CLINICAL EPIDEMIOLOGY ROUNDS

This series of Clinical Epidemiol-ogy Rounds has been prepared forthose clinicians who are behind intheir clinical reading. As nearly aswe can tell from several informalpolls, this includes all of us. Andwell it should. To keep up with the10 leading journals in internal med-icine a clinician must read 200 ar-ticles and 70 editorials per month.'There are now over 20 000 differ-ent biomedical journals published(up from 14 000 10 years ago); to"read up" on viral hepatitis requiresselection from among 16 000 cita-tions published on this topic inEnglish alone in the last 10 years.

The biomedical literature is ex-panding at a compound rate of 6%to 7% per year;2 thus, it doublesevery 10 to 15 years and increases10-fold every 35 to 50 years. Bycontrast, our time available forreading the clinical literature is con-stantly being whittled away by otherdemands. Accordingly, our recom-mendations in this set of roundswill stress efficiency as well as va-lidity and applicability, and manyof our prescriptions for the busyclinical reader will call for tossingan article aside early rather thandevoting time to its detailed study,only to reject it later. Thus, theguidelines we propose will permitclinicians to rapidly separate the"wheat from the chaff" in the din-

Reprint requests to: Dr. D.L. Sackett,McMaster University Health SciencesCentre, Rm. 3V43E, 1200 Main St. W,Hamilton, Ont. L8N 3Z5

ical literature so that their clinicalskills can be sharpened rather thansmothered by reports of innova-tions in diagnosis, prognosis andtherapy.We confront a given article in

two ways. First, it can find us, as aresult of our subscribing to its par-ent journal or because somebodygave it to us. Second, we can findit, as a result of trying to trackdown information that will help usmake a diagnosis or manage a par-ticular patient. Both routes reflectour priority for keeping up with de-velopments in medicine, the neces-sity for which is underscored in thefollowing presentation:

In 1973, 230 hypertensive menwere identified at a steel mill in Ha-milton, Ont. When their diastolicblood pressures remained at 95 mmHg or higher after 3 months of ob-servation, they underwent a thoroughhistory, physical and laboratory work-up. Then each hypertensive man, plusa record of his work-up. was linkedto a clinician who decided whetherand how to treat him.3Two thirds of these men were

started on drug therapy and one thirdremained untreated, making it pos-sible for us to go back and identifythree major determinants of this clin-ical decision to treat some but notother hypertensive patients. The firsttwo determinants were the level ofdiastolic blood pressure (the men withmore severe hypertension were morelikely to be treated) and the presenceof target organ damage (those withevidence of damage to the heart,brain, kidney, eye or major arteries

were more likely to be treated), bothof which are logical and appropriate.

However, the third determinant ofwhether a hypertensive man wasstarted on treatment was the year ofgraduation from medical school ofthe physician to whom he was re-ferred; the more recent graduates weremore likely to treaC Indeed, it ap-peared that these physicians, botholder and younger, were practisingthe sort of medicine that prevailedat the time they finished their train-ing. They had been taught the appro-priate contemporaneoLls managementof hypertension but often appearednot to have been taught how to de-cide when to change this management.

This presentation dramatizes acontinuing challenge to the practiceof medicine: the necessity (if we areto continue to do more good thanharm to our patients) to recognizeand respond to the need to changeour diagnostic and therapeuticmaneuvers so that they remain con-sistent with valid new knowledge.

The issue is a fundamental oneand extends far beyond hyperten-sion. For example, should we stillautomatically use clofibrate in treat-ing asymptomatic middle-aged menwho have moderate hypercholeste-rolemia?' Should we now considertherapy with acetylsalicylic acid inmen with transient ischemic at-tacks?5 If we see such patients, yethave not asked ourselves thesequestions, we may not .imply bebehind in our reading; we may befalling short in our clinical practice.How can busy clinicians meet this

challenge to recognize and respond

CMA JOURNAL/MARCH 1, 1981/VOL. 124 555

to the need to change their clinicalpractice? The current strategies in-clude continuing education, recerti-fication and the like. The strategythat is the focus of this series ofClinical Epidemiology Rounds isreading clinical journals.

Why do we read clinical journals?

There are many reasons why weread clinical journals; 10 are listedin Table I. Most of them are notpertinent, to the topic of theserounds and will be disposed ofquickly.

First, of course, is journal read-ing, or at least journal "flashing",to impress others. The audience canbe either lay people (fellow travel-lers on public transport, relativesetc.) or fellow clinicians (at lunch,on rounds, at continuing educationseminars etc.). The former are im-pressed by our erudition and thelatter by our apparent ability tokeep up.

Second, we read journals to keepabreast of professional news; manyjournals (including CMAJ) serve inpart as house organs for our pro-fessional organizations and there-fore serve to keep us informed ofthe actions of these organizationsand of our colleagues.

Third, we sometimes read jour-nals to better understand new, oftenexciting, insights into the patho-biology of the clinical problems weencounter in our practices.

Fourth, we often read journals tofind out how a seasoned and wide-ly respected clinician works up ortreats a specific illness, especiallyif the illness is one that we don'tencounter often enough to want todecide for ourselves on the valueof these clinical maneuvers. Ofcourse, we give up more than clin-ical judgement when we let an au-thority tell us how to manage ourpatients. We also usually give upthe oppcwtunity to look at the clin-ical evidence to see whether it isboth valid and applicable to ourpractice.

Fifth, we read clinical journals tofind out whether a new or existingdiagnostic test will improve the ac-curacy, comfort, safety or efficien-cy with which we work up our pa-tients.

Sixth, we read these journals to

learn more about the clinical courseand prognosis of the disorders weencounter. The disorder might be awell known one whose course andprognosis are now changing or be-coming more clear. Alternatively, itmight be a "new" disorder, likeLegionnaires' disease. After thisreading we can decide whether anyintervention is warranted and cando a better job of reassuring andcounselling our patients and pal-hating their illnesses.

Seventh, we read clinical journalsto determine etiology and causa-tion, both to better advise our pa-tients whether, for example, lifestyleattributes such as obesity, lack ofexercise and job stress really con-stitute health risks, and to betterprotect our patients from the ad-verse effects of drugs and other clin-ical maneuvers.

Eighth, we read journals so thatwe can distinguish the preventive,therapeutic and rehabilitative man-euvers that really do benefit pa-tients from those that either simplywaste their (and our) time andmoney or actually generate moreharm than good.

Ninth, we read clinical journalsto understand the "new wave" ofclaims, judgements and threatsabout health needs, quality of careand the efficiency of clinical andother health care. *

Finally, we read some clinicaljournals (especially those from Bri-tain) to be titillated by the lettersto the editor. After being called asnail in a letter to the Lancet,6 one*The volume and importance of this newwave is so great that we shall devote aseries of Clinical Epidemiology Roundsto it. Stay tuned.

of this series' authors is convincedthat the offended British generalpractitioner has no equal in the ar-ticulation of outrage.

Reasons 5 to 8 in Table I con-stitute the essence of sensing andresponding to the need to changeour approach to diagnosis, progno-sis, etiology and therapeutics, andwill be the focus of this series offive Clinical Epidemiology Rounds.The strategies we shall suggest

assume that clinical readers are al-ready behind in their reading andthat they will never have more timeto read than they do now. For thisreason, and because the guides thatfollow call for closer attention to"Materials and methods" and othermatters that often appear in smalltype, many of the guides recom-mend tossing an article aside as notworth reading, usually on the basisof quite preliminary evidence. It isonly through the early rejection ofmost articles that busy clinicianscan focus on the few that are bothvalid and applicable in their ownpractices.

The first four guides

Fig. 1, a flowchart of guides forreading articles in clinical journals,shows that the first four guides,which follow, are common to allthe reasons for reading them.

Look at the title

Is the article potentially interest-ing or possibly useful in your prac-tice? If not, reject it and go on tothe next article, to some other taskor to the hockey rink.

Review the list of authors

In addition to occasionally rec-

556 CMA JOURNAL/MARCH 1, 1981/VOL. 124

ognizing a former classmate, theseasoned reader will know the trackrecord of many authors. If thistrack record is one of careful andthoughtful work that has stood thetest of time, read on. If, on theother hand, the track record is aseries of unsupported conclusionsthat remain in vogue only until theletters to the editor catch up withthem or indicate a repeated preju-dice in search of supporting data,reject the article. However, manyauthors will be new or otherwiseunknown, and, like the work of un-known sculptors, that of unknownauthors deserves at least the fol-lowing passing glances.

Read the summary

The objective here is simply todecide whether the conclusion, ifvalid, would be important to youas a clinician. At issue here is notwhether the article's results aretrue (for you can rarely tell thisby reading an abstract*), but wheth-er the results, if true, are useful.

Those who have been reading

clinical journals for some time willrecall that their format has changedsubstantially over the years. Theold ''Summary and conclusions..section that used to tag along atthe end of articles moved to thefront and became an abstract in thelate 1 960s in the Lancei., the NewEngland Journal of Medicine andthe British Medical Journal, fol-lowing the lead set earlier by theJournal of the American MedicalAssociation and CMAJ. This re-vised format has made the quickstudy of medical articles mucheasier for the busy clinician.

Consider the site

Is the site of the study sufficient-ly similar to yours that the study'sresults, if valid, would apply to pa-tients in your practice?t There aretwo issues here. First, is your ac-cess to the required facilities, ex-pertise and technology sufficient topermit you to implement the man-euvers described in the article? Sec-ond, are the patients at the facilitywhere the article originated likely

0Look at the TITLE: interesting or useful?YES

NO© Review the AUTHORS: good track record?

YES or DON'T KNOW

. .'.eaci theSUMMARY: if valid, would these results be useful?NYES 4

.l (Consider the SITE: if valid, would these results apply in your practice?

READ THE "PATIENTS AND METHODS" SECTION(.) K 7

to be similar to your patients inseverity of their disease, treatment.age, sex, race or other key featuresthat have an important bearing onclinical outcome?

Put another way, are the resultsreadily transferable to your ownclinical practice? For example, ifyou are a family physician seeingprimary care patients, the results ofstudies carried out in specialty clin-ics at tertiary referral centres maynot apply. This is not reverse snob-bery. Consider hypertension: foryears, primary care clinicians havebeen urged by tertiary care nephrol-ogists to carry out rapid-sequenceintravenous pyelography, endocrinework-ups and other extensive labo-ratory tests on newly detected hy-pertensive patients to detect thosewho could be cured.7 One reasonfor this recommendation was theappreciable yield of surgically cor-rectable hypertension from the ex-tensive investigation of hypertensivepatients referred to tertiary carecentres. An example of this yieldis found in Table II: 6% of hyper-tensives referred to the ClevelandClinic were found to have surgicallycurable disease;8 however, when asimilar set of laboratory studieswere carried out among hyperten-sive patients in an Ontario generalpractice, only about one tenth asmuch surgically curable hyperten-sion was found.9

Both conclusions are right. Theirdifference arises from the referral"filters" through which generalpractice patients must pass beforethey get to tertiary care centres likethe Cleveland Clinic. General prac-titioners preferentially refer, andtertiary care centres preferentiallyaccept, patients with a relativelyhigh likelihood of secondary hyper-tension. Thus, patients with sub-costal bruits or low serum potas-sium concentrations travel to ter-

*Sometimes, of course, you can't eventell whether the results are true afteryou've read the entire article.

tWe shall return to this consideration inlater rounds. For now, one useful wayto consider this guide is to phrase it inits negative form: Is the site so dissimilarto your own that its results, even if theyare valid, would not apply in your prac-tice?FIG. 1-The first steps in how to read articles in a clinical journal.

tiary care centres and give, themtheir high rates of curable hyper-tension; most patients without thesefeatures stay home. Because *ofthese referral filters, different diag-nostic tests are and should be car-ried out in primary and tertiarycare centres. It is only by payingattention to the site where a re-ported study was carried out thatwe shall reduce the misapplicationof its results.

The parting of the ways

Thus we must view published ex-perience critically (if not biblically),for too often the "Conclusion" giveth,but the "Materials and Methods"taketh away.10

The review and editorial policiesof even the best and most highly re-spected journals provide incom-plete protection from error, and asingle subscription can provide bothtruth and a carnival of bias. Ac-cordingly, we know of no alterna-tive for clinical readers (once theyare satisfied with the title, authors,summary and site) but to investtime early, reviewing the Methodssection of an article, so as to avoidwasting time and money later inthe execution of useless or evenharmful clinical procedures.

Time and again during the courseof these rounds we shall see thatthe hasty clinician who accepts theconclusions of an article after read-ing only its summary does so atconsiderable risk both to truth andto patients. Thus, although readingan article's summary can some-times tell you that it is invalid (forexample, when it has based the ef-

ficacy of a risky regimen on thetestimonials of its survivors), suchan inspection can almost never tellyou whether any* article is valid.This latter, crucial judgement callsfor bringing that particular com-hination of healthy scepticism andapplied common sense that ErnestHemingway labelled "crap detec-tion" to bear on the Methods sec-tion of the article.The guides branch at this point,

depending upon the clinical read-er's intent; this arborization isshown in Fig. 1. The next in thisseries of Clinical EpidemiologyRounds will consider guides to usewhen reading a clinical journal inorder to decide whether to use aspecific diagnostic test.

References

I. WARREN KS (ed): Qualitative aspectsof the biomedical literature. In Cop-ing with the Biomedical Literature.Praeger, New York (in press)

2. PRICE DS: The development andstructure of the biomedical litera-ture. Ibid

3. SACKETT DL, HAYNES RB, GIBSONES, HACKETT BC, TAYLOR DW,ROBERTS RS, JOHNSON AL: Ran-domised clinical trial for improvingmedication compliance in primaryhypertension. Laticet 1975; 1: 1205-1208

4. OLIVER MF, HEADY JA, MORR'S JN,COOPER J: A co-operative trial inthe primary prevention of ischaemicheart disease using clofibrate. Re-port from the Committee of Prin-cipal Investigators. Br Heart J 1978;40: 1069-1118

5. Canadian Cooperative Study (.oup:A randomized trial of aspirin andsulfinpyrazone in threatened stroke.N Engi J Med 1978; 299: 53-59

6. HART iT: Screening for hyperten-

IJ.Th.$Iv4ftb 4tew.I. Uy.xwiM.

.Qr

.rInw*iy 90202LI0.2

"39,

sion (C). Lancet 1974; 2: 1380-1381

7. MELBY JC: Extensive hypertensivework-up: pro. JAMA 1975; 231:399-401

8. GIFFORD RW JR: Evaluation of thehypertensive patient with emphasison detecting curable causes. Mu-bank Mem Fuiid Q 1969; 47 (pt 2):170-186

9. RUDNICK KV, SACKETT DL, HIRsT S,HOLMES C: Hypertension in a fam-ily practice. Can Med Assoc J 1977:117: 492-497

10. SPODICK DH: On experts and ex-pertise: the effect of variability inobserver performance. A in J Cardiol1975; 36: 529-596

I BOOKS Icontinued from page 551

EVALUATING HOSPITAL-BASED AMBU-LATORY CARE. A Case Study. WilliamC. Stratmann and Ralph UlIman. 177 pp.Illust. Lexington Books, Lexington, Mas-sachusetts; D.C. Heath Canada Ltd.,Toronto, 1980. $27.95. ISBN 0-669-02096-6EVALUATION OF OUALITY OF CAREIN PSYCHIATRY. Edited by A.G. Awad,H.B. Durost and W.O. McCormick. 123pp. lllust. Pergamon Press, Toronto,1980. Price not stated. ISBN 0-08-025364-4HEALTH PROTECTION AND DRUGLAWS. Published by authority of theMinister of National Health and Wel-fare, Educational Services, Health Pro-tection Branch. 43 pp. lIlust. Health andWelfare Canada, Ottawa, 1980. $2.95(Can.), paperbound. ISBN 0-660-10264-1;catalogue number H495/1980ENEUROLOGICAL CLINICAL PHARMA-COLOGY. Mervyn J. Eadie and John H.Tyrer. 470 pp. IlIust. ADIS Press U.S.A..Inc., New York, 1980. $47.50. ISBN0-909337-07-1THE NEW DRINKERS. Teenage Use andAbuse of Alcohol. 2nd ed. Reginald G.Smart. 180 pp. lIlust. Addiction Re-search Foundation, Toronto, 1980.$5.95 (Can.), paperbound. ISBN 0-88868-043-0PHARMANUAL 1. A ComprehensiveGuide to the Therapeutic Use of Cef-sulodin. 94 pp. lIlust. S. Karger AG,Basel, 1980. $14.50, paperbound. ISBN3-8055-1 042-XTHE PRACTICAL MANAGEMENT OFTHE DEVELOPMENTALLY DISABLEDCHILD. Albert P. Sheiner and IsraelF. Abroms. 461 pp. Illust. The C.V.Mosby Company, Saint Louis, 1980.$47.50 (Can.). ISBN 0-801 6-0061-8PROGRESS IN CANCER RESEARCHAND THERAPY. Volume 13. ColorectalCancer: Prevehtion, Epidemiology, andScreening. Edited by Sidney J. Winawer,David Schottenfeld and Paul Sherlock.410 pp. lIlust. Raven Press, New York,1980. $39.50. ISBN 0-89004-477-3

continued on page 590

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