Designing a Medical Screening and Surveillance Programme structure

The technique used to design the Medical Surveillance Programmes for each exposure group is described in detail in the SOP for the construction of the Worker Allocated Surveillance Programmes (WASPs) using information from the Risk Assessment, and an understanding of appropriate test selection. The details can be found in the Medical Surveillance Guideline documents.

This is a complex process but can be summarised as follows:

Step1: Determine which employee groups require medical surveillance.

The basis for constructing these employee groups follows the same logic as the OREPs. Occupations in which exposures and requirements are similar are chosenm, and constitute Homogeneous Exposure Groups (HEGs). A HEG may comprise only a single job category (eg. fitters), or may also comprise a number of groups or job categories with similar exposures (e.g. admin staff, supervisors and senior management).

The key determinants of who should be required to undergo medical surveillance are the findings of the Health Risk Assessment, which are recorded in the Occupational Risk Exposure Profiles (OREPs). Hence in the first step in the design of the medical surveillance programme, the OREPs are consulted, and the data therein is transferred to the WASPs.

This is done as follows:

• The Inherent Requirements standards of the OREPs are transferred to the Job Fitness page of the WASPs.
• The Exposure levels (values) are transferred to the corresponding places in the Effect Monitoring page in the WASPs.
• The data entered into these two pages of the WASPs are summarised on the Summary page of the WASPs, for easy reference.

Step 2: Determine which tests are required: TEST SELECTION.

This is done by using the WASP pages referred to in the preceding paragraph, and the reference tables in the WASPs documentation.

The tests comprise combinations of questionnaires, clinical examination and special investigations (x-rays, laboratory tests, audiograms, etc.).

It is important that the selected tests are valid. This is determined by their sensitivity and specificity, and the availability of reliable testing facilities (laboratories, testing equipment, trained occupational health programme staff (including CXR’s, audiograms, PFT’s, etc.). For further information on screening tests including the concepts of sensitivity and specificity, refer to Appendix 2. Test performance or sensitivity and specificity are also dealt with in Module 2: Epidemiology materials viz. EPI Section 9.

Step 3: Determine the required STANDARDS for medical adjudication.

Two types of standard are considered:

1. The medical standards that must be met to "pass" the examination (Job Fitness standards).
   
2. The action criteria that must be triggered when biological exposure levels or certain exposure effects are exceeded (Biological Exposure standards which describe the "standard" that addresses the thresholds for action with reference to exposure effects and biological marker levels, in other words, determined by exposure issues, rather than meeting standards of fitness).

The extensive reference tables in the WASP documentation assist the examining health team in this task, as well as providing pointers to likely exclusions

Step 4: Determine the TEST FREQUENCY.

This is determined by the degree of risk to which the employees are faced, and the outcomes of the medicals themselves. The higher the risk, the more frequent the tests. The more adverse the outcomes, the more frequent the tests. Test frequencies usually vary from quarterly to every 5 years, but the most common is annual. For certain industries such as the mining industry, audiometry, lead, asbestos, driver medicals, amongst others, this is regulated by appropriate legislation

Step 5: The ethics of medical testing should be considered, with special regard to:

• Confidentiality.

  This is particularly sensitive when test outcomes are computerised, which increases the risk that these results may get into the wrong hands. However, even paper records go astray. It is a temptation to flag records by means of the use of markers on the outside of the medical folders - a practice that should be implemented with caution, as this may constitute a breach of confidentiality (when the "coded" flags are interpreted (correctly, or, worse, incorrectly) by the employees or management.

  (For example, the diabetics could be flagged by means of a pink coloured sticker, the hypertensives by means of a blue one, etc. The employees may interpret a certain sticker as marking those with HIV (correctly or incorrectly), which could spark an industrial relations crisis.

• Communication of results.

  This is regarded as an important part of the medical surveillance programme, as it not only provides employees with the results of their tests, as is their constitutional right, but also allays fears that the company is hiding information deliberately. The feedback may be verbal or written, but the written route is favoured.

• Education and Training.

  Whilst employee education is not a direct responsibility of the medical team, the annual medical provides an ideal opportunity to provide the employees with a further reminder of the issues which they need to be aware in their occupations, with particular reference to the effective use of their PPE, as well as safe work practices, and also the important relevant risk factors outside of the work-place.