Ronald J. Halbert

Global burden of COPD: systematic review and meta-analysis

The aim of this study was to quantify the global prevalence of chronic obstructive pulmonary disease (COPD) by means of a systematic review and random effects meta-analysis. PubMed was searched for population-based prevalence estimates published during the period 1990–2004. Articles were included if they: 1) provided total population or sex-specific estimates for COPD, chronic bronchitis and/or emphysema; and 2) gave method details sufficiently clearly to establish the sampling strategy, approach to diagnosis and diagnostic criteria. Of 67 accepted articles, 62 unique entries yielded 101 overall prevalence estimates from 28 different counties. The pooled prevalence of COPD was 7.6% from 37 studies, of chronic bronchitis alone (38 studies) was 6.4% and of emphysema alone (eight studies) was 1.8%. The pooled prevalence from 26 spirometric estimates was 8.9%. The most common spirometric definitions used were those of the Global Initiative for Chronic Obstructive Lung Disease (13 estimates). There was significant heterogeneity, which was incompletely explained by subgroup analysis (e.g. age and smoking status). The prevalence of physiologically defined chronic obstructive pulmonary disease in adults aged ≥40 yrs is ∼9–10%. There are important regional gaps, and methodological differences hinder interpretation of the available data. The efforts of the Global Initiative for Chronic Obstructive Lung Disease and similar groups should help to standardise chronic obstructive pulmonary disease prevalence measurement.

Population impact of different definitions of airway obstruction

There is currently no consensus on the criteria for diagnosing chronic obstructive pulmonary disease. This study evaluated the impact of different definitions of airway obstruction on the estimated prevalence of obstruction in a population-based sample. Using the Third National Health and Nutrition Examination Survey, obstructive airway disease was defined using the following criteria: 1) self-reported diagnosis of chronic bronchitis or emphysema; 2) forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) <0.70 and FEV1 <80% predicted (Global Initiative for Chronic Obstructive Lung Disease (GOLD) Stage IIA); 3) FEV1/FVC below the lower limit of normal; 4) FEV1/FVC <88% pred in males and <89% pred in females; 5) FEV1/FVC <0.70 (“fixed ratio”). Spirometry in this dataset did not include reversibility testing, making it impossible to distinguish reversible from irreversible obstruction. Rates in adults varied from 77 per 1,000 (self-report) to 168 per 1,000 (fixed ratio). For persons aged >50 yrs, the fixed ratio criteria produced the highest rate estimates. For all subgroups tested, the GOLD Stage II criteria produced lower estimates than other spirometry-based definitions. Different definitions of obstruction may produce prevalence estimates that vary by >200%. International opinion leaders should agree upon a clear definition of chronic obstructive pulmonary disease that can serve as a population-based measurement criterion as well as a guide to clinicians.

Misdiagnosis of COPD and Asthma in Primary Care Patients 40 Years of Age and Over

Chronic obstructive pulmonary disease (COPD) is often misdiagnosed as asthma, leading to inappropriate treatment and suboptimal patient outcomes. As part of a prospective study of patients with a history consistent with obstructive lung disease, we compared prior diagnostic labels with a study diagnosis based on spirometric results. We enrolled persons 40 years of age or older with prior diagnoses or medications consistent with obstructive lung disease. Patients were recruited via random mailing to primary care practices in Aberdeen, Scotland, and Denver, Colorado. Prior diagnoses of chronic bronchitis or emphysema (CBE) and asthma were reported by the subjects. Participants underwent pre- and post-bronchodilator spirometry. A study diagnosis of COPD was defined using post-bronchodilator forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) < 0.70. Spirometric examination was complete in 597 patients, of whom 235 (39.4%) had a study diagnosis of COPD. Among subjects with a spirometry-based study diagnosis of COPD, 121 (51.5%) reported a prior diagnosis of asthma without concurrent CBE diagnosis, 89 (37.9%) reported a prior diagnosis of CBE, and 25 (10.6%) reported no prior diagnosis of obstructive lung disease. Despite the availability of consensus guideline diagnostic recommendations, diagnostic confusion between COPD and asthma appears common. Increased awareness of the differences between the two conditions is needed to promote optimal patient management and treatment.

Symptom-based questionnaire for identifying COPD in smokers

Background: Symptom-based questionnaires may enhance chronic obstructive pulmonary disease (COPD) screening in primary care. Objectives: We prospectively tested questions to help identify COPD among smokers without prior history of lung disease. Methods: Subjects were recruited via random mailing to primary care practices in Aberdeen, UK, and Denver, Colo., USA. Current and former smokers aged 40 or older with no prior respiratory diagnosis and no respiratory medications in the past year were enrolled. Participants answered questions covering demographics and symptoms and then underwent spirometry with reversibility testing. A study diagnosis of COPD was defined as fixed airway obstruction as measured by postbronchodilator FEV1/FVC <0.70. We examined the ability of individual questions in a multivariate framework to correctly discriminate between persons with and without COPD. Results: 818 subjects completed all investigations and proceeded to analysis. The list of 54 questions yielded 52 items for analysis, which was reduced to 17 items for entry into multivariate regression. Eight items had significant relationships with the study diagnosis of COPD, including age, pack-years, body mass index, weather-affected cough, phlegm without a cold, morning phlegm, wheeze frequency, and history of any allergies. Individual items yielded odds ratios ranging from 0.23 to 12. This questionnaire demonstrated a sensitivity of 80.4 and specificity of 72.0. Conclusions: A simple patient self-administered questionnaire can be used to identify patients with a high likelihood of having COPD, for whom spirometric testing is particularly important. Implementation of this questionnaire could enhance the efficiency and diagnostic accuracy of current screening efforts.

The chronic bronchitis phenotype in subjects with and without COPD: the PLATINO study

Little information exists regarding the epidemiology of the chronic bronchitis phenotype in unselected chronic obstructive pulmonary disease (COPD) populations. We examined the prevalence of the chronic bronchitis phenotype in COPD and non-COPD subjects from the PLATINO study, and investigated how it is associated with important outcomes. Post-bronchodilator forced expiratory volume in 1 s/forced vital capacity <0.70 was used to define COPD. Chronic bronchitis was defined as phlegm on most days, at least 3 months per year for ≥2 yrs. We also analysed another definition: cough and phlegm on most days, at least 3 months per year for ≥2 yrs. Spirometry was performed in 5,314 subjects (759 with and 4,554 without COPD). The proportion of subjects with and without COPD with chronic bronchitis defined as phlegm on most days, at least 3 months per year for ≥2 yrs was 14.4 and 6.2%, respectively. Using the other definition the prevalence was lower: 7.4% with and 2.5% without COPD. Among subjects with COPD, those with chronic bronchitis had worse lung function and general health status, and had more respiratory symptoms, physical activity limitation and exacerbations. Our study helps to understand the prevalence of the chronic bronchitis phenotype in an unselected COPD population at a particular time-point and suggests that chronic bronchitis in COPD is possibly associated with worse outcomes.

Symptom-Based Questionnaire for Differentiating COPD and Asthma

Background: Many patients with obstructive lung disease (OLD) carry an inaccurate diagnostic label. Symptom-based questionnaires could identify persons likely to need spirometry. Objectives: We prospectively tested questions derived from a comprehensive literature review and an international Delphi panel to help identify chronic OLD (COPD) in persons with prior evidence of OLD. Methods: Subjects were recruited via random mailing to primary-care practices in Aberdeen, Scotland, and Denver, Colorado. Persons aged 40 and older reporting any prior diagnosis of OLD or any respiratory medications in the past year were enrolled. Participants answered 54 questions covering demographics and symptoms and underwent spirometry with reversibility testing. A study diagnosis of COPD was defined by fixed airway obstruction as measured by post-bronchodilator FEV1/FVC <0.70. We examined ability of individual questions in a multivariate framework to discriminate between persons with and without the study diagnosis of COPD. Results: 597 persons completed all investigations and proceeded to analysis. The list of 54 questions yielded 52 items for analyses, which was reduced to 19 items for entry into a multivariate regression model. Nine items had significant relationships with the study diagnosis of COPD, including increased age, pack-years, worsening cough, breathing-related disability or hospitalization, worsening dyspnea, phlegm quantity, cold going to the chest, and receipt of treatment for breathing. Individual items yielded odds ratios ranging from 0.33 to 20.7. This questionnaire demonstrated a sensitivity of 72.0 and a specificity of 82.7. Conclusions: A short, symptom-based questionnaire identifies persons more likely to have COPD among persons with prior evidence of OLD.

Sex-related differences in COPD in five Latin American cities: the PLATINO study

There is evidence to suggest sex differences exists in chronic obstructive pulmonary disease (COPD) clinical expression. We investigated sex differences in health status perception, dyspnoea and physical activity, and factors that explain these differences using an epidemiological sample of subjects with and without COPD. PLATINO is a cross-sectional, population-based study. We defined COPD as post-bronchodilator forced expiratory volume in 1 s/forced vital capacity ratio <0.70, and evaluated health status perception (Short Form (SF)-12 questionnaire) and dyspnoea (Medical Research Council scale). Among 5,314 subjects, 759 (362 females) had COPD and 4,555 (2,850 females) did not. In general, females reported more dyspnoea and physical limitation than males. 54% of females without COPD reported a dyspnoea score ≥2 versus 35% of males. A similar trend was observed in females with COPD (63% versus 44%). In the entire study population, female sex was a factor explaining dyspnoea (OR 1.60, 95%CI 1.40–1.84) and SF-12 physical score (OR -1.13, 95%CI -1.56– -0.71). 40% of females versus 28% of males without COPD reported their general health status as fair-to-poor. Females with COPD showed a similar trend (41% versus 34%). Distribution of COPD severity was similar between sexes, but currently smoking females had more severe COPD than currently smoking males. There are important sex differences in the impact that COPD has on the perception of dyspnoea, health status and physical activity limitation.

Treatment of patients with metastatic renal cell cancer: a RAND Appropriateness Panel.

New developments in the treatment of patients with metastatic renal cell cancer (MRCC) have suggested a need to reevaluate the role of systemic therapies. The authors convened a panel of medical and urologic oncologists to rate the appropriateness of the main options.

Development of a Population-Based Screening Questionnaire for COPD

COPD is commonly under-diagnosed, in part because people at risk are unaware of the relevant risk factors and do not recognize related symptoms. Providing this information might permit earlier disease identification but the questions chosen should identify those with spirometrically defined airflow obstruction. Using a population-based data set, we have determined which questions identify persons most likely to have airflow obstruction. Potential questions were selected by review of COPD risk factors and clinical features. Validation was by retrospective analysis of the NHANES III data set, a population-based U.S. household survey that included spirometry. We examined the predictive ability of individual questions in a multi-variate framework to correctly discriminate between persons with and without spirometric airway obstruction (defined as FEV1/FVC < 0.70). We then tested the discriminatory ability of the questions in combination. The following items showed significant predictive ability: increased age, smoking status, pack-years, cough, wheeze, and prior diagnosis of asthma or COPD. The best performing combination was age, smoking status, pack-years smoked, wheeze, phlegm, body mass index, and prior diagnosis of obstructive lung disease. Using this combination in a population of current and former smokers aged 40 and over, we achieved a sensitivity of 85% and specificity of 45%, with a positive predictive value of 38% and a negative predictive value of 88%. Performance of this tool is comparable to other screening methods designed for use in a general population. Symptom-based questionnaires can be a viable method to identify persons likely to have COPD in the general population. Dissemination of such tools should raise awareness among at-risk persons and help identify COPD patients in the primary care setting.

Comparison of existing symptom‐based questionnaires for identifying COPD in the general practice setting

Objective:  Underdiagnosis of COPD is widespread, at least in part due to underuse of spirometry. Symptom‐based questionnaires may be helpful as an adjunct to spirometry. The aim of this study was to determine which types of questions might aid in identifying COPD.