The unpredictability paradox: Review of empirical comparisons of randomised and non-randomised clinical trials

BMJ

Volumn 317, Issue 7167, 1998, Pages 1185-1190

  Kunz, Regina ^a   Oxman, Andrew D ^b  

^a CHARITÉ UNIVERSITÄTSMEDIZIN BERLIN   (Germany)

^b NORWEGIAN INSTITUTE OF PUBLIC HEALTH   (Norway)

Author keywords

[No Author keywords available]

Indexed keywords

ANTICOAGULANT AGENT; DIETHYLSTILBESTROL; HORMONE; QUINIDINE;

ACUTE HEART INFARCTION; ARTICLE; CLINICAL TRIAL; COMPARATIVE STUDY; CRYPTORCHISM; HEART ATRIUM FIBRILLATION; HUMAN; META ANALYSIS; METHODOLOGY; PRIORITY JOURNAL; RANDOMIZATION; RANDOMIZED CONTROLLED TRIAL; SPONTANEOUS ABORTION;

CLINICAL TRIALS; DATA COLLECTION; QUALITY CONTROL; RANDOM ALLOCATION; RANDOMIZED CONTROLLED TRIALS; SELECTION BIAS;

EID: 0032585188     PISSN: 09598138     EISSN: 14685833     Source Type: Journal    
DOI: 10.1136/bmj.317.7167.1185     Document Type: Article

References (42)

1. Cochrane AL. Effectiveness and efficiency: random reflections on health services. London: Nuffield Provincial Hospitals Trust, 1972: 20–25.
2. Committee for Evaluating Medical Technologies in Clinical Use. Assessing medical technologies. Washington DC: National Academy Press, 1985: 76–78.
3. US Congress, Office of Technology Assessment. Identifying health technologies that work: searching for evidence, OTA-H-608. Washington DC: US Government Printing Office, 1994: 41–51.
4. Black N. Why we need observational studies to evaluate the effectiveness of health care. BMJ 1996; 312: 1215–1218.
5. Weiss CH. Evaluation. Methods for studying programs and policies. 2nd ed. Upper Saddle River: Prentice Hall, 1998: 229–233.
6. Cochrane Review Methodology Database. In: Clarke M, Carling C, Oxman AD, eds. The Cochrane Library. Oxford: Update Software, 1998 Issue 3.
7. Chalmers TC, Matta RJ, Smith H Jr, Kunzler AM. Evidence favoring the use of anticoagulants in the hospital phase of acute myocardial infarction. N Engl J Med 1977; 297: 1091–1096.
8. Sacks H, Chalmers TC, Smith H Jr. Randomized versus historical controls for clinical trials. Am J Med 1982; 72: 233–240.
9. Diehl LF, Perry DJ. A comparison of randomized concurrent control groups with matched historical control groups: are historical controls valid? J Clin Oncol 1986; 4: 1114–1120.
10. Reimold SC, Chalmers TC, Berlin JA, Antman EM. Assessment of the efficacy and safety of antiarrhythmic therapy for chronic atrial fibrillation: observations on the role of trial design and implications of drug related mortality. Am Heart J 1992; 124: 924–932.
11. Recurrent Miscarriage Immunotherapy Trialists Group. Worldwide collaborative observational study and meta analysis on allogenic leukocyte immunotherapy for recurrent spontaneous abortion. Am J Reprod Immunol 1994; 32: 55–72.
12. Watson A, Vandekerckhove P, Lilford R, Vail A, Brosens I, Hughes E. A meta-analysis of the therapeutic role of oil soluble contrast media at hysterosalpingography: A surprising result? Fertil Steril 1994; 61: 470–477.
13. Pyorala S, Huttunen NP, Uhari M. A review and meta-analysis of hormonal treatment of cryptorchidism. J Clin Endocrinol Metab 1995; 80: 2795–2799.
14. Carroll D, Tramer M, McQuay H, Nye B, Moore A. Randomization is important in studies with pain outcomes: systematic review of transcutaneous electrical nerve stimulation in acute postoperative pain. Br J Anaesth 1996; 77: 798–803.
15. Colditz GA, Miller JN, Mosteller F. How study design affects outcomes in comparisons of therapy. I: medical. Stat Med 1989; 8: 441–454.
16. Miller JN, Colditz GA, Mosteller F. How study design affects outcomes in comparisons of therapy. II: surgical. Stat Med 1989; 8: 455–466.
17. Ottenbacher K. Impact of random assignment on study outcome: an empirical examination. Control Clin Trials 1992; 13: 50–61.
18. Chalmers TC, Celano P, Sacks HS, Smith H Jr. Bias in treatment assignment in controlled clinical trials. N Engl J Med 1983; 309: 1358–1361.
19. Schulz KF, Chalmers I, Hayes RJ, Altman DG. Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA 1995; 273: 408–412.
20. Emerson JD, Burdick E, Hoaglin DC, Mosteller F, Chalmers TC. An empirical study of the possible relation of treatment differences to quality scores in controlled randomized clinical trials. Control Clin Trials 1990; 11: 339–352.
21. Imperiale TF, McCullough AJ. Do corticosteroids reduce mortality from alcoholic hepatitis? A meta analysis of the randomized trials. Ann Intern Med 1990; 113: 299–307.
22. Nurmohamed MT, Rosendaal FR, Buller HR, Dekker E, Hommes DW, Vandenbroucke JP, et al. Low molecular weight heparin versus standard heparin in general and orthopaedic surgery: A meta-analysis. Lancet 1992; 340: 152–156.
23. Khan KS, Daya S, Jadad A. The importance of quality of primary studies in producing unbiased systematic reviews. Arch Intern Med 1996; 156: 661–666.
24. Ortiz Z, Shea B, Suarez Almazor ME, Moher D, Wells GA, Tugwell P. The efficacy of folic acid and folinic acid in reducing methotrexate gastrointestinal toxicity in rheumatoid arthritis. A meta-analysis of randomized controlled trials. J Rheumatol 1998; 25: 36–43.
25. Chalmers I. Assembling comparison groups to assess the effects of health care. J R Soc Med 1997; 90: 379–386.
26. NHS Centre for Reviews and Dissemination. Database of abstracts of reviews of effectiveness. The Cochrane Library. Oxford: Update Software, 1998 Issue 3.
27. Cochrane Empirical Methodological Studies Methods Group. The Cochrane Library. Oxford: Update Software, 1998 Issue 3.
28. Forgie MA, Wells PS, Laupacis A, Fergusson D. Preoperative autologous donation decreases allogeneic transfusion but increases exposure to all red blood cell transfusion: results of a meta-analysis. Arch Intern Med 1998; 158: 610–616.
29. Colditz GA, Brewer TF, Berkey CS, Wilson ME, Burdick E, Fineberg HV, et al. Efficacy of BCG vaccine in the prevention of tuberculosis. Meta analysis of the published literature. JAMA 1994; 271: 698–702.
30. Stieb D, Frayha HH, Oxman AD, Shannon HS, Hutchison BG, Crombie F. The effectiveness and usefulness of Haemophilus influenzae type b vaccines: A systematic overview (meta-analysis). Can Med Assoc J 1990; 142: 719–732.
31. Kleijnen J, G⊘tzsche P, Kunz RH, Oxman AD, Chalmers I. So what's so special about randomisation? In: Maynard A, Chalmers I, eds. Non-random reflections on health services research: on the 25th anniversary of Archie Cochrane's effectiveness and efficiency. London: BMJ Publishing Group, 1997: 93–106.
32. Dicksersin K, Min YI. NIH clinical trials and publication bias. Online J Curr Clin Trials [serial online] 1993; document No 50.
33. Dickersin K. How important is publication bias? A synthesis of available data. AIDS Education and Prevention 1997; 9(suppl A): 15–21.
34. Stern JM, Simes RJ. Publication bias: evidence of delayed publication of clinical research projects. BMJ 1997; 315: 640–645.
35. Ioannidis JPA. Effect of the statistical significance of results on the time to completion and publication of randomized efficacy trials. JAMA 1998; 279: 281–286.
36. Counsell CE, Clarke MJ, Slattery J, Sandercock PAG. The miracle of DICE therapy for acute stroke: fact or fictional product of subgroup analysis? BMJ 1994; 309: 1677–1681.
37. Egger M, Davey SG, Schneider M, Minder C. Bias in meta-analysis detected by a simple, graphical test. BMJ 1997; 315: 629–634.
38. Guyatt GH, Sackett DL, Cook DJ, for the Evidence-Based Working Group. Users' guides to the medical literature, II: how to use an article about therapy or prevention, A: are the results of the study valid?. JAMA 1993; 270: 2598–2601.
39. Dans AL, Dans LF, Guyatt GH, Richardson S. Users' guides to the medical literature:ow to decide on the applicability of clinical trial results to your patient. JAMA 1998; 279: 545–549.
40. Cochrane Methods Working Group on Applicability and Recommendations. The Cochrane Library. Oxford: Update Software, 1998 Issue 3.
41. Guyatt GH, Sackett DL, Cook DJ, for the Evidence-Based Working Group. Users' guides to the medical literature, II: how to use an article about therapy or prevention, B: what were the results and will they help me in caring for my patients?. JAMA 1994; 270: 59–63.
42. Oxman AD, Flottorp S. An overview of strategies to promote implementation of evidence based health care. In: Silagy C, Haines A, eds. Evidence based practice. London: BMJ Books, 1998: 91–109.