Preventive medecine: more about screening programmes


        PREVENTIVE MEDECINE: MORE ABOUT SCREENING PROGRAMMES

These are often said to be an essential part of any preventive medical system in so far as they pick up disease early and enable it to be treated more quickly and presumably more cheaply. When calculating the cost-effectiveness of a screening programme, though, many things have to be taken into account including: the cost of the screening itself; the cost of any treatments that are thought to be necessary as a result of the screening; and the various costs of false-negative and false-positive results. This latter-the chasing of red herrings-can be very costly. On the benefit side there will be some value in catching things early and there may well be an increase in wellness of the screened population because they don't walk around worrying whether or not they have the condition.
Perhaps the most widely used and accepted screening programme is for phenylketonuria. If an affected baby is not detected and treated very soon after birth, irreversible mental retardation results. The test is simple. A pinprick in the child's heel very soon after birth allows a drop of blood to be analyzed. Several studies have shown that this simple, effective screening test is cost-effective even though the condition itself is very rare. Screening for other metabolic diseases has not been found to be cost-effective.
Screening for high blood pressure is cheap but because so many people do not take their medicines properly the benefits that accrue are not nearly as great as they could be and the cost-benefit analysis looks rather poor. Selective screening of high-risk populations almost certainly is worth while, but even this is not as simple as it might appear in the light of the Canadian study mentioned earlier which found that newly diagnosed hypertensives who did not bring their blood pressure under control had an 80 per cent increase in work absenteeism due to illness-attributed largely to an awareness of their condition. Here the cost of the screening was low but the accompanying costs of the drugs (a large proportion of which are not taken by blood-pressure patients) and the work days lost were high. This illustrates just how difficult it is to put a value on preventive measures.
A wide range of estimates has been published concerning the benefits of screening for cervical cancer. Evidence on the efficacy of this screening is complicated by the fact that death rates have been falling in unscreened as well as in screened populations and by uncertainty about the natural course of the disease. Those women who are most likely to be examined regularly (middle- and upper-income women) normally have a lower rate of cervical cancer than do lower-income women. Recent Canadian studies show that cervical cancer screening is cost-effective. The frequency at which it should take place, however, is still open to debate.
The evidence for the cost-effectiveness of screening for breast cancer is better than that for cervical cancer. A New York study found that the screening did not affect the survival rate of women aged 40-44 but it did lead to a significant reduction in mortality in women aged 50-59. It also seemed to be beneficial to women aged 60-64. The cost-benefit ratio of mammography appears to be very favourable. The US National Cancer Institute estimated that 20 per cent of breast cancers were discovered at the localized stage as a result of mammography. At a cost of 40 dollars per mammogram the minimum cost per life prolonged is 240,000 dollars (24,000 dollars per year of life saved) for women aged 55-64.
Quite recently then, and prompted by the vast and escalating cost of modern sickness intervention (as compared with health care), governments the world over have started to question the sense and economic viability of continuing down the 'more-is-better' path. The primary prevention of chronic disease looks like being the most cost-effective area in which to start off, if only because the after-the-fact treatments of many chronic diseases range from the expensive and basically unsuccessful to the almost endlessly expensive maintenance of a generally lower quality of life for many of the sufferers. Lifespans are getting longer, and a person with an untreated chronic disease today will probably be around with his or her condition for many years. This need not be the case, however, because the control of high blood pressure, for example, can postpone or prevent about a third of all strokes at a hundredth of the cost of living with a stroke.
But it is not just in chronic diseases that prevention definitely pays. An educational programme for surgical patients in a Massachusetts hospital explained the risk, the pain, and the post-operative effects the patients could expect. Doing these simple things reduced the need for painkilling drugs by 50 per cent and hospital stays by 2.7 days. In another study the education of asthmatics, who used an emergency room produced a cost saving of $6 for every dollar spend educating the patient to care for him or herself. Even more dramatic results have been obtained with hemophiliacs. Education on care, prevention of injury and simple treatment reduced hospital stays from 432 to 42 days!
Quite clearly prevention can pay but does not necessarily do so. Every new programme has to be looked at very carefully before it is implemented on any large scale, if only to make sure that it does not fall into the trap that so much western medicine has historically-that of doing something simply because it could be done and then worrying about the cost of it all afterwards.

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GENERAL HEALTH
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