The use of "peak flow monitors", which measure the breathing volumes of asthmatics, does nothing to reduce the likelihood of death or illness from the condition.
Some asthmatics are being encouraged by their doctors to use peak flow monitors to measure their current lung function against their supposedly optimum level. When the monitor shows their level has dropped by a certain proportion below their "personal best", they are expected to up their intake of doses of bronchodilators, anti inflammatory treatment or steroids.
However, research from the Grampian Asthma Study of Integrated Care, published in the British Medical Journal, suggests that such a programme does nothing to improve the patient's health, and may just mean he ends up going to see his doctor more often and taking increasing amounts of potentially harmful drugs.
They conclude that "peak flow meters, even when accompanied by guidelines for self management neither reduce [illness] nor improve anxiety, depression, self efficacy, or social and physical functioning. However, our findings do suggest that possessing a meter leads to some improvement in management for the more serious patients in the form of increased use of oral steroids [our emphasis]".
An Australian study of asthmatic children, in the same edition of the journal, concludes that mini peak flow monitors often give hopelessly inaccurate results. "We found that the meters performed remarkably poorly . . . many of the results were either meaningless or misleading and therefore potentially dangerous", warned the researchers.
!AB Med J, 26 February 1994.