Identification of late asthmatic reactions following specific inhalation challenge.

Moore, Vicky C, Walters, Gareth Iestyn, Robertson, Alastair S and Burge, P Sherwood (2020) Identification of late asthmatic reactions following specific inhalation challenge. Occupational and environmental medicine. ISSN 1470-7926. This article is available to all UHB staff and students via ASK Discovery tool http://tinyurl.com/z795c8c by using their UHB Athens login IDs

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Official URL: http://oem.bmj.com/

Abstract

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 (FEV) 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 FEV from three control days.

METHODS

Fifty consecutive workers being investigated for occupational asthma were asked to self-record FEV 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 FEV, but was unrelated to the baseline FEV (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 FEV 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 FEV <2.5 L, a 15% fall is within the 95% CI.

Item Type: Article
Additional Information: This article is available to all UHB staff and students via ASK Discovery tool http://tinyurl.com/z795c8c by using their UHB Athens login IDs
Subjects: W Public health. Health statistics. Occupational health. Health education
WF Respiratory system. Respiratory medicine
Divisions: Planned IP Care > Respiratory Medicine
Related URLs:
Depositing User: Jamie Edgar
Date Deposited: 05 Aug 2020 09:38
Last Modified: 05 Aug 2020 09:38
URI: http://www.repository.uhblibrary.co.uk/id/eprint/3339

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