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 asthma.

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.
• Rest-Work 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 their asthma.

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 periods.

The third module calculates a score indicating the likelihood of the patient having occupational asthma.

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