Prevalence and features of asthma–chronic obstructive pulmonary disease overlap in Northern Italy general population

Objective: There is controversy about the diagnostic criteria, prevalence, symptoms, and spirometry characteristics of asthma–chronic obstructive pulmonary disease (COPD) overlap (ACO). Recent data indicate that the fixed method for diagnosing airway obstruction (AO) may overestimate ACO prevalence in the elderly, and a variable method may be more accurate. We aimed at estimating ACO prevalence in a general population sample and comparing patient and clinical features in subjects with ACO, COPD, and asthma. Methods: We analyzed data from a cross-sectional study estimating COPD prevalence in randomly selected adults aged 20–79 years in Verona, Italy, and estimated prevalence and analyzed characteristics of asthma, COPD, and ACO. ACO was defined as AO (Forced Expiratory Volume in one second–FEV₁/ Forced Vital Capacity–FVC < Lower Limit of Normal–LLN), highly positive bronchodilator test (≥15% increase in FEV₁ and FVC ≥400 mL), and personal self-reported history of physician diagnosed asthma and atopy. Results: One thousand two hundred and thirty-six patients were included; 207 (16.7%) had asthma, COPD, or ACO (mean ages: 61.2, 59.7, and 57.2 years, respectively). The 3 groups had similar clinical and demographic variables; however, spirometry revealed differences between ACO and COPD patients, particularly post-bronchodilator FEV₁ reversibility, which was detected in ACO and asthma patients but not in those with COPD. Conclusion: ACO prevalence in Northern Italy was estimated at 2.1%, in the range of values reported by previous studies. Marked differences between ACO and COPD revealed by spirometry may have important clinical implications in terms of treatment for patients with ACO.     

Chronic Airflow Obstruction in a Black African Population: Results of BOLD Study,Ile-Ife,Nigeria

Global estimates suggest that Chronic Obstructive Pulmonary Disease (COPD) is emerging as a leading cause of death in developing countries but there are few spirometry-based general population data on its prevalence and risk factors in sub-Saharan Africa. We used the Burden of Obstructive Lung Disease (BOLD) protocol to select a representative sample of adults aged 40 years and above in Ile-Ife, Nigeria. All the participants underwent spirometry and provided information on smoking history, biomass and occupational exposures as well as diagnosed respiratory diseases and symptoms. Chronic Airflow Obstruction (CAO) was defined as the ratio of post-bronchodilator (BD) one second Forced Expiratory Volume (FEV₁) to Forced Vital Capacity (FVC) below the lower limit of normal (LLN) of the population distribution for FEV₁/FVC.

The overall prevalence of obstruction (post-BD FEV₁/FVC < LLN) was 7.7% (2.7% above LLN) using Global Lung Function Initiative (GLI) equations. It was associated with few respiratory symptoms; 0.3% reported a previous doctor-diagnosed chronic bronchitis, emphysema or COPD. Independent predictors included a lack of education (OR 2·5, 95% CI: 1.0, 6.4) and a diagnosis of either TB (OR 23.4, 95% CI: 2.0, 278.6) or asthma (OR 35.4, 95%CI: 4.9, 255.8). There was no association with the use of firewood or coal for cooking or heating. The vast majority of this population (89%) are never smokers. We conclude that the prevalence of CAO is low in Ile-Ife, Nigeria and unrelated to biomass exposure. The key independent predictors are poor education, and previous diagnosis of tuberculosis or asthma.     

Prevalence of Airflow Obstruction in Nonsmoking Older Individuals Using Different Spirometric Criteria: The AGES Reykjavik Study

Abstract

Background: The prevalence and characteristics of airway obstruction in older individuals varies widely with the definition used. We used a random sample of never smoking older population in Iceland to compare the prevalence and clinical profile of subjects diagnosed with Chronic Obstructive Pulmonary Disease (COPD) based on different spirometric criteria. Material and methods: The study uses data from the Age, Gene/Environment Susceptibility–Reykjavik Study, comprising survivors from the Reykjavik Study. Procedures included standardized questionnaires and pre-bronchodilator spirometry for measurement of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). Results: Total of 495 individuals (150 men and 345 women) met study criteria. Mean age 77 years (range 66-92 years) using fixed ratio (FEV1/FVC < 70%) up to 29% of the population were diagnosed with COPD Stage I. The prevalence of COPD increased with age. Only 7 among 495 (1.4%) were diagnosed with COPD using FEV1/FVC LLN and FEV1 LLN. Conclusion: Application of the GOLD criteria for diagnosis of COPD in older lifelong never smoking subjects identifies a substantial number of non-symptomatic subjects as having COPD. If airway obstruction is defined by FEV1/FVC and FEV1 being below the LLN using appropriate reference equations, only very few non-smoking older individuals fulfill the criteria for COPD.     

Prevalence and characteristics of chronic obstructive pulmonary disease in China with a diagnostic criterion of FEV1/FVC less than the lower limit of normal—a reanalysis of Chinese epidemiological survey of COPD (CESCOPD) study

BackgroundTo reappraise the prevalence and characteristics of chronic obstructive pulmonary disease (COPD) in China with a criterion of FEV₁/FVC < the lower limit of normal (LLN).MethodsWe assessed the incidence and characteristics of airflow limitation using data from the Chinese Epidemiological Survey of COPD study—a multicenter, randomized trial, with an age-dependent LLN reference equation [established by the Guangzhou Institute of Respiratory Health (GIRH)]. Questionnaire and spirometry data were collected for all eligible subjects. COPD prevalence, risk factors, severity distribution, as well as comparisons of characteristics between the LLN and 0.7 were analyzed.ResultsCOPD prevalence was 9.0% among participants aged 40–80 years in China with the criterion of LLN. Greater prevalence was observed in female sex, rural areas and never smokers than with the GOLD 0.7 fixed ratio. Age distribution showed a higher incidence of COPD in people under 60 years but lower in participants over 60 years of age. With the LLN FEV₁ reference equation, patients in stage I were decreased (15.8% vs. 24.6%, P<0.001), while the proportion of patients in stage III and IV were increased when compared with the China 2002 revised equation (27.7% vs. 21.1%, for stage III, P<0.001; 8.7% vs. 5.6% for stage IV, P=0.001). Only 30.8% of patients with COPD had ever been “diagnosed” with COPD and 60.6% of the patients had respiratory symptoms, both lower than that under the GOLD 0.7 fixed-ratio criterion (35.5%, P=0.004; 64.8% for symptoms, P=0.014).ConclusionsWith the GIRH-LLN criterion, COPD prevalence was slightly higher, and a large number of women, rural patients and nonsmokers with young age and little symptoms were diagnosed when compared with GOLD 0.7 fixed ratio. These subjects may, therefore, deserve further attention and may warrant regular follow-up.Trial RegistrationRegistration number: ChiCTR-ECS-13004110.     

The prognostic significance of lung function in stable heart failure outpatients

Background

This study investigated the impact on all‐cause mortality of airflow limitation indicative of chronic obstructive pulmonary disease or restrictive spirometry pattern (RSP) in a stable systolic heart failure population.

Hypothesis

Decreased lung function indicates poor survival in heart failure.

Methods

Inclusion criteria: NYHA class II‐IV and left ventricular ejection fraction (LVEF) < 45%. Prognosis was assessed with multivariate Cox proportional hazards models. Two criteria of obstructive airflow limitation were applied: FEV₁/FVC < 0.7 (GOLD), and FEV₁/FVC < lower limit of normality (LLN). RSP was defined as FEV₁/FVC > 0.7 and FVC<80% or FEV₁/FVC > LLN and FVC <LLN.

Results

There where 573 patients in the cohort (85% of eligible patients in study period). Median follow‐up was 4.7 years and 176 patients died (31%). Age, NYHA class, smoking, body mass index and LVEF were independent prognostic factors (p<0.01). Obstructive airflow limitation increased mortality using both criteria (HR_GOLD 2.07 [95% CI 1.45–2.95] p<0.01 and HR_LLN 2.00 [1.40–2.84] p<0.01) and was an independent marker when using LLN criteria (HR 1.74 [1.17‐2.59] p=0.006). RSP was independently associated with mortality when defined as FVC < LLN (HR 1.54 [1.01–2.35] p=0.04) but not as FVC < 80%. Multivariate hazard ratios for a 10% decrease in predicted value of FEV1 or FVC were 1.42 (p<0.001) and 1.33 (p<0.001) in patients exhibiting airflow obstruction, and 1.36 (p=0.031) and 1.38 (p=0.041) in RSP.

Conclusions

Presence of obstructive airflow limitation indicative of COPD or RSP were associated with increased all‐cause mortality, however only independently when using the LLN definition.

     

Pathophysiology of Evolution of Small Airways Disease to Overt COPD

ABSTRACT

Background: The slope of phase III (single breath nitrogen test), an index of ventilation inhomogeneity, has been used for early detection of COPD. Tidal airway closure (cyclic opening and closure of the peripheral airways during tidal breathing; AC_T) and expiratory flow limitation (attainment of maximal expiratory flow during tidal expiration; EFL_T) cause small airways disease (SAD). The relationships of these indices with COPD severity may reflect the progress from SAD to overt COPD. Methods: In this cross-sectional study we have assessed for the first time the phase III slope, AC_T and EFL_T in 10 smokers with normal spirometry (group O) and 40 COPD patients with GOLD scores from I to IV. Results: In most group O smokers the phase III slope was increased, and further increased with GOLD severity (up to 800%pred in GOLD IV). A close correlation was found of slope with GOLD (r = 0.77). AC_T was absent in smokers with normal spirometry and in most patients with mild COPD. EFL_T first appeared in GOLD II patients and its prevalence progressively increased in GOLD III and IV patients. Conclusions: Most group O smokers exhibit increased phase III. With overt COPD there is a progressive increase in phase III and reduction of FEV₁/FVC ratio from GOLD I to IV. A reduction of FEV₁ occurs from GOLD stage II. As the disease progresses from moderate to severe, there is an increasing presence of AC_T. Tidal EFL, with dynamic hyperinflation and severe dyspnea is present only in GOLD III and IV.     

Prevalence of Airflow Obstruction as Measured by Spirometry,in Rural Southern Indian Adults

Abstract

Rural population-based estimates of airflow obstruction based on spirometry are unavailable from southern India. This study assessed the prevalence of spirometry-defined airflow obstruction in Vellore, Tamil Nadu.

A cross sectional survey was done in nine villages, among adults aged ≥30?years, where previous cardiovascular surveys had been conducted (1994, 2011). Population proportional to size sampling was used to select 20 clusters, with sampling from all streets proportional to the number of households. One person randomly selected per household was interviewed for symptoms and risk factors. A respiratory therapist performed pre and post bronchodilator spirometry on all, following American Thoracic Society criteria. Airflow obstruction was defined as pre-bronchodilator Forced Expiratory Volume 1?s/Forced Vital Capacity (FEV1/FVC)?<?Lower Limit of Normal (LLN, derived from local prediction equations) and compared to other criteria.

Of 1015 participants, 787 completed technically acceptable spirometry. The prevalence of airflow obstruction was 9.0% (95% CI: 5.8%–9.6%, 71). Fixed obstruction (post bronchodilator FEV1/FVC?<?LLN) was 4.6% (95% CI: 3.1%–6.1%, 36), and 4.1% (95% CI: 2.7%–5.5%, 32) using post bronchodilator FEV1/FVC?<?70%. The GOLD criteria missed 56% (40) of those with airflow obstruction, of which 87.5% were females. Although 63.4% with airflow obstruction had moderate to severe disease, 82.2% were not on treatment and only 48.9% reported symptoms in the previous year.

This study estimates prevalence of airflow obstruction based on spirometry in rural southern India. Despite significant impairment on spirometry, majority were undiagnosed, and half did not report symptoms.     

Spirometric Thresholds for Diagnosing COPD: 0.70 or LLN,Pre- or Post-dilator Values?

Abstract

In absence of a gold standard for chronic obstructive pulmonary disease (COPD) it remains difficult to compare the true diagnostic characteristics of the forced expiratory volume in 1 second to the forced vital capacity (FEV₁/FVC) <0.70 and < lower limit of normal (LLN). COPD is a clinical diagnosis, based on symptoms signs and lung function results combined, and an expert panel assessment would be an adequate reference standard. We compared the diagnostic properties of FEV₁/FVC <LLN and <0.70 against this panel diagnosis: 342 participants, aged >50, consulting for persistent cough, but without physician-diagnosed COPD, were prospectively enrolled. All underwent extensive history taking, physical examination, spirometry and diffusion testing. An expert panel, including a board certified respiratory physician, assessed all diagnostic information to determine the presence or absence of COPD and served as reference standard. Then, 104 participants were diagnosed with COPD by the panel. The reproducibility of the panel diagnosis was high (kappa of 0.94). Sensitivity estimates of <0.70 were significantly higher than that of <LLN (0.73 and 0.47, respectively, p < 0.001). The fixed approach was less specific than the LLN (0.95 and 0.99, respectively, p < 0.001). There was no significant difference in diagnostic property when using pre- or post-bronchodilator FEV₁/FVC (p = 0.615). In a symptomatic primary care population, the FEV₁/FVC <0.70 was more accurate to detect COPD.     

The prevalence of chronic obstructive pulmonary disease in Uppsala, Sweden--the Burden of Obstructive Lung Disease (BOLD) study: cross-sectional population-based study

Objectives: To estimate chronic obstructive pulmonary disease (COPD) prevalence in Uppsala and the impact of risk factors on disease prevalence using the standardised methods of the Burden of Obstructive Lung Disease (BOLD) study initiative. Methods: Randomly selected participants, aged 40 years or more (n = 548) responded to a questionnaire regarding smoking habits, respiratory symptoms, medical history, and exposure to airway irritants. Spirometry, with a post‐bronchodilator test, was performed and COPD defined as post‐bronchodilatory forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) < 0.70 or FEV₁/FVC < lower limit of normality (LLN). Circulatory inflammatory markers were measured. Results: COPD prevalence was 16.2%, which was the fourth lowest prevalence of COPD, compared with 12 other BOLD centres. Main risk factors for COPD were increasing age [odds ratio (OR) = 2.08 per 10 years] and smoking (OR = 1.33 per 10 pack years). Higher education was protective (OR = 0.70 per 5 years). Previous tuberculosis was an almost significant risk factor for COPD (P = 0.08). Subjects with COPD reported more respiratory symptoms but only 29% had previous doctor diagnosed COPD, asthma, chronic bronchitis or emphysema. Participants with COPD had higher levels of C‐reactive protein (P = 0.01), but no difference was observed in interleukin 6 (IL‐6) levels. Using LLN instead of the fixed FEV₁/FVC ratio reduced the prevalence of COPD to 10%. Conclusion: COPD prevalence in Uppsala was similar to other BOLD centres in high‐income countries. Apart from known COPD risk factors (age, smoking, lower educational level), a history of tuberculosis may be associated with COPD even in high‐income countries. COPD remains under‐diagnosed, as only 29% of subjects with COPD had a previously diagnosed lung disorder. Please cite this paper as: Danielsson P, Ólafsdóttir IS, Benediktsdóttir B, Gíslason T and Janson C. The prevalence of chronic obstructive pulmonary disease in Uppsala, Sweden – the Burden of Obstructive Lung Disease (BOLD) study: cross‐sectional population‐based study. Clin Respir J 2012; 6: 120–127.     

The Utility of Spirometry in Diagnosing Pulmonary Restriction

The aim of this retrospective study was to determine the utility of the spirometric measurements FVC, FEV₁, and FEV₁/FVC in diagnosing pulmonary restriction. Spirometry and lung volume measurements performed on the same patient visit were analyzed. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of (1) FVC < lower limit of normal (LLN) (NHANES III reference values) and (2) FVC < LLN and FEV₁/FVC ≥ LLN were compared to diagnose restriction based on lung volume measurements. In all, 18,282 pulmonary function tests from 8,315 patients were analyzed. Twenty-six percent of the patients (n = 2,213) had restriction based on lung volume measurements. The sensitivity, specificity, PPV, and NPV of FVC < LLN to diagnose restriction based on lung volume measurement criteria were 88.6%, 56.8%, 39.9%, and 93.9%, respectively. The sensitivity, specificity, PPV, and NPV of FVC < LLN and FEV₁/FVC ≥ normal to diagnose restriction based on lung volume criteria were 72.4%, 87.1%, 64.4%, and 90.7%, respectively. Analysis of ROC curves showed that spirometric criteria based on FVC alone performed better (area under the curve = 0.817) than those based on the combined criteria of FVC and FEV₁/FVC (area under the curve = 0.584). Consistent with earlier findings, the negative predictive value for a normal FVC (≥ LLN) to exclude pulmonary restriction was high in this series (up to 95.7%). Also, a spirometric diagnosis of “restriction” (FVC < LLN and FEV₁/FVC ≥ LLN) had a positive predictive value of 26.3–73.9%. On this basis, normal FVC can be regarded as excluding restriction with high reliability. Saiprakash B. Venkateshiah and Octavian C. Ioachimescu authors contributed equally to this work.     

Diferencias geográficas en la prevalencia de EPOC en España: relación con hábito tabáquico,tasas de mortalidad y otros determinantes

Background

The EPI-SCAN study (Epidemiologic Study of COPD in Spain), conducted from May 2006 to July 2007, determined that the prevalence of COPD in Spain according to the GOLD criteria was 10.2% of the 40 to 80 years population. Little is known about the current geographical variation of COPD in Spain.

Objectives

We studied the prevalence of COPD, its under-diagnosis and under-treatment, smoking and mortality in the eleven areas participating in EPI-SCAN. COPD was defined as a post-bronchodilator FEV₁/FVC ratio <0.70 or as the lower limit of normal (LLN).

Results

The ratio of prevalences of COPD among the EPI-SCAN areas was 2.7-fold, with a peak in Asturias (16.9%) and a minimum in Burgos (6.2 %) (P<0.05). The prevalence of COPD according to LLN was 5.6% (95% CI 4.9–6.4) and the ratio of COPD prevalence using LLN was 3.1-fold, but with a peak in Madrid-La Princesa (10.1%) and a minimum in Burgos (3.2%) (P<0.05). The ranking of prevalences of COPD was not maintained in both sexes or age groups in each area. Variations in under-diagnosis (58.6% to 72.8%) and under-treatment by areas (24.1% to 72.5%) were substantial (P<0.05). The prevalence of smokers and former smokers, and cumulative exposure as measured by pack-years, and the age structure of each of the areas did not explain much of the variability by geographic areas. Nor is there any relation with mortality rates published by Autonomous Communities.

Conclusion

There are significant variations in the distribution of COPD in Spain, either in prevalence or in under-diagnosis and under-treatment     

Chronic obstructive pulmonary disease in patients admitted with heart failure

Objective. Chronic obstructive pulmonary disease (COPD) is an important differential diagnosis in patients with heart failure (HF). The primary aims were to determine the prevalence of COPD and to test the accuracy of self‐reported COPD in patients admitted with HF. Secondary aims were to study a possible relationship between right and left ventricular function and pulmonary function. Design. Prospective substudy. Setting. Systematic screening at 11 centres. Subjects. Consecutive patients (n = 532) admitted with HF requiring medical treatment with diuretics and an episode with symptoms corresponding to New York Heart Association class III‐IV within a month prior to admission. Interventions. Forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) were measured by spirometry and ventricular function by echocardiography. The diagnosis of COPD and HF were made according to established criteria. Results. The prevalence of COPD was 35%. Only 43% of the patients with COPD had self‐reported COPD and one‐third of patients with self‐reported COPD did not have COPD based on spirometry. The prevalence of COPD in patients with preserved left ventricular ejection fraction (i.e. LVEF ≥45%) was significantly higher than in patients with impaired LVEF (41% vs. 31%, P = 0.03). FEV₁ and FVC were negatively correlated with right ventricular end‐diastolic diameter and tricuspid annular plane systolic excursion and FVC positively correlated with systolic gradient across the tricuspid valve. Conclusion. Chronic obstructive pulmonary disease is frequent in patients admitted with HF and self‐reported COPD only identifies a minority. The prevalence of COPD was high in both patients with systolic and nonsystolic HF.     

Severity of Airflow Obstruction in Chronic Obstructive Pulmonary Disease (COPD): Proposal for a New Classification

Current classifications of Chronic Obstructive Pulmonary Disease (COPD) severity are complex and do not grade levels of obstruction. Obstruction is a simpler construct and independent of ethnicity. We constructed an index of obstruction severity based on the FEV₁/FVC ratio, with cut-points dividing the Burden of Obstructive Lung Disease (BOLD) study population into four similarly sized strata to those created by the GOLD criteria that uses FEV₁. We measured the agreement between classifications and the validity of the FEV₁-based classification in identifying the level of obstruction as defined by the new groupings. We compared the strengths of association of each classification with quality of life (QoL), MRC dyspnoea score and the self-reported exacerbation rate. Agreement between classifications was only fair. FEV₁-based criteria for moderate COPD identified only 79% of those with moderate obstruction and misclassified half of the participants with mild obstruction as having more severe COPD. Both scales were equally strongly associated with QoL, exertional dyspnoea and respiratory exacerbations. Severity assessed using the FEV₁/FVC ratio is only in moderate agreement with the severity assessed using FEV₁ but is equally strongly associated with other outcomes. Severity assessed using the FEV₁/FVC ratio is likely to be independent of ethnicity.     

Impaired Carbon Monoxide Diffusing Capacity is the Strongest Predictor of Exercise Intolerance in COPD

Abstract

Background: Exercise intolerance is a hallmark of chronic obstructive pulmonary disease (COPD) and forced expiratory volume in one second (FEV₁) is the traditional metric used to define the severity of COPD. However, there is dissociation between FEV₁ and exercise capacity in a large proportion of subjects with COPD. The aim of this study was to investigate whether other lung function parameters have an additive, predictive value for exercise capacity and whether this differs according to the COPD stage. Methods: Spirometry, body plethysmography and diffusing capacity for carbon monoxide (DLCO) were performed on 88 patients with COPD GOLD stages II-IV. Exercise capacity (EC) was determined in all subjects by symptom-limited, incremental cycle ergometer testing. Results: Significant relationships were found between EC and the majority of lung function parameters. DLCO, FEV₁ and inspiratory capacity (IC) were found to be the best predictors of EC in a stepwise regression analysis explaining 72% of EC. These lung function parameters explained 76% of EC in GOLD II, 72% in GOLD III and 40% in GOLD IV. DLCO alone was the best predictor of exercise capacity in all GOLD stages. Conclusions: Diffusing capacity was the strongest predictor of exercise capacity in all subjects. In addition to FEV₁, DLCO and IC provided a significantly higher predictive value regarding exercise capacity in COPD patients. This suggests that it is beneficial to add measurements of diffusing capacity and inspiratory capacity when clinically monitoring COPD patients.     

Effects of changing reference values and definition of the normal range on interpretation of spirometry

Background and objective: Recent spirometry reference studies are arguably the most valid ever performed and the ATS/ERS now recommend the National Health and Nutrition Assessment Survey (NHANES) equations for North America. It is timely to consider adopting these reference values in Australasia; however, an evaluation of the consequences of such a change is required. Methods: We analysed data from 1108 patients tested in two pulmonary function laboratories in public hospitals. Lower limits of normal (LLN) were calculated using European Community for Steel and Coal (ECSC) (1993), Knudson (1983), NHANES (1999) and Health Survey of England (HSE) (2004) equations and used to define restriction (FVC < LLN) and obstruction (FEV₁/FVC < LLN). This interpretative strategy was also compared with the GOLD definition of obstruction (FEV₁/FVC < 70%). Results: Average age for all patients (50% female) was 60 years (range: 20–91). The mean predicted FVC from NHANES and HSE were similar and consistently higher than those from ECSC and Knudson (average 270 mLs). This translates into a 76% increase in the incidence of ‘restrictive’ interpretations using NHANES data compared with ECSC and Knudson, and a smaller increase of 40% for HSE. Using FEV₁/FVC < 70% to diagnose obstruction in those over 65 years would result in false positive rates of approximately 28%. Using the same definition in a younger group (<50 years old) results in a false negative rate of approximately 14%. Conclusions: Changing to either NHANES or HSE predicted values will significantly increase the rate of ‘restrictive’ interpretation, and alter the rate of obstructive findings. The NHANES and HSE data confirm that using FEV₁/FVC < 70% to define obstruction causes misdiagnosis in elderly and younger subjects.     

COPD ‘diagnosis’ based on spirometric reference equations

Introduction: Chronic obstructive pulmonary disease (COPD) is suspected if the ratio between forced expired volume in 1 s (FEV₁) and forced vital capacity is below 0.7 after bronchodilatation, according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD). As this ratio varies with age and gender, the lower limit of normality (LLN) of appropriate reference equations appears more adequate. Objectives: To study the prevalences of suspected COPD according to the GOLD criterion and various reference equations in a well‐defined population sample. Methods: Spirometries obtained in a random population sample of 598 men, 50 or 60 years of age, were analysed. The prevalences of suspected COPD were calculated according to the GOLD criterion and the LLNs of four Nordic and two European reference equations. Results: The GOLD criterion resulted in prevalences of COPD of 9.3% and 23.7% in the 50‐ and 60‐year‐old never‐smokers, respectively. Depending on the reference equation, the calculated prevalences of COPD varied between 9.3% and 23.4% and 12.0% and 39.1% among all of the 50‐ and 60‐year‐old men, respectively. Conclusions: The GOLD criterion is inadequate because of substantial overestimation in 60‐year‐old never‐smokers. LLNs of the various reference equations are unreliable because of obvious lack of consistency. Spirometric criteria for airway obstruction, and suspicion of COPD, therefore need to be revised. Please cite this paper as: Olofson J, Bake B, Tengelin MN and Houltz B. COPD ‘diagnosis’ based on spirometric reference equations. The Clinical Respiratory Journal 2008; 2: 214–219.     

Cardiovascular Disease is Associated with COPD Severity and Reduced Functional Status and Quality of Life

Introduction: Smoking is a major risk factor for both cardiovascular disease (CVD) and chronic obstructive pulmonary disease (COPD). More individuals with COPD die from CVD than respiratory causes and the risk of developing CVD appears to be independent of smoking burden. Although CVD is a common comorbid condition within COPD, the nature of its relationships to COPD affection status and severity, and functional status is not well understood. Methods: The first 2,500 members of the COPDGene cohort were evaluated. Subjects were current and former smokers with a minimum 10 pack-year history of cigarette smoking. COPD was defined by spirometry as an FEV₁/FVC < lower limit of normal (LLN) with further identification of severity by FEV₁ percent of predicted (GOLD stages 2, 3, and 4) for the main analysis. The presence of physician-diagnosed self-reported CVD was determined from a medical history questionnaire administered by a trained staff member. Results: A total of 384 (15%) had pre-existing CVD. Self-reported CVD was independently related to COPD (Odds Ratio = 1.61, 95% CI = 1.18–2.20, p = 0.01) after adjustment for covariates with CHF having the greatest association with COPD. Within subjects with COPD, pre-existing self-reported CVD placed subjects at greater risk of hospitalization due to exacerbation, higher BODE index, and greater St. George's questionnaire score. The presence of self-reported CVD was associated with a shorter six-minute walk distance in those with COPD (p < 0.05). Conclusions: Self-reported CVD was independently related to COPD with presence of both self-reported CVD and COPD associated with a markedly reduced functional status and reduced quality of life. Identification of CVD in those with COPD is an important consideration in determining functional status.     

The Prevalence of Alpha-1 Antitrypsin Deficiency Among Patients Found to Have Airflow Obstruction

Abstract

Introduction: Alpha-1 antitrypsin deficiency (AATD) is a genetic disease that may be manifested by chronic obstructive pulmonary disease. Despite professional society guidelines that recommend broad testing of at-risk individuals, fewer than 10% of affected individuals have been identified. The goals of this study were to estimate the frequency of abnormal AAT genotypes among patients found to have fixed airflow obstruction and to assess the feasibility of having Pulmonary Function Laboratory personnel administer the study. Methods: Nineteen medical centers in the United States participated in the study. Eligible patients (> GOLD II, FEV₁/FVC ratio < 0.7, with post-bronchodilator FEV₁<80% predicted) were offered testing for AATD by the Pulmonary Function Laboratory personnel at the time of pulmonary function testing. Results: A total of 3,457 patients were tested, of whom 3152 were eligible. Deficient patients (ZZ, SZ) constituted 0.63% of subjects, while 10.88% were carriers (MS, MZ). Neither demographic (except African-American race) nor post-bronchodilator pulmonary function variables (FEV₁, FVC, FEV₁/FVC ratio, TLC, and FEV₁/FVC) allowed us to predict AAT heterozygote or deficiency status. Conclusions: The prevalence of AATD among patients undergoing pulmonary function tests with fixed airflow obstruction was 0.63%. Pulmonary Function Laboratory personnel effectively conducted the study.     

A new staging strategy for chronic obstructive pulmonary disease

Background:

The best method for expressing lung function impairment is undecided. We tested in a population of patients with chronic obstructive pulmonary disease (COPD) whether forced expiratory volume in 1 second (FEV₁) or FEV₁ divided by height squared (FEV₁/ht²) was better than FEV₁ percent predicted (FEV₁PP) for predicting survival.

Method:

FEV₁, FEV₁PP, and FEV₁/ht² recorded post bronchodilator were compared as predictors of survival in 1095 COPD patients followed for 15 years. A staging system for severity of COPD was defined from FEV₁/ht² and compared with the Global Initiative for Obstructive Lung Disease (GOLD) staging system.

Result:

FEV₁/ht² was a better univariate predictor of survival in COPD than FEV₁ and both were better than FEV₁PP. The best multivariate model for predicting survival included FEV₁/ht², age and sex. Comparing the GOLD stages with the FEV₁/ht² groups found that survival was more coherent within each FEV₁/ht group than it was within each GOLD stage. FEV₁/ht² had 60% more people in its most severe group than the severest GOLD stage with these extra subjects having equivalently poor survival and had 155% more in the least severe group with equivalent survival. GOLD staging misclassified 51% of subjects with regard to survival.

Conclusion:

We conclude that GOLD criteria using FEV₁PP do not optimally stage COPD with regard to survival. An alternative strategy using FEV₁/ht² improves the staging of this disease. Studies which stratify COPD patients to determine the effect of interventions such as drug trials, rehabilitation, or management guidelines should consider alternatives to the GOLD classification.     

Reference values for spirometry,including vital capacity,in Japanese adults calculated with the LMS method and compared with previous values

BackgroundReference values for lung function tests should be periodically updated because of birth cohort effects and improved technology. This study updates the spirometric reference values, including vital capacity (VC), for Japanese adults and compares the new reference values with previous Japanese reference values.MethodsSpirometric data from healthy non-smokers (20,341 individuals aged 17–95 years, 67% females) were collected from 12 centers across Japan, and reference equations were derived using the LMS method. This method incorporates modeling skewness (lambda: L), mean (mu: M), and coefficient of variation (sigma: S), which are functions of sex, age, and height. In addition, the age-specific lower limits of normal (LLN) were calculated.ResultsSpirometric reference values for the 17–95-year age range and the age-dependent LLN for Japanese adults were derived. The new reference values for FEV₁ in males are smaller, while those for VC and FVC in middle age and elderly males and those for FEV₁, VC, and FVC in females are larger than the previous values. The LLN of the FEV₁/FVC for females is larger than previous values. The FVC is significantly smaller than the VC in the elderly.ConclusionsThe new reference values faithfully reflect spirometric indices and provide an age-specific LLN for the 17–95-year age range, enabling improved diagnostic accuracy. Compared with previous prediction equations, they more accurately reflect the transition in pulmonary function during young adulthood. In elderly subjects, the FVC reference values are not interchangeable with the VC values.