Do laboratory challenge tests for occupational asthma represent what happens in the workplace?

Occupational asthma in teachers

BACKGROUND

Work-related asthma symptoms are common in teachers and teaching assistants, there are few studies evaluating their causes.

AIMS

To identify causes of occupational asthma in teachers and teaching assistants referred to the Birmingham Occupational Lung Disease clinic 2000-20 using evaluation of serial Peak Expiratory Flow (PEF) records.

METHODS

Teachers and teaching assistants with possible occupational asthma were asked to record PEF 2-hourly at home and work for 4 weeks. Their records were evaluated with the Oasys programme. Those with a positive score for any of the three scores (area between curves (ABC), timepoint and Oasys score from discriminant analysis) were included. Repeat records were made as indicated to help identify the cause and the effects of remedial actions.

RESULTS

Thirty-eight teachers or teaching assistants met the inclusion criteria with all three Oasys scores positive in 24, 2/3 scores in nine and 1/3 in five. The building was the likely cause in 17 (in new builds particularly acrylates from carpet adhesives and in old buildings mould and construction dust), bystander exposure to agents in the schools in 12 (cleaning agents, acrylates from photocopiers and chloramines from indoor pools) and materials used in the classroom in 9 (most commonly MDF in design and technology classes). We illustrate how the PEF records helped identify the cause.

CONCLUSIONS

Oasys analysis of PEF records is a useful method of evaluating occupational asthma in teachers and identified difficult to confirm causes where successful remediation or redeployment was achieved.

Improving detection of work-related asthma: a review of gaps in awareness, reporting and knowledge translation

Background

Work-related asthma (WRA) accounts for up to 25% of all adults with asthma. Early diagnosis is key for optimal management as delays in diagnosis are associated with worse outcomes. However, WRA is significantly underreported and the median time to diagnosis is 4 years. The objective of this review is to identify the gaps in awareness and reporting of WRA and identify gaps in current knowledge translation strategies for chronic disease in general, and asthma specifically. This will identify reasons for delays in WRA diagnosis, as well inform suggestions to improve knowledge translation strategies for dissemination and implementation of WRA prevention and management guidelines.

Methods

Non-systematic literature reviews were conducted on PubMed with a focus on work-related asthma screening and diagnosis, and knowledge translation or translational medicine research in asthma and chronic disease. In total, 3571 titles and abstracts were reviewed with no restriction on date published. Of those, 207 were relevant and fully read. Another 37 articles were included and reviewed after citation reviews of articles from the initial search and from suggestions from editors. In total, 63 articles were included in the final review.

Results

Patients, employers, and healthcare professionals lack awareness and under-report WRA which contribute to the delayed diagnosis of WRA, primarily through lack of education, stigma associated with WRA, and lack of awareness and screening in primary care. Knowledge translation strategies for asthma research typically involve the creation of guidelines for diagnosis of the disease, asthma care plans and tools for education and management. While there are some prevention programs in place for certain industries, gaps in knowledge translation strategies including lack of screening tools currently available for WRA, poor education of employers and physicians in identifying WRA, and education of patients is often done post-diagnosis and focuses on management rather than prevention or screening.

Conclusion

Future knowledge translation strategies should focus on educating employees and employers well before potential exposure to agents associated with WRA and screening for WRA in primary care to enable health care providers to recognize and diagnose WRA.

Identification of late asthmatic reactions following specific inhalation challenge

Specific inhalation challenge (SIC) is the reference standard for the diagnosis of occupational asthma. Current guidelines for identifying late asthmatic reactions are not evidence based.

OBJECTIVES

To identify the fall in forced expiratory volume in 1 s (FEV₁) required following SIC to exceed the 95% CI for control days, factors which influence this and to show how this can be applied in routine practice using a statistical method based on the pooled SD for FEV₁ from three control days.

METHODS

Fifty consecutive workers being investigated for occupational asthma were asked to self-record FEV₁ hourly for 2 days before admission for SIC. These 2 days were added to the in-hospital control day to calculate the pooled SD and 95% CI.

RESULTS

45/50 kept adequate measurements. The pooled 95% CI was 385 mL (SD 126), or 14.2% (SD 6.2) of the baseline FEV₁, but was unrelated to the baseline FEV₁ (r=0.06, p=0.68), or gender, atopy, smoking, non-specific reactivity or treatment before or during SIC. Thirteen workers had a late asthmatic reaction with ≥2 consecutive FEV₁ measurements below the 95% CI for pooled control days, 4/13 had <15% and 9/13 >15% late fall from baseline. The four workers with ≥2 values below the 95% CI all had independent evidence of occupational asthma.

CONCLUSION

The pooled SD method for defining late asthmatic reactions has scientific validity, accounts for interpatient spirometric variability and diurnal variation and can identify clinically relevant late asthmatic reactions from smaller exposures. For baseline FEV₁ <2.5 L, a 15% fall is within the 95% CI.

Praćenje vršnog ekspiratornog protoka u dijagnozi profesionalne astme

Prema podacima iz Registra profesionalnih bolesti Hrvatskoga zavoda za zaštitu zdravlja i sigurnost na radu, u posljednjih deset godina (2008. ‒ 2017.) prijavljeno je samo 20 slučajeva profesionalne astme od ukupno 2234 prijavljene profesionalne bolesti. To upućuje na značajne nedostatke u prepoznavanju toga poremećaja u našoj radnoj populaciji. Cilj ovoga rada bio je opisati standardnu metodu praćenja vršnog ekspiratornog protoka zraka (eng. peak expiratory flow, PEF) i predložiti praktičnu smjernicu za korištenje te dijagnostičke metode u ambulantama medicine rada i sporta. Praćenje vršnog ekspiratornog protoka zraka (PEF-monitoring) jednostavna je, jeftina, neinvazivna i pouzdana metoda za utvrđivanje funkcije dišnog sustava u stvarnim uvjetima rada i radnog okoliša. Sadašnje smjernice preporučuju PEF-monitoring kao inicijalnu dijagnostičku metodu prilikom sumnje na profesionalnu astmu. Pozitivan test upozorava na povezanost promjene plućne funkcije s radnom izloženošću i važan je dio dijagnostičkoga procesa utvrđivanja profesionalne astme. Najveći je nedostatak te metode da se tim testom ne može utvrditi uzrok astme, tj. on ne razlikuje profesionalnu astmu od astme pogoršane na radu, nema standardizirane metode za interpretaciju rezultata, a mjerenja provode sami radnici pa su moguće namjerne i nenamjerne manipulacije rezultatima mjerenja. U radu je predložena praktična smjernica za primjenu te metode u ambulantama medicine rada i sporta, s preporukama protokola mjerenja PEF-a, prikaza rezultata mjerenja i njihove interpretacije u sklopu dijagnosticiranja profesionalne astme.

Hospital Attendances and Acute Admissions Preceding a Diagnosis of Occupational Asthma

PURPOSE

Occupational exposures are a common cause of adult-onset asthma; rapid removal from exposure to the causative agent offers the best chance of a good outcome. Despite this, occupational asthma (OA) is widely underdiagnosed. We aimed to see whether chances of diagnosis were missed during acute hospital attendances in the period between symptom onset and the diagnosis of OA.

METHODS

Patients diagnosed with OA at the regional occupational lung disease service in Birmingham between 2007 and 2018 whose home address had a Birmingham postcode were included. Emergency department (ED) attendances and acute admission data were retrieved from acute hospitals in the Birmingham conurbation for the period between symptom onset and diagnosis.

RESULTS

OA was diagnosed in 406 patients, 147 having a Birmingham postcode. Thirty-four percent (50/147) had acute hospital attendances to a Birmingham conurbation hospital preceding their diagnosis of OA, including 35 (24%) with respiratory illnesses, which resulted in referral for investigation of possible OA in 2/35. The median delay between symptom onset and diagnosis of OA was 30 months (IQR = 13-60) and between first hospital attendance with respiratory illness and diagnosis 12 months (IQR = 12-48, range 3-96 months) CONCLUSIONS: The chance to reduce the delay in the diagnosis of OA was missed in 33/35 patients admitted or seen in ED with respiratory symptoms in the period between symptom onset and diagnosis of OA. The diagnosis of OA was delayed by a median of 12 months by failure to ask about employment and work relationship of symptoms.