Risk factors in chronic obstructive pulmonary malfunction and "chronic bronchitis" symptoms in Beijing district: a joint study between Japan and China

Association between age, gender, body mass index, and pulmonary function in preoperative patients with lung cancer

INTRODUCTION

Many confounding factors such as sex, age, and body mass index (BMI) affect pulmonary function parameters, but there are limited data about the direct and/or indirect effects of small airway function on lung function for differences in confounding factors.

OBJECTIVES

This study aimed to use structural equation model (SEM) to explain the influence of the confounding factors (age, sex, and BMI) on the relationship between small airway function and lung function in patients with lung cancer.

METHODS

A cross-sectional observational study was conducted in a single medical center. Subjects were assessed; small airway function was specified by MEF25% and MEF50%; lung function by FVC; pulmonary obstruction by FEV1, FEV1%, and FEV1/FVC; and PEF and PEF% reflected the strength of abdominal muscles. The measurement model was analyzed by confirmatory factor analysis. The SEM was conducted to analyze the structural models of the effects of the confounding factors.

RESULTS

In the measurement model, variables were fit to their domains, the path linking age and sex to pulmonary obstruction was positive and statistically significant, and the path linking sex to muscle strength was also positive and statistically significant. Muscle strength positively and significantly mediates the path between sex and FVC. As a moderator, BMI increased the effects of small airway function on FVC.

CONCLUSION

Age and sex were directed to pulmonary obstruction, and muscle strength as a mediator between sex and lung function was novel, and BMI adjusted the effects of small airway function on FVC.

Systematic review with meta-analysis of the epidemiological evidence relating smoking to COPD, chronic bronchitis and emphysema

BACKGROUND

Smoking is a known cause of the outcomes COPD, chronic bronchitis (CB) and emphysema, but no previous systematic review exists. We summarize evidence for various smoking indices.

METHODS

Based on MEDLINE searches and other sources we obtained papers published to 2006 describing epidemiological studies relating incidence or prevalence of these outcomes to smoking. Studies in children or adolescents, or in populations at high respiratory disease risk or with co-existing diseases were excluded. Study-specific data were extracted on design, exposures and outcomes considered, and confounder adjustment. For each outcome RRs/ORs and 95% CIs were extracted for ever, current and ex smoking and various dose response indices, and meta-analyses and meta-regressions conducted to determine how relationships were modified by various study and RR characteristics.

RESULTS

Of 218 studies identified, 133 provide data for COPD, 101 for CB and 28 for emphysema. RR estimates are markedly heterogeneous. Based on random-effects meta-analyses of most-adjusted RR/ORs, estimates are elevated for ever smoking (COPD 2.89, CI 2.63-3.17, n = 129 RRs; CB 2.69, 2.50-2.90, n = 114; emphysema 4.51, 3.38-6.02, n = 28), current smoking (COPD 3.51, 3.08-3.99; CB 3.41, 3.13-3.72; emphysema 4.87, 2.83-8.41) and ex smoking (COPD 2.35, 2.11-2.63; CB 1.63, 1.50-1.78; emphysema 3.52, 2.51-4.94). For COPD, RRs are higher for males, for studies conducted in North America, for cigarette smoking rather than any product smoking, and where the unexposed base is never smoking any product, and are markedly lower when asthma is included in the COPD definition. Variations by sex, continent, smoking product and unexposed group are in the same direction for CB, but less clearly demonstrated. For all outcomes RRs are higher when based on mortality, and for COPD are markedly lower when based on lung function. For all outcomes, risk increases with amount smoked and pack-years. Limited data show risk decreases with increasing starting age for COPD and CB and with increasing quitting duration for COPD. No clear relationship is seen with duration of smoking.

CONCLUSIONS

The results confirm and quantify the causal relationships with smoking.

Effect of air pollution on peak expiratory flow rate variability

Exposure to air pollution affects pulmonary functions adversely. Effect of exposure to pollution on diurnal variation of peak flow was assessed in healthy students. Three hundred healthy age-matched nonsmoker students were studied. They were categorized into two groups on the basis of their residence: commuters and living on campus. Peak expiratory flow (PEF) recordings were made twice daily for 2 days with the Pink City Flow Meter. The measurement was then used to calculate for each subject the amplitude percentage mean, which is an index for expressing PEF variability for epidemiological purposes (Higgins BG, Britton JR, Chinns Jones TD, Jenkinson D, Burnery PG, Tattersfield AE. Distribution of peak expiratory flow variability in a population sample. Am Rev Respir Dis 1989; 140:1368-1372). Air pollution parameters were quantified by measurement of sulfur dioxide (SO2), oxides of nitrogen (NO2), carbon monoxide (CO), and respirable suspended particulate matter (RSPM) in the ambient air at the campus and on the roadside. The mean values of PEF variability (amplitude percent mean) in the students living on campus and in the commuters were 5.7 +/- 3.2 and 11 +/- 3.6, respectively (P < .05). Among the commuters, maximum number of subjects showed amplitude percentage mean PEFR at the higher end of variability distribution, as compared to the students living on campus, among whom the majority of subjects fell in the lower ranges of variability distribution. The ambient air quality parameters, namely SO2, NO2, CO, and RSPM were significantly lower on the campus. It can be concluded that long-term periodic exposure to air pollution can lead to increased PEF variability even in healthy subjects. Measurement of PEF variability may prove to be a simple test to measure effect of air pollution in healthy subjects.

Prevalence and risk factors for chronic bronchitis in Pelotas, RS, Brazil: a population-based study

BACKGROUND

Chronic bronchitis causes high morbidity and mortality throughout the world. It is basically a preventable disease. However, few population based studies of chronic bronchitis have been carried out in less developed countries.

METHODS

A population based cross sectional survey was conducted to determine the prevalence of chronic bronchitis and associated risk factors in an urban area (Pelotas) of southern Brazil. 1053 subjects aged 40 years and over (90.3% of eligible subjects) were interviewed using the ATS-DLD-78 questionnaire.

RESULTS

Of the subjects interviewed 12.7% were classified as having chronic bronchitis. In univariate analyses a significant increase in the relative odds of chronic bronchitis was seen in men (OR = 2.17, 95% CI 1.50 to 3.13), low family income (OR = 2.60, 95% CI 1.47 to 4.47 for lowest quartile), low schooling (OR = 4.65, 95% CI 2.36 to 9.18 for those with no schooling), smoking habits (OR = 6.92, 95% CI 4.22 to 11.36 for smokers of 20 or more cigarettes per day), high occupational exposure to dust (OR = 2.48, 95% CI 1.56 to 3.94), inadequate housing (OR = 2.09, 95% CI 1.22 to 3.58), high level of indoor air pollution (OR = 1.86, 95% CI 1.16 to 2.99), and reported childhood respiratory illnesses (OR = 2.08, 95% CI 1.25 to 3.49). Multiple logistic regression resulted in the identification of the following independent risk factors: family income (OR = 1.99, 95% CI 1.04 to 3.81 for subjects in the lowest quartile compared with those in the highest quartile), schooling (OR = 5.60, 95% CI 2.52 to 12.45 for subjects with no schooling compared with those with nine or more years), smoking (OR = 8.10, 95% CI 4.46 to 14.71 for smokers of 20 or more cigarettes per day compared with non-smokers), and history of major respiratory illnesses in childhood (OR = 2.16, 95% CI 1.20 to 3.85).

CONCLUSIONS

Low family income, poor schooling, smoking, and childhood respiratory illnesses were significantly associated with chronic bronchitis.

Respiratory function changes from inhalation of polluted air

Exposure to polluted air may trigger respiratory symptoms in certain subjects. Maximal expiratory flow volume measurements and methacholine bronchial challenges were conducted in 25 asthmatics and 30 healthy volunteers, before and after breathing bagged polluted air for 30 min, to determine whether exposures to polluted air influence respiratory function and bronchial reactivity. No differences in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), total respiratory resistance (Rrs), and bronchial reactivity were noted for normal subjects after they inhaled polluted air and ambient air. Significant decreases in FEV1.0 and FEV1.0/FVC, an increase in airway reactivity, and elevation of baseline Rrs values occurred in the asthmatic subjects, after exposure to polluted air. These findings suggest that asthmatic patients are more vulnerable to the adverse effects of polluted air.