CORRESPONDENCE

Too many pills To the editor: The editorial by Dr. Eugene Vayda "Use of medications: a growing concern" (Can Med Assac J 114: 287, 1976) called to mind a recent article by Christopher and Crooks1 in World Health, entitled "Are we overconsuming?". These writers drew attention to the huge and increasing number of prescriptions dispensed in the United States, England, Wales and other Western countries. In the United States in 1970 an average of about 10 prescriptions were dispensed per person per year (i.e., 1 a week for a family of five), a 50% increase over the previous decade. In England the average was about five prescriptions per person per year. The figure for Sweden was intermediate. One study revealed that in England and Wales "more than half the adult population and almost a third of all children take some kind of medication every day."1 Christopher and Crooks stated, "Many questions remain unanswered: Is the accepted 'norm' of well-being increasingly difficult to attain without the use of psycho-active drugs? Is a higher standard of wellbeing now sought by more people? Ho. is this related to specific factors operating in the society? Are individuals becoming more intolerant of the everyday stresses that affect them physically or mentally? Are these stresses more prevalent in to-day's world and, if so, why? How is this related to alcohol consumption, tobacco smoking, drug dependence?" The writers also stated, "In the UK about 70 per cent of all currently marketed drugs were unknown or unavailable 15 years ago." Other writers are also alarmed. For example, Clements' has noted "mdiContributions to the Correspondence section are welcomed and if considered suitable will be published as space permits. They should be t.written double spaced and, except for case Ieports, should not exceed 1½ pages in length.

viduals are taking pharmaceutical preparations containing vitamins and minerals, and some common foods are enriched with vitamins and minerals in excess of the amounts present in the product originally." How definable are the health benefits derived from this multitude of prescriptions and preparations? Is our general health situation improving? The answer is probably, No. Cochrane,3 from his careful examination of the British National Health Services, emphasized that despite a magnificent and increasing "input" in total services, the dividends from improved "output", in terms of decreases in morbidity and mortality, were disappointingly small. In the United States Burch4 has averred that "people live no longer any more". Others have pointed out that expectations of life at 60 years and at 80 years have scarcely risen in the last 300 years.5 Further, in a study undertaken in South Africa it was shown that in the segments of populations who are 50 or more years old, South African Negroes have a greater chance than whites of reaching 70 or more years.6 There is no doubt, as Christopher and Crooks1 believe, that the enormous increases in the number of prescriptions is part of a total situation that includes increases in smoking, in drug dependence and in alcohol consumption. In the latter respect, for example, in England and Wales from 1950 to 1970 increases occurred in consumption of beer, from 85 to 101 1 per person per year; of imported wines, from 0.78 to 2.88 1; and of spirits, in terms of pure alcohol, from 0.52 to 0.91 l.. The issue, of course, is not pill taking - that will always be With us. The burden is the overconsumption of preparations for therapeutic purposes. There is a very small minority of populations whose attitude is like that of

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Macbeth, "Throw physic to the dogs: I'll none of it." On the other hand, there is the huge majority who partake of a medicament almost daily. In large measure this manner of life with its associated characteristics is a reflection not of those who are happy in the present and hopeful for the future, but rather of those who are uncertain, insecure and fearful of what lies ahead. ALEXANDER R.P. WALKER, D SC MRC human biochemistry research unit South African Institute for Medical Research Johannesburg, South Africa

References 1. CHRISTOPHER L, CROOKS J: Are we overcon-

suming? World Health April issue: 16, 1974 2. CLEMENTS Fw: Nutrition 7: vitamin and mineral supplementation. Med J Aust 1: 595, 1975 3. COCHRANE AL: Effectiveness and Efficiency, London, Nuffield Provincial Hospitals Trust, 1972 4. BURCH GE: People live no longer any more. Am Heart J 83: 285. 1972 5. wIEsLER H: The investigation of mortality. Ann Life Insur Med 1: 3, 1962 6. wALKER ARP: Survival rate at middle age in developing and western populations. Posigrad Med J 50: 29, 1974 7. AYLWARD F: Symposium on 'Alcohol in Nutrition'. Proc Nutr Soc 31: 77, 1972

The Canadian Home Fitness Test To the editor: I wondered whether the two reports in the Apr. 17, 1976 issue of the Journal on the Canadian Home Fitness Test (CHFT) by Shephard, Bailey and Mirwald and by Jett. and colleagues did not belong in a marketing section rather than the scientific section. There was no attempt at validating the test properly by having subjects measure their fitness at home, then comparing the results with values obtained under laboratory conditions. "Home" is a misnomer as applied to this test, for the authors actually found that most Canadians cannot come close to measuring fitness with it at home.

A high correlation coefficient between two fitness tests is easily obtained by using subjects with a wide range of age and fitness. The 0.84 R value of Jett6 and colleagues between the measured and the step-predicted Vo, max is misleading; the important statistic is that the 95% confidence range of a single prediction was about 45% of the mean value. A person with a predicted value of 30 ml/kg *min might really have an "unfit" value of 22. Thus, even with the electrocardiographic counting of heart rate the test is of borderline value. Add to this prediction error a sizable error in counting the heart rate, and the test as it now stands hasn't a hope of coming close to predicting the Vo1 max in the homes of most of our citizens. For example, the missing of two pulse beats in the time allowed for counting the heart rate would lead to an overprediction of Vo2 max by as much as 25%. Subjects would probably better assess their "fitness" from age, weight based on height, and a grading of their physical activity into three categories. It is fascinating how the authors get around the safety aspect. Despite defibrillators and full resuscitative potential and a highly trained physician in attendance, 5% of the subjects in the initial testing of the CHFT were turned down on the basis of a telephone interview, 8% were turned down after medical screening and 8% were rejected because of electrocardiographic or other abnormalities. The questionnaire included with the CHFT package would have caught the initial 5% if they had read it, yet many might ignore* it. It is stated that extreme caution seemed reasonable when full medical care was available, but apparently this is not necessary when the test is sent out to the general public. I suggest that the authors planned their study and chose their monitoring personnel unwisely, for the place to prove the safety of a test is under control conditions. Fortunately, the dangers of exercise and exercise testing are usuafly overplayed and there is likely little danger, but the method used to investigate this point is a classic example of a poorly designed study. There is no evidence that "the CHFT will serve as a useful motivating tool" for the population; this is hope and speculation. Perhaps the test might serve as a gimmick to increase awareness of activity and thus be useful, but this hypothesis has yet to be tested. One should not expect anything but a rough estimate of fitness with a home test, but the CHFT in the hands of most Canadians will overpredict fitness and possibly lead to complacency. While the objective of Health and Wel-

fare Canada, to improve the fitness of Canadians, is admirable, the scientific section of CMAJ should be reserved for objective evaluations of such programs and not serve as a medium for marketing. If the purpose of the article is to provide professional information and education, objectivity is particularly important. GoiwoN R. CUMMING, MD Head, section of cardiology Children's Centre 685 Bannatyne Ave. Winnipeg, MB

To the editor: Dr. Cumming's spirited criticism of the CHFT is a unique reaction among those of the many hundreds of professional investigators who have seen and experienced the test. However, a reply may be helpful not only to Dr. Cumming but also to others who are coming into contact with the test for the first time. To attack the CHFT on the basis of its limited scientific precision is to miss the point of the procedure. It is intended to be fun rather than a solemn laboratory exercise and, as such, it is designed to increase awareness of fitness and motivate Canadians to greater activity. If Dr. Cumming had read the more detailed account in the Canadian Journal of Applied Sports Sciences1 he would have discovered his point already firmly made: "Under home circumstances, the test should not be considered a refined tool; there will inevitably be vagaries of stepping and counting in an unsupervised situation". The reason for discussing the precision of the test was not to prove that the average citizen could make a more accurate measurement of maximum oxygen intake than Dr. Cumming, but rather to see how well the procedure would work when evaluating as many as 100 people per hour in a field laboratory. Given multichannel electrocardiographic equipment, the test is then highly cost-effective. Dr. Cumming apparently believes we carried out a "poorly designed study" to evaluate the safety of the procedure. We did, in fact, operate very cautiously in the early stages, recognizing the adverse publicity that could stem from even a minor misadventure rightly or wrongly attributed to performance of the test. However, we were not naive enough to believe that safety could be either proven or disproven with a sample of 14 000 adults. Such statistics can emerge only from use of the test by the entire adult population for many years. The value of the record as a motivating tool also can only be proven when it has been available to the general public for a long time. However, the

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test-marketing data indicate encouraging initial interest of those receiving free copies of the record and, given an equally positive attitude of health professionals, "hope and speculation" may soon be replaced by evidence of the motivation that Canadians need badly. Roy J. SHEPHARD, MD, PH 1) Professor of applied physiology Department of preventive medicine and biostatistics University of Toronto Toronto, ON

References 1. BAILEY DA, Sssm'siAaI) RJ, MIRWALD RL: Validation of a self-administered home test of cardio-respiratory fitness. Can I Appi Sports Sci 1: 67, 1976

To the editor: In studying the GHFT we found by multiple regression analysis that Vo5 max in a defined population could be predicted with a multiple R of 0.905 (not 0.84 as stated by Gumming). The predictor variables that best accounted for the Vo2 max were the Vo2 of the last completed stage of the test, postexercise heart rate, age and body weight, providing a prediction capability of 81%. Dr. Gumming's statistical interpretation of the data is misleading. Thus it is erroneous to state that "the 95% confidence range of a single prediction was about 45% of the mean value". He most likely means that at the 95% confidence range, 95% of a population selected at random would fall within 45% (more precisely, 47.5%) of the area on each side of a normal distribution curve (± two standard errors of measurement). With the data cited in his example - that is, for a person who would be at the outer limit of the distribution - the prediction would be off by 26.7%. However, if the value was within one standard error of measurement (4.01 ml! kg omin) the prediction would be within 13 %. Furthermore, again using Dr. Gumming's example, the error in missing two pulse beats is in the order of 5% and not 25% as he indicated. The purpose of formulating the prediction equation, as outlined in our paper, was specific. The equation certainly was not intended for use by the general population. Notwithstanding, in the absence of other suitable methods to predict Vo2 max, the equation presented provides a limited alternative for those acquainted with the concept of Vo2 max. For instance, we have compared the predictions of Vo5 max using the Astrand-Ryhming procedure and the GHFT prediction equation against Vo2 max as determined by our protocol. In a sample of 26 sedentary subjects the mean Vo2 max measured on the treadmill was 33.5 (± 6) ml/kg omin, while

Letter: The Canadian home fitness test.

CORRESPONDENCE Too many pills To the editor: The editorial by Dr. Eugene Vayda "Use of medications: a growing concern" (Can Med Assac J 114: 287, 197...
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