imply, that the treatment of urolithiasis by lithotripsy is cost effective. Any technology (treatment or program) cannot, by definition, be judged to be cost effective until its efficacy and effectiveness have been scientifically established, the best means being (to the best of our knowledge) through the use of an RCT that minimizes both extraneous variance2-4 and observer bias.5'6 Surely we all agree that comparison of oranges and lemons or of the old days and open surgery has little to do with establishing these parameters. The introduction of hemodialysis, originally, was different and would fall within the framework set forth by Feeny, Guyatt and Tugwell,7 as mentioned in the final recommendation of our paper. Hemodialysis would have been one of the noteworthy exceptions that would not have required an RCT to establish its effectiveness. Refinements of hemodialysis devices, however, have often been introduced without scientific evidence of increased efficacy. Kaye and Prichard agree that some form of evaluation of "new equipment" seems reasonable if it is done at "university centres." They go on to state that "this evaluation does not necessarily have to involve an RCT" but offer no hint as to how they would go about these evaluations. If one intends to use a new device against historical controls one must be aware of Plum's warning8 that "scientifically based medicine requires more than just post-hoc testimonials or uncontrolled studies reporting post-operative improvements to justify its therapies, especially when the recommendations are expensive, potentially dangerous, or both." We cannot agree with Kaye and Prichard in this regard. Just because a technology (program or procedure) is new does not mean, necessarily, that it is beneficial. Canada may find that "technology

need not necessarily result in progress, but may in the absence of caution and restraint prove a major threat." 9 In the hope that this will not occur we have offered a preliminary framework regarding technology assessment, and we offer it for discussion being fully cognizant of the words of Platt,'0 who in 1952 wrote that "scientific discipline is the antidote to a surfeit of the art of medicine, which, carried too far degenerates into medical lifesmanship." Platt concluded: "Self-deception is the sin against which scientific discipline protects." When the opportunity presents itself, for the benefit of all let us be scientific in our approach to this problem. Lawrence C. Wiser, MD, MHSA 119-4070 Pasqua St. Regina, Sask. Richard H.M. Plain, PhD Professor of economics John B. Dossetor, MD, PhD, FRCPC Director Joint-Faculties Bioethics Project University of Alberta Edmonton, Alta.

References 1. Spodick DH: Randomized controlled clinical trials: the behavioral case. JAMA 1982; 247: 2258-2260 2. Rubinson L, Neutens JJ: Research

Techniques for the Health Sciences, Macmillan, New York, 1987: 316-317 3. Campbell DT, Stanley JC: Experimental and Quasi-Experimental Designs for Research, HM, Boston, 1966: 2226 4. Carlsmith JM, Ellsworth PC, Aronson E: Methods of Research in Social Psychology, Random, New York, 1976: 26-35 5. Tversky A, Kahneman D: Judgement and uncertainty: heuristics and biases. Science 1974; 185: 1124-1131 6. Weinstein MC, Fineberg HV, Elstein AS et al: Clinical Decision Analysis, Saunders, Philadelphia, 1980: 37-74 7. Feeny D, Guyatt G, Tugwell P (eds): Health Care Technology: Effectiveness, Efficiency and Public Policy, Institute for Research on Public Policy, Montreal, 1986: 57-67 8. Plum F: Extracranial-intracranial arterial bypass and cerebral vascular disease. N Engl JMed 1985; 313: 12211223

9. Ginzberg E: Political economy of public health. In Last JM (ed): Public Health and Preventive Medicine, 11th ed, ACC, New York, 1980: 1846-1854 10. Platt R: Wisdom is not enough. Lancet 1952; 2: 977-980

ESWL: the choice of many urologists W r ith reference to the artix cle "Kidney stones and

lithotripters: critical analysis of the introduction of extracorporeal shock wave lithotripsy [ESWL] into Canada" (Can Med Assoc J 1990; 143: 12991303), by Drs. Lawrence C. Wiser, Richard H.M. Plain and John B. Dossetor, in November 1989 we conducted a postal questionnaire survey of all Canadian urologists actively engaged in the practice of adult urology; 279 of the 383 questionnaires (73%) were returned and the results presented at the annual meeting of the Canadian Urological Association in Vancouver in June 1990. The urologists were asked to select how they would wish to be treated if they had a stone in four different clinical situations. In each situation four accepted treatment alternatives were offered. For an asymptomatic stone 5 mm in diameter in the renal pelvis 67% chose no treatment and 31% ESWL. For a stone 9 mm in diameter obstructing the ureteropelvic junction 88% chose ESWL and 10% percutaneous surgery. For a stone 7 mm in diameter blocking the upper ureter 79% chose ESWL. However, for such a stone obstructing the lower ureter just 14% chose ESWL; 73% would have the stone removed by ureteroscopy. Urologists have witnessed tremendous advances in the treatment of urinary stone disease over the past decade. Major surgery was temporarily replaced by percutaneous techniques in the infancy of ESWL. We are aware that CAN MED ASSOC J 1991; 144 (6)

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none of these options ensures complete and permanent removal of stones. We know that there may be long-term effects of ESWL, but the results of this survey show that Canadian urologists (surgeons) would choose an outpatient, nonoperative form of treatment for their stones rather than surgery, with all its risks and complications. Norman G. Futter, MB, FRCSC Christine Lajeunesse, MD Department of Urology Ottawa General Hospital Ottawa, Ont.

Management of people exposed to pertussis and control of pertussis outbreaks W r hile x

emphasizing the importance of immunization this Epidemiologic Report (Can Med Assoc J 1990; 143: 751-753), from the National Advisory Committee on Immunization, the Advisory Committee on Epidemiology and the Canadian Paediatric Society, recommends accelerating the diphtheria toxoid-pertussis vaccine-tetanus toxoid (DPT) schedule only after an outbreak has started, despite admitting its limited usefulness in outbreak control. Electively accelerating the immunization schedule does not cost 1¢ more and reduces the period during which infants lack immunity and are most likely to succumb. Furthermore, intellectual impairment can also occur in children with apneic episodes or convulsions, complications that correlate with lack of protection through immunization.' It would have been desirable for the report to emphasize that pertussis be diagnosed on clinical grounds since bacteriologic studies are slow and insensitive. The report should have offered 638

CAN MED ASSOC J 1991; 144 (6)

practical advice on clinical diag-

3. Biellik RJ, Patriarca PA, Mullen JR et al: Risk factors for community- and household-acquired pertussis during a large-scale outbreak in central Wisconsin. J Infect Dis 1988; 157: 1134-1141 4. Mortimer EA Jr: Pertussis and its prevention: a family affair. J Infect Dis 1990; 161: 473-479 5. Granstrom G, Sterner G, Nord CE et al: Use of erythromycin to prevent pertussis in newborns of mothers with pertussis. J Infect Dis 1987; 155: 12 1 01214

nosis.' The report has confused many who have read it, and rereadings generate more questions rather than a clearer understanding. For example, the recommendations for chemoprophylaxis range from coverage of contacts under 1 year of age to coverage of all contacts. The basis for choice is practicability at the local level. It is difficult to reconcile this with [Two authors respond.] the recommendations under the heading "Surveillance and exclu- We welcome Dr. Clarkson's comsion." What the effect will be of ments on the pertussis control administering chemoprophylaxis guidelines, which are intended to to a select group of household give health care providers a genercontacts is not known. Further- al practical approach to the conmore, there is growing evidence trol of pertussis. It is only through that infants commonly acquire in- such feedback that advisory fection from adults.3'4 groups are able to improve the Is the management of preg- quality of the advice that they nant contacts so complex that it give. We also wish to respond to cannot be set out in a national some of his comments. protocol, and is updating and The current immunization alerting physicians, other health schedule for infants is well estabcare workers, schools and the pub- lished throughout many countries lic about pertussis not more effec- and is working well. The accelertive than "active surveillance of ated schedule results in complephysicians' offices, hospitals and tion of immunization at 4 months schools" by public health offi- rather than 6 months of age. Such cials? a schedule is important only when The report recommends a there is a serious risk of exposure surprisingly low maximum daily to one of the agents in the vacdose of erythromycin without cine. Except for some areas of providing supporting references. Canada in 1989 and 1990 there Rather than noting that "some has not been such a risk associatexperts recommend the use of ed with pertussis for infants aged erythromycin estolate in children" 4 to 6 months for the past 30 it might have been more pertinent years. It is unnecessary to change to note that the estolate has been a routine schedule that is working banned in Sweden because of a well to deal with what is essentialhigher incidence of side effects.5 ly a time-limited, local problem. The National Advisory CommitGrahm Clarkson, MB, MPH, FAPHA tee on Immunization regularly reConsultant medical officer of health views immunization schedules, Peace River Health Unit and when there is good evidence Peace River, Alta. that alterations in the schedule carry more benefit than risk, References changes are recommended. The guidelines are clearly 1. Miller CL, Fletcher WB: Severity of notified whooping cough. Br Med J identified as pertaining only to 1976; 1: 117-119 the management of exposed peo2. Patriarca PA, Biellik RJ, Sanden G et ple and outbreak control. They al: Sensitivity and specificity of clinical case definitions for pertussis. Am J are not intended to be clinical guidelines on the diagnosis and Public Health 1988; 78: 833-836 For prescribing information see page 808-