That ‘70%’ claim again …

Salinas et al. ¹ present useful data on inter-practice regional variation in the requesting of urinary albumin estimations by general practitioners in Spain. However, it is unfortunate that they introduce their paper with the sentence ‘The clinical laboratory intervenes in 70% of clinical decisions …’. They reference this claim with a 1996 publication by Forsman, ² which they incorrectly cite as a 2016 reference. As I have previously discussed in an Annals editorial, ³ the Forsman paper was based on unpublished conversations with colleagues, and in any event related to critical clinical decisions (admission, discharge, therapy) in acute situations, not to all clinical decisions.

In a study of 79 oncologists and cardiologists, Rohr et al. ⁴ found that 75% of patients underwent in vitro diagnostic (IVD) testing, which led to a substantial clinical decision in 66% of these patients. This means that laboratory testing informed clinical decision-making in approximately 50% of patients, in two specialties that would be expected to have above average reliance on IVD testing compared with other areas of medicine, such as orthopaedic surgery, mental health, etc. It is extremely unlikely that a blanket figure of 70% of all clinical decisions across all specialties can be justified.

This does not in any way undermine the importance of laboratory medicine and its potential to add value to the clinical decision-making process. It does mean, as I concluded in the editorial cited above, that use of ‘70%’ claims in their various forms should be resisted in favour of specific and evidence-based indices of added value.