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The Air we Breathe

The Air We Breathe…Early Detection of Small Airway Disease in Poultry Production Farmers


Submitted by: Rose-Marie Dolinar RN (EC) PhD, Health & Rehabilitation Sciences, The Universtiy of Western Ontario

Introduction
Chronic Obstructive Pulmonary Disease (COPD) is preventable and treatable.
The Global Initiative for Chronic Obstructive Lung Disease (GOLD) (1) states that COPD is “characterized by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases.” The Global Initiative for Chronic Obstructive Lung Disease further explains the variable nature of COPD as a mixture of small airway disease (e.g., obstructive bronchiolitis) and parenchymal destruction (emphysema), and that both conditions vary from person to person (2).

Volgemeir et al. (2017) summarized the changes in the 2017 GOLD diagnostic and treatment recommendations, which now include both spirometry and symptom evaluations (3). Since COPD encompasses both small airway and terminal airway diseases of chronic bronchitis and emphysema, using both spirometry and a standardized lung health questionnaire provides a more comprehensive picture of each person’s lung health, especially for those at high risk of developing chronic obstructive lung diseases.

Patients with ongoing symptoms of cough and phlegm are not being diagnosed according to a Canadian study. The range of undetected COPD is between 25 and 50% of patients with COPD symptoms and risk factors (4) (5). According to Hill, Goldstein, Guyatt et al. (2010), as many as one in five adults with known risk factors for COPD who meet spirometric criteria are not diagnosed for COPD (5). Under-diagnosis of COPD suggests a need for greater screening of at-risk individuals.

Persons at Risk for COPD
Persons at highest risk for developing COPD are those who smoke cigarettes, with a 25% prevalence of moderate to severe COPD for both men and women equally (6). Although cigarette smoking is a major risk factor, occupational health studies indicate that more than 15% of all cases of COPD are work-related (7).

Poultry Farmers Lung Health Study
This study is the result of a meeting held in January 2015 between poultry farmers and a lung health researcher to discuss concerns of the poultry farmers regarding lung health in the workplace. Following approval, obtained from the Health Sciences Research Ethics Board at the University of Western Ontario (protocol #107685), the Poultry Producers Lung Health Study was launched.

The study’s aim was to promote and protect the lung health of poultry farmers. Results of the N95 Respirator Fit-testing outreach article have been published in the 2018 Winter edition of Update. This article will report the measurement of lung health of poultry farmers, which included the spirometry and lung health symptoms and MD-confirmed diagnostic findings.

The study design was a cohort observational study with a convenience sample, based on the available two-day lung health clinic appointments. Two clinic days were available for the pilot study due to health centre booking and resource availability, as well as timing of harvest for the farmers. Participants were required to meet the following inclusion criteria: a poultry farmer 40 years of age or older who is fluent in English and has a family physician or health-care provider for ongoing medical care. Those who did not have a doctor were excluded from the study since reports of the spirometry were sent to each of the participant’s health-care provider for follow-up care.

METHODS

Measuring Lung Symptoms
The standardized American Thoracic Society (ATS) Lung Health Questionnaire (LHQ) from the Division of Lung Diseases (DLD) of the National Heart, Lung, and Blood Institute, ATS-DLD78 (9), was administered to all participants. The Medical Research Council (MRC) Breathlessness Scale, which grades breathlessness related to exercise and activity, was included in the ATS-DLD78 with the following grading scale: Grade 1 Not troubled by breathlessness except on strenuous exercise; Grade 2 Short of breath when hurrying on the level or walking up a slight hill; Grade 3 Walks slower than most people on the level, stops after a mile or so, or stops after 15 minutes walking at own pace; Grade 4 Stops for breath after walking about 100 yards or after a few minutes on level ground; and Grade 5 Too breathless to leave the house, or breathless when undressing (8).

Measuring Lung Function
Pre/post bronchodilator spirometry was performed using the National Health and Nutrition Examination Survey (NHANES III) Hankinson et al. (1999) standard reference prediction equations (9). A certified Registered Respiratory Therapist (RRT) performed all the pre/post spirometry according to Canadian Thoracic Society guidelines (10). Interpretation of the pre/post spirometry were based on GOLD 2017 (1) and D’Urzo (2011) (11) spirometry interpretation logarithms for the identification of COPD and asthma. Chronic obstructive pulmonary disease diagnostic criteria included the post-bronchodilator forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC) ratio (FEV1/FVC) of less than 0.70 (<0.70), and asthma was defined as an improvement in FEV1 of 12% or over, and 200 mL after the bronchodilator challenge.

The Forced Expiratory Flow between 25 and 75% of the FVC (FEF25–75) is one of the most commonly cited measures of small airways pathology (13). The reasons that tests of small airways such as FEF 25-75% have not been utilized as part of lung function measurement include variability in test results and a lack of validated reference ranges (13). However, the FEF 25-75% was included to ensure the pre/post spirometry was able to capture any changes in both large airways and small airways of the lungs.

Independent Data Collection
Each participant’s spirometry lung function was performed independently from the Lung Health Questionnaire (LHQ) administration. Results were compared as blinded since LHQ and spirometry data were collected separately.

Results
Two rural lung health clinics were held in Seaforth, Ontario and Clinton, Ontario on August 3rd and August 4th, 2016, respectively, to fit within harvest times for the participants.

A total of 16 poultry farmers (N=16) participated in the study. The average age of participants was 56.8 years (SD 9.74), with 82% males and 18% females.

Farm dust exposure, in numbers of years, was reported by all 16 participants with an average of 38 years (SD 14.95). Smoking status was reported as current smoker, within the last month, never smoked, or an ex-smoker for the past month. Duration of smoking was calculated by the standard measure of pack years (one pack year equivalent to 20 cigarettes per day) for one year.

Table 1: Cigarette Smoking (n=16)

Cigarette smoking Result
Current smokers 1/16 (6.25%)
Never smoked 8/16 (50%)
Pack years 5.07 (SD 6.93)

The lung health questionnaire asked if the participant had a doctor who confirmed the presence of bronchitis, emphysema and asthma.  The answers to the presence of MD-confirmed lung diseases provided an independent evaluation.  There were no reports of MD-confirmed emphysema.  However, three participants reported that their physicians confirmed chronic bronchitis, and two participants reported confirmation of asthma.

Table 2: Reporting of lung symptoms of cough and phlegm, wheeze, and breathlessness

Symptom Result (n=16)
Cough and phlegm   3/16
Wheeze   8/16
Exercise limitations
(MRC grade 3,4,5)
  0/16

 

Table 3: Results of MD-confirmed lung disease

MD-confirmed lung condition Result (n=16)
Chronic bronchitis 3/16
Emphysema 0/16
Asthma 2/16


Spirometry Results

Sixteen (16) pre/post spirometry tests were performed and interpreted. Upon reviewing the results of the de-identified pre/post spirometry data, two spirometry results were excluded, one as it identified a pre-existing lung health condition, and the other showed non-reproducible manoeuvres. Fourteen (14) spirometry results were included in the grouped data.

All fourteen (14) post bronchodiolator FEV1/FVC ratios were above 70%. There were no results meeting FEV1 criteria for a spirometric diagnosis of asthma, as none of the 14 spirometry results showed an improvement in FEV1 of 12% or over, and 200 mL after bronchodilator.
Four of the results of post FEV1/FVC ratios were between 70 and 75%, with three approaching COPD criteria. These same four spirometry results demonstrated post FEF 25-75% reductions from predicted (between -12% and -22%), whereas all other spirometry results had no reductions in the mid-range FEF 25-75% small airway region.

Comparison of Symptoms, MD-confirmed Diagnoses and Spirometry Results
When comparing the lung health questionnaire data to the spirometry results, the participants with symptoms of cough and phlegm, and MD-confirmed diagnosis of chronic bronchitis, matched the reduced FEV1/FVC results between 70 and 75%. The post FEV1/FVC results also matched the reductions of the FEF 25-75% results.

Discussion
The poultry producers’ lung health study included both pre/post spirometry and a standardized questionnaire to gather symptoms and screen for early detection of lung disease.

Results indicated that symptoms of cough and phlegm and MD-confirmed bronchitis matched FEV1/FVC ratios between 70% and 75%. According to McDonough et al. (2011), as bronchitis becomes more widespread over time, more of the small airways (<2 mm in diameter) become affected (12).

The study found that participants smoked an average of five pack years, equivalent to 20 cigarettes per day for 5 years. The average age of the poultry farmers was 56 years of age). Although individual susceptibility for the development of COPD varies, there is no minimum number of pack years which would put one person at greater risk for COPD (15).

Results of the pre/post spirometry confirmed a relationship between symptoms of chronic bronchitis and the spirometry results between 70 and 75%. The results of the post FEF 25-75% may be an important indicator to report for agricultural workers. With early detection of small airway disease, there is a potential for reversal of early stages of COPD (16).

These results point to the need for lung health screening through ongoing lung health clinics for those at high risk for developing COPD.

Conclusion
Lung health monitoring through standardized questionnaires and pre/post spirometry is recommended for poultry farmers. Physician-confirmed presence of bronchitis matched the presence of reduced post-FEV1/FVC spirometry and FEF 25-75% (n=14), indicating early detection of small airway disease. Future studies are required to support the use of both standardized measures.

Respiratory care health professionals, including RRTs, physicians and nurses, providing care to farmers are needed to provide screening for early signs of lung disease through pre/post bronchodilator spirometry, to be able to prevent the development of COPD.

Occupational exposure to dusts, chemicals, and gases found in poultry farming are risk factors for developing COPD (7) (14). The implications of occupational lung exposures in contributing to a diagnosis of COPD must be considered in research planning, in public policy decision-making, and in clinical practice.

References

  1. Global Initiative for Chronic Obstructive Lung Disease (GOLD). GOLD 2017 Global Strategy for the Diagnosis, Management and Prevention of COPD. Global Strategy for the Diagnosis, Management and Prevention of COPD. 2017.
  2. GOLD. Global Initiative for Chronic Obstructive Lung A Guide for Health Care Professionals Global Initiative for Chronic Obstructive Disease. Glob Initiat chronic Obstr lung Dis. 2017.
  3. Vogelmeier CF, Criner GJ, Martinez FJ, Anzueto A, Barnes PJ, Bourbeau J, et al. Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Lung Disease 2017 Report. GOLD Executive Summary. Am J Respir Crit Care Med [Internet]. 2017;195(5):557–82.
  4. Lyngso AM, Gottlieb V, Backer V, Nybo B, Ostergaard MS, Jorgensen HL, et al. Early detection of COPD in primary care: The Copenhagen COPD screening project. COPD J Chronic Obstr Pulm Dis. 2013; 10(2):208-15. doi: 10.3109/15412555.2012.714426.
  5. Hill K, Goldstein RS, Guyatt GH, Blouin M, Tan WC, Davis LL, et al. Prevalence and underdiagnosis of chronic obstructive pulmonary disease among patients at risk in primary care. CMAJ. 2010;182(7):673–8.
  6. Løkke A, Lange P, Scharling H, Fabricius P, Vestbo J. Developing COPD: a 25 year follow up study of the general population. Thorax. 2006;61(11). doi: 10.1136/thx.2006.062802.
  7. Boschetto P, Quintavalle S, Miotto D, Lo Cascio N, Zeni E, Mapp CE. Chronic obstructive pulmonary disease (COPD) and occupational exposures. J Occup Med Toxicol. 2006; 1:11.
  8. Stenton C, Shah SA, Gibson O, Clifford G, Heneghan C, Rutter H, et al. The MRC breathlessness scale. Occup Med (Chic Ill) [Internet]. 2008;58(3):226–7.
  9. Hankinson JL, Odencrantz JR, Fedan KB. Spirometric reference values from a sample of the general U.S. Population. Am J Respir Crit Care Med. 1999;159(1):179–87.
  10. Coates AL, Graham BL, McFadden RG, McParland C, Moosa D, Provencher S, et al. Spirometry in primary care. Can Respir J. 2013;20(1):13–22.
  11. D’Urzo AD. Spirometry interpretation in primary care. Canadian Family Physician. 2011; 57 (10) 1122.
  12. McDonough JE, Yuan R, Suzuki M, Seyednejad N, Elliott WM, Sanchez PG, et al. Small-Airway Obstruction and Emphysema in Chronic Obstructive Pulmonary Disease. N Engl J Med. 2011; 365:1567-1575. doi: 10.1056/NEJMoa1106955.
  13. Stockley J, Cooper B, Stockley R, Sapey E. Small airways disease: time for a revisit? Int J Chron Obstruct Pulmon Dis. 2017;12:2343–53.
  14. Viegas S, Faísca VM, Dias H, Clérigo a, Carolino E, Viegas C. Occupational exposure to poultry dust and effects on the respiratory system in workers. J Toxicol Environ Health A [Internet]. 2013;76(4–5):230–9.
  15. Aaron SD, Tan WC, Bourbeau J, Sin DD, Loves RH, MacNeil J, et al. Diagnostic instability and reversals of chronic obstructive pulmonary disease diagnosis in individuals with mild to moderate airflow obstruction. Am J Respir Crit Care Med. 2017; 196(3):306-314. doi: 10.1164/rccm.201612-2531OC.

Disclaimer: No endorsement by The Lung Association – Ontario is intended or should be inferred. The analyses, conclusions, opinions and statements expressed herein are those of the author and not necessarily those of The Lung Association.

Funding: This study was funded by The Lung Association, Ontario Respiratory Care Society (ORCS) Fellowship Grant.

Acknowledgments: The author wishes to thank Sandra Mohr, RRT for performing the standardized pre/post spirometry; Dr. Tony D’Urzo for spirometry interpretation consultation; Dr. Bruce Roberts, Ph.D., Executive Director, Canadian Poultry Research Council; Gwen Devereaux, Gateway Centre of Excellence in Rural Health. Special thank you to the poultry farmers of Huron County.

Competing interests: None declared

Poster photo credit: RM Doyon Dolinar 2017.
Poster graphic design: Jamie McLennan, Character Creative 2018.

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