How to prescribe loop diuretics in oedemaBMJ 2019; 364 doi: https://doi.org/10.1136/bmj.l359 (Published 21 February 2019) Cite this as: BMJ 2019;364:l359
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I am afraid there is another key point in prescribing decisions with regard to loop diuretics missed in this article which raises some useful points. This key point is that the low marginal clinical benefit in choosing between the loop diuretics means that relative cost is extremely important in rational clinical decision making. The general properties, comparative properties and dose equivalence mentioned in the article are useful to know by both primary and secondary care prescribers, when prescribers are faced with apparent loop diuretic ineffectiveness, loop diuretic intolerance and supply chain instability. The comparative cost issue, which has been long standing, should be a significant factor in both individual and formulary guided prescribing decisions because of the marked contrast in costs for equivalent doses. As the rate of diuretic use per 1000 population for oedema is over 40/1000 and loop diuretics make up over 70% of such diuretic use in Europe  there are significant whole population resource implications in moving a significant number of patients from oral frusemide to oral torsemide which costs about thirty times as much for the equivalent dose. In the UK context, at BNF (drug tariff) current cost 80mg oral frusemide (two 40mg tablets a day) costs £1.10 for every 28 days while 40mg oral torsemide costs £32.56 (it is only available as four 10mg tablets in the UK). Bumetamide 1mg orally daily costs £1.15 for every 28 days. In the current UK context torsemide use therefore might arguably be an useful prescribing indicator as it could well reflect poor understanding of how to prescribe frusemide and bumetamide effectively, which those who read the article will be able to address . Similar cost differences are likely to be found in other health economies and can be just as important for prescribing decisions where a patient has to pay for their medicine themselves or where a prescriber has a responsibility to prescribe cost effectively for other reasons. Accordingly how to prescribe loop diuretics in oedema world wide is more than just a formulary decision, it is a prime example of responsible prescribing, often driven by best use of healthcare associated resources.
1) Straand J, Rokstad K. Are prescribing patterns of diuretics in general practice good enough? A report from the Møre & Romsdal Prescription Study. Scand J Prim Health Care. 1997 Mar;15(1):10-5.
Competing interests: No competing interests