview.
“We know that among African Americans there is a low prevalence of smoking and a high prevalence of sedentary lifestyle,” she said.
In this study, the researchers examined the joint effect of smoking and sedentary lifestyle on heart health in blacks, using data from the Jackson Heart Study, a population-based observational study including black adults aged 21–94 years living in the area of Jackson, Miss.
The researchers measured pulmonary function using forced vital capacity (FVC) and forced expiratory volume per second (FEV1). The study findings were presented in a poster at the meeting.
The participants were divided into four groups: nonsmoking nonsedentary, nonsmoking sedentary, smoking nonsedentary, and smoking sedentary. Sedentary lifestyle was defined as the lowest quartile of physical activity.
The mean percentages of predicted FEV1 values in women in the nonsmoking nonsedentary, nonsmoking sedentary, smoking nonsedentary, and smoking sedentary groups were 95%, 94%, 89%, and 85%. The differences between women in the nonsmoking sedentary and in the smoking nonsedentary groups were significant after controlling for multiple variables.
The mean percentages of predicted FVC values in women in the nonsmoking nonsedentary, nonsmoking sedentary, smoking nonsedentary, and smoking sedentary groups was 94%, 92%, 89%, and 88%, respectively.
The differences between women in the nonsmoking sedentary and in the smoking nonsedentary groups were significant after adjustment for multiple variables.
For men, the mean percentages of predicted FEV1 values in the four groups were 93%, 89%, 88%, 76%, respectively, but these differences were not significant. In addition, the mean percentages of predicted FVC values in each group were 91%, 88%, 91%, and 80%, respectively, and these differences were not significant.
However, after controlling for multiple variables, the mean FEV1 to FVC ratio was significantly higher among men in the nonsmoking sedentary group, compared with the smoking nonsedentary group (78.8 vs. 77.5).
Based on these findings, smoking and sedentary lifestyle were both negatively associated with lung function, but smoking tended to have more harmful effects, which was consistent with the literature, noted Dr. Sarpong, director, co—principal investigator, and senior biostatistician of the Jackson Heart Study.
However, more research is needed to determine the clinical implications of the findings.
Study participants were enrolled during 2000–2004. The current study included 1,191 men and 2,065 women aged 21–93 years (average, 54 years). Participants with prevalent cardiovascular disease, asthma, and incomplete measures of smoking or lung function were excluded.
The researchers had no financial conflicts to disclose. The study was supported by grants from the National Heart, Lung, and Blood Institute and the National Center for Minority Health and Health Disparities.