Extract from Statistical Questions in Evidence-based Medicine by Martin Bland and Janet Peacock.
We hope that the topic will be useful in own right, as well as giving a flavour of the book.
A cross-sectional study investigated the association between raised body temperature and acute mountain sickness in 60 climbers in Switzerland. The climbers were examined at low altitude (490 m above sea level), two to six hours after arrival at a mountain hut at 4,559m and each morning during the next three days. Each day, symptoms and signs of acute mountain sickness were assessed and climbers were classified as healthy, as having mild acute mountain sickness or as having severe acute mountain illness. Climbers were also classified as having or not having high altitude cerebral or pulmonary oedema according to symptoms and chest radiography. Body temperature and blood gases were also measured. Fifteen climbers who were found to have cerebral or pulmonary oedema were evacuated by helicopter (Maggiorini et al. 1997).
The study showed a strong relation between body temperature, hypoxaemia and the severity of acute mountain sickness on the same day. The researchers concluded that a rise in temperature after rapid ascent to high altitude is a sign of acute mountain sickness and is associated with the severity of hypoxaemia.
1. Why is this a cross-sectional study?
Check answer 1
2. The study was approved by the ethics committee of the
University Hospital Zurich. Do you think that this study was ethical?
Check answer 2
Reference: Maggiorini, M., Bartsch, P., and Oelz, O. (1997) Association between raised body temperature and acute mountain sickness: cross sectional study. British Medical Journal 315 403-4.
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