Although practising evidence-based medicine is the goal of most physicians, it can be a real challenge to sift through the vast body of data to determine the best strategies. Most clinical guidelines regard replicated randomized controlled trials (RCTs), metaanalyses, and systematic reviews as the highest level of evidence to support treatment recommendations. High-quality metaanalyses can overcome many of the drawbacks of individual RCTs and qualitative reviews. They can reduce bias, provide adequate power to demonstrate real differences in outcomes, and resolve the results of inconsistent studies. This paper focuses on basic principles and terms used in metaanalysis, so that clinicians can appropriately evaluate and use their results to guide treatment decisions.
BlierPBergeronR.Effectiveness of pindolol with selected antidepressant drugs in the treatment of major depression. J Clin Psychopharmacol1995;15:217–22.
2.
PerezVSolerJPuigdemontDAlvarezEArtigasF.A double-blind, randomized, placebo-controlled trial of pindolol augmentation in depressive patients resistant to serotonin reuptake inhibitors. Grup de Recerca en Trastorns Afectius. Arch Gen Psychiatry1999;56:375–9.
3.
KennedySHLamRWCohenNRavindranA.Clinical guidelines for the treatment of depressive disorders. IV. Medications and other biological treatments. Can J Psychiatry2001;46(Suppl 1):38S–58S.
4.
MoherDJadadAKlassenT.Guides for reading and interpreting systematic reviews: III. How did the authors synthesize the data and make their conclusions? Arch Pediatr Adolesc Med1998;152:915–20.
5.
KlassenTJadadAMoherD.Guides for reading and interpreting systematic reviews: I. Getting started. Arch Pediatr Adolesc Med1998;152:70–4.
6.
CookDSackettDSpitzerW.Methodologic guidelines for systematic reviews of randomized controlled trials in health care from the Potsdam consultation on meta-analysis. J Clin Epidemiol1995;167–71.
7.
AndersonI.Meta-analytical studies on new antidepressants. Br Med Bull2001;57:161–78.
8.
BeroLRennieD.The Cochrane Collaboration. Preparing, maintaining, and disseminating systematic reviews of the effects of health care. JAMA1995;274:1935–8.
9.
JadadAHaynesR.The Cochrane Collaboration—advances and challenges in improving evidence-based decision making. Med Decis Making1998;18:2–9, discussion 16–8.
10.
JadadACookDJonesAKlassenTTugwellPMoherM, and others. Methodology and reports of systematic reviews and meta-analyses: A comparison of Cochrane reviews with articles published in paper-based journals. JAMA1998;280:278–80.
MoherDCookDEastwoodSOlkinIRennieDStroupD.Improving the quality of reports of meta-analyses of randomised controlled trials: The QUOROM statement. Quality of reporting of meta-analyses. Lancet1999;354:1896–900.
13.
MoherDSchulzKAltmanD.The CONSORT statement: Revised recommendations for improving the quality of reports of parallel-group randomized trials. JAMA2001;285:1987–91.
14.
OxmanACookDGuyattG.Users' guides to the medical literature. VI. How to use an overview. Evidence-Based Medicine Working Group. JAMA1994;272:1367–71.
15.
PogueJYusufS.Overcoming the limitations of current meta-analysis of randomised controlled trials. Lancet1998;351:47–52.
16.
OxmanAGuyattG.Guidelines for reading literature reviews. CMAJ1988;138:697–703.
17.
RosenthalR.The “file drawer problem” and tolerance for null results. Psychol Bull1979;638–41.
18.
DickersinKChanSChalmersTSacksHSmithH.Publication bias and clinical trials. Control Clin Trials1987;8:343–53.
19.
DickersinKMinY.Publication bias: The problem that won't go away. Ann N Y Acad Sci1993;703:135–46, discussion 46–8.
20.
DickersinKMinYMeinertC.Factors influencing publication of research results. Follow-up of applications submitted to two institutional review boards. JAMA1992;267:374–8.
21.
McAuleyLPhamBTugwellPMoherD.Does the inclusion of grey literature influence estimates of intervention effectiveness reported in meta-analyses?Lancet2000;356:1228–31.
22.
WhittingtonCJKendallTFonagyPCottrellDCotgroveABoddingtonE.Selective serotonin reuptake inhibitors in childhood depression: Systematic review of published versus unpublished data. Lancet2004;363:1341–5.
23.
LamRWKennedySH. Prescribing antidepressants for depression in 2005: Recent concerns and recommendations. Can J Psychiatry. Forthcoming.
24.
JadadAMoherDKlassenT.Guides for reading and interpreting systematic reviews: II. How did the authors find the studies and assess their quality? Arch Pediatr Adolesc Med1998;152:812–7.
25.
MoherDPhamBJonesACookDJadadAMoherM, and others. Does quality of reports of randomised trials affect estimates of intervention efficacy reported in meta-analyses?Lancet1998;352:609–13.
26.
GuyattGSackettDCookD.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? Evidence-Based Medicine Working Group. JAMA1994;271:59–63.
ThaseMEntsuahARudolphR.Remission rates during treatment with venlafaxine or selective serotonin reuptake inhibitors. Br J Psychiatry2001;178:234–41.
29.
NemeroffCEntsuahAWillardLDemitrackMThaseM.Venlafaxine and SSRIs: Pooled remission analysis [Abstract NR 263]. Presented at 156th APA Annual Meeting; 2003 May 17–22; San Francisco (CA).
30.
StreinerD.Using meta-analysis in psychiatric research. Can J Psychiatry1991;36:357–62.
31.
StreinerD.Sample size and power in psychiatric research. Can J Psychiatry1990;35:616–20.
32.
CohenJ.Statistical power analysis for the behavioural sciences. Orlando (FL): Academic Press; 1977.
33.
LamRWGormanCMichalonMSteinerMLevittAJCorralM, and others. Multicenter, placebo-controlled study of fluoxetine in seasonal affective disorder. Am J Psychiatry1995;152:1765–70.
34.
BechPCialdellaPHaughMBirkettMHoursABoisselJ, and others. Meta-analysis of randomised controlled trials of fluoxetine vs placebo and tricyclic antidepressants in the short-term treatment of major depression. Br J Psychiatry2000;176:421–8.
35.
WestenDMorrisonK.A multidimensional meta-analysis of treatments for depression, panic, and generalized anxiety disorder: An empirical examination of the status of empirically supported therapies. J Consult Clin Psychol2001;69:875–99.
36.
WeislerRJohnstonJLineberryCSamaraBBranconnierRBillowA.Comparison of bupropion and trazodone for the treatment of major depression. J Clin Psychopharmacol1994;14:170–9.
37.
SmithDDempsterCGlanvilleJFreemantleNAndersonI.Efficacy and tolerability of venlafaxine compared with selective serotonin reuptake inhibitors and other antidepressants: A meta-analysis. Br J Psychiatry2002;180:396–404.
38.
BurtTLisanbySSackeimH.Neuropsychiatric applications of transcranial magnetic stimulation: A meta analysis. Int J Neuropsychopharmacol2002;5:73–103.
39.
HoltzheimerPRussoJAveryD.A meta-analysis of repetitive transcranial magnetic stimulation in the treatment of depression. Psychopharmacol Bull2001;35:149–69.
40.
MartinJBarbanojMSchlaepferTThompsonEPerezVKulisevskyJ.Repetitive transcranial magnetic stimulation for the treatment of depression. Systematic review and meta-analysis. Br J Psychiatry2003;182:480–91.
41.
LauJIoannidisJSchmidC.Summing up evidence: One answer is not always enough. Lancet1998;351:123–7.
42.
PresbyS.Overly broad categories obscure important differences between therapies. Am Psychol1978;33:514–5.
43.
LightR.Accumulating evidences from independent studies: What we can win and what we can lose. Stat Med1987;6:221–8.
44.
GlassG.Primary, secondary and meta-analysis research. Educ Res1976;5:3–8.
45.
SmithMGlassG.Meta-analysis of psychotherapy outcome studies. Am J Psychol1977;32:752–60.
46.
GuyattGPugsleySSullivanMThompsonPBermanLJonesN, and others. Effect of encouragement on walking test performance. Thorax1994;818–22.
47.
PerettiSJudgeRHindmarchI.Safety and tolerability considerations: Tricyclic antidepressants vs. selective serotonin reuptake inhibitors. Acta Psychiatr Scand Suppl2000;403:17–25.
48.
OxmanT.Antidepressants and cognitive impairment in the elderly. J Clin Psychiatry1996;57(suppl 5):38–44.
49.
LamRWKennedySH. Evidence based strategies for achieving and sustaining full remission in depression: Focus on metaanalyses. Can J Psychiatry2004;49(suppl 1):17S–26S.
50.
LaupacisASackettDRobertsR.An assessment of clinically useful measures of the consequences of treatment. N Engl J Med1988;318:1728–33.
51.
WahlbeckKCheineMEssaliM.Clozapine versus typical neuroleptic medication for schizophrenia. Cochrane Database Syst Rev2000:CD000059.
52.
MooreACollinsSCarrollDMcQuayHEdwardsJ.Single dose paracetamol (acetaminophen), with and without codeine, for postoperative pain. Cochrane Database Syst Rev2000:CD001547.
53.
O'ConnorPSpannSWoolfS.Care of adults with type 2 diabetes mellitus. A review of the evidence. J Fam Pract1998;47:S13–S22.
54.
DeeksJSmithLBradleyM.Efficacy, tolerability, and upper gastrointestinal safety of celecoxib for treatment of osteoarthritis and rheumatoid arthritis: Systematic review of randomised controlled trials. BMJ2002;325:619.
55.
GreenL.Selections from current literature: The fight over fat. Is pharmacological lipid lowering useful for coronary primary prevention? Fam Pract1997;14:411–5.
