Diagnostic accuracy of pre-bronchodilator FEV1/FEV6 from microspirometry to detect airflow obstruction in primary care: a randomised cross-sectional study.
ABSTRACT: Forced expiratory volume in 1s/forced expiratory volume in 6 s ( FEV1/FEV6) assessment with a microspirometer may be useful in the diagnostic work up of subjects who are suspected of having COPD in primary care.To determine the diagnostic accuracy of a negative pre-bronchodilator (BD) microspirometry test relative to a full diagnostic spirometry test in subjects in whom general practitioners (GPs) suspect airflow obstruction.Cross-sectional study in which the order of microspirometry and diagnostic spirometry tests was randomised. Study subjects were (ex-)smokers aged ≥50 years referred for diagnostic spirometry to a primary care diagnostic centre by their GPs. A pre-BD FEV1/FEV6 value <0.73 as measured with the PiKo-6 microspirometer was compared with a post-BD FEV1/FVC (forced vital capacity) <0.70 and FEV1/FVC
Project description:<h4>Background</h4>A low FEV1/FVC from post-bronchodilator spirometry is required to diagnose COPD. Both the FEV1 and the FVC can vary over time; therefore, individuals can be given a diagnosis of mild COPD at one visit, but have normal spirometry during the next appointment, even without an intervention.<h4>Methods</h4>We analyzed two population-based surveys of adults with spirometry carried out for the same individuals 5-9 years after their baseline examination. We determined the factors associated with a change in the spirometry interpretation from one exam to the next utilizing different criteria commonly used to diagnose COPD.<h4>Results</h4>The rate of an inconsistent diagnosis of mild COPD was 11.7% using FEV1/FVC <0.70, 5.9% using FEV1/FEV6 <the lower limit of the normal range, LLN and 4.1% using the GOLD stage 2-4 criterion. The most important factor associated with diagnostic inconsistency was the closeness of the ratio to the LLN during the first examination. Inconsistency decreased with a lower FEV1.<h4>Conclusions</h4>Using FEV1/FEV6 <LLN or GOLD stage 2-4 as the criterion for airflow obstruction reduces inconsistencies in the diagnosis of mild COPD. Further improvement could be obtained by defining a borderline zone around the LLN (e.g. plus or minus 0.6 SD), or repeating the test in patients with borderline results.
Project description:QUESTION: A 6-second spirometry test is easier than full exhalations. We compared the reliability of the ratio of the Forced expiratory volume in 1 second/Forced expiratory volume in 6 seconds (FEV1/FEV6) to the ratio of the FEV1/Forced vital capacity (FEV1/FVC) for the detection of airway obstruction. METHODS: The PLATINO population-based survey in individuals aged 40 years and over designed to estimate the prevalence of post-Bronchodilator airway obstruction repeated for the same study participants after 5-9 years in three Latin-American cities. RESULTS: Using the FEV1/FVC<Lower limit of normal (LLN) index, COPD prevalence apparently changed from 9.8 to 13.2% in Montevideo, from 9.7 to 6.0% in São Paulo and from 8.5 to 6.6% in Santiago, despite only slight declines in smoking prevalence (from 30.8% to 24.3%). These changes were associated with differences in Forced expiratory time (FET) between the two surveys. In contrast, by using the FEV1/FEV6 to define airway obstruction, the changes in prevalence were smaller: 9.7 to 10.6% in Montevideo, 8.6 to 9.0% in São Paulo, and 7.5 to 7.9% in Santiago. Changes in the prevalence of COPD with criteria based on FEV1/FVC correlated strongly with changes in the FET of the tests (R(2) 0.92) unlike the prevalence based on a low FEV1/FEV6 (R(2)?=0.40). CONCLUSION: The FEV1/FEV6 is a more reliable index than FEV1/FVC because FVC varies with the duration of the forced exhalation. Reporting FET and FEV1/FEV6<LLN helps to understand differences in prevalence of COPD obtained from FEV1/FVC-derived indices.
Project description:In chronic obstructive pulmonary disease, both smaller and larger airways are affected. FEV1 mainly reflects large airways obstruction, while the later fraction of forced exhalation reflects reduction in terminal expiratory flow. In this study, the objective was to evaluate the relationship between spirometric ratios, including the ratio of forced expiratory volume in 3 and 6 seconds (FEV3/FEV6), and small airways measures and gas trapping at quantitative chest CT scanning, and clinical outcomes in the Genetic Epidemiology of COPD (COPDGene) cohort.Seven thousand eight hundred fifty-three current and ex-smokers were evaluated for airflow obstruction by using recently defined linear iteratively derived equations of Hansen et al to determine lower limit of normal (LLN) equations for prebronchodilator FEV1/FVC, FEV1/FEV6, FEV3/FEV6, and FEV3/FVC. General linear and ordinal regression models were applied to the relationship between prebronchodilator spirometric and radiologic and clinical data.Of the 10,311 participants included in the COPDGene phase I study, participants with incomplete quantitative CT scanning or relevant spirometric data were excluded, resulting in 7,853 participants in the present study. Of 4,386 participants with FEV1/FVC greater than or equal to the LLN, 15.4% had abnormal FEV3/FEV6. Compared with normal FEV3/FEV6 and FEV1/FVC, abnormal FEV3/FEV6 was associated with significantly greater gas trapping; St. George's Respiratory Questionnaire score; modified Medical Research Council dyspnea score; and BMI, airflow obstruction, dyspnea, and exercise index and with shorter 6-min walking distance (all P < .0001) but not with CT scanning evidence of emphysema.Current and ex-smokers with prebronchodilator FEV3/FEV6 less than the LLN as the sole abnormality identifies a distinct population with evidence of small airways disease in quantitative CT scanning, impaired indexes of physical function and quality of life otherwise deemed normal by using the current spirometric definition.
Project description:Acknowledgement of COPD underdiagnosis and misdiagnosis in primary care can contribute to improved disease diagnosis. PUMA is an international primary care study in Argentina, Colombia, Venezuela and Uruguay.To assess COPD underdiagnosis and misdiagnosis in primary care and identify factors associated with COPD underdiagnosis in this setting.COPD was defined as post-bronchodilator (post-BD) forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) <0.70 and the lower limit of normal (LLN). Prior diagnosis was self-reported physician diagnosis of emphysema, chronic bronchitis, or COPD. Those patients with spirometric COPD were considered to have correct prior diagnosis, while those without spirometric criteria had misdiagnosis. Individuals with spirometric criteria without previous diagnosis were considered as underdiagnosed.1,743 patients were interviewed, 1,540 completed spirometry, 309 (post-BD FEV1/FVC <0.70) and 226 (LLN) had COPD. Underdiagnosis using post-BD FEV1/FVC <0.70 was 77% and 73% by LLN. Overall, 102 patients had a prior COPD diagnosis, 71/102 patients (69.6%) had a prior correct diagnosis and 31/102 (30.4%) had a misdiagnosis defined by post-BD FEV1/FVC ?0.70. Underdiagnosis was associated with higher body mass index (?30 kg/m2), milder airway obstruction (GOLD I-II), black skin color, absence of dyspnea, wheezing, no history of exacerbations or hospitalizations in the past-year. Those not visiting a doctor in the last year or only visiting a GP had more risk of underdiagnosis. COPD underdiagnosis (65.8%) and misdiagnosis (26.4%) were less prevalent in those with previous spirometry.COPD underdiagnosis is a major problem in primary care. Availability of spirometry should be a priority in this setting.
Project description:BACKGROUND:The identification of smoking-related lung disease in current and former smokers with normal FEV1 is complex, leading to debate regarding using a ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1/FVC) of less than 0.70 versus the predicted lower limit of normal (LLN) for diagnosis of airflow obstruction. We hypothesized that the discordant group of ever-smokers with FEV1/FVC between the LLN and 0.70 is heterogeneous, and aimed to characterize the burden of smoking-related lung disease in this group. METHODS:We compared spirometry, chest CT characteristics, and symptoms between 161 ever-smokers in the discordant group and 940 ever-smokers and 190 never-smokers with normal FEV1 and FEV1/FVC?>?0.70 in the SPIROMICS cohort. We also estimated sensitivity and specificity for diagnosing objective radiographic evidence of chronic obstructive pulmonary disease (COPD) using different FEV1/FVC criteria thresholds. RESULTS:The discordant group had more CT defined emphysema and non-emphysematous gas trapping, lower post-bronchodilator FEV1 and FEF25-75, and higher respiratory medication use compared with the other two groups. Within the discordant group, 44% had radiographic CT evidence of either emphysema or non-emphysematous gas trapping; an FEV1/FVC threshold of 0.70 has greater sensitivity but lower specificity compared with LLN for identifying individuals with CT abnormality. CONCLUSIONS:Ever-smokers with normal FEV1 and FEV1/FVC?<? 0.70 but > LLN are a heterogeneous group that includes significant numbers of individuals with and without radiographic evidence of smoking-related lung disease. These findings emphasize the limitations of diagnosing COPD based on spirometric criteria alone.
Project description: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 (HRGOLD 2.07 [95% CI 1.45-2.95] p<0.01 and HRLLN 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.
Project description:Consistent estimation of the burden of chronic obstructive pulmonary disease (COPD) has been hindered by differences in methods, including different spirometric cut-offs for impaired lung function. The impact of different definitions on the prevalence of potential airflow obstruction, and its associations with key risk factors, is evaluated using cross-sectional data from two nationally representative population surveys.Pooled cross-sectional analysis of Wave 2 of the UK Household Longitudinal Survey and the Health Survey for England 2010, including 7879 participants, aged 40-95?years, who lived in England and Wales, without diagnosed asthma and with good-quality spirometry data. Potential airflow obstruction was defined using self-reported physician-diagnosed COPD; a fixed threshold (FT) forced expiratory volume in 1?s/forced vital capacity (FEV1/FVC) ratio <0.7 and an age-specific, sex-specific, height-specific and ethnic-specific lower limit of normal (LLN). Standardised questions elicited self-reported information on demography, smoking history, ethnicity, occupation, respiratory symptoms and cardiovascular disease.Consistent across definitions, participants classed with obstructed airflow were more likely to be older, currently smoke, have higher pack-years of smoking and be engaged in routine occupations. The prevalence of airflow obstruction was 2.8% (95% CI 2.3% to 3.2%), 22.2% (21.2% to 23.2%) and 13.1% (12.2% to 13.9%) according to diagnosed COPD, FT and LLN, respectively. The gap in prevalence between FT and LLN increased in older age groups. Sex differences in the risk of obstruction, after adjustment for key risk factors, was sensitive to the choice of spirometric cut-off, being significantly higher in men when using FT, compared with no significant difference using LLN.Applying FT or LLN spirometric cut-offs gives a different picture of the size and distribution of the disease burden. Longitudinal studies examining differences in unscheduled hospital admissions and risk of death between FT and LLN may inform the choice as to the best way to include spirometry in assessments of airflow obstruction.
Project description:RATIONALE:Although chronic obstructive pulmonary disease has been related to heart failure, the relationship between the restrictive spirometry pattern (forced vital capacity [FVC] < 80% predicted with preserved forced expiratory volume in 1 second [FEV1]/FVC ratio) and heart failure is poorly understood. OBJECTIVES:To determine whether having a restrictive spirometry pattern is associated with incident heart failure hospitalization. METHODS:Community-dwelling African Americans from the Jackson Heart Study (total n = 5,306; analyzed n = 4,210 with spirometry and heart failure outcome data) were grouped by restrictive spirometry (FEV1/FVC ≥ 0.70, FVC < 80%; n = 840), airflow obstruction (FEV1/FVC < 0.70; n = 341), and normal spirometry (FEV1/FVC ≥ 0.70, FVC ≥ 80%; n = 3,029) at the time of baseline examination in 2000-2004. We assessed relationships of echocardiographic parameters and biomarkers with spirometry patterns using regression models. Incident heart failure was defined as an adjudicated hospitalization for heart failure after January 1, 2005 in subjects with no self-reported heart failure history. We used multivariable-adjusted Poisson regression models and Cox proportional hazards models, with death treated as a competing risk in the Cox models, to test associations between spirometry patterns and incident heart failure. We also modeled the association of FVC% predicted with heart failure hospitalization risk using a restricted cubic spline after excluding subjects with airflow obstruction. RESULTS:At the time of baseline spirometry, participants with restrictive spirometry had a median age of 57.2 years (interquartile range, 47.8-64.1); 38.1% were male. Compared with normal spirometry, restrictive spirometry was associated with a higher transmitral early (E) wave velocity to atrial (A) wave velocity ratio, higher pulmonary artery systolic pressure, and higher endothelin levels. After a median follow-up time of 8.0 years, 8.0% of subjects with restrictive spirometry (n = 67) had developed incident heart failure, compared with 3.8% of those with normal spirometry (n = 115) and 10.6% of those with airflow obstruction (n = 36). After risk adjustment, both a restrictive pattern (hazard ratio [HR], 1.5; 95% confidence interval [CI], 1.1-2.0) and airflow obstruction (HR, 1.7; 95% CI, 1.1-2.5) were associated with increased rates of incident heart failure hospitalization compared with normal spirometry. Using flexible modeling, the lowest hazards of heart failure hospitalization were observed around FVC 90-100%, with lower FVC% values associated with an increased incidence of heart failure. CONCLUSIONS:Both a restrictive pattern on spirometry and airflow obstruction identify African Americans with impaired lung health at risk for heart failure.
Project description:A hallmark of the diagnosis of chronic obstructive pulmonary disease (COPD) is the measurement of post-bronchodilator (post-BD) airflow obstruction (AO) by spirometry, but spirometry is not enough for the provision of a clinical diagnosis. In the majority of previous epidemiological studies, COPD diagnosis has been based on spirometry and a few clinical characteristics. The aim of our study was to identify outcomes in patients newly diagnosed with airflow obstruction (AO) based on a diagnostic work-up conducted as part of a population-based cross-sectional study in North-Western Russia. Spirometry was performed before (pre-BD) and after BD administration, and AO was defined using the FEV1/FVC <0.70 and FEV1/FVC <lower limit of normal cut-off values. Relevant symptoms were recorded. Participants with AO identified at baseline were then examined by a pulmonologist, including a clinical examination and second spirometry with BD test. Of the 102 participants with post-BD AO in the initial assessment, only 60.8% still had AO identified at the second examination; among these patients, the following final diagnoses were reported: COPD (n?=?41), asthma (n?=?5), asthma-COPD overlap syndrome (ACOS) (n?=?4) and likely ACOS (n?=?5). Of the 65 participants with pre-BD AO, 23.1% had post-BD AO at the second assessment, and these patients had been diagnosed with COPD (n?=?12), asthma (n?=?1), ACOS (n?=?1), likely ACOS (n?=?1). Serial spirometric assessments complemented by a comprehensive clinical evaluation are recommended in new epidemiological studies.
Project description:We aimed to assess the validity of using the Global Lung Function Initiative's (GLI) 2012 equations to interpret lung function data in a healthy workforce of South Australian Metropolitan Fire Service (SAMFS) personnel.Spirometry data from 212 healthy, nonsmoking SAMFS firefighters were collected and predicted normal values were calculated using both the GLI and local population derived (Gore) equations for forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC. Two-tailed paired sample Student's t-tests, Bland-Altman assessments of agreement, and z-scores were used to compare the two prediction methods.The equations showed good agreement for mean predicted FEV1, FVC, and FEV1/FVC. Mean z-scores were similar for FEV1 and FVC, although not FEV1/FVC, but greater than 0.5. Differences between the calculated lower limits of normal (LLN) were significant (p < 0.01), clinically meaningful, and resulted in an 8% difference in classification of abnormality using the FEV1/FVC ratio.The GLI equations predicted similar lung function as population-specific equations and resulted in a lower incidence of obstruction in this sample of healthy SAMFS firefighters. Further, interpretation of spirometry data as abnormal should be based on both an FEV1 and FEV1/FVC ratio < LLN.