Interpretation of occupational peak flow records: level of agreement between expert clinicians and Oasys-2

Abstract

Background: Oasys-2 is a validated diagnostic aid for occupational asthma that interprets peak expiratory flow (PEF) records as well as generating summary plots. The system removes inconsistency in interpretation, which is important if there is limited agreement between experts. A study was undertaken to assess the level of agreement between expert clinicians interpreting serial PEF measurements in relation to work exposure and to compare the responses given by Oasys-2. Method: 35 PEF records from workers under investigation for suspected occupational asthma were available for review. Records included details of nature of work, intercurrent illness, drug therapy, predicted PEF, rest periods, and holidays. Simple plots of PEF and the Oasys-2 generated plots were available. Experts were advised that approximately 1 hour was available to review the records. They were asked to score each work-rest-work (WRW) period and each rest-work-rest (RWR) period for evidence of occupational effect. At the end of each record scores of 0-100% were given for evidence of "asthma" and "occupational effect" for the whole record. Kappa values were calculated for each scored period and for the opinions on the whole record. The scores were converted into four groups (0-25%, 26-50%, 51-75%, 76-100%) and two groups (0-50% and 51-100%) for analysis. This is relevant to scores produced by Oasys-2. Agreement between Oasys-2 scores and each expert was calculated. Kappa values for the median expert score v Oasys-2 were 0.75 for two groups and 0.67 for four groups. Agreement was poor for records with intermediate probability, as defined by Oasys-2. Conclusion: Considerable variation in agreement was seen in expert interpretation of occupational PEF records which may lead to inconsistencies in diagnosis of occupational asthma. There is a need for an objective scoring system which removes human variability, such as that provided by Oasys-2.

Are we failing workers with symptoms suggestive of occupational asthma?

“…Many patients with negative OASYS charts were confirmed as having occupational asthma. This paradox may be partially explained by variation between expert raters when assessing PEF data, 19 and may also represent the current lack of clear diagnostic consensus generally between expert centres 20 -although the sensitivity and specificity of OASYS analysis of serial PEF measurements depends on data quality. For records of adequate quality, the specificity of a positive PEF chart is high (around 94%), but the sensitivity using the work effect score generated by OASYS 2 software alone is 70%.…”

Notified cases of occupational asthma in Norway: Exposure and consequences for health and income

“…However, there is little agreement as to the diagnostic criteria and diagnostic tests are interpreted variously, even by experts [Baldwin et al, 2002]. In this study, asthma was diagnosed by a doctor, but some of the cases may have been misdiagnosed cases of chronic obstructive bronchitis.…”

Controversies in epidemiology of occupational asthma

“…OA has been defined as: 1) the presence of respiratory symptoms at work (e.g. symptoms of wheezing, cough, dyspnoea, chest tightness that resolve after some time away from work [18,29,30]; or 2) as one or the other of combinations that include work-related respiratory symptoms, specific immunological sensitisation [31], variation in serial peak-flow measurements [32][33][34] and increased nonspecific bronchial responsiveness [7]. As uncertainty persists in the ascertainment of OA in epidemiological studies, the terms "asthma-like," "possible OA" [25] and "probable OA" [7,25] have been used to describe the syndrome.…”