Description of the Oasys-2 Program
Oasys-2 is a computer program that plots and interprets serial peak
expiratory flow (PEF) readings of patients suspected as having occupational
Specifications for the Oasys 2 Program
- Reference describing
the algorithm for calculating the Oasys 2 Score. The Oasys program scores
each rest-work-rest or work-rest-work complex in a serial peak flow record
between 1 and 4. 1 is < 1% chance of occupational asthma, 2 is 1% - 49%, 3 is
50% to 99% and 4 is > 99%. The Oasys score for the record is made by meaning
all these complex scores, double weighting the 1's and 4's.
- Wasif Score. The Oasys program produces
another score for occupational asthma nicknamed after the research registrar at
the time. It was found by comparing indices of PEF variability in three groups
of subjects: healthy grain exposed farmers and dockers; patients with
independently confirmed occupational asthma and non-occupational asthmatics.
- Day Interpetation
Specification. The Oasys program interprets days into "Pseudo Days" to
improve the analysis. The primary aim of day interpretation is to create pseudo
days in which peak flow readings are either all exposed or all non-exposed.
Additionally each pseudo day must contain exactly one waking reading.
- Reference defining
the quality criteria for Oasys. A serial peak flow record is defined as
being of adequate quality if it is of >=2.5 weeks duration, with >=4 readings per
day and >=3 consecutive workdays in each work period. The sensitivity and
specificity respectively of adequate records were 78.1% and 91.8% versus 63.6%
and 83.3% for inadequate records.
Motivation behind the Oasys 2 Program
In patients with or suspected as having asthma, it is important to know
whether substances encountered in the work environment are contributing to their
breathing problems. If the work environment is wholly or partly the cause of the
patient's asthma, then it is unlikely that the asthma will get better unless
exposure to the causative factor can be avoided. The longer the worker continues
to be exposed to the particular cause, the worse the long-term prognosis is
likely to be, even if they are treated with inhaled corticosteroids. The
difficulty is knowing whether there is a genuine work related deterioration in
the patient's breathing. Often the patient may be unaware of a relationship
between their work and their breathing problems (and this is suspected by their
doctor). Conversely, they may wrongly suspect that their work is the cause of
In these cases, the recording of serial peak flow measurements is often the
most appropriate initial investigation. A work related fall in peak flow
readings suggests a diagnosis of occupational asthma. However, interpreting peak
flow recordings can be difficult and usually requires an expert. The Oasys-2
program has been shown to be a sensitive and specific tool for detecting work
related changes in peak expiratory flow readings, overcoming many of the
difficulties of visual analysis of records.
The Oasys-2 program consists of three modules; one for allowing entry of peak
flow readings that have been recorded by the patient. Another module plots these
recordings in a graph format. These graphs include a plot of mean peak flow for
each two hour period separated into work days and rest days, and also plots of
daily maximum, minimum and mean readings again divided into work and rest
The third module calculates a score indicating the likelihood of the patient
having occupational asthma.
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