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Reassessing the need for sport diving medicals
  1. P Smith
  1. School of Ocean and Earth Science University of Southampton Southampton SO14 3ZH, UK I.P.Smith{at}soton.ac.uk
    1. S Glen1,
    2. J Douglas2
    1. 1Department of Cardiology Edinburgh Royal Infirmary Lauriston Place, Edinburgh EH3 9YW, Scotland, UK SKGlen{at}sheriffbank.freeserve.co.uk
    2. 2Tweeddale Medical Centre High Street, Fort William, Scotland, UK

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      Editor,—Dr Stephen Glen and his coauthors conclude from an analysis of medical records held by the Scottish Sub-Aqua Club (SSAC) that routine medical examination of sport divers can safely be replaced by a system of self declaration, with a questionnaire designed to indicate whether referral to a doctor with experience of diving medicine is necessary.1 This conclusion should be regarded as preliminary, however, because the data were not disaggregated sufficiently to reveal the additional screening value of a routine medical examination beyond that of an initial questionnaire. In addition, there are inherent statistical biases in the SSAC data that have not been addressed.

      The risks associated with discontinuing routine examinations could have been investigated by quantifying the number of cases in which disqualifying conditions were found in medical examination but not declared in the prior questionnaire. However, the authors' listing of abnormalities recorded at examination apparently includes those due to conditions declared in the questionnaire. Similarly, the listing of formal referrals to approved medical referees does not indicate how many were initiated by a questionnaire response and how many as a result of an examination finding only. Crucially, the cases that were ultimately failed were not classified by type of disqualifying condition or by stage at which the condition was first detected. The prevalence of disqualifying conditions that subjects were unaware of, or otherwise did not declare, before the examination is therefore obscured.

      Under the SSAC system during the study period, general practitioners could certify candidates with certain conditions as “unfit to dive”, without referring them to a medical referee. As a certificate of fitness to dive was a prerequisite of membership of the SSAC, these subjects would not join the organisation and details of their medical examination would be unlikely to enter the medical database. The discriminatory value of medical examinations may therefore have been underestimated. It may have been rare that subjects were failed outright without a medical referee being consulted (when their details would be more likely to enter the database), but that eventuality should be considered and, if possible, quantified.

      The data set is also biased by the inclusion of “repeat” medicals (routine periodic re-examination of divers), which comprised nearly 30% of the records analysed. This probably involved some degree of pseudoreplication, but even if there was only one record for each individual, one may expect a lower prevalence of disqualifying conditions among a group who had previously been certified “fit” than among first time applicants. The prevalence of disqualifying conditions among new applicants therefore needs to be estimated separately.

      The authors may be correct that routine medical examinations for sport diving are unnecessary, but if policy on such an important safety issue is to be changed, the justification for doing so should be clearly demonstrated and qualified according to the limitations of the available data.

      References

      Authors' reply

      The main conclusions of our paper were that no significant unexpected abnormalities were found on clinical examination of divers in the Scottish Sub-Aqua Club, and that the questionnaire was the important part of the screening assessment of divers. This remains the case regardless of how the information is analysed.

      In response to the questions raised by Philip Smith, only 391 divers responded “No” to all questions, and none had abnormalities on clinical examination. All of the referrals to medical referees were prompted by positive questionnaire responses, and the divers were assessed by doctors with diving medicine experience. The interim step of clinical examination by a doctor without such experience did not alter the final outcome.

      Divers start training with the SSAC by undergoing basic snorkel and rescue training (as with most diving organisations) and may progress to scuba training after a medical examination. They entered the SSAC system during the snorkel training, however, and in our experience GPs did not fail divers outright before contacting SSAC headquarters or a medical referee. It is not possible to confirm that all divers were referred in this way, but it is reassuring that an analysis of the medical forms after the introduction of a self certifying system has confirmed an increase in the number of divers failing on the basis of questionnaire responses alone.

      It was necessary to include the repeat medicals in the analysis because the introduction of a new system must be as effective in the existing divers as it is in the new entrants. New medical conditions may develop in the period between medicals, which can be up to five years. Removing the repeat medicals from the analysis does not affect the final conclusion, and confirms that the questionnaire is the most important part of the screening process.

      A new questionnaire system was introduced in March 2000 and analysis of the short term safety data has confirmed a slight increase in the number of divers failing their medical assessment. A complete report will be submitted for publication shortly. In addition, all forms submitted by divers are now reviewed by diving doctors, and assessment is only performed by doctors with diving medicine experience. This helps to ensure a consistent application of the medical standards recommended by the UK Sport Diving Medical Committee. There has been no change in the incident pattern although it is too early to expect major differences to become apparent.

      It is worth noting that the role of routine medical examinations has been questioned elsewhere, and that the number of diving accidents related to medical conditions did not significantly change when compulsory medicals were introduced in Australia and New Zealand.1 The main problem in assessing fitness to dive has been the fact that divers have been assessed by doctors without diving medicine experience, and the introduction of the new system has allowed this to be rectified. Divers should not be falsely reassured by the value of a screening medical examination performed by a doctor without diving medicine experience.

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