Lung function as a risk factor for coronary heart disease

Exploring the 175-year history of spirometry and the vital lessons it can teach us today

175 years have elapsed since John Hutchinson introduced the world to his version of an apparatus that had been in development for nearly two centuries, the spirometer. Though he was not the first to build a device that sought to measure breathing and quantify the impact of disease and occupation on lung function, Hutchison coined the terms spirometer and vital capacity that are still in use today, securing his place in medical history. As Hutchinson envisioned, spirometry would become crucial to our growing knowledge of respiratory pathophysiology, from Tiffeneau and Pinelli's work on forced expiratory volumes, to Fry and Hyatt's description of the flow-volume curve. In the 20th century, standardization of spirometry further broadened its reach and prognostic potential. Today, spirometry is recognized as essential to respiratory disease diagnosis, management and research. However, controversy exists in some of its applications, uptake in primary care remains sub-optimal and there are concerns related to the way in which race is factored into interpretation. Moving forward, these failings must be addressed, and innovations like Internet-enabled portable spirometers may present novel opportunities. We must also consider the physiologic and practical limitations inherent to spirometry and further investigate complementary technologies such as respiratory oscillometry and other emerging technologies that assess lung function. Through an exploration of the storied history of spirometry, we can better contextualize its current landscape and appreciate the trends that have repeatedly arisen over time. This may help to improve our current use of spirometry and may allow us to anticipate the obstacles confronting emerging pulmonary function technologies.

Longitudinal change in lung function and subsequent risks of cardiovascular events: evidence from four prospective cohort studies

BACKGROUND

Lung function is constantly changing over the life course. Although the relation of cross-sectional lung function measure and adverse outcomes has been reported, data on longitudinal change and subsequent cardiovascular (CV) events risks are scarce. Therefore, this study is to determine the association of longitudinal change in lung function and subsequent cardiovascular risks.

METHODS

This study analyzed the data from four prospective cohorts. Subjects with at least two lung function tests were included. We calculated the rate of forced respiratory volume in 1 s (FEV1) and forced vital capacity (FVC) decline for each subject and categorized them into quartiles. The primary outcome was CV events, defined as a composite of coronary heart disease (CHD), chronic heart failure (CHF), stroke, and any CV death. Cox proportional hazards regression and restricted cubic spline models were applied.

RESULTS

The final sample comprised 12,899 participants (mean age 48.58 years; 43.61% male). Following an average of 14.79 (10.69) years, 3950 CV events occurred. Compared with the highest FEV1 quartile (Q4), the multivariable HRs for the lowest (Q1), 2nd (Q2), and 3rd quartiles (Q3) were 1.33 (95%CI 1.19, 1.49), 1.30 (1.16, 1.46), and 1.07 (0.95, 1.21), respectively. Likewise, compared with the reference quartile (Q4), the group that experienced a faster decline in FVC had higher HRs for CV events (1.06 [95%CI 0.94-1.20] for Q3, 1.15 [1.02-1.30] for Q2, and 1.28 [1.14-1.44] for Q1). The association remained robust across a series of sensitivity analyses and nearly all subgroups but was more evident in subjects < 60 years.

CONCLUSIONS

We observed a monotonic increase in risks of CV events with a faster decline in FEV1 and FVC. These findings emphasize the value of periodic evaluation of lung function and open new opportunities for disease prevention.

Association of lung function with coronary heart disease and cardiovascular disease outcomes in elderly: the Rancho Bernardo study

INTRODUCTION

Lung function is inversely associated with coronary heart disease (CHD) and cardiovascular disease (CVD). We evaluated the prospective association of reduced lung function by spirometry and CHD or CVD events in older community-dwelling adults.

METHODS

We studied 1548 participants (mean age 73.6 ± 9.2 years, 42% males) from the Rancho Bernardo Study using age, sex, and risk-factor adjusted Cox regression to assess pulmonary function (FEV1, FVC, and FEV1/FVC ratio) as a predictor of CHD and CVD events followed for up to 22 years.

RESULTS

Of CVD risk factors, older age, male sex, current/past smoking, physical exercise (<3× a week), and prevalent CVD predicted an increased risk of CHD and CVD. Higher FEV1 and FVC were each associated with a decreased risk of CHD [HR 0.80 (0.73-0.88) for both FEV1 and FVC, per SD, p < 0.01] and CVD [HR 0.82 (0.74-0.91) for both FEV1 and FVC, per SD, p < 0.01]. Those in the lowest quartiles of FEV1 and FVC had hazard ratios of 1.68 (1.33-2.13) and 1.55 (1.21-2.00) respectively for CHD and 1.74 (1.34-2.25) and 1.49 (1.13-1.96) respectively for CVD (all p < 0.01, relative to those in the highest quartile). Similar findings were observed for CHD and CVD mortality. Sex- and age-stratified analyses showed the strongest associations for CHD and CVD events in women and in the oldest participants.

CONCLUSIONS

FEV1 and FVC are inversely associated with risk of future CHD and CVD events in older community-dwelling adults and may add to CVD risk stratification in the elderly.

Joint effects of smoking and sedentary lifestyle on lung function in African Americans: the Jackson Heart Study cohort

This study examined: (a) differences in lung function between current and non current smokers who had sedentary lifestyles and non sedentary lifestyles and (b) the mediating effect of sedentary lifestyle on the association between smoking and lung function in African Americans. Sedentary lifestyle was defined as the lowest quartile of the total physical activity score. The results of linear and logistic regression analyses revealed that non smokers with non sedentary lifestyles had the highest level of lung function, and smokers with sedentary lifestyles had the lowest level. The female non-smokers with sedentary lifestyles had a significantly higher FEV1% predicted and FVC% predicted than smokers with non sedentary lifestyles (93.3% vs. 88.6%; p = 0.0102 and 92.1% vs. 86.9%; p = 0.0055 respectively). FEV1/FVC ratio for men was higher in non smokers with sedentary lifestyles than in smokers with non sedentary lifestyles (80.9 vs. 78.1; p = 0.0048). Though smoking is inversely associated with lung function, it seems to have a more deleterious effect than sedentary lifestyle on lung function. Physically active smokers had higher lung function than their non physically active counterparts.

Understanding socioeconomic and racial differences in adult lung function

RATIONALE

The contribution of socioeconomic factors to racial differences in the distribution of lung function is not well understood.

OBJECTIVES

We investigated the contribution of socioeconomic factors to racial differences in FEV₁ using statistical tools that allow for examination across the population distribution of FEV₁.

METHODS

We compared FEV₁ for white and African-American participants (aged 20-80 yr) in NHANES III with greater than or equal to two acceptable maneuvers to a restricted sample following the routine exclusion criteria used to derive population reference equations. Ordinary least squares and quantile regression analyses using spirometric, anthropometric, and socioeconomic data (high school completion) were performed separately by sex for both data sets.

MEASUREMENTS AND MAIN RESULTS

In the entire sample with acceptable spirometry (n ¼ 9,658), high school completion was associated with a mean 69.13-ml increase in FEV₁ for males (P , 0.05) and a mean 50.75-ml increase in FEV₁ for females (P , 0.01). In quantile regression analysis, we observed a significant racial difference in the association of high school completion with FEV₁ among both sexes that varied across the distribution; college completion was associated with an additional increase in FEV₁ for white males (70.36-250.76 ml) and white females (57.87-317.77 ml). Routine exclusion criteria differentially excluded individuals by age, race, and education. In the restricted sample (n ¼ 2,638), the association with high school completion was not significant.

CONCLUSIONS

High school completion is associated with racially patterned improvements in the FEV₁ of adults in the general population. The application of routine exclusion criteria leads to underestimates of the role of high school completion on FEV₁.

Vital capacity and selected metabolic diseases in middle-aged Japanese men

OBJECTIVE

To elucidate the association between vital capacity and the presence of selected metabolic diseases in middle-aged Japanese men.

METHODS

A cross-sectional analysis of the associations among forced vital capacity (FVC), static vital capacity as a percentage of that predicted (%VC) and the presence of metabolic diseases was performed.

RESULTS

In a univariate linear regression analysis, FVC and %VC were inversely associated with poor vegetable intake, cigarette smoking and body mass index, but not with physical activity or ethanol consumption. In a logistic regression analysis adjusted for lifestyle factors, body mass index and age, the odds ratios for the presence of metabolic disease per 0.54 L (1 SD) decrease in FVC were 1.24 (95% CI 1.03 to 1.50) for type II diabetes, 1.21 (95% CI 1.02 to 1.42) for hypertension, 1.34 (95% CI 1.11 to 1.63) for hypertriglyceridemia, 1.23 (95% CI 1.03 to 1.46) for high gamma-glutamyl transferase levels and 1.63 (95% CI 1.10 to 2.41) for an episode of cardiovascular disease. FVC did not correlate with hyperhomocysteinemia, hypercholesterolemia or high white blood cell count. Similar results were also obtained for the association between %VC and metabolic diseases.

CONCLUSIONS

A decrease in FVC or %VC was associated with the presence of some metabolic diseases. The association may partly explain the reported association between low FVC and cardiovascular disease.

Early life factors contribute to the decrease in lung function between ages 18 and 40: the Coronary Artery Risk Development in Young Adults study

Early life factors may influence pulmonary function. We measured forced expiratory volume in 1 second (FEV(1)) in 1985-1986 and 2, 5, and 10 years later in approximately 4,000 black and white men and women initially aged 18-30 years. We estimated the age pattern of FEV(1) according to family smoking status, early diagnosis of asthma, early smoking initiation, adult asthma, and cigarette smoking. FEV(1) followed a quadratic pattern from age of peak through age 40. The pattern varied by race and sex. Early smoking initiation was associated with a faster decrease in FEV(1). Smoking by family members was related to early life asthma and may have contributed to faster FEV(1) decrease by encouraging behaviors such as heavier smoking or earlier smoking initiation. Prevalence of smoking was 28% when no family member smoked, compared with 59% when four or more members smoked. The FEV(1) decline was 8.5% in never-smokers without asthma; 10.1% in nonsmoking individuals diagnosed with asthma; and 11.1% in baseline smokers who smoked 15 or more cigarettes per day. The combination of asthma and heavier smoking was synergistic (17.8% decline). This study delineates an increased rate of decline in those with asthma or in those who smoke cigarettes and implicates early life exposures as contributing to the faster rate of FEV(1) decline.

Pulmonary function and cardiovascular risk factor relationships in black and in white young men and women. The CARDIA Study

Pulmonary function is known to be related inversely to incidence of coronary heart disease, congestive heart failure, chronic obstructive lung disease, lung cancer, and death from all causes. Reasons for some of these associations are poorly understood. Relationships between cardiovascular disease risk factors and pulmonary function were examined in 5,115 18- to 30-year-old black and white male and female participants in the study of Coronary Artery Risk Development in Young Adults (CARDIA). Forced expiratory volume in 1 s adjusted for height (FEV1/Ht2) was significantly lower in smokers than nonsmokers and in persons who reported shortness of breath; FEV1/Ht2 was correlated positively with a history of strenuous physical activity, duration of exercise on the treadmill, and high-density lipoprotein cholesterol. It was associated negatively with skinfold thicknesses, serum triglycerides, fasting serum insulin, and the Cook Medley scale of hostility. The association between pulmonary function and heart disease risk may reflect associations with physical fitness, vigor, fatness, and lipid profiles, as well as with cigarette smoking.

Smoking, pulmonary function, and mortality

The association of pulmonary function (as percent of predicted forced expiratory volume in 1 second [FEV1]) with total and cause-specific mortality over 15 to 18 years was investigated in a large cohort (5924) of prospectively followed Japanese-American men. Among those who never smoked, pulmonary function was found not to be significantly predictive of total mortality in a multivariate model in which adjustment for variables that might confound the results was made. Among past and current smokers, highly significant associations were found (P < 0.0001). The positive relationship of pulmonary function to mortality in smokers was so strong that it overshadowed these differences in nonsmokers in a model including all smoking groups combined, even after adjusting for smoking. A smoking-pulmonary function interaction term added to this model was statistically significant (P < 0.003). This illustrates the need for attention to the potential for complex interactions between biologic variables when carrying out multivariate statistical analysis. Findings for cardiovascular and noncardiovascular mortality were similar. This analysis indicates that while pulmonary function is associated with subsequent mortality, the relationship is significantly associated with smoking history.

The epidemiology of pulmonary function and COPD mortality in the multiple risk factor intervention trial

The potential determinants of the changes in chronic obstructive pulmonary disease (COPD) mortality were evaluated using both the Multiple Risk Factor Intervention Trial (MRFIT) screenees, the longitudinal analysis of the participants, and the differences in special intervention (SI) and usual care (UC) groups. COPD was the underlying cause for only one third of all death certificates listing COPD. Small changes in classification will have a major impact on reported COPD death rates. Cigarette smoking is clearly the primary determinant of COPD mortality. Decreased pulmonary function is an independent risk factor for coronary heart disease (CHD) mortality. Smoking cessation results in a slower rate of decline in pulmonary function over time, especially among heavy smokers. Careful evaluation of smoking cessation, including repeat chemical measures, suggest that the percentage of long-term quitters, especially among heavy smokers has been overestimated. The low percentage of quitters substantially reduced the power to detect an intervention effect. The increased cigarette smoking among recent older cohorts, and failure to substantially reduce smoking, especially among heavy smokers, may be an important factor accounting for the failure to note a decline in COPD mortality among older persons.

Cardiovascular disease and work place exposures

The typical occupational cohort study includes all causes of mortality. However, emphasis is usually placed on the presence or absence of excess cancer mortality. A systematic review of completed occupational cohort studies to assess the findings and patterns of cardiovascular mortality would be useful. Although many of these studies will illustrate the "healthy worker effect" with deficits in mortality, particularly from cardiovascular causes, a thorough review should indicate certain exposures needing further research. A recently published study of heart disease mortality in the rubber industry illustrates the potential use of such a literature review with subsequent follow up. Production workers in the rubber industry have shown small excesses in CAHD mortality. A follow-up study at one plant confirmed the known association between carbon disulfide and atherosclerosis, as well as suggested two new causal associations between CAHD and the use of phenol and ethanol as solvents. What additional techniques can be used to generate hypotheses on heart disease and occupation? Some possibilities include: A recent article describes the use of the results of occupational disease surveillance systems for occupational cancer research. A review of such systems for heart disease would be equally useful. It would be useful to review the quality and quantity of occupational data that has been collected in prospective cohort studies, such as those in Framingham and Evans County. The importance of examining the association between occupational exposures and heart disease include: Assessing whether adequate protection is afforded by current limits on exposure to substances known to cause heart disease (carbon disulfide, nitrates, and carbon monoxide).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular disease and environmental exposure

This paper reviews the possible association between cardiovascular disease and occupational and environmental agents. The effects of carbon monoxide, fibrogenic dusts, carbon disulphide, heavy metals, noise, radiation, heat, cold, solvents and fluorocarbons are discussed. New directions for investigation are suggested.

Lung function and risk of myocardial infarction and sudden cardiac death

In a serach for risk factors for myocardial infarction and sudden cardiac death, the mean total vital capacity as measured at multiphasic health checkups was lower in persons who later had a first myocardial infarction than in risk-factor-matched controls (3.17 vs. 3.29 liters, 395 pairs, P less than 0.05) and non-risk-factor-matched controls (3.16 vs. 3.41 liters, 401 pairs, P less than 0.001). Findings were little affected by age and height adjustment and were similar for sudden cardiac death. The first-second vital capacity was also inversely related to later development of these conditions, but the ratio of that measurement to total vital capacity was not. Heavy smoking, productive cough, exertional dyspnea and cardiac enlargement were associated with diminished total capacity. However, exclusion of subjects with these findings did not reduce the predictive value of total vital capacity. Diminished vital capacity deserves continued attention as a possible coronary risk factor. Its relation to subsequent coronary events is not well explained.

Risk factors for myocardial infarction and death due to ischemic heart disease and other causes

As part of a study of the male population in an industrial city in Sweden, one third of all male inhabitants of Göteborg born in 1913 were invited to an examination in 1963. Of those invited, 855 (88 percent) accepted. This report examines the incidence of nonfatal myocardial infarction and death from ischemic heart disease and other causes in this group of men during the ensuing 10 years. There were 6l deaths; autopsy was performed in 56 cases. Nineteen men died of ischemic heart disease and 18 of cancer; 12 men died violently. Thirty-one men survived an acute myocardial infarction. Cigarette smoking and registration with the Temperance Board at the time of the initial examination were more common in men who later had a nonfatal myocardial infarction or died of ischemic heart disease or other causes than in surviving subjects and men who did not have an infarction. Dyspnea was more common in men who died of ischemic heart disease but was less common in those who died of other causes than in the remaining subjects. Values for systolic blood presure were higher and those for peak expiratory flow lower in men who died of ischemic heart disease. Serum cholesterol values were higher and those for serum triglycerides tended to be higher in men who died of ischemic heart disease than in other subjects. Heart size tended to be greater in those who had nonfatal or fatal ischemic heart disease. Obesity, the level of physical activity, fasting blood glucose levels, doffee consumption, hematocrit and erythrocyte sedimentation rate as determined at age 50 years had no predictive value for assissing the risk of nonfatal myocardial infarction, fatal ischemic heart disease or death from other causes before age 60. The results indicate that many so-called risk factors have a different relation to fatal than to nonfatal ischemic heart disease.