Tracking

Performances of a tracking

At the end of the consecutive investigations to a tracking, the person is classified in one or the other of the two following categories: the required disease is regarded as present or the required disease is regarded as absent. In each one of these two situations, the investigators could be mistaken. Thus actually, there exist four possibilities of results:

the disease really exists and it was found (true positive)
the investigations found a disease which does not exist (false-positive or surdiagnostic)
the disease really exists but the investigations did not find it (false negative)
the disease does not exist and the investigations did not find anything (true negative)

The performances of a tracking in a population are good if the negative false-positives and forgeries are very few.

Goal of tracking

Tracking seeks to find diseases or risk factors at an early stage, before the person does not present symptoms of this disease.

This will have several interests:

Mettre in obviousness a risk factor can make it possible to correct it to avoid occurred of a disease. For example, one detects the Hypercholestérolémie to be able, after having treated it by a mode or a drug, to avoid seeing appearing a Cardiovascular disease (Myocardial infarction, Cerebral vascular accident…)
To highlight a lesion supporting another disease. For example, if one highlights a polyp colon, one knows that this polyp at the risks to degenerate into Cancer: it will thus be necessary to remove it and supervise the patient to make sure that it does not develop a cancer of the colonist.
To treat at an early stage a disease. Often, the treatments of cancers are less heavy and more effective when the disease is discovered at an early stage that at a develop stage, where the patient presents symptoms.
To treat the disease before after-effects do not occur. Thus, one systematically carries out blood testings with the newborns to detect diseases before they obstruct the development of the child (for example, treatment of a Hypothyroïdie before having a deficit of growth and a mental deficit)

Danger of tracking

The major disadvantages of tracking are the Surdiagnostic and the Surtraitement.

Let us take the example of the tracking of breast cancer in a population of 1000 women: 996 without cancer and 4 with a still unknown breast cancer. It is supposed that the sequence of the examinations carried out gives a negative forgery for 10 truths case and a false-positive for 100 women without cancer. Let us see what tracking would give. Even while being mistaken once on 10, there are good lucks identify 4 truths case. On the other hand, while being mistaken once on 100, one obtains on average an error each time one examined 100 people without cancer. As there are 996 of them, one is highly likely thus to have 10 false-positives. On the 14 diagnoses obtained, 4 are truths cancers and 10 are false cancers. They are surdiagnostics. When these cases are treated, they give the illusion of the cure. This danger of tracking has caused for more than 50 years the medical error most serious ever made in the world industrialized by unnecessarily looking after million false cancers. The apparent cures make accept the effectiveness of the care whereas one unnecessarily treated a disease which did not exist.

Requirements with tracking

To implement a tracking, certain conditions should initially be met:

the disease must be enough frequent . Indeed, to detect a rare disease would make carry out examinations with many people, would be very expensive for final treating only few patients.
the disease must be enough serious . To detect a minor illness has only little interest.
the disease must have a early stage more easily manageable . Obviously, it is not beneficial to discover something which one cannot treat.
It is necessary to lay out of a good test of tracking. A test is never perfect, it always gives false-positives (positive test whereas the person is not sick) and of the false negative (negative test whereas the person is sick); a screening test should not have too negative forgeries (ineffective tracking) nor too many false-positives (one should make complementary examinations too much, which can be dangerous and expensive among people who are not in fact not sick and do not complain about nothing).
tracking should not be expensive since it applies to populations of big size.
It must lead to therapeutic or preventive measures concrete.
tracking must be simple to implement.

Concept of population target and tracking of mass

It is necessary to distinguish trackings from mass of trackings on targeted population. Trackings of mass or trackings systematic relate to a not selected population. In the particular case of the criterion of age, tracking is regarded as generalized with the whole of the section considered.

Means of tracking

Clinical examination: palpation of the centres, rectal examination, touch testiculaire…
biological Examinations: blood tests, search for blood in the saddles, Spermogramme…
Taking away like a cervical smear…
Search for genetic mutation: BRCA1 and 2 of certain breast cancers and/or the ovary,…
Medical imagery: Mammography, echography…

Tracking by country

France

Tracking at the new born one: phénylcétonurie, hyperplasy congenital of the suprarenals, hypothyroïdie congenital, drépanocytose and mucoviscidose.

Tracking in the nourisson and the child: disorder of the growth, the catch of weight, psychomotor development, hearing, sight trouble.

At the adulthood:

Cardiovascular tracking of the risk factors: HTA, dyslidemy, diabetes, overweight and obesity.

Tracking of cancers: cancers likely to be detected in the general population are colo-rectal breast cancers, of the cervix, cancers, cancers of the prostate, the melanomist; in addition in targeted populations or during the appearance of symptoms: the cancer of the ovary, the lung, the testicle,…

Tracking of the complications of the diabetes: retinopathy diabetic, microphone then macroalbuminurie, impaired renal function, neuropathy diabetic, complications podologic, obliterating arteriopathy of the lower extremities,…

Tracking of the osteoporosis

Tracking of the DMLA

Internal bonds

External bonds

Detection of the diseases Impact of tracking on the life expectancy in France.
HTTP: /www.amazon.fr/Dois-je-faire-tester-pour-cancer/dp/2763781586/ref=sr_1_58/403-9138578-7542854?ie=UTF8&s=books&qid=1179440223&sr=1-58 do I Have to be made test for cancer? Perhaps not and here why. An excellent book, written by a qualified American specialist. To read absolutely by the adults to avoid the dangers of the tracking of cancer.
HTTP: /www.pharmactu.com/article.php?sid=56 Doubts about the benefit of the tracking of breast cancer
Tracking of breast cancer in general medicine, HAS 2004

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