Assessing Technical Competence in Surgical Trainees: A Systematic Review.

OBJECTIVE To systematically examine the literature describing the methods by which technical competence is assessed in surgical trainees. BACKGROUND The last decade has witnessed an evolution away from time-based surgical education. In response, governing bodies worldwide have implemented competency-based education paradigms. The definition of competence, however, remains elusive, and the impact of these education initiatives in terms of assessment methods remains unclear. METHODS A systematic review examining the methods by which technical competence is assessed was conducted by searching MEDLINE, EMBASE, PsychINFO, and the Cochrane database of systematic reviews. Abstracts of retrieved studies were reviewed and those meeting inclusion criteria were selected for full review. Data were retrieved in a systematic manner, the validity and reliability of the assessment methods was evaluated, and quality was assessed using the Grading of Recommendations Assessment, Development and Evaluation classification. RESULTS Of the 6814 studies identified, 85 studies involving 2369 surgical residents were included in this review. The methods used to assess technical competence were categorized into 5 groups; Likert scales (37), benchmarks (31), binary outcomes (11), novel tools (4), and surrogate outcomes (2). Their validity and reliability were mostly previously established. The overall Grading of Recommendations Assessment, Development and Evaluation for randomized controlled trials was high and low for the observational studies. CONCLUSIONS The definition of technical competence continues to be debated within the medical literature. The methods used to evaluate technical competence predominantly include instruments that were originally created to assess technical skill. Very few studies identify standard setting approaches that differentiate competent versus noncompetent performers; subsequently, this has been identified as an area with great research potential.

[1]  Daniel B. Jones,et al.  Evaluating surgical competency with the American Board of Surgery In-Training Examination, skill testing, and intraoperative assessment. , 2000, Surgery.

[2]  P Barach,et al.  Integrating patient safety into the clinical microsystem , 2004, Quality and Safety in Health Care.

[3]  Leif Hedman,et al.  Proficiency-based virtual reality training significantly reduces the error rate for residents during their first 10 laparoscopic cholecystectomies. , 2007, American journal of surgery.

[4]  Dimitrios Stefanidis,et al.  Performance goals on simulators boost resident motivation and skills laboratory attendance. , 2010, Journal of surgical education.

[5]  D. Cook,et al.  Mastery learning simulation-based curriculum for laparoscopic TEP inguinal hernia repair. , 2012, Journal of surgical education.

[6]  Michelle C Specht,et al.  Effects of limited work hours on surgical training. , 2002, Journal of the American College of Surgeons.

[7]  G. Fried,et al.  Relationship between objective assessment of technical skills and subjective in-training evaluations in surgical residents. , 2004, Journal of the American College of Surgeons.

[8]  J. Mcaleer,et al.  Measuring competence in endoscopic sinus surgery. , 2008, The surgeon : journal of the Royal Colleges of Surgeons of Edinburgh and Ireland.

[9]  R. Satava,et al.  Virtual Reality Simulation for the Operating Room: Proficiency-Based Training as a Paradigm Shift in Surgical Skills Training , 2005, Annals of surgery.

[10]  Timothy M. Kowalewski,et al.  Virtual reality robotic surgery warm-up improves task performance in a dry laboratory environment: a prospective randomized controlled study. , 2013, Journal of the American College of Surgeons.

[11]  G. Fried,et al.  Evaluating laparoscopic skills: setting the pass/fail score for the MISTELS system. , 2003, Surgical endoscopy.

[12]  C. Pellegrini.  To Err Is Human … Or Is It? , 2006 .

[13]  E. Verdaasdonk,et al.  Objective assessment of technical surgical skills , 2010, The British journal of surgery.

[14]  Nancy J Hogle,et al.  Does training novices to criteria and does rapid acquisition of skills on laparoscopic simulators have predictive validity or are we just playing video games? , 2008, Journal of surgical education.

[15]  J. Jelovsek,et al.  Establishing cutoff scores on assessments of surgical skills to determine surgical competence. , 2010, American journal of obstetrics and gynecology.

[16]  A. Peracchia.  Presidential Address: Surgical education in the third millennium. , 2001, Annals of surgery.

[17]  M. Ishii,et al.  Development and Pilot-Testing of a Feasible, Reliable, and Valid Operative Competency Assessment Tool for Endoscopic Sinus Surgery , 2009, American journal of rhinology & allergy.

[18]  John C. Hall,et al.  Towards a hybrid philosophy of surgical education , 2004, ANZ journal of surgery.

[19]  Stacey L Ishman,et al.  Development and pilot testing of an operative competency assessment tool for pediatric direct laryngoscopy and rigid bronchoscopy , 2010, The Laryngoscope.

[20]  J. Norcini,et al.  Setting standards on educational tests , 2003, Medical education.

[21]  Technical skills assessment as part of the selection process for a fellowship in minimally invasive surgery , 2009, Surgical Endoscopy.

[22]  M. Curet,et al.  Early, intermediate, and late effects of a surgical skills "boot camp" on an objective structured assessment of technical skills: a randomized controlled study. , 2010, Journal of the American College of Surgeons.

[23]  A. Galakatos,et al.  Assessment of resident surgical skills: is testing feasible? , 2005, American journal of obstetrics and gynecology.

[24]  J. Birkmeyer,et al.  Surgical skill and complication rates after bariatric surgery. , 2013, The New England journal of medicine.

[25]  H. Francis,et al.  Using a Virtual Reality Temporal bone Simulator to Enhance Surgical Competency in Procedural Tasks: A Pilot Study , 2011 .

[26]  A. Park,et al.  Determinants of competency judgments by experienced laparoscopic surgeons , 2004, Surgical Endoscopy And Other Interventional Techniques.

[27]  P. Forbes,et al.  Development and Validation of an Objective Instrument to Measure Surgical Performance at Tonsillectomy , 2005, The Laryngoscope.

[28]  A. Darzi,et al.  Qualitative and quantitative analysis of the learning curve of a simulated surgical task on the da Vinci system , 2004, Surgical Endoscopy And Other Interventional Techniques.

[29]  James R Korndorffer,et al.  Simulator training for laparoscopic suturing using performance goals translates to the operating room. , 2005, Journal of the American College of Surgeons.

[30]  J. Beard,et al.  Assessment of operative competence during carotid endarterectomy , 2007, The British journal of surgery.

[31]  Jeroan J Allison,et al.  Identifying achievable benchmarks of care: concepts and methodology. , 1998, International journal for quality in health care : journal of the International Society for Quality in Health Care.

[32]  Frank Krummenauer,et al.  Determination of valid benchmarks for outcome indicators in cataract surgery: a multicenter, prospective cohort trial. , 2011, Ophthalmology.

[33]  Teodor P. Grantcharov,et al.  Development and Validation of a Comprehensive Curriculum to Teach an Advanced Minimally Invasive Procedure: A Randomized Controlled Trial , 2012, Annals of surgery.

[34]  C. Pellegrini.  Surgical education in the United States 2010: developing intellectual, technical and human values , 2012, Updates in Surgery.

[35]  E. Siegel,et al.  A study of resident proficiency with thyroid surgery: Creation of a thyroid-specific tool , 2010, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[36]  Krishna Moorthy,et al.  Technical skills continue to improve beyond surgical training. , 2006, Journal of vascular surgery.

[37]  R. Satava,et al.  Virtual Reality Training Improves Operating Room Performance: Results of a Randomized, Double-Blinded Study , 2002, Annals of surgery.

[38]  Thomas S. Lendvay,et al.  Robotic Surgical Skills: Acquisition, Maintenance, and Degradation , 2012, JSLS : Journal of the Society of Laparoendoscopic Surgeons.

[39]  Gordon H Guyatt,et al.  GrADe : what is “ quality of evidence ” and why is it important to clinicians ? rATING quALITY of evIDeNCe AND STreNGTH of reCommeNDATIoNS , 2022 .

[40]  C. V. D. van der Vleuten,et al.  The assessment of professional competence: building blocks for theory development. , 2010, Best practice & research. Clinical obstetrics & gynaecology.

[41]  Carla M Pugh,et al.  Can skills coaches be used to assess resident performance in the skills laboratory? , 2012, Surgery.

[42]  Johan J. Swartz,et al.  The Oxford English Dictionary (Second Edition) , 2013 .

[43]  G. Warnock.  Preparing Canadian surgeons to provide care in the 21st century. , 2012, Canadian journal of surgery. Journal canadien de chirurgie.

[44]  C. Schmitz,et al.  Using objective structured assessment of technical skills to evaluate a basic skills simulation curriculum for first-year surgical residents. , 2009, Journal of the American College of Surgeons.

[45]  G. Asimakopoulos,et al.  How safe is it to train residents to perform off-pump coronary artery bypass surgery? , 2015, Interactive cardiovascular and thoracic surgery.

[46]  A. Bath,et al.  Objective assessment of surgical competency – ENT trainees , 2007, Clinical otolaryngology : official journal of ENT-UK ; official journal of Netherlands Society for Oto-Rhino-Laryngology & Cervico-Facial Surgery.

[47]  R. Reznick,et al.  Testing technical skill via an innovative "bench station" examination. , 1997, American journal of surgery.

[48]  Richard Reznick,et al.  Using the Judgments of Physician Examiners in Setting the Standards for a National Multi-center High Stakes OSCE , 1997, Advances in health sciences education : theory and practice.

[49]  E. Copeland,et al.  American Surgical Association Blue Ribbon Committee Report on Surgical Education: 2004 , 2006 .

[50]  A. Park,et al.  Development of Simulator Guidelines for Resident Assessment in Flexible Endoscopy , 2013, The American surgeon.

[51]  Sonja N. Buzink,et al.  Criterion-based laparoscopic training reduces total training time , 2011, Surgical Endoscopy.

[52]  Rajesh Aggarwal,et al.  Objective assessment of technical skills in cardiac surgery. , 2005, European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery.

[53]  C. W. Bowen,et al.  Evaluating the competency of gynecology residents in the operating room: validation of a new assessment tool. , 2008, American journal of obstetrics and gynecology.

[54]  P. Maurette,et al.  [To err is human: building a safer health system]. , 2002, Annales francaises d'anesthesie et de reanimation.

[55]  D. Newble,et al.  Standard setting in an objective structured clinical examination: use of global ratings of borderline performance to determine the passing score , 2001, Medical education.

[56]  Standard setting in an objective structured clinical examination: use of global ratings of borderline performance to determine the passing score , 2002, Medical education.

[57]  Travis P. Webb,et al.  Tackling technical skills competency: a surgical skills rating tool. , 2012, The Journal of surgical research.

[58]  George C Velmahos,et al.  Cognitive task analysis for teaching technical skills in an inanimate surgical skills laboratory. , 2004, American journal of surgery.

[59]  A Darzi,et al.  The challenge of objective assessment of surgical skill. , 2001, American journal of surgery.

[60]  D. Hogg,et al.  Two-year skill retention and certification exam performance after fundamentals of laparoscopic skills training and proficiency maintenance. , 2010, Surgery.

[61]  R. Reznick,et al.  Validation of an objective structured assessment of technical skill for surgical residents , 1996, Academic medicine : journal of the Association of American Medical Colleges.

[62]  J. Beard,et al.  Setting standards for the assessment of operative competence. , 2005, European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery.

[63]  A. Darzi.  Quality and the NHS Next Stage Review , 2008, The Lancet.

[64]  C. Wilasrusmee,et al.  Vascular anastomosis model: relation between competency in a laboratory-based model and surgical competency. , 2007, European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery.

[65]  M. Fried,et al.  Criterion-based (proficiency) training to improve surgical performance. , 2012, Archives of otolaryngology--head & neck surgery.

[66]  H. Tajiri,et al.  Tu1688 How Fast Does a Surgical Resident Learn Colonoscopy? -Analysis of Competency in Colonoscopy for Ten Surgical Residents Supervised by Expert Endoscopists (Gastroenterologists) in the High-Volume Endoscopy Center in Japan- , 2012 .

[67]  Daniel J Scott,et al.  A cost-effective proficiency-based knot-tying and suturing curriculum for residency programs. , 2007, The Journal of surgical research.

[68]  Reed G. Williams,et al.  Verification of proficiency in basic skills for postgraduate year 1 residents. , 2010, Surgery.

[69]  N. Seymour,et al.  Novices Outperform Experienced Laparoscopists on Virtual Reality Laparoscopy Simulator , 2008, JSLS : Journal of the Society of Laparoendoscopic Surgeons.

[70]  P J Baldwin,et al.  Validity of surgical simulation for the assessment of operative skill , 2001, The British journal of surgery.

[71]  Lee L Swanstrom,et al.  Beta test results of a new system assessing competence in laparoscopic surgery. , 2006, Journal of the American College of Surgeons.

[72]  Paul G Gauger,et al.  Laparoscopic simulation training with proficiency targets improves practice and performance of novice surgeons. , 2010, American journal of surgery.

[73]  T. Villaneuva.  European Working Time Directive faces challenges , 2010, Canadian Medical Association Journal.

[74]  P. Gove.  Webster's Third New International Dictionary , 1986 .

[75]  D. DaRosa,et al.  Description and impact of using a standard-setting method for determining pass/fail scores in a surgery clerkship. , 2007, American journal of surgery.

[76]  M. Donnelly,et al.  Faculty sensitivity in detecting medical students' clinical competence , 1995 .

[77]  A. E. Park,et al.  Evaluating minimally invasive surgery training using low-cost mechanical simulations , 2003, Surgical Endoscopy And Other Interventional Techniques.

[78]  Nick Sevdalis,et al.  Validation of an operating room immersive microlaryngoscopy simulator , 2012, The Laryngoscope.

[79]  R. Reznick,et al.  Objective structured assessment of technical skill (OSATS) for surgical residents , 1997, The British journal of surgery.

[80]  J. Korndorffer,et al.  Intensive continuing medical education course training on simulators results in proficiency for laparoscopic suturing. , 2006, American journal of surgery.

[81]  C. W. Cummings,et al.  Competency in surgical residency training: defining and raising the bar. , 2007, Academic medicine : journal of the Association of American Medical Colleges.

[82]  G. Moneta,et al.  Evaluation of distributed practice schedules on retention of a newly acquired surgical skill: a randomized trial. , 2011, American journal of surgery.

[83]  Melina C Vassiliou,et al.  Fundamentals of laparoscopic surgery simulator training to proficiency improves laparoscopic performance in the operating room-a randomized controlled trial. , 2010, American journal of surgery.

[84]  Timothy J. Wood,et al.  The Ottawa Surgical Competency Operating Room Evaluation (O-SCORE): A Tool to Assess Surgical Competence , 2012, Academic medicine : journal of the Association of American Medical Colleges.

[85]  M B Donnelly,et al.  The Objective Structured Clinical Examination The New Gold Standard for Evaluating Postgraduate Clinical Performance , 1995, Annals of surgery.

[86]  A. Darzi,et al.  Observational tools for assessment of procedural skills: a systematic review. , 2011, American journal of surgery.

[87]  C. W. Cummings,et al.  Comparing Performance between Male and Female Residents in Otolaryngology , 2011 .

[88]  Defining milestones toward competency in mastoidectomy using a skills assessment paradigm , 2010, The Laryngoscope.

[89]  P. Scardino,et al.  Lack of agreement between subjective ratings of instructors and objective testing of knowledge acquisition in a urological continuing medical education course. , 1979, The Journal of urology.

[90]  Rajesh Aggarwal,et al.  Construction of an evidence-based, graduated training curriculum for D-box, a webcam-based laparoscopic basic skills trainer box. , 2012, American journal of surgery.

[91]  Dimitri A Raptis,et al.  Basic laparoscopic training using the Simbionix LAP Mentor: setting the standards in the novice group. , 2012, Journal of surgical education.

[92]  Teodor P. Grantcharov,et al.  Validation of a Structured Training and Assessment Curriculum for Technical Skill Acquisition in Minimally Invasive Surgery: A Randomized Controlled Trial , 2013, Annals of surgery.

[93]  R. Hawes,et al.  Training resident physicians in fiberoptic sigmoidoscopy. How many supervised examinations are required to achieve competence? , 1986, The American journal of medicine.

[94]  John P. Sarwark,et al.  A new computer enhanced visual learning method to train urology residents in pediatric orchiopexy: a prototype for Accreditation Council for Graduate Medical Education documentation. , 2008, The Journal of urology.

[95]  T. Berkey,et al.  Benchmarking in health care: turning challenges into success. , 1994, The Joint Commission journal on quality improvement.

[96]  C. Brady,et al.  The impact of rolling theatre closures on core urology training. , 2013, Irish medical journal.

[97]  W E G Thomas,et al.  Teaching and assessing surgical competence. , 2006, Annals of the Royal College of Surgeons of England.

[98]  A. K. Sachdeva,et al.  National efforts to reform residency education in surgery. , 2007, Academic medicine : journal of the Association of American Medical Colleges.

[99]  Stacey L Ishman,et al.  Assessment of improvement of trainee surgical skills in the operating room for tonsillectomy , 2013, The Laryngoscope.

[100]  W. B. van den Hout,et al.  Implementation of the laparoscopic simulator in a gynecological residency curriculum , 2007, Surgical Endoscopy.

[101]  R. Reznick,et al.  A comprehensive examination for senior surgical residents. , 2000, American journal of surgery.

[102]  R C Camp,et al.  Learning from the best leads to superior performance. , 1992, The Journal of business strategy.

[103]  Ali Alaraj,et al.  Role of cranial and spinal virtual and augmented reality simulation using immersive touch modules in neurosurgical training. , 2013, Neurosurgery.

[104]  J. Korndorffer,et al.  Developing and testing competency levels for laparoscopic skills training. , 2005, Archives of surgery.

[105]  Teodor P Grantcharov,et al.  Can everyone achieve proficiency with the laparoscopic technique? Learning curve patterns in technical skills acquisition. , 2009, American journal of surgery.

[106]  Rajesh Aggarwal,et al.  A Comparison of 2 Ex Vivo Training Curricula for Advanced Laparoscopic Skills: A Randomized Controlled Trial , 2012, Annals of surgery.

[107]  M. Bridges,et al.  The financial impact of teaching surgical residents in the operating room. , 1999, American journal of surgery.

[108]  Clare Faurie,et al.  Technical competence in surgeons , 2012, ANZ journal of surgery.

[109]  Marlies P. Schijven,et al.  European consensus on a competency-based virtual reality training program for basic endoscopic surgical psychomotor skills , 2010, Surgical Endoscopy.

[110]  A. Nicol,et al.  Objective assessment of surgical training in flexor tendon repair: the utility of a low-cost porcine model as demonstrated by a single-subject research design. , 2012, Journal of surgical education.

[111]  C. Daniel Smith,et al.  Should surgical novices trade their retractors for joysticks? Videogame experience decreases the time needed to acquire surgical skills , 2008, Surgical Endoscopy.

[112]  W. Cioffi,et al.  Surgical residents' perceptions of 2011 Accreditation Council for Graduate Medical Education duty hour regulations. , 2013, JAMA surgery.

[113]  J. Dankelman,et al.  Incorporation of proficiency criteria for basic laparoscopic skills training: how does it work? , 2008, Surgical Endoscopy.

[114]  Melina C Vassiliou,et al.  A global assessment tool for evaluation of intraoperative laparoscopic skills. , 2005, American journal of surgery.

[115]  A. Ziv,et al.  Simulation-based medical education: an ethical imperative. , 2006, Simulation in healthcare : journal of the Society for Simulation in Healthcare.

[116]  Charles J Limb,et al.  Pilot testing of an assessment tool for competency in mastoidectomy , 2009, The Laryngoscope.

[117]  G. Binenbaum,et al.  Microsurgical lab testing is a reliable method for assessing ophthalmology residents’ surgical skills , 2007, British Journal of Ophthalmology.

[118]  Adrian E Park,et al.  A valid method of laparoscopic simulation training and competence assessment. , 2003, The Journal of surgical research.

[119]  M. Ishii,et al.  In‐training assessment and predictors of competency in endoscopic sinus surgery , 2010, The Laryngoscope.

[120]  A. Darzi,et al.  Use of Suturing as a Measure of Technical Competence , 2003, Annals of plastic surgery.

[121]  James R Korndorffer,et al.  Skill retention following proficiency-based laparoscopic simulator training. , 2005, Surgery.

[122]  R. Arciero,et al.  The development of an objective model to assess arthroscopic performance. , 2009, The Journal of bone and joint surgery. American volume.

[123]  J. Allison,et al.  Achievable benchmarks of care: the ABC TM s of benchmarking , 1999 .

[124]  G. Fried,et al.  FLS simulator performance predicts intraoperative laparoscopic skill , 2007, Surgical Endoscopy.

[125]  C. L. Yau,et al.  Determining Standards for Laparoscopic Proficiency Using Virtual Reality , 2005, The American surgeon.

[126]  W. Berry.  Surgical malpractice: myths and realities. , 2006, The Journal of medical practice management : MPM.

[127]  J. Allison,et al.  Achievable benchmarks of care: the ABCs of benchmarking. , 1999, Journal of evaluation in clinical practice.

[128]  A. K. Sachdeva,et al.  American Surgical Association Blue Ribbon Committee Report on Surgical Education: 2004. , 2005, Annals of surgery.

[129]  E. Grober,et al.  The concept and trajectory of "operative competence" in surgical training. , 2006, Canadian journal of surgery. Journal canadien de chirurgie.

[130]  Andrew L Warshaw,et al.  Residency training in surgery in the 21st century: a new paradigm. , 2004, Surgery.

[131]  D. Proctor,et al.  Prospective Evaluation of a Teaching Model to Determine Competency in Performing Flexible Sigmoidoscopies , 1998, American Journal of Gastroenterology.

[132]  E. Frezza,et al.  Competency-based instruction in critical invasive skills improves both resident performance and patient safety. , 1998, Surgery.

[133]  D. Moher,et al.  Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. , 2010, International journal of surgery.

[134]  S. Tesfay,et al.  Implementation, construct validity, and benefit of a proficiency-based knot-tying and suturing curriculum. , 2008, Journal of surgical education.

[135]  G. Guiton,et al.  Characterizing the learning curve in phacoemulsification , 2011, Journal of cataract and refractive surgery.

[136]  Teodor Grantcharov,et al.  Ex Vivo Technical Skills Training Transfers to the Operating Room and Enhances Cognitive Learning: A Randomized Controlled Trial , 2011, Annals of surgery.

[137]  K. Kahol,et al.  The effect of call on neurosurgery residents' skills: implications for policy regarding resident call periods. , 2012, Journal of neurosurgery.

[138]  Adam Dubrowski,et al.  Computer-assisted assessment of one-handed knot tying skills performed within various contexts: a construct validity study. , 2006, American journal of surgery.

[139]  Carlos A Pellegrini,et al.  Surgical Education in the United States: Navigating the White Waters , 2006, Annals of surgery.

[140]  T. Dielman,et al.  Dimensionality, internal consistency and interrater reliability of clinical performance ratings , 1987, Medical education.

[141]  A. Peracchia,et al.  Surgical Education in the Third Millennium , 2001 .

[142]  S. Dreyfus,et al.  A Five-Stage Model of the Mental Activities Involved in Directed Skill Acquisition , 1980 .

[143]  R. Reznick,et al.  Teaching the surgical craft: From selection to certification. , 2002, Current problems in surgery.

[144]  M. Pyfer.  Impact of Resident Participation in Cataract Surgery on Operative Time and Cost , 2012 .

[145]  G. Guyatt,et al.  GRADE: an emerging consensus on rating quality of evidence and strength of recommendations , 2008, BMJ : British Medical Journal.

[146]  G. Hanna,et al.  Development, validation and implementation of a monitoring tool for training in laparoscopic colorectal surgery in the English National Training Program , 2011, Surgical Endoscopy.

[147]  M. Nathan,et al.  Assessment of technical competency in pediatric cardiac surgery , 2012 .

[148]  Anthony M. Harrison,et al.  Development and evaluation of a simulator-based laparoscopic training program for surgical novices , 2012, Surgical Endoscopy.

[149]  J L Rees,et al.  Transferring simulated arthroscopic skills to the operating theatre: a randomised blinded study. , 2008, The Journal of bone and joint surgery. British volume.

[150]  M. Short,et al.  Using a simulated surgical skills station to assess laceration management by surgical and nonsurgical residents. , 2011, Journal of graduate medical education.

[151]  P. Wei,et al.  Role of appendectomy in laparoscopic training. , 2006, Journal of laparoendoscopic & advanced surgical techniques. Part A.

[152]  D M Berwick,et al.  Continuous improvement as an ideal in health care. , 1989, The New England journal of medicine.