Reference values for spirometry and their use in test interpretation: A Position Statement from the Australian and New Zealand Society of Respiratory Science

Which reference equation should we use for interpreting spirometry values for First Nations Australians? A cross-sectional study

OBJECTIVES

To evaluate the suitability of the Global Lung Function Initiative (GLI)-2012 other/mixed and GLI-2022 global reference equations for evaluating the respiratory capacity of First Nations Australians.

DESIGN, SETTING

Cross-sectional study; analysis of spirometry data collected by three prospective studies in Queensland, the Northern Territory, and Western Australia between March 2015 and December 2022.

PARTICIPANTS

Opportunistically recruited First Nations participants in the Indigenous Respiratory Reference Values study (Queensland, Northern Territory; age, 3-25 years; 18 March 2015 - 24 November 2017), the Healthy Indigenous Lung Function Testing in Adults study (Queensland, Northern Territory; 18 years or older; 14 August 2019 - 15 December 2022) and the Many Healthy Lungs study (Western Australia; five years or older; 10 October 2018 - 7 November 2021).

MAIN OUTCOME MEASURES

Goodness of fit to spirometry data for each GLI reference equation, based on mean Z-score and its standard deviation, and proportions of participants with respiratory parameter values within 1.64 Z-scores of the mean value.

RESULTS

Acceptable and repeatable forced expiratory volume in the first second (FEV1) values were available for 2700 First Nations participants in the three trials; 1467 were classified as healthy and included in our analysis (1062 children, 405 adults). Their median age was 12 years (interquartile range, 9-19 years; range, 3-91 years), 768 (52%) were female, and 1013 were tested in rural or remote areas (69%). Acceptable and repeatable forced vital capacity (FVC) values were available for 1294 of the healthy participants (88%). The GLI-2012 other/mixed and GLI-2022 global equations provided good fits to the spirometry data; the race-neutral GLI-2022 global equation better accounted for the influence of ageing on FEV1 and FVC, and of height on FVC. Using the GLI-2012 other/mixed reference equation and after adjusting for age, sex, and height, mean FEV1 (estimated difference, -0.34; 95% confidence interval [CI], -0.46 to -0.22) and FVC Z-scores (estimated difference, -0.45; 95% CI, -0.59 to -0.32) were lower for rural or remote than for urban participants, but their mean FEV1/FVC Z-score was higher (estimated difference, 0.14; 95% CI, 0.03-0.25).

CONCLUSION

The normal spirometry values of healthy First Nations Australians may be substantially higher than previously reported. Until more spirometry data are available for people in urban areas, the race-neutral GLI-2022 global or the GLI-2012 other/mixed reference equations can be used when assessing the respiratory function of First Nations Australians.

Referential equations for pulmonary diffusing capacity generated from the Japanese population using the Lambda, Mu, or Sigma method and their comparisons with prior referential equations

BACKGROUND

This study aimed to establish reference equations for single-breath lung carbon monoxide diffusing capacity (DLCO), alveolar volume (VA), and transfer coefficient of the lungs for carbon monoxide (KCO, sometimes written as DLCO/VA) in the Japanese population. A generalised additive model for location size and shape (GAMLSS) was used to build each equation.

METHODS

To collect pulmonary function data throughout a broad age range, we prospectively obtained pulmonary function data from healthy volunteers and retrospectively obtained data from patients with normal diffusing capacity aged 16-85 years.

RESULTS

In total, 702 tests were conducted. The validation group z-scores, except for DLCO in males, showed substantial discrepancies between the Global Lung Initiative (GLI) baseline prediction equations and the present study's prediction equations, indicating the need for a new reference value prediction approach. The root mean square errors of the DLCO, VA, and KCO reference values obtained from the present study's prediction equations were lower than those derived from the GLI and previous linear regression equations.

CONCLUSIONS

Reference values obtained in this study were more appropriate for our sample than those derived from the existing baseline prediction equations. This research's contribution is the development of a more precise prediction equation that can be used to establish a reference value range for pulmonary diffusing capacity.

ETHICS AND DISSEMINATION

This research does not include any dissemination plan (publications, data deposition and curation).

Developing Fractional Exhaled Nitric Oxide Predicted and Upper Limit of Normal Values for a Disadvantaged Population

BACKGROUND

Fractional exhaled nitric oxide (Feno), used as a biomarker, is influenced by several factors including ethnicity. Normative data are essential for interpretation, and currently single cutoff values are used in children and adults.

RESEARCH QUESTION

Accounting for factors that influence Feno, (1) what are appropriate predicted and upper limit of normal (ULN) Feno values in an underserved population (First Nations Australians), (2) how do these values compare with age-based interpretive guidelines, and (3) what factors influence Feno and what is the size of the effect?

STUDY DESIGN AND METHODS

Feno data of First Nations Australians (age < 16 years, n = 862; age ≥ 16 years, n = 348) were obtained. Medical history using participant questionnaires and medical records were used to define healthy participants. Flexible regression using spline functions, as used by the Global Lung Function Initiative, were used to generate predicted and ULN values.

RESULTS

Look-up tables for predicted and ULN values using age (4-76 years) and height (100-200 cm) were generated and are supplied with a calculator for clinician use. In healthy First Nations children (age < 18 years), ULN values ranged between 25 and 60 parts per billion (ppb) when considering only biologically plausible age and height combinations. For healthy adults, ULN values ranged between 39 and 88 ppb. Neither the current Feno interpretation guidelines, nor the currently recommended cutoff of 50 ppb for First Nations children 16 years of age or younger were appropriate for use in this cohort. Our modelling revealed that predicted and ULN values of healthy participants varied nonlinearly with age and height.

INTERPRETATION

Because single pediatric, adult, or all-age Feno cutoff values used by current interpretive guidelines to define abnormality fail to account for factors that modify Feno values, we propose predicted and ULN values for First Nations Australians 4 to 76 years of age. Creating age- and height-adjusted predicted and ULN values could be considered for other ethnicities.

Exposure to dust and respiratory health among Australian miners

PURPOSE

Occupational exposure to dust has been recognised as a significant health hazard to mine workers. This study aimed to investigate the association between exposure to inhalable (INH) and respirable (RES) dust and respiratory health among mine workers in Western Australia using an industry-wide exposure database.

METHODS

The database comprised cross-sectional surveys conducted by mining companies for the period 2001-2012. The study population consisted of 12,797 workers who were monitored for exposure to INH and RES dust and undertook health assessments including a respiratory questionnaire and spirometry test.

RESULTS

Despite the general trend of declining exposure to both INH and RES dust observed over the 12 years period, mine workers reported a higher prevalence of phlegm and cough when exposed to elevated concentrations of INH and RES dust. Logistic regression analysis further confirmed the positive association between INH dust exposure and the prevalence of phlegm with an adjusted odds ratio of 1.033 (95% CI 1.012-1.052). Overall, 6.3% of miners might have potential airway obstruction, and exposure to INH dust was associated with impaired lung function parameters.

CONCLUSION

Exposure levels of INH and RES dust particles among mine workers have reduced considerably and were well below currently legislated occupational exposure limits. However, given the reported higher prevalence of phlegm and cough among those with elevated dust concentrations, there is a continued need for effective dust exposure monitoring and control in the mineral mining industry.

Validation of the Global Lung Function Initiative 2012 Spirometry Reference Values in a Healthy Italian Working Population

BACKGROUND

Several studies showed important differences in the interpretation of spirometry based on different reference values, in particular by comparing European Respiratory Society (ERS) 1993 and Global Lung Function Initiative (GLI) 2012. The validation of new reference values in local populations is essential before they can be used in an appropriate manner. This study aimed to investigate the fit of GLI reference values in a healthy Italian working population.

METHODS

Spirometry data were collected in 1355 workers during their health surveillance medical examination conducted for exposure to chemical and biological risk factors. A single portable spirometer that met the ATS/ERS recommendations for occupational testing was used and calibrated daily.

RESULTS

Average z-score were -0.13 (with a median of -0.17), -0.25 (with a median of -0.24), and 0.18 (with a median of 0.17) for FEV₁, FVC, and FEV₁/FVC ratio, respectively. Considering only the normal-weighted workers, the average z-scores were -0.07 (with a median of -0.16), -0.15 (with a median of -0.16), and 0.07 (with a median of 0.02) for FEV₁, FVC, and FEV₁/FVC ratio, respectively.

CONCLUSIONS

GLI 2012 reference values fit the Italian data satisfactorily, resulting as more accurate than ERS 1993, especially in women, normal-weighted subjects, aged 30-50 years, and for height < 165 cm.

Implications of using the GLI-2012, GOLD and Australian COPD-X recommendations in assessing the severity of airflow limitation on spirometry among an Indigenous population with COPD: an Indigenous Australians perspective study

BACKGROUND

Assessment of airflow limitation (AFL) is crucial in the clinical evaluation of patients with chronic obstructive pulmonary disease (COPD). However, in the absence of normative reference values among adult Australian Indigenous population, the implications of utilising the Global Lung Function Initiative (GLI-2012), Global Initiative for Chronic Obstructive Lung Disease (GOLD) and the Australian concise COPD-X recommended severity classifications is not known. Moreover, spirometry values (forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)) are observed to be 20%-30% lower in an apparently healthy Indigenous population in comparison to Caucasian counterparts.

METHODS

Adult Indigenous patients diagnosed to have COPD on spirometry (postbronchodilator (BD) FEV1/FVC <0.7 ((GOLD, (COPD-X)) and ≤lower limit of normal (others/mixed reference equations) for GLI-2012) were assessed for AFL severity classifications on Post-BD FEV1 values (mild, moderate, severe, very severe) as per the recommended classifications.

RESULTS

From a total of 742 unique patient records of Indigenous Australians, 253 were identified to have COPD via GOLD/COPD-X criteria (n=238) or GLI-2012 criteria (n=238) with significant agreeance between criteria (96%, κ=0.901). Of these, the majority were classified as having moderate or severe/very-severe AFL with significant variability across classification criteria (COPD-X (40%-43%), GOLD (33%-65%), GLI-2012 (18%-75%)). The FVC and FEV1 values also varied significantly between classification criterion (COPD-X/GOLD/GLI-2012) within the same AFL category, with COPD-X 'moderate' AFL almost matching 'severe' AFL categorisation by GOLD or GLI-2012.

CONCLUSIONS

Health professionals caring for Indigenous patients with COPD should be aware of the clinical implications and consequences of utilising various recommended AFL classifications in the absence of validated spirometry reference norms among adult Indigenous patients.

Critical analysis of spirometric patterns in correlation to chest computed tomography among adult Indigenous Australians with chronic airway diseases

Background: There is sparse literature evidence in the spirometric patterns of adult Indigenous Australians with and without chest computed tomography (CT)-proven chronic airway diseases (CADs).Methods: Participants spirometry testing graded as acceptable for quality and had a chest CT scan showing radiographic evidence of CADs were included for analysis.Results: Of the 1350 spirometric tests performed between 2012 and 2020, a total of 212 patients with a mean age of 53 years and 54% females were eligible to be included. One-third (30%) had normal chest CT (without CADs), 35% had predominant COPD, 19% bronchiectasis and 16% combined COPD and bronchiectasis. Percentage predicted values for forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁) both pre- and post- bronchodilator were significantly reduced for all participants - FVC: CT-normal 64%, 65%; COPD 58%, 62%; bronchiectasis 54%, 54%; combined COPD and bronchiectasis 50%, 53%. FEV₁: CT-normal 62%, 65%; COPD 46%, 49%; bronchiectasis 48%,51%; combined COPD and bronchiectasis 36%,40%. FEV₁/FVC was only reduced for CT abnormality patients - CT-normal 96%,98%; COPD 77%,77%; bronchiectasis 87%,89%; combined COPD and bronchiectasis 71%,72%.Conclusions: Restrictive spirometric pattern is common and an obstructive pattern with COPD, in isolation or when COPD coexists with bronchiectasis.

Deterioration of pulmonary function: An early complication in Fibrodysplasia Ossificans Progressiva

Fibrodysplasia Ossificans Progressiva (FOP) is a genetic disease characterized by the formation of heterotopic ossification (HO) in connective tissues. HO first develops in the thoracic region, before more peripheral sites are affected. Due to HO along the thoracic cage, its movements are restricted and pulmonary function deteriorates. Because development of HO is progressive, it is likely that pulmonary function deteriorates over time, but longitudinal data on pulmonary function in FOP are missing. Longitudinal pulmonary function tests (PFTs) from seven FOP patients were evaluated retrospectively to assess whether there were changes in pulmonary function during aging. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), total lung capacity (TLC), residual volume (RV) and diffusing lung capacity for carbon dioxide divided by alveolar volume (DLCO/VA) were included. In addition, HO volume along the thorax together with its progression as identified by whole body low dose CT scans were correlated to PFT data. Per patient, aged 7-57 years at the time of the first PFT, three to nine PFTs were available over a period of 6-18 years. Restrictive pulmonary function, identified by TLC or suspected by FVC, was found in all, but one, patients. In three patients, TLC, FVC or both decreased further during the follow-up period. All, but one, patients had an increased RV. The DLCO/VA ratio was normal in all FOP patients. Interestingly, FEV1 increased after a surgical intervention to unlock the jaw. In four out of five patients total HO volume in the thoracic region progressed beyond early adulthood, but no further decline in FVC was observed. In conclusion, restrictive pulmonary function was found in the majority of patients already at an early age. Our data suggest that the deterioration in pulmonary function is age dependent.

Lung function parameters among Australian Aboriginal 'apparently healthy' adults: an Australian Caucasian and Global Lung Function Initiative (GLI-2012) various ethnic norms comparative study

Background: There is sparse literature evidence evaluating the applicability of the GLI-2012 spirometric norms for Australian Aboriginal adults.Methods: Lung function parameters (LFPs) were compared between Australian Aboriginal and Australian Caucasians, and the fit of Australian Aboriginals LFPs with various ethnic GLI equations was tested.Results: Of 1350 and 5634 Pulmonary function tests (PFTs) in Australian Aboriginal and Australian Caucasian adults, 153 and 208 PFTs matched for anthropometrics and normal chest radiology, respectively. Absolute FVC and FEV₁ values were 20% lower in Australian Aboriginals compared to Australian Caucasians. Differences remained significant after accounting for age, sex, height, weight and smoking status in multivariate regression (FVC -0.84 L (-0.98, -0.71), FEV₁ - 0.72 L (-0.84, -0.59), but with nearly preserved FEV₁/FVC. GLI-2012 transformation resulted in z-scores significantly below zero for each of FVC, FEV₁ and FEV₁/FVC with z-scores ranging from -4.52 (-4.87, -4.16) for North East Asian FVC transformation for males, to -0.34 (-0.73, 0.05) for Black FVC transformation for females.Conclusions: Australian Aboriginal adults had 20% lower values for FVC and FEV₁ but nearly preserved absolute FEV₁/FVC in comparison to Australian Caucasians. The GLI-2012 spirometric norms do not appear to fit for Australian Aboriginal adults regardless of which ethnicity options selected, including 'others/mixed'.

Longitudinal Analysis of Lung Function in Pregnant Women with and without Asthma

BACKGROUND

Spirometry is commonly used to assess and monitor lung function. It may also be a useful tool to monitor maternal health during pregnancy. However, large studies examining lung function across gestation are limited. Also, whether spirometry values follow the same pattern during pregnancy in women with and without asthma is unknown.

OBJECTIVE

To investigate the effect of advancing gestation, and its interaction with asthma, on lung function in a large well-defined cohort of pregnant women.

METHODS

Data were obtained from prospective cohorts involving women with (n = 770) and without (n = 259) asthma (2004-2017), recruited between 12 and 22 weeks' gestation. Lung function (forced vital capacity [FVC], FEV₁, FEV₁:FVC%) was assessed periodically during pregnancy using spirometry. Multilevel mixed-effect regression models were used to assess changes in lung function over gestation.

RESULTS

Asthma had a significant effect on baseline lung function (FEV₁%, -9%; FVC%, -3%; FEV₁:FVC%, -4%). FVC% decreased with advancing gestation (-0.07%/wk; 95% CI, -0.10 to -0.04]), as did FEV₁%, but only among those without asthma (women without asthma: -0.14%/wk, 95% CI, -0.22 to -0.06%; compared with women with asthma: 0.02%/wk, 95% CI, -0.01 to 0.06). FEV₁:FVC% remained relatively stable for women without asthma (0.03%/wk; 95% CI, -0.08 to 0.02), but increased for women with asthma (0.06%/wk; 95% CI, 0.04 to 0.16).

CONCLUSIONS

Data suggest that advancing gestation negatively affects FVC% and FEV₁%. This is consistent with extrapulmonary restriction from advancing pregnancy. Yet, the presence of asthma altered the trajectories of FEV₁% and FEV₁:FVC%. Optimal asthma management during pregnancy might have opposed the negative effects of gestation on lung function.

Spirometry Assessment and Correlation With Postoperative Pulmonary Complications in Cardiac Surgery Patients

Objective

To observe spirometry and its correlation with postoperative pulmonary complications in cardiac surgery patients.

Study design

Prospective observational study

Place and duration of the study

Chaudhary Pervaiz Elahi Institute of Cardiology (CPEIC) Multan, from January 1, 2017, to June 30, 2020

Methodology

Written informed consent was taken from 357 patients. Spirometry was performed in all the patients using the conventional method. Baseline data, including gender, age, body mass index (BMI), living area, smoking history, known lung illness, six-minute walk distance, predicted forced vital capacity (FVC) %, predicted forced expiratory volume in one second (FEV1) %, and type of the procedure such as aortic valve replacement (AVR), coronary artery bypass grafting (CABG), double-valve replacement (DVR), and mitral valve replacement (MVR) were documented for all the patients. Outcome data included postoperative ICU length of stay (LOS), respiratory failure, respiratory infection, atelectasis, and mortality.

Results

The most common procedure was CABG and MVR proceeded by n=254 (71.1%) and n=83 (23.2%) patients, respectively. Postoperative complications, such as respiratory failure, respiratory infection, and atelectasis, was noted in n=29 (8.1%), n=28 (7.8 %), and n=127 (35.6 %) patients, respectively, while n=5 (1.4%) patients died.

Conclusion

Deranged pulmonary function tests (PFTs) are associated with poor prognosis following elective cardiac surgery in terms of postoperative pulmonary complications such as pulmonary infection, respiratory failure, and atelectasis. There is a significant difference in percentage predicted of FVC and FEV1 in patients who developed atelectasis and respiratory tract infection.

Respiratory Health of Pacific Youth: An Observational Study of Associated Risk and Protective Factors Throughout Childhood

BACKGROUND

Respiratory disease is the third most common cause of death in New Zealand, with Pacific people living in New Zealand bearing the greatest burden of this type of disease. Although some epidemiological outcomes are known, we lack the specifics required to formulate targeted and effective public health interventions. The Pacific Islands Families (PIF) birth cohort study is a study that provides a unique source of data to assess lung function and current respiratory health among participants entering early adulthood and to examine associations with early life events during critical periods of growth.

OBJECTIVE

This paper aims to provide an overview of the design, methods, and scope of the Respiratory Health of Pacific Youth Study, which uses the overall PIF study cohort aged 18-19 years.

METHODS

From 2000-2019, the PIF study has followed, from birth, the growth, and the development of 1398 Pacific children born in Auckland, New Zealand. Participants were nested within the overall PIF study (at ages 18-19 years) from June 2018, and assessments were undertaken until mid-November 2019. The assessments included respiratory and general medical histories, a general physical examination, assessment of lung function (forced expiratory volume and forced vital capacity), self-completed questionnaires (St George's Respiratory Questionnaire, European Quality of Life 5 Dimensions-3 Level, Epworth Sleepiness Scale for Children and Adolescents, and Leicester Cough Questionnaire), blood tests (eosinophils, Immunoglobulin E, Immunoglobulin G, Immunoglobulin A, Immunoglobulin M, and C-reactive protein), and chest x-rays. Noninferential analyses will be carried out on dimensionally reduced risk and protective factors and confounders.

RESULTS

Data collection began in June 2018 and ended in November 2019, with a total of 466 participants recruited for submission of the paper. Collection and collation of chest x-ray data is still underway, and data analysis and expected results will be published by November 2020.

CONCLUSIONS

This is the first longitudinal observational study to address the burden of respiratory disease among Pacific youth by determining factors in early life that impose long-term detriments in lung function and are associated with the presence of respiratory illness. Identifying risk factors and the magnitude of their effects will help in adopting preventative measures, establishing whether any avoidable risks can be modified by later resilient behaviors, and provide baseline measurements for the development of respiratory disease in later adult life. The study results can be translated into practice guidelines and inform health strategies with immediate national and international impact.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/18916.

ERS International Congress, Madrid, 2019: highlights from the Allied Respiratory Professionals' Assembly

This article provides an overview of outstanding sessions that were (co)organised by the Allied Respiratory Professionals' Assembly during the European Respiratory Society International Congress 2019 in Madrid, Spain. Session content was mainly targeted at allied respiratory professionals such as respiratory physiologists, respiratory physiotherapists and respiratory nurses, and is summarised in this document. Short take-home messages related to pulmonary function testing highlight the importance of quality control. Furthermore, novel findings regarding the assessment of functional status call attention to bodily factors that can affect functional status. Regarding pulmonary rehabilitation, data were presented about the use of equipment and type of exercise training in COPD and lung cancer. Recent developments in physical activity-related research give insight in enablers of physical activity after hospital admission. The importance of integrated respiratory care was also highlighted, with the occupational therapist, nurse, and nutritional and psychological counsellor playing a pivotal role, which relates directly to research in the field of respiratory nursing that formulates the need for more nursing led-interventions in the future. To conclude, this review provides readers with valuable insight into some of the emerging and future areas affecting clinical practice of allied healthcare professionals.

A highlights review of selected presentations from #ERSCongress 2019 by @ERS_Assembly9http://bit.ly/2VNFgAj

Reference equations for spirometry in healthy Asian children aged 5 to 18 years in Taiwan

Background and objective

This study aimed to establish reference equations for spirometry in healthy Taiwanese children and assess the applicability of the Global Lung Function Initiative (GLI)-2012 equations to Taiwanese children.

Methods

Spirometric data collected from 757 healthy Taiwanese children aged 5 to 18 years in a population-based cohort study. Prediction equations derived using linear regression and the generalized additive models for location, scale and shape (GAMLSS) method, respectively.

Results

The GLI-2012 South East Asian equations did not provide a close fit with mean ± standard error z-scores of −0.679 ± 0.030 (FVC), −0.186 ± 0.044 (FEV₁), −0.875 ± 0.049 (FEV₁/FVC ratio) and −2.189 ± 0.063 (FEF_25-75) for girls; and 0.238 ± 0.059, −0.061 ± 0.053, −0.513 ± 0.059 and −1.896 ± 0.077 for boys. The proposed GAMLSS models took age, height, and weight into account. GAMLSS models for boys and girls captured the characteristics of spirometric data in the study population closely in contrast to the linear regression models and the GLI-2012 equations.

Conclusion

This study provides up-to-date reference values for spirometry using GAMLSS modeling in healthy Taiwanese children aged 5 to 18 years. Our study provides evidence that the GLI-2012 reference equations are not properly matched to spirometric data in a contemporary Taiwanese child population, indicating the urgent need for an update of GLI reference values by inclusion of more data of non-Caucasian decent.

Abnormal pulmonary function tests are associated with prolonged ventilation and risk of complications following elective cardiac surgery

Elective cardiac surgery accounts for a significant proportion of perioperative resource allocation in Australasia. Preoperative pulmonary function testing (PFT) is routinely undertaken in some centres to identify patients who may require prolonged ventilation and intensive care unit (ICU) stay, although there are currently no data supporting this practice. Routine PFT places a burden on respiratory diagnostic laboratories, is inconvenient to patients and may delay surgery. We aimed to identify whether PFT parameters identify patients requiring prolonged mechanical ventilation after elective cardiac surgery. Adult patients admitted to the Royal Adelaide Hospital ICU following elective cardiac surgery between July 2013 and December 2017 were identified retrospectively from the local ICU database. Preoperative PFT and operative and postoperative outcome data were retrieved from local databases, and multivariable logistic regression was undertaken to identify which PFT variables were associated with prolonged mechanical ventilation. PFT data were available for 835/1139 (73%) elective cardiac surgical cases. The best independent predictors of prolonged mechanical ventilation were post-bronchodilator forced vital capacity (FVC) and single-breath diffusing capacity for carbon monoxide (DLCO). Patients with FVC <80% predicted and DLCO <60% predicted had an odds ratio for prolonged postoperative ventilation of 7.5 (95% confidence intervals 3.6–15.6; P < 0.001). The area under the receiver operating characteristic curve derived from this model was 0.68. Abnormal PFT results were associated with prolonged postoperative mechanical ventilation. A PFT-based prediction tool does not accurately predict individual patient outcome but identifies a cohort of patients at higher risk of requiring prolonged ventilation, potentially informing ICU resource allocation and surgical planning.

Substantial variation exists in spirometry interpretation practices for airflow obstruction in accredited lung function laboratories across Australia and New Zealand

BACKGROUND

Spirometry forms the foundation investigation for the diagnosis and monitoring of common pulmonary conditions. However, potential variation in spirometry interpretation for airflow obstruction may impact subsequent clinical management.

AIM

To audit spirometry interpretation practices for airflow obstruction in Thoracic Society of Australia and New Zealand accredited laboratories.

METHODS

Thirty-nine accredited complex lung function laboratories were invited to participate in an online survey. The survey enquired about demographics, definition of lower limit of normal range for spirometry parameters, spirometric parameters used for identifying airflow obstruction, spirometric definition of airflow obstruction, definition of significant bronchodilator response and chosen spirometry reference equations.

RESULTS

Thirty-six laboratories provided complete responses (response rate, 92%). To define the lower limit of normal, 26 of 36 used the 5th percentile, 7 of 36 used a fixed cut-off and 3 used other. Twenty-nine laboratories utilised forced expiratory volume in 1 s/forced vital capacity (FEV₁ /FVC) as the sole parameter to identify airflow obstruction, 3 of 36 used FEV₁ /FVC and FEF_25-75% , and 4 used other. To define airflow obstruction, 25 of 36 laboratories used FEV₁ /FVC < 5th percentile, 9 of 36 used a fixed cut-off (FEV₁ /FVC < 0.7, 6/36; FEV₁ /FVC < 0.8, 2/36; FEV₁ /FVC < 0.75, 1/36) and 2 of 36 used other. Twenty-six laboratories defined a significant bronchodilator response as an increase of at least 200 mL and 12% in FEV₁ and/or FVC, 9 of 36 used ≥200 mL and ≥ 12% increase in FEV₁ only, and 1 used other criteria. Reference equations utilised for interpretation of spirometry data included: Quanjer 2012 Global Lung Initiative (16/36), the third National Health and Nutritional Examination Survey (8/36), European Community of Coal and Steel (8/36) and other (4/36).

CONCLUSIONS

Significant heterogeneity in spirometry interpretation for airflow obstruction exists across Australian and New Zealand accredited lung function laboratories. Lack of standardisation may translate into clinically appreciable differences for the diagnosis and management of common respiratory conditions. Ongoing discussion regarding formal standardisation is required.

[Spirometric reference values in the Bantu population aged 20-70 years in Kinshasa]

INTRODUCTION

Spirometric reference values cannot be extrapolated in the populations, being subject to many environmental and human variables; hence the interest of local studies in this field.

METHODS

This study aims to determine the reference values among healthy adults in Kinshasa. We conducted a cross-sectional study including 7443 subjects (3208 women, 43%). FEV1, FVC, PEF were correlated with anthropometric data. Five age groups were formed and comparisons were made on the basis of sex, age, BMI and of the practice of sporting activity.

RESULTS

Differences are evident between the sexes, in terms of FEV1 (3.00 vs 2.21 L), FVC (3.19 vs 2.38) and the PEF (6.8 vs 5.70 L/s); same as for the outer age categories. FEV1 ranged between 2.33 et 4.54 vs 1.93-3.3 L in the age group 20-29 years and 1,76-3,39 vs 1,60 vs 2,53 L in the age group 60-70 years; FVC ranged between 2,44-4,89 vs 1,96-3,56 L and 1,79-3,78 vs 1,66-2,74 L ; PEF ranged between 4,34-12.2 vs 3,62-8.58 L/s and 2.99-6.76 vs 2.99-7.34L/s in the age group 60-70 years.

CONCLUSION

The differences related to gender, age, anthropometric data as well as to the practice of sporting activity are obvious. These results warrant further and more extended investigations and show the relevance of values based on percentiles in the determinantion of a spirometry standard in a given population.

Socioeconomic circumstances and respiratory function from childhood to early adulthood: a systematic review and meta-analysis

OBJECTIVE

Disadvantaged socioeconomic circumstances in early life have the potential to impact lung function. Thus, this study aimed to summarise evidence on the association between socioeconomic circumstances and respiratory function from childhood to young adulthood.

DESIGN

Systematic review and meta-analysis.

METHODS

Following the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines, Medline, ISI-Web of Science and Scopus were searched from inception up to January 2018. Original studies on the association between socioeconomic circumstances and respiratory function in early ages (ie, participants younger than 25 years of age) were investigated. Two investigators independently evaluated articles, applied the exclusion criteria, extracted data and assessed the risk of bias using the Newcastle-Ottawa Scale. A meta-analysis of the standardised mean difference and 95% CI in respiratory function between participants from different socioeconomic circumstances was conducted, using a random-effects model.

RESULTS

Thirty-three papers were included in this review and 23 showed that disadvantaged socioeconomic circumstances were significantly associated with reduced respiratory function. The meta-analysis including seven papers showed a significant difference of -0.31 (95% CI -0.42 to -0.21) litres in forced expiratory volume in the first second between children, adolescents and young adults from disadvantaged versus advantaged socioeconomic circumstances. Specifically a difference of -0.31 (95% CI -0.51 to -0.10) litres in girls and -0.43 (95% CI -0.51 to -0.35) litres in boys was observed.

CONCLUSIONS

Children, adolescents and young adults from disadvantaged socioeconomic circumstances had lower respiratory function, and boys presented higher respiratory health inequalities. This information contributes to explain the social patterning of respiratory diseases, and might enable health policy makers to tackle respiratory health inequalities at early ages.

Increased physical activity post-exacerbation is associated with decreased systemic inflammation in cystic fibrosis - An observational study

Background and Objective: We assessed whether measured physical activity in adults with cystic fibrosis (CF) following in-hospital treatment for an acute exacerbation was impacted by levels of systemic and airway inflammation, and whether physical activity post-discharge predicted for time to next pulmonary exacerbation. Methods: Adults with CF were included following hospitalization for a pulmonary exacerbation, and were followed for 12 months. Inflammatory markers and physical activity were measured immediately post-discharge via sputum and plasma concentrations of interleukin-6, interleukin-8, and tumor necrosis factor-α. Physical activity was monitored for 7 days via a Sensewear Armband. Statistical analyses included Shapiro-Wilk's test and Q-Q plots to determine normal distribution, t-tests, Pearson's correlational analyses, and one-way MANOVAs. Results: Thirty-one adults with CF (13 females, 28.8 ± 8.8 years, forced expiratory volume in 1 s (FEV₁) 59.4 ± 23.0% predicted) were prospectively recruited. Physical activity negatively correlated with plasma inflammation (r = -0.48, p < 0.01), and positively with FEV₁ (r = 0.45, p < 0.05) and body mass index (r = 0.39, p < 0.05). There was no significant relationship between time to re-exacerbation and any inflammatory markers or measurement of physical activity (all p > 0.05). Conclusion: Increased physical activity following exacerbation in CF is associated with lower levels of systemic inflammation. Time to re-exacerbation is not related to post-discharge inflammation or physical activity levels.

Predicting spirometry readings using cough sound features and regression

OBJECTIVE

Spirometry is a commonly used method of measuring lung function. It is useful in the definitive diagnosis of diseases such as asthma and chronic obstructive pulmonary disease (COPD). However, spirometry requires cooperative patients, experienced staff, and repeated testing to ensure the consistency of measurements. There is discomfort associated with spirometry and some patients are not able to complete the test. In this paper, we investigate the possibility of using cough sound analysis for the prediction of spirometry measurements.

APPROACH

Our approach is based on the premise that the mechanism of cough generation and the forced expiratory maneuver of spirometry share sufficient similarities enabling this prediction. Using an iPhone, we collected mostly voluntary cough sounds from 322 adults presenting to a respiratory function laboratory for pulmonary function testing. Subjects had the following diagnoses: obstructive, restrictive, or mixed pattern diseases, or were found to have no lung disease along with normal spirometry. The cough sounds were automatically segmented using the algorithm described in Sharan et al (2018 IEEE Trans. Biomed. Eng.). We then represented cough sounds with various cough sound descriptors and built linear and nonlinear regression models connecting them to spirometry parameters. Augmentation of cough features with subject demographic data is also experimented with. The dataset was divided into 272 training subjects and 50 test subjects for experimentation.

MAIN RESULTS

The performance of the auto-segmentation algorithm was evaluated on 49 randomly selected subjects from the overall dataset with a sensitivity and PPV of 84.95% and 98.51%, respectively. Our regression models achieved a root mean square error (and correlation coefficient) for standard spirometry parameters FEV1, FVC, and FEV1/FVC of 0.593L (0.810), 0.725L (0.749), and 0.164 (0.547), respectively, on the test dataset. In addition, we could achieve sensitivity, specificity, and accuracy of 70% or higher by applying the GOLD standard for COPD diagnosis on the estimated spirometry test results.

SIGNIFICANCE

The experimental results show high positive correlation in predicting FEV1 and FVC and moderate positive correlation in predicting FEV1/FVC. The results show possibility of predicting spirometry results using cough sound analysis.

Peak expiratory flow among healthy children aged 5-14 years in China

Background

Guidelines of the Global Initiative for Asthma recommend the use of peak expiratory flow (PEF) in the assessment and management of patients with asthma. However, normal PEF values for Chinese children have not been thoroughly investigated.

Methods

This was a cross-sectional study of 3,169 healthy children aged 5-14 years from research centers in five cities of China: Guangzhou, Suzhou, Chengdu, Xi'an, and Beijing. We established pediatric reference values for PEF using a mini peak flow meter. PEF values recorded by the mini peak flow meter were compared with those obtained using a spirometer.

Results

Height was the biometric variable with greatest correlation to PEF for both sexes. Significant differences were noted between males and females. The regression equation for boys was calculated as PEF =4.39× height (cm) -300.48 (R² =0.76, P<0.001); for girls, this equation was PEF =4.13× height (cm) -278.04 (R² =0.72, P<0.001). PEF values for Chinese children according to age were close to those of Irish, Turkish, and British children but were lower than those of children in Greece; PEF values according to height were similar to those of Turkish and Danish children but lower than values for children in Ireland.

Conclusions

We established normal PEF values and developed predictive equations using linear regression analysis for Chinese children aged 5-14 years, while Greece and Ireland references were inappropriate for Chinese children.

Relationship between oral habits and spirometry maneuvers, in children

ABSTRACT Purpose: to analyze whether deleterious oral habits can influence the number of attempts of forced spirometry maneuvers performed by healthy children. Methods: this observational and cross-sectional analytical study included 149 healthy children aged 6-12 years attending public and private schools in Florianópolis, SC, Brazil. A validated protocol was applied for the analysis of deleterious oral habits. The children were grouped according to the number of spirometry maneuvers needed to achieve successful spirometry results, as follows: G1) children who needed 3 maneuvers; G2) 4 maneuvers; G3) 5-8 maneuvers. Data were analyzed with the Kolmogorov-Smirnov test and the Kruskal-Wallis test was applied to compare quantitative variables between the groups. The Chi-square test was used to assess the association between the groups and qualitative variables. Results: there was no association between the number of attempts and the qualitative variables evaluated by the protocol. There was also no difference between the groups regarding quantitative variables for breastfeeding time, breastfeeding occurrence, use of pacifiers, and thumb sucking. Conclusion: the presence of DOH did not influence the number of forced spirometry maneuvers, performed by the healthy children in this study.

Recommendations for a Standardized Pulmonary Function Report. An Official American Thoracic Society Technical Statement

BACKGROUND

The American Thoracic Society committee on Proficiency Standards for Pulmonary Function Laboratories has recognized the need for a standardized reporting format for pulmonary function tests. Although prior documents have offered guidance on the reporting of test data, there is considerable variability in how these results are presented to end users, leading to potential confusion and miscommunication.

METHODS

A project task force, consisting of the committee as a whole, was approved to develop a new Technical Standard on reporting pulmonary function test results. Three working groups addressed the presentation format, the reference data supporting interpretation of results, and a system for grading quality of test efforts. Each group reviewed relevant literature and wrote drafts that were merged into the final document.

RESULTS

This document presents a reporting format in test-specific units for spirometry, lung volumes, and diffusing capacity that can be assembled into a report appropriate for a laboratory's practice. Recommended reference sources are updated with data for spirometry and diffusing capacity published since prior documents. A grading system is presented to encourage uniformity in the important function of test quality assessment.

CONCLUSIONS

The committee believes that wide adoption of these formats and their underlying principles by equipment manufacturers and pulmonary function laboratories can improve the interpretation, communication, and understanding of test results.

Spirometry training courses: Content, delivery and assessment - a position statement from the Australian and New Zealand Society of Respiratory Science

Spirometry training courses are provided by health services and training organizations to enable widespread use of spirometry testing for patient care or for monitoring health. The primary outcome of spirometry training courses should be to enable participants to perform spirometry to international best practice, including testing of subjects, quality assurance and interpretation of results. Where valid results are not achieved or quality assurance programmes identify errors in devices, participants need to be able to adequately manage these issues in accordance with best practice. It is important that potential participants are confident in the integrity of the course they attend and that the course meets their expectations in terms of training. This position statement lists the content that the Australian and New Zealand Society of Respiratory Science (ANZSRS) has identified as required in a spirometry training course to adequately meet the primary outcomes mentioned above. The content requirements outlined in this position statement are based on the current international spirometry standards set out by the American Thoracic Society and European Respiratory Society. Furthermore, recommendations around course delivery for theoretical and practical elements of spirometry testing and post-course assessment are outlined in this statement.

Spirometry reference values for population aged 7-80 years in China

BACKGROUND AND OBJECTIVE

Lung function tests are widely used in clinical and public health practice; however, no valid spirometry reference values were available for the general population in China. This study aimed to provide valid spirometry predictive equations for the general population in China, and to evaluate the predictive performance of previously used equations.

METHODS

Data from the China National Health Survey 2012-2015 and the 'Generalized Additive Models for Location, Scale and Shape' statistical modelling method were used to establish spirometry predictive equations for forced expiratory volume in 1 s (FEV₁ ), forced vital capacity (FVC) and FEV₁ /FVC. Paired t-tests were used to examine differences between spirometry measurements in this sample and predicted values of four previous spirometry predictive equations.

RESULTS

This study included 3130 lifetime non-smokers (713 males and 2417 females) aged 7-80 years in China. Spirometry predictive equations with age and height as predictive variables plus age-specific splines were established separately by gender. Most previous spirometry predictive equations were found to significantly overestimate (maximum of 3.69% in FEV₁ , 1.87% in FVC and 4.19% in FEV₁ /FVC for males; 11.46% in FEV₁ , 7.28% in FVC and 3.78% in FEV₁ /FVC for females) or underestimate (maximum of 5.75% in FEV₁ and 8.12% in FVC for males; 7.89% in FEV₁ and 9.32% in FVC for females) lung function measurements when applied to this sample population.

CONCLUSION

This study addressed the urgent need for valid and up-to-date spirometry reference values for the general population in China. Moreover, previous spirometry predictive equations showed unfavourable generalizability to this sample population.