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The recent Best Evidence topic report article by Fayomi1 clearly illustrates the dangers of too narrow a focus when practising evidence based medicine. Firstly, the search strategy is too narrow, as three papers2,3,4 which have studied this have been missed. All of these papers found tissue turgor time to be closely associated with the presence of dehydration, while the paper cited by Gorelick et al5 found this sign to be very specific, but of low sensitivity.
Secondly, the focus of the question is too narrow. A number of studies, including Gorelick et al,5 has revealed that combinations of clinical findings traditionally associated with dehydration greatly enhanced accuracy, sensitivity and specificity.4,5,6,7,8 Accuracy, sensitivity and specificity figures of over 80% have been published, with combinations of clinical signs.5 In addition, some of these papers have demonstrated improvements in clinical care of the dehydrated patients with the use of scoring systems for dehydration based on combinations of clinical signs.
Many of the clinical signs of dehydration individually have high specificity, but low sensitivity. Combinations of signs are more accurate, especially when used by experienced clinicians, and are probably more accurate for lower levels of dehydration than classically taught.4,5,6,7,8 There is a tendency therefore to overestimate the level of dehydration, and this can lead to over treatment. However, there is an absence of any useful proven prospective diagnostic tools, and clinical examination is therefore still an acceptable method for determining treatment.
The usefulness of the Best Evidence topic reports have been debated in the correspondence section of this journal on previous occasions; like all medical literature, interpretation and implementation should be considered with caution, especially with regard to a wider, more strategic aspect.
Competing interests: none declared