Chronic bronchitis: prevalence, smoking habits, impact, and antismoking advice

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.

The relationship of chronic sputum expectoration to physiologic, radiologic, and health status characteristics in alpha(1)-antitrypsin deficiency (PiZ)

STUDY OBJECTIVES

First, to determine the relationships among chronic sputum expectoration (CSE), exacerbations, airflow obstruction, and emphysema in patients with alpha(1)-antitrypsin deficiency (alpha(1)-ATD) [PiZ]. Second, to use multivariate analysis to determine how these factors influence health status.

DESIGN

Cross-sectional, single-center.

SETTING

UK center for alpha(1)-ATD, university teaching hospital.

PATIENTS

One hundred seventeen nonsmoking patients underwent lung function testing, high-resolution CT (HRCT) scanning with density mask analysis, and health status assessment using the St. George's Respiratory Questionnaire (SGRQ) and short form 36 (SF-36) health survey questionnaire.

RESULTS

Patients with CSE (n = 50) had worse postbronchodilator airflow obstruction than those who did not (p = 0.03), with a median FEV(1) of 1.15 L (interquartile range [IQR], 0.76 to 1.82) vs 1.44 L (IQR, 0.99 to 2.93), respectively, and higher HRCT scan voxel index (VI) values indicating more extensive emphysema (patients with CSE: median lower zone VI, 50; IQR, 28 to 61; patients without CSE: median lower zone VI, 41; IQR, 5 to 53; p = 0.04). Patients with CSE also had worse health status, as assessed by the SGRQ (p < 0.01 for all domains) and SF-36 questionnaire (p < 0.05 for seven of nine domains). Exacerbation frequency was greater in those patients with CSE (p < 0.001), with a median of two episodes per year (IQR, 1 to 3) vs 0.66 episodes per year (IQR, 0 to 2) for those without CSE. Stepwise linear regression analysis revealed FEV(1), exacerbation frequency, and lower zone VI to be the most important predictors of health status.

CONCLUSIONS

Among patients with alpha(1)-ATD, those with CSE expectoration exhibit greater physiologic impairment and more extensive emphysema than those without. This is reflected in an inferior health status, which is also influenced independently by an increased exacerbation frequency in those with CSE.

Assessing quality of life in chronic non-specific lung disease--a review of empirical studies published between 1980 and 1994

Chronic non-specific lung disease (CNSLD), a chronic disease with considerable prevalence and mortality rates, is not only a medical problem, it also has significant psychological and social consequences for the patients concerned. Quality of life research on CNSLD has been rather underdeveloped for quite a long period of time, but has recently become an important topic in research as well as in patient care. In order to get insight into the state of the art of empirical research on quality of life (QOL) in CNSLD, a review of the literature between 1980-1994 on this topic is presented. Special attention is paid to definitions and operationalizations of the QOL concept as well as on questionnaires used to assess QOL and the aims of QOL research. Analysis reveals that QOL is seldom defined clearly and is operationalized in a variety of ways. Most studies have a descriptive nature or pertain to clinical trials. The negative impact of CNSLD on QOL is well-documented and shows the importance of incorporating assessment of QOL in research as well as in patient care. Future research is called for, which should be theory-driven, taking into account recent developments concerning disease-specific measures of QOL.