Subjects with Discordant Airways Obstruction: Lost between Spirometric Definitions of COPD

[The FEV1/VC ratio to define bronchial obstruction: Should we use a fixed ratio or the lower limit of normal?]

INTRODUCTION

While the screening of chronic obstructive lung diseases (COPD, asthma, etc.) constitutes a major public health issue in France and worldwide, simple spirometry appears currently as the key to meeting the challenge. Since description of the forced expiratory maneuver by Robert Tiffeneau in 1947, it has been admitted that the FEV1/VC ratio permits diagnosis obstructive pulmonary diseases. However, the diagnostic criteria for this ratio remain uncertain. The long-lasting debate between advocates of a 0.7 "fixed ratio" (FR) of 0.7 and advocates of the "lower limit of normal" (LLN) remains relevant.

STATE OF THE ARTS

In this general review, we describe the respective advantages of the FR and LLN criteria according to the most recently published studies, and characterize the conditions associated with discrepancies between these criteria.

PERSPECTIVES AND CONCLUSIONS

FR and LLN appear not to share similar diagnosis values and the use of both criteria facilitates proposal of an up-to-date interpretation and diagnosis strategy in the context of first-line spirometry, particularly for patients with FEV1/VC ratio in the "grey zone".

Airway Obstruction in Primary Care Patients: Need for Implementing Spirometry Use

(1) Background: To detect early airway obstruction in an adult primary care setting. (2) Methods: Seventeen general practitioners (GP) were involved. A total of 912 patients consulting their GPs over 40 years were recruited: 583 of them (323M) agreed to perform/undergo all the procedures: respiratory questionnaire, mMRC questionnaire, and spirometry. We identified four subgroups: physician COPD patients; physician asthma patients; asthma-COPD overlap syndrome patients; and no respiratory diagnosis subjects, on the basis of physician diagnosis. For screening purposes, an FEV1/FVC < 70% was considered a marker of airway obstruction (AO). (3) Results: Prevalence rates of COPD, A, and ACOS were 12.5%, 7.8%, and 3.6%, respectively. In the overall sample 16.3% showed airway obstruction: 26% mild, 56% moderate, 17% severe, and 1% very severe. In obstructed subjects, those reporting neither respiratory symptoms nor a physician’s respiratory diagnosis were 60% level I; 43% level II; 44% level III; and none level IV. Wheezing (p < 0.001), sputum (p = 0.01), older age (p < 0.0001), and male gender (p = 0.002) were the best predictors of airway obstruction. (4) Conclusions: A high prevalence of AO was found. In AO we found a high prevalence of subjects without respiratory symptoms or respiratory chronic diagnosis. Airway obstruction was predicted by the presence of wheezing, sputum, older age, and male gender.

Personalised Lung Cancer Screening (PLuS) study to assess the importance of coexisting chronic conditions to clinical practice and policy: protocol for a multicentre observational study

INTRODUCTION

Lung cancer is the leading cause of cancer death in the USA and worldwide, and lung cancer screening (LCS) with low-dose CT (LDCT) has the potential to improve lung cancer outcomes. A critical question is whether the ratio of potential benefits to harms found in prior LCS trials applies to an older and potentially sicker population. The Personalised Lung Cancer Screening (PLuS) study will help close this knowledge gap by leveraging real-world data to fully characterise LCS recipients. The principal goal of the PLuS study is to characterise the comorbidity burden of individuals undergoing LCS and quantify the benefits and harms of LCS to enable informed decision-making.

METHODS AND ANALYSIS

PLuS is a multicentre observational study designed to assemble an LCS cohort from the electronic health records of ~40 000 individuals undergoing annual LCS with LDCT from 2016 to 2022. Data will be integrated into a unified repository to (1) examine the burden of multimorbidity by race/ethnicity, socioeconomic status and age; (2) quantify potential benefits and harms; and (3) use the observational data with validated simulation models in the Cancer Intervention and Surveillance Modeling Network (CISNET) to provide LCS outcomes in the real-world US population. We will fit a multivariable logistic regression model to estimate the adjusted ORs of comorbidity, functional limitations and impaired pulmonary function adjusted for relevant covariates. We will also estimate the cumulative risk of LCS outcomes using discrete-time survival models. To our knowledge, this is the first study to combine observational data and simulation models to estimate the long-term impact of LCS with LDCT.

ETHICS AND DISSEMINATION

The study was approved by the Kaiser Permanente Southern California Institutional Review Board and VA Portland Health Care System. The results will be disseminated through publications and presentations at national and international conferences. Safety considerations include protection of patient confidentiality.

Relationship between Multimorbidity and Quality of Life in a Primary Care Setting: The Mediating Role of Dyspnea

Multimorbidity is known to impair Quality of Life (QoL) in patients in a primary setting. Poor QoL is associated with higher dyspnea perception. How multimorbidity and dyspnea perception are related to QoL needs clarification. The aim of the present study is to evaluate the mediating role of dyspnea perception in the relationship between multimorbidity and QoL in adults with and without airflow obstruction in a primary care setting. Seventeen general practitioners participated in the study: a total of 912 adult patients attending the practitioner’s surgery for a generic consultation completed a preliminary respiratory screening; 566 of them answered a respiratory questionnaire between January and June 2014, and 259 of the latter (148 M, aged 40–88) agreed to go through all the of procedures including spirometry, the IMCA and QoL (SF-36 through Physical Health “PCS” and Mental Health components) questionnaires, evaluation of comorbidities and the mMRC Dyspnea Scale. For screening purpose, a cut-off of FEV₁/FVC < 70% was considered a marker of airflow obstruction (AO). Of the sample, 25% showed airflow obstruction (AO). No significant difference in mMRC score regarding the number of comorbidities and the PCS was found between subjects with and without AO. Multimorbidity and PCS were inversely related in subjects with (p < 0.001) and without AO (p < 0.001); mMRC and PCS were inversely related in subjects with (p = 0.001) and without AO (p < 0.001). A mediation analysis showed that the relation between number of comorbidities and PCS was totally mediated by mMRC in subjects with AO and partially in subjects without AO. We conclude that the effect of multimorbidity on PCS is totally mediated by mMRC only in AO. Detecting and monitoring mMRC in a primary care setting may be a useful indicator for evaluating a patient’s global health.

Spirometry for the diagnosis of airway obstruction in patients with risk factors for COPD: the GOLD and lower limit of normal criteria

OBJECTIVE

The identification of persistent airway obstruction is key to making a diagnosis of COPD. The GOLD guidelines suggest a fixed criterion-a post-bronchodilator FEV1/FVC ratio < 70%-to define obstruction, although other guidelines suggest that a post-bronchodilator FEV1/FVC ratio < the lower limit of normal (LLN) is the most accurate criterion.

METHODS

This was an observational study of individuals ≥ 40 years of age with risk factors for COPD who were referred to our pulmonary function laboratory for spirometry. Respiratory symptoms were also recorded. We calculated the prevalence of airway obstruction and of no airway obstruction, according to the GOLD criterion (GOLD+ and GOLD-, respectively) and according to the LLN criterion (LLN+ and LLN-, respectively). We also evaluated the level of agreement between the two criteria.

RESULTS

A total of 241 individuals were included. Airway obstruction was identified according to the GOLD criterion in 42 individuals (17.4%) and according to the LLN criterion in 23 (9.5%). The overall level of agreement between the two criteria was good (k = 0.67; 95% CI: 0.52-0.81), although it was lower among the individuals ≥ 70 years of age (k = 0.42; 95% CI: 0.12-0.72). The proportion of obese individuals was lower in the GOLD+/LLN+ category than in the GOLD+/LLN- category (p = 0.03), as was the median DLCO (p = 0.04).

CONCLUSIONS

The use of the GOLD criterion appears to be associated with a higher prevalence of COPD. The agreement between the GOLD and LLN criteria also appears to be good, albeit weaker in older individuals. The use of different criteria to define airway obstruction seems to identify individuals with different characteristics. It is essential to understand the clinical meaning of discordance between such criteria. Until more data are available, we recommend a holistic, individualized approach to, as well as close follow-up of, patients with discordant results for airway obstruction.

Use of the terms "overdiagnosis" and "misdiagnosis" in the COPD literature: a rapid review

Challenges in the diagnostic process of chronic obstructive pulmonary disease (COPD) can result in diagnostic misclassifications, including overdiagnosis. The term "overdiagnosis" in general has been associated with variable definitions. In connection with efforts to reduce low-value care, "overdiagnosis" has been defined as a true positive diagnosis of a condition that is not associated with any harm in the diagnosed person. It is, however, unclear how the term "overdiagnosis" is used in the COPD literature. We conducted a rapid review of the literature to explore how the terms "overdiagnosis" and "misdiagnosis" are used in the context of COPD. Electronic searches of Medline were conducted from inception to October 2018, to identify primary studies that reported on over- and/or misdiagnosis of COPD using these terms. 28 articles were included in this review. Overdiagnosis and misdiagnosis in COPD were found to be used to describe five main concepts: 1) physician COPD diagnosis despite normal spirometry (14 studies); 2) discordant results for COPD diagnosis based on different spirometry-based definitions for airflow obstruction (10 studies); 3) COPD diagnosis based on pre-bronchodilator spirometry results (three studies); 4) comorbidities (e.g. heart failure or asthma) that affect spirometry and have clinical features which overlap with COPD (two studies); and 5) normalisation of abnormal (post-bronchodilator) spirometry at follow-up (one study). The terms "overdiagnosis" and "misdiagnosis" were often used interchangeably and almost always referred to a false positive diagnosis. Performing (technically correct) spirometry with correct interpretation of the results could probably reduce misdiagnosis in a large proportion of the misdiagnosed cases of COPD. In addition, guidelines need to provide a more acceptable consensus spirometric definition of airflow obstruction.

KEY POINTS

In the COPD literature, the terms "overdiagnosis" and "misdiagnosis" are often used interchangeably and almost always refer to a false positive diagnosis.Use of spirometry with correct interpretation of the results can avoid a substantial proportion of cases of misdiagnosis of COPD.

EDUCATIONAL AIMS

To explore the use of the terms "overdiagnosis" and "misdiagnosis" in the COPD literature.To identify the main sources of overdiagnosis and misdiagnosis in COPD.

Clinical characteristics of patients newly diagnosed with COPD by the fixed ratio and lower limit of normal criteria: a cross-sectional analysis of the TargetCOPD trial

Background

Consensus on the definition of airflow obstruction to diagnose COPD remains unresolved.

Methods

We undertook systematic case finding for COPD in primary care using the fixed ratio (FR) criterion (forced expiratory volume in 1 s/forced vital capacity [FEV1/FVC] <0.7) for defining airflow obstruction and also using the lower limit of normal (LLN). We then compared the clinical characteristics of those identified by the 2 criteria.

Results

A total of 3,721 individuals reporting respiratory symptoms were invited for spirometry. A total of 2,607 attended (mean age 60.4 years, 52.8% male, 29.8% current smokers) and 32.6% had airflow obstruction by FR ("FR+") and 20.2% by LLN ("LLN+"). Compared with the LLN+/FR+ group, the LLN-/FR+ group (12.4%) was significantly older, had higher FEV1 and FEV1/FVC, lower COPD assessment test scores, and less cough, sputum, and wheeze, but was significantly more likely to report a diagnosis of heart disease (14.2% versus 6.9%, p<0.001). Compared with the LLN+/FR+ group, the LLN-/FR- group was younger, had a higher body mass index, fewer pack-years, a lower prevalence of respiratory symptoms except for dyspnea, and lower FVC and higher FEV1. The probability of known heart disease was significantly lower in the LLN+/FR+ group compared with those with preserved lung function (LLN-/FR-) (adjusted odds ratio 0.62, 95% CI: 0.43-0.90) but this was not seen in the LLN-/FR+ group (adjusted odds ratio 0.90, 95% CI: 0.63-1.29).

Conclusion

In symptomatic individuals, defining airflow obstruction by FR instead of LLN identifies a significant number of individuals who have less respiratory and more cardiac clinical characteristics.

[Utility of normality low limit of spirometry in diagnosed COPD patients]

AIM

To evaluate the differences in COPD patients below the lower limit of normal (LLN) of the fixed ratio FEV1/FVC < 0.70 and those above this limit.

PATIENTS AND METHODS

Cross-sectional study. COPD patients between 40 and 85 years old included in primary care clinical record database were randomly selected. Baseline and postbronchodilator spirometries were performed. Two groups of patients were established: FEV1/FVC<0.70 and ≤LIN (group1) and FEV/FVC<0.70 and >LIN (group 2). Sociodemographic, clinical, pulmonary obstruction, quality of life and attendance to health services variables were measured. The results of both groups were compared.

RESULTS

22.3% of the subjects were misdiagnosed FEV1/FVC < 0,70. Patients in group 2 (FEV1/FVC<0.70 y > LLN) are diagnosed at an older age, they have a lower exposure to tobacco and better pulmonary function (FEV1: 74.9% vs 54.6%). 35.5% of those patients belong to stage i of GOLD, vs 8.5%, this patients have an increased comorbidity. Patients in group 1 have more COPD exacerbations, worse quality of life, a higher BODEx index 2,3 (1.8) vs 1.1 (1.5); 55.1% of those patients were high risk patients (GoldC or Gold D). Diagnose before being 56 years old, an increased exposure to tobacco, the FEV>50%, and a lower comorbidity are associated with a greater chance of suffering COPD with LLN criteria.

CONCLUSION

We obtain two groups of patients with differentiated clinical characteristics if we use LLN. Subjects with FEV1/FVC<0.7 and >LLN have less obstruction, less severity and more comorbidity, suggesting the possibility of overdiagnosis or misdiagnosis. On the other hand, younger age at the time of diagnosis, higher tobacco consumption and more severe obstruction are related with FEV1/FVC >0.70 and<LLN (group 1).

Development and validation of the Salzburg COPD-screening questionnaire (SCSQ): a questionnaire development and validation study

Chronic obstructive pulmonary disease prevalence rates are still high. However, the majority of subjects are not diagnosed. Strategies have to be implemented to overcome the problem of under-diagnosis. Questionnaires could be used to pre-select subjects for spirometry and thereby help reducing under-diagnosis. We report a brief, simple, self-administrable and validated chronic obstructive pulmonary disease questionnaire to increase the pre-test probability for chronic obstructive pulmonary disease diagnosis in subjects undergoing confirmatory spirometry. In 2005, we completed the Austrian Burden of Obstructive Lung Disease-study in 1258 subjects aged >40 years. Post-bronchodilator spirometry was performed, and non-reversible airflow limitation defined by FEV1/FVC ratio below the lower limit of normal. Questions from the Salzburg chronic obstructive pulmonary disease screening-questionnaire were selected using a logistic regression model, and risk scores were based on regression-coefficients. A training sub-sample (n = 800) was used to create the score, and a test sub-sample (n = 458) was used to test it. In 2008, an external validation study was done, using the same protocol in 775 patients from primary care. The Salzburg chronic obstructive pulmonary disease screening questionnaire was composed of items related to "breathing problems", "wheeze", "cough", "limitation of physical activity", and "smoking". At the >=2 points cut-off of the Salzburg chronic obstructive pulmonary disease screening questionnaire, sensitivity was 69.1% [95%CI: 56.6%; 79.5%], specificity 60.0% [95%CI: 54.9%; 64.9%], the positive predictive value 23.2% [95%CI: 17.7%; 29.7%] and the negative predictive value 91.8% [95%CI: 87.5%; 95.7%] to detect post bronchodilator airflow limitation. The external validation study in primary care confirmed these findings. The Salzburg chronic obstructive pulmonary disease screening questionnaire was derived from the highly standardized Burden of Obstructive Lung Disease study. This validated and easy to use questionnaire can help to increase the efficiency of chronic obstructive pulmonary disease case-finding.

CHRONIC OBSTRUCTIVE PULMONARY DISEASE

QUESTIONNAIRE FOR PRE-SCREENING POTENTIAL SUFFERERS: Scientists in Austria have developed a brief, simple questionnaire to identify patients likely to have early-stage chronic lung disease. Chronic obstructive pulmonary disease (COPD) is notoriously difficult to diagnose, and the condition often causes irreversible lung damage before it is identified. Finding a simple, cost-effective method of pre-screening patients with suspected early-stage COPD could potentially improve treatment responses and limit the burden of extensive lung function ('spirometry') tests on health services. Gertraud Weiss at Paracelsus Medical University, Austria, and co-workers have developed and validated an easy-to-use, self-administered questionnaire that could prove effective for pre-screening patients. The team trialed the five-point Salzburg COPD-screening questionnaire on 1258 patients. Patients scoring 2 points or above on the questionnaire underwent spirometry tests. The questionnaire seems to provide a sensitive and cost-effective way of pre-selecting patients for spirometry referral.

GOLD criteria overestimate airflow limitation in one-third of cases in the general Finnish population

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) diagnostic criteria for chronic obstructive pulmonary disease (COPD) use a fixed threshold of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio (<0.70) in post-bronchodilation spirometry to indicate disease, which has been shown to underestimate and overestimate disease prevalence in younger and older adults, respectively, whilst criteria based on reference values have better accuracy. Differences in reference values have limited their use in international studies. However, the new Global Lung Function Initiative reference values (GLI2012) showed FEV1/FVC to be the least dependent on ethnicity. The aim of this study was to assess the prevalence of airflow limitation with GLI2012 and the degree of underdetection or overestimation related to the use of GOLD in the general population. A Finnish population sample of 1323 subjects (45% male) with post-bronchodilation spirometry was studied. 80 subjects (6.0%) and 55 subjects (4.2%) were identified with airflow limitation with GOLD and GLI2012 criteria, respectively. The proportion of overestimation with GOLD increased with age from 25% of cases in 50-year-olds to 54% in 70-year-olds. Using z-score-based grading resulted in more dispersion in severity grading. In conclusion, the GOLD criteria cause a marked overestimation already from 50-year-olds and should be replaced with the GLI2012 criteria to improve diagnostic accuracy.

Lung function, forced expiratory volume in 1 s decline and COPD hospitalisations over 44 years of follow-up

The use of baseline lung function in the prediction of chronic obstructive pulmonary disease (COPD) hospitalisations, all-cause mortality and lung function decline was assessed in the population-based "Men Born in 1914" cohort.Spirometry was assessed at age 55 years in 689 subjects, of whom 392 had spirometry reassessed at age 68  years. The cohort was divided into three groups using fixed ratio (FR) and lower limit of normal (LLN) criterion: forced expiratory volume in 1 s (FEV1)/vital capacity (VC) ≥70%, FEV1/VC <70% but ≥LLN (FR(+)LLN(-)), and FEV1/VC <70% and <LLN (FR(+)LLN(+)).Over 44 years of follow-up, 88 men were hospitalised due to COPD and 686 died. Hazard ratios (95% CI) for incident COPD hospitalisation were 4.15 (2.24-7.69) for FR(+)LLN(-) and 7.88 (4.82-12.87) for FR(+)LLN(+) (reference FEV1/VC ≥70%). Hazard ratios for death were 1.30 (0.98-1.72) for FR(+)LLN(-) and 1.58 (1.25-2.00) for FR(+)LLN(+). The adjusted FEV1 decline between 55 and 68 years of age was higher for FR(+)LLN(-) and FR(+)LLN(+) relative to the reference. Of those with FR(+)LLN(-) at 55 years, 53% had progressed to the FR(+)LLN(+) group at 68 years.Airflow obstruction at age 55 years is a powerful risk factor for future COPD hospitalisations. The FR(+)LLN(-) group should be carefully evaluated in clinical practice in relation to future risks and potential benefit from early intervention. This is reinforced by the increased FEV1 decline in this group.

Incidence of chronic obstructive pulmonary disease based on three spirometric diagnostic criteria in Sao Paulo, Brazil: a nine-year follow-up since the PLATINO prevalence study

CONTEXT AND OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a respiratory disease of high prevalence and socioeconomic impact worldwide. It affects approximately 16% of the population of São Paulo. The incidence of COPD is still unknown in Brazil. The aim of this study was to estimate new cases of COPD in a population-based sample in São Paulo, Brazil, using three different spirometric diagnostic criteria, and to assess the concordance between these criteria.

DESIGN AND SETTING

Prospective cohort study, in the city of São Paulo, Brazil.

METHODS

A questionnaire was applied and anthropometry and pre and post-bronchodilator spirometry were performed on the same subjects as in the initial PLATINO study (2003) in São Paulo. Data from this follow-up study were added to the original database of the initial phase. Incident COPD cases refer to subjects who developed the disease in accordance with each spirometric criterion during the nine-year follow-up period. The Statistical Package for the Social Sciences, version 17.0 (SPSS Inc., Chicago, IL, USA) was used in the analysis and the significance level was set at P < 0.05.

RESULTS

613 subjects participated in the follow-up. New COPD cases ranged in frequency from 1.4% to 4.0%, depending on the diagnostic criterion used. The concordance between the criteria ranged from 35% to 60%.

CONCLUSION

The incidence of COPD after a nine-year follow-up was high, but varied according to the spirometric criterion used. The agreement between the criteria for identifying new cases of the disease ranged from 35% to 60%.

PLATINO, a nine-year follow-up study of COPD in the city of São Paulo, Brazil: the problem of underdiagnosis

OBJECTIVE:

To determine the underdiagnosis rate in new COPD cases at the end of a nine-year follow-up period-in the study designated "Projeto Latino-Americano de Investigação em Obstrução Pulmonar" (PLATINO, Latin-American Pulmonary Obstruction Investigation Project)-and compare that with the underdiagnosis rate during the initial phase of the study, as well as to identify the clinical features exhibited by the subjects who were not diagnosed until the end of the follow-up phase.

METHODS:

The study population comprised the 1,000 residents of the city of São Paulo, Brazil, who took part in the PLATINO study. Of those, 613 participated in the follow-up phase, during which the subjects were assessed with the same instruments and equipment employed in the initial phase of the study. We used the chi-square test or the independent sample t-test to analyze the underdiagnosis rate and to identify the characteristics of the subjects who were not diagnosed until the end of the follow-up phase.

RESULTS:

The underdiagnosis rate for new COPD cases at the end of the nine-year follow-up period was 70.0%. The underdiagnosis rate during the follow-up phase was 17.5% lower than that reported for the initial phase of the study. The subjects who were not diagnosed until the end of the follow-up phase presented with fewer respiratory symptoms, better pulmonary function, and less severe disease than did those previously diagnosed with COPD.

CONCLUSIONS:

The underdiagnosis rate for new COPD cases was lower in the follow-up phase of the study than in the initial phase. The subjects who were not diagnosed until the end of the follow-up phase of the PLATINO study presented with the same clinical profile as did those who were not diagnosed in the initial phase. These findings underscore the need for spirometry in order to confirm the diagnosis of COPD and provide early intervention.

COPD in chronic heart failure: less common than previously thought?

BACKGROUND

Using a fixed ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1/FVC) < 0.70 instead of the lower limit of normal (LLN) to define chronic obstructive pulmonary disease (COPD) may lead to overdiagnosis of COPD in elderly patients with heart failure (HF) and consequently unnecessary treatment with possible adverse health effects.

OBJECTIVE

The aim of this study was to determine COPD prevalence in patients with chronic HF according to two definitions of airflow obstruction.

METHODS

Spirometry was performed in 187 outpatients with stable chronic HF without pulmonary congestion who had a left ventricular ejection fraction <40% (mean age 69 ± 10 years, 78% men). COPD diagnosis was confirmed 3 months after standard treatment with tiotropium in newly diagnosed COPD patients.

RESULTS

COPD prevalence varied substantially between 19.8% (LLN-COPD) and 32.1% (GOLD-COPD). Twenty-three of 60 patients (38.3%) with GOLD-COPD were potentially misclassified as having COPD (FEV1/FVC < 0.7 but > LLN). In contrast to patients with LLN-COPD, potentially misclassified patients did not differ significantly from those without COPD regarding respiratory symptoms and risk factors for COPD.

CONCLUSIONS

One fifth, rather than one third, of the patients with chronic HF had concomitant COPD using the LLN instead of the fixed ratio. LLN may identify clinically more important COPD than a fixed ratio of 0.7.

Clinical relevance of diagnosing COPD by fixed ratio or lower limit of normal: a systematic review

BACKGROUND

Different spirometric criteria in diagnosing COPD have been advocated by different groups, debilitating adequate diagnosis and treatment of COPD. We reviewed the clinical relevance of fixed ratio and lower limit of normal (LLN) in diagnosing COPD and explored if modifying factors may affect their clinical relevance.

METHODS

Two reviewers independently searched PubMed and Embase for papers that compared both criteria on any clinically relevant outcome, published before June 1st, 2012, without any language restriction. Two reviewers independently extracted the study characteristics, including study design, population characteristics and diagnostic criteria used, and summarized the results of clinical relevance. Study quality was assessed by scoring forms for bias and level of evidence.

RESULTS

Of 394 studies retrieved, 11 studies were included, with a median of 1,258 participants. Although both criteria appeared related with various clinically relevant outcomes, we were unable to prefer one criterion over the other, with various performances of the criteria for different outcomes. Should the criteria disagree on diagnosis, an alternative diagnosis should be suspected, in particular in those (elderly) with less severe airflow limitation for whom the LLN appears a better criterion. The fixed ratio appears to perform better in subjects with more severe airflow limitation.

CONCLUSION

In diagnosing COPD, severity of airflow limitation appears an important factor for choosing whether the fixed ratio or LLN. Disagreement between the criteria is suggestive for an alternative diagnosis. Future studies on clinical relevance should further reveal the criterion of choice, in order to improve adequate diagnosis and consequent treatments.

Diagnosis of airway obstruction in the elderly: contribution of the SARA study

BACKGROUND

The choice between lower limit of normal or fixed value of forced expiratory volume in one second/forced vital capacity ratio (FEV(1)/FVC) < 0.70 as the criterion for confirming airway obstruction is an open issue. In this study, we compared the criteria of lower limit of normal and fixed FEV(1)/FVC for diagnosis of airway obstruction, with a focus on healthy elderly people.

METHODS

We selected 367 healthy nonsmoking subjects aged 65-93 years from 1971 participants in the population-based SARA (Salute Respiratoria nell'Anziano, Italian for "Respiratory Health in the Elderly") study, analyzed their spirometric data, and tested the relationship between spirometric indices and anthropometric variables. The lower limit of normal for FEV(1)/FVC was calculated as the fifth percentile of the normal distribution for selected subjects.

RESULTS

While FEV(1) and FVC decreased significantly with aging, the relationship between FEV(1)/FVC and age was not statistically significant in men or women. The lower limit of normal for FEV(1)/FVC was 0.65 in men and 0.67 in women. Fifty-five participants (15%) had FEV(1)/FVC < 0.70 and would have been inappropriately classified as obstructed according to the Global Initiative for Obstructive Lung Disease, American Thoracic Society/European Respiratory Society, and Canadian guidelines on chronic obstructive pulmonary disease. By applying different FEV(1)/FVC thresholds for the different age groups, as previously proposed in the literature, (0.70 for <70 years, 0.65 for 70-80 years, and 0.60 for >80 years) the percentage of patients classified as obstructed decreased to 6%. No subjects older than 80 years had an FEV(1)/FVC < 0.60.

CONCLUSION

The present results confirm the inadequacy of FEV(1)/FVC < 0.70 as a diagnostic criterion for airway obstruction after the age of 65 years. FEV(1)/FVC < 0.65 and <0.67 (for men and women, respectively) could identify subjects with airway obstruction in such a population. Further reduction of the threshold after 80 years is not justified.

Issues in pulmonary function testing for the screening and diagnosis of chronic obstructive pulmonary disease

PURPOSE OF REVIEW

The purpose of this review article is to provide an up-to-date summary on the current evidence for or against the use of lung function tests as screening and diagnostic tools for airflow obstruction in chronic obstructive pulmonary disease (COPD), and to consider the relevant issues in context.

RECENT FINDINGS

COPD is characterized by chronic respiratory symptoms and airflow limitation with only partial reversibility on lung function testing. However, screening on a population basis or of an enriched 'at-risk' subset like chronic smokers is not supported by findings from previous epidemiological studies, screening trials or in currently published clinical management guidelines by professional societies and review bodies. The definition of airflow obstruction and the classification of disease severity of COPD also differ slightly between guidelines and statements from different professional societies.

SUMMARY

Given the experience from previous screening trials and controversial classification of airflow obstruction by severity, it is impossible to have accurate screening results for COPD based on lung function tests alone. Clinical respiratory symptoms should be taken into consideration in terms of the diagnosis and management of COPD, as well as in any screening trial or programme that is to be attempted or implemented.

Addressing geographical variation in the progression of non-communicable diseases in Peru: the CRONICAS cohort study protocol

Background The rise in non-communicable diseases in developing countries has gained increased attention. Given that around 80% of deaths related to non-communicable diseases occur in low- and middle-income countries, there is a need for local knowledge to address such problems. Longitudinal studies can provide valuable information about disease burden of non-communicable diseases in Latin America to inform both public health and clinical settings. Methods The CRONICAS cohort is a longitudinal study performed in three Peruvian settings that differ by degree of urbanisation, level of outdoor and indoor pollution and altitude. The author sought to enrol an age- and sex-stratified random sample of 1000 participants at each site. Study procedures include questionnaires on socio-demographics and well-known risk factors for cardiopulmonary disease, blood draw, anthropometry and body composition, blood pressure and spirometry before and after bronchodilators. All participants will be visited at baseline, at 20 and 40 months. A random sample of 100 households at each site will be assessed for 24 h particulate matter concentration. Primary outcomes include prevalence of risk factors for cardiopulmonary diseases, changes in blood pressure and blood glucose over time and decline in lung function. Discussion There is an urgent need to characterise the prevalence and burden of non-communicable diseases in low- and middle-income countries. Peru is a middle-income country currently undergoing a rapid epidemiological transition. This longitudinal study will provide valuable information on cardiopulmonary outcomes in three different settings and will provide a platform to address potential interventions that are locally relevant or applicable to other similar settings in Latin America.