tion of Black et al that in several stage distribution was less favorable after the publicity than before. Finally, the beneficial influence of

groups

mammography

or

any

early-detection

method will be least apparent in its initial application to a raw population, such as in this study, when patients with cancer of all stages will be discov¬ ered. Any beneficial influence on stage will be more apparent when the tech¬ nique is applied to a group already screened once so that, presumably, patients with disease already estab¬ lished have been removed from the group. The data of Strax (Cancer 37:30-35, 1976) cited by Black et al clearly demonstrate this. Michael D. Decker, Senior Medical Student

Rush Medical

Chicago

In

Reply. \p=m-\Ithank

comments

College

Mr Decker for his

regarding our report on

stage characteristics of breast

the

cancers

diagnosed at our institution before and after November 1974. The point at issue was the influence, if any, of the unusual public and professional concern on the stage at diagnosis. Associated with the increased concern was an increased use of mammography and an increased use of diagnostic biopsy. Our study made no attempt to assess the independent influence of mammog-

Precautions With

Fasting

Supplemented

To the Editor. \p=m-\"Supplemented Fast-

ing as a Large-Scale Outpatient Program" (p 2151), reviews our results with 519 massively obese patients treated up to March 1976. Since that time, our total patient experience has

enlarged

to

approximately 1,300.

Four instances of sudden death have now been seen in this enlarged series, three since acceptance of our manuscript. One was judged to be accidental, but three occurred in patients, aged 39 to 51 years and 115.3 to 144.6 kg in weight, who were found dead at home. Prior to institution of supplemented fasting, these three patients all evidenced cardiac disease (likely of coronary etiology) as well as one or more of the following risk factors: hypertension, hypertriglyceridemia, or diabetes. Sudden death is a well-known hazard of coronary disease, and its frequency is reported to increase directly with body weight.1 Its occasional occurrence in a large aggregation of obese persons, many of whom have risk factors for or bear evidence

raphy on the decision to operate. Our findings indicate that the increased concern was not rewarded by a more

favorable stage distribution either in the first six months or subsequently. Table 2 expands the period of study before and after November 1974. There is no substantial difference between the stage distribution in the different time periods. It is a disconcerting

reality that,

to

date, attempts

to

control breast cancer by means of educational programs and diagnostic clinics have had no demonstrable effect on the average annual mortality from the disease. Our report suggests that even with the panic-like public concern, coupled with a massive educational effort, increased numbers of biopsies and the more widespread use of mammography failed to improve the stage distribution at diagnosis. In short, our best efforts are still inadequate. It seems unlikely that increasing the expenditure of time and money on massive detection pro¬ grams will substantially improve our control of the disease. It might be more profitable to direct our expertise and funds to increasing our understanding of the etiology, pathogenesis, and biolo¬ gy of the disease. Maurice M. Black, MD

New York Medical College Flower and Fifth Avenue

Hospitals New York

of coronary

insufficiency, is not sur¬ prising. Therefore, three such deaths in 1,300 patients over a period of 3'/2 years do not establish a causal relationship to therapeutic weight reduction by supplemented fasting. They do strongly suggest a need for special caution in accepting for supplemented fasting candidates who have ECG evidence of ischemia or of ventricular irritability, particularly of a multifocal or sequen¬ tial nature, or who have clinical evidence of recent or impending myo¬ cardial infarction. In such patients, supplemented fasting should only be undertaken after thorough evaluation and stabilization; furthermore, weight reduction should have a clearly demon¬ strable medical goal, ie, alleviation or elimination of associated coronary risk factors or facilitation of coronary angiography and bypass surgery.

Ankylosing Spondylitis To the Editor.\p=m-\The recent report by Calin et al (237:2613, 1977) suggests that a medical history is a sensitive and specific screening test for ankylosing spondylitis. However, the authors confuse the concept of specificity (the proportion of patients without ankylosing spondylitis who have a negative test) with the concept of predictive value (the proportion of patients with a positive test who prove to have ankylosing spondylitis). Specificity is not dependent on prevalence since it is determined by patients free of the disease in question, whereas predictive value depends strongly on prevalence and may be calculated from the specificity and sensitivity of the test and the prevalence of the disease.1 The Table compares the sensitivity, specificity, and predictive values of a positive HLA-B27, four or five affirmative answers, or five affirmative answers to the five most discriminating questions, using the author's values for prevalence, sensitivity, and specificity. Note that the specificity of the HLA-B27 test is not 20%, as given by Calin, but 94%, the proportion of patients without ankylosing spondylitis who have a negative test. The number of patients with a positive screening test who require further investigation for each case of ankylosing spondylitis found is the reciprocal of the predictive value, and these numbers also vary from the estimates given by Calin. However, in view of the ease and economy of use, the clinical history is a potentially useful tool for screening populations and deserves further eval¬ uation. George Crawford, MD US Public Health Service

Hospital Seattle 1. Vecchio TJ: Predictive value of a

in unselected

populations.

Cleveland

WB, Gordon T: Some determinants of obesity and its impact as a cardiovascular risk factor, in Howard A (ed): Recent Advances in Obesity Research: Proceedings of the 1st International Congress on Obesity. London, Newman Publishing Ltd, 1975, pp 14-27. 1. Kannel

Downloaded From: http://jama.jamanetwork.com/ by a Carleton University User on 06/18/2015

Engl

single diagnostic test

J Med 274:1171-1173,

1966.

In

Reply.\p=m-\In our article the single question should read "B27 testing is 95% sensitive and 94% specific," as pointed out by Dr Crawford. The change does not alter the discussion or conclusion of the article, sentence in

Comparison of Screening Tests for Ankylosing Spondylitis

Victor Vertes, MD Saul M. Genuth, MD Irene M. Hazelton, MD The Mt Sinai Hospital of Cleveland

N

Positive

_HLA-B27 Sensitivity Specificity Predictive value

4

or

5*

5*

.95

.95

.94

.85

.60 .97

.14

.06

.17

"Affirmative answers to the five most discrimi¬

nating questions.

Ankylosing spondylitis.

tion of Black et al that in several stage distribution was less favorable after the publicity than before. Finally, the beneficial influence of group...
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