World Health Organization responds to Fiona Godlee and Ray MoynihanBMJ 2011; 342 doi: https://doi.org/10.1136/bmj.d3830 (Published 20 June 2011) Cite this as: BMJ 2011;342:d3830
All rapid responses
Diseases (diagnoses when applied to an individual patient) are titles
to theories or hypotheses that explain and anticipate . Definitions of
diseases are rules that provide general agreement as to whom such
hypotheses should be applied. However, in order to treat patients we also
need treatment indication criteria that identify subgroups of patients
that will probably benefit. These can be obtained in an evidence-based
way from the selection criterion of a randomised controlled trial (RCT) by
examining at what cut-off point patients begin to benefit .
The corollary to this is that absence of disease or diagnosis implies
that the patient is not considered for its related actions such as
treatment, advice or follow up. It is important therefore that on the
continuum of disease (mental or physical), the cut-off should be set so
that few if any patients are deprived of such consideration if the
diagnosis is 'ruled out'. (This is why the cut-off point for diabetes
mellitus was reduced just over 10 years ago ). The danger with this is
that to be on the safe side, some patients labelled with a diagnosis but
may not gain practical benefit. In addition they may be saddled with
unnecessary treatment and also psychological, social and financial
One way around this is for WHO not to define disease fully but to set
the 'necessary' criteria that allow the diagnosis to be ruled out if this
criterion is absent but for the diagnosis to be seriously considered it if
the criterion is present. The diagnosis could be confirmed and the
patient labelled with the diagnosis when there is evidence of benefit from
some action (e.g. treatment or follow up) that can be explained by that
diagnosis. The indication for action thus doubles as one of the
'sufficient' criteria for the diagnosis. This also means that the
definition of disease can change in a flexible way with the emergence of
new treatments and other management methods.
So WHO could suggest the criteria for who should or should not be
considered for a diagnosis. An optimum entry criterion for a RCT can
provide one of the sufficient criteria for the diagnosis . In the
absence of satisfactory RCT evidence, a doctor would have to make an
educated guess based on other evidence when deciding to treat or follow up
in a clinic for potential complications.
1. Llewelyn H, Ang AH, Lewis K, Abdullah A. The Oxford Handbook of
Clinical Diagnosis, 2nd edition. Oxford University Press, Oxford 2009.
2. Llewelyn D E H, Garcia-Puig, J. How different urinary albumin
excretion rates can predict progression to nephropathy and the effect of
treatment in hypertensive diabetics. JRAAS 2005, 5; 141-5.
3. Alberti KG, Zimmet PZ. Definition, diagnosis and classification of
diabetes mellitus and its complications. Part 1: diagnosis and
classification of diabetes mellitus provisional report of a WHO
consultation. Diabet Med 1998; 15:539.
4.Moynihan R. A new deal on disease definition. BMJ 2011;342:d2548.
Competing interests: No competing interests