In this short film I will explain to you why I have come to understand that case-finding and screening are actually one and the same.
All around us national clinical leads and disease champions argue that early detection policies are exercises in ethical case-finding. They insist that such policies are not screening. This is important because criteria have been set for the introduction of any national “screening” programme. It appears that by calling any programme “case-finding”, these criteria can be ignored.
In this film I will briefly look at the historical development of case-finding and screening. This provides clear evidence that these terms have been consistently used one and the same. This film will argue, along with Dr James Maxwell Glover Wilson, that the ten principles that are considered necessary by the World Health Organisation for screening, should also apply to case-finding. One and the same.
As an approach, case-finding emerged in the first few years of the 1930’s: “to designate the pre-clinical stage of a tuberculous pulmonary infiltration, when it is demonstrable by x-ray examination but does not yet manifest itself clinically by symptoms or signs perceptible to the patient or by the usual methods of classical physical examination.”
The success of this case-finding approach led to its use for detection of other diseases. By 1968 the World Health Organisation had listed ten requirements necessary for the introduction of a public health screening programme. Note that this list refers to case-finding. Screening and case-finding are one and the same.
The condition sought should be an important health problem.
- There should be an accepted treatment for patients with recognized disease.
- Facilities for diagnosis and treatment should be available.
- There should be a recognizable latent or early symptomatic stage.
- There should be a suitable test or examination.
- The test should be acceptable to the population.
- The natural history of the condition, including development from latent to declared disease, should be adequately understood.
- There should be an agreed policy on whom to treat as patients.
- The cost of case-finding (including diagnosis and treatment of patients diagnosed) should be economically balanced in relation to possible expenditure on medical care as a whole.
- Case-finding should be a continuing process and not a ‘once and for all’ project.
Into the next decade and case-finding moved into many other areas.
In 1970 diabetes was considered as one area that might benefit:
“Many are truly asymptomatic, even on direct questioning. Despite this, diagnosis of the diabetes is not usually difficult, for random or post-glucose blood sugar levels are sufficiently high to allow of no doubt. Nevertheless, when screening by blood sugar level is employed for case finding, diagnosis becomes more problematic.”
As the 1970’s progressed case-finding of hypertension became a priority.
Hypertension in general practice
21 April 1984
“SIR, I support Dr John Coope’s comments on the lamentable state of management of patients with hypertension, benefits can be achieved from treatment. The practical answer surely lies in case finding.”
Into the 1980s and case-finding methods are underway to detect dementia:
Do general practitioners miss dementia in elderly patients?
Some of the difficulties of this were discussed at this time and reveal that the Wilson & Junger principles for screening were considered necessary:
“We have made some progress with the problem of assessing mild dementia. However, there are as yet no widely accepted criteria for mild dementia, nor are there any clinically useful biological markers. Consequently, whether normal ageing, benign senescent forgetfulness and mild dementia lie on a continuum, or whether mild dementia is categorically distinct, is uncertain.
Thus, prospective longitudinal studies using a range of reasonably standardised diagnostic criteria are imperative, as they may show which of the existing criteria most effectively distinguish those cases which progress from those which remain stable.”
Those who know me and my writings will realise that it was with the early diagnosis of dementia where my interest first started in case-finding and screening, one and the same thing. It was clear to me that early diagnosis of dementia could not just side-step the ten principles as established by the World Health Organisation. However it took the support of doctors like Dr McCartney, Heath, Brunet and Cosgrove (the Grassroot doctors) to reason why a timely approach to the diagnosis of dementia would be a better, and less harmful approach than case-finding or screening, one and the same.
The UK National Screening Committee have been approached by policy advisors to tabulate similarities and differences between screening and case-finding. Having looked at these carefully it is clear to me that the majority of differences are in fact interpretational and demonstrate that case-finding has been, in recent years, wrongly separated from screening. The main cost of this is that the ten principles need not to be followed.
For example with screening one is generally invited and formal information of benefits and harms are shared. This generally does not happen with case-finding.
For example with screening there is generally formal quality assurance whilst with case-finding this is generally not so.
Time to finish but first let me dispel a myth. It has been argued that for case-finding one has already “symptoms” but with screening generally one does not. This is a false divide. Symptoms are not all or nothing and may or may not be experienced. Dr Wilson and Jungner made no distinction here and the World Health Organisation agreed.
Screening and case-finding are one and the same thing.