Presentation on theme: "8 th Workshop Prática Clinica Baseada em Evidências Angra do Reis, 2014 REVISÕES SISTEMÁTICAS: Como interpretá-las? SYSTEMATIC REVIEWS: How to interpret."— Presentation transcript:
8 th Workshop Prática Clinica Baseada em Evidências Angra do Reis, 2014 REVISÕES SISTEMÁTICAS: Como interpretá-las? SYSTEMATIC REVIEWS: How to interpret them Luz M. Letelier Associate Professor Internal Medicine Faculty of Medicine, P. Universidad Católica de Chile
PLEASE…..Don’t start here ….. Sze, Man Wai et al. Palliation of metastatic bone pain: single fraction versus multifraction radiotherapy Cochrane Database of Systematic Reviews. Issue 5, 2011.
Meta-analysis might be the most glamorous part of a Systematic Review. DO NOT FORGET it is just a tool to combine the results of included studies. SYSTEMATIC REVIEW META – ANÁLISIS
Navegando pelas RSs Sailing arround SRs..... What is a SR & why are they useful. How to use / analyze a SR.
Estamos atualizados em relação a conhecimento médico? Are we up-to-date on medical information? How many articles do you read a month? How many should you read? 2005: Medline index 560.000 new articles /year = 1.534/ día. 2013: Medline index 734.000 new articles /year = 2.010/día
Ento, tem algum problema? We are in trouble Então, tem algum problema? We are in trouble Need to handle large amounts of current information to deliver the best care to our patients Is difficult to find and then appraise all the information.
You’ve become expert on efficient literature searches. CLINICAL SCENARIO Your last patient, a heavy smoker, asks if he should start taking vitamin A to prevent lung cancer. During this workshop
SEARCH FOR EVIDENCE P: SMOKERS I: VITAMIN A C: NO TREATMENT O: REDUCE LUNG CANCER
Using PubMed Search Terms Hits 2003 Hits 2006 Hits 2009 Hits 2012 Hits 2014 Beta-carotene or vitamin A 33.00040.06545.65651.46855.045 (Beta- carotene or vitamin A) and lung cancer 75187511071.1971.275 Clinical Query: Therapy & specific =112 hits
BETA-CAROTENE FOR LUNG CANCER PREVENTION NEJM 1994; 330:1029-1035 The Effect of Vitamin E and Beta Carotene on the Incidence of Lung Cancer and Other Cancers in Male Smokers. Beta Carotene Cancer Prevention Study Group The Alpha-Tocopherol CONCLUSIONS: We found no reduction in the incidence of lung cancer among male smokers after five to eight years of dietary supplementation with alpha-tocopherol or beta carotene. In fact, this trial raises the possibility that these supplements may actually have harmful as well as beneficial effects. N Engl J Med 1996 May 2;334(18):1150-5 Effects of a Combination of Beta Carotene and Vitamin A on Lung Cancer and Cardiovascular Disease. CARET Study CONCLUSIONS: After an average of four years of supplementation, the combination of beta carotene and vitamin A had no benefit and may have had an adverse effect on the incidence of lung cancer and on the risk of death from lung cancer, cardiovascular disease, and any cause in smokers and workers exposed to asbestos.
BETA-CAROTENE FOR LUNG CANCER PREVENTION Cancer Causes Control 2000 Aug;11(7):617-26 Effects of beta-carotene supplementation on cancer incidence by baseline characteristics in the Physicians' Health Study (PHS). CONCLUSIONS: The PHS found no overall effect of beta-carotene on total cancer, or the three most common site-specific cancers. The possibility of risk reduction within specific subgroups remains. Am J Clin Nutr 2000 Oct;72(4):990-7 Intake of specific carotenoids and risk of lung cancer in 2 prospective US cohorts CONCLUSION: Data from 2 cohort studies suggest that several carotenoids may reduce the risk of lung cancer.
BETA-CAROTENE FOR LUNG CANCER PREVENTION Cancer Epidemiol Biomarkers Prev. 2006 ;15(8):1562-4. Lung cancer chemoprevention: a randomized, double-blind trial in Linxian, China. Conclusion: Supplementation with combinations of vitamins and minerals at nutrient-repletion levels for 5.25 years did not reduce lung cancer mortality in this nutrient-inadequate population in Linxian, China. Rev Med Suisse. 2010 May 26;6:1046-8, 1050-2. Nutrition and physical activity: two targets for cancer prevention. The scientific evidence is presented in a report of the World Cancer Research Foundation (WCRF). Protective factors towards overall cancer risk are fruit and vegetable consumption and physical activity. Overweight and obesity, intakes of alcoholic beverage, fat, salt, high temperature cooked and processed red meat, increase cancer risk. In addition, beta-carotene systematic supplementation could increase lung cancer risk in smokers.
BETA-CAROTENE AND LUNG CANCER PREVENTION Resumindo ( Summarizing) BETA-CAROTENE AND LUNG CANCER PREVENTION May have harmful as well as beneficial effects. 1994 No benefit and may have adverse effect on lung cancer 1996 No overall effect of beta-carotene on total cancer 2000 Several carotenoids may reduce the risk of lung cancer. 2000 Supplementation did not reduce lung cancer mortality 2006 Beta-carotene could increase lung cancer risk in smokers 2010 Betacarotene no late effect on cancer incidence. 2014 QUAIS RESULTADOS EU DEVO APLICAR? WHICH RESULTS SHOULD I APPLY?
Why are the studies result so different and even contradictory ? Are the studies similar? In their risk of bias (validity)? Are they looking at the same population? Is it the same intervention? etc
ENTÃO... SO.... Besides handling lots of information we need to decide which results to believe....and apply to our patient. Além de lidar com muita informação, precisamos decidir quais resultados para acreditar... e aplicar ao nosso paciente.
SOLUÇÃOS? Collect some information and give your best opinion. NARRATIVE REVIEW –expert opinion DESTROY THE EVIDENCE DESTRUIR AS PROVAS
SOLUÇÃO Summarize ALL available information using explicit, reproducible methods for finding, selecting and appraising the information. REVISÕES SISTEMÁTICAS SYSTEMATIC REVIEW
DEFINIÇÃO REVISÕES SISTEMÁTICAS SYSTEMATIC REVIEW Summary of ALL available information regarding a specific clinical question, using explicit methods towards reducing bias. Questions on Therapy / Diagnosis / Prognosis
META - ANALYSIS Statistical method to combine (summarize) the results of studies included in a Systematic Review. Método estatístico para combinar (resumir) os resultados dos estudos incluídos em uma revisão sistemática DEFINIÇÃO
REVISÕES Reviews Narrative Review a topic in several different aspects. No explicit method for searching the evidence. No explicit method for selecting information. No explicit method for appraising information Should not have statistical analysis. Systematic Answers a specific question. Explicit method for searching the evidence Explicit method for selecting information. Explicit method for appraising information. Might have statistical analysis (Meta-analysis)
Navegando pelas RSs Sailing arround SRs…next STOP SRs what are they & why are they useful. How to use/appraise a SR
Appraising a STEP 1 Appraising a SR: STEP 1 IS THERE A SENSIBLE SPECIFIC QUESTION? a) Any antibiotic for any infection b)Any macrolide for any respiratory infection c)Any dose of claritromicine for Community Acquired Pneumonia (CAP) ATS I&II d)Claritromicine 250 mg vs 500mg bid for CAP in patients 20 years old with asthma and allergy to penicillin. REMEMBER: NOT TOO BROAD NOT TOO NARROW
Appraising a STEP 2 Appraising a SR: STEP 2 SEARCH FOR ALL AVAILABLE EVIDENCE Broad search strategy: Several databases Hand searches: References Abstracts from conferences Ask experts, researchers on the topic and pharmaceutical industry for unpublished data. AIM: GET ALL AVAILABLE EVIDENCE AVOID PUBLICATION BIAS
Evaluating publication bias: Funnel plot 1 A. Symmetric distribution of studies, no publication bias. B. Asymmetric distribution. Small studies with negative results undetected. Probably publication bias. 1 Cochrane Handbook for Systematic Reviews of Interventions 5.2. The Cochrane Collaboration, 2009.
Appraising a STEP 3 Appraising a SR: STEP 3 CRITICAL APPRAISAL OF INCLUDED STUDIES Very important Avoid “garbage in” “garbage out” Could be done: Descriptive Quantitative: Scores (ie. Jadad score)
COCHRANE COLLABORATION’S APPROACH to assess risk of bias of included studies Cochrane Handbook for Systematic Reviews of Interventions 5.0.2 The Cochrane Collaboration, 2009.
Appraising a STEP 4 Appraising a SR: STEP 4 REPRODUCIBILITY OF PROCESS 2 independent reviewers: Selection Inclusion Critical Appraisal REDUCE BIAS AND RANDOM ERROR
Meta-analysis: statistical tool to combine the results of included studies. Forest Plot Like any statistics: crucial to use the correct data set Before looking at the forest plot (meta-analysis) BE SURE the data is right. Critical appraisal of data gathering process = systematic review (step 1 to 4). …E FINALMENTE… META – ANALYSIS
Appraising a STEP 5 Appraising a SR: STEP 5 STATISTICAL ANALYSIS (META – ANALYSIS) Test for heterogeneity: Q statistic (χ 2 )p-value I 2 0 to 100 Sources of heterogeneity.
BETA-CAROTENO Y PREVENCION DE CANCER PULMONAR Drugs for preventing lung cancer in healthy people M Cortés-Jofré, JR Rueda, G Corsini-Muñoz, C Fonseca-Cortés, M Caraballoso, X Bonfill Cosp. Published Online: 17 OCT 2012. Assessed as up-to-date: 7 DEC 2011 Includes 9 RCTs of low risk of bias P: > 203.000 healthy participants with low and high risk (smokers or exposed to asbestos) of lung cancer. I/C: Vitamin A, vitamin C and selenio compared to placebo Treatment duration 2 - 9 years O: lung cancer and mortality Follow up 4 – 12 years
Drugs for preventing lung cancer in healthy people M Cortés-Jofré et al. The Cochrane Database of Systematic Reviews 2012 Issue 10
MENSAGENS PARA CASA SYSTEMATICS REVIEWS : Summarizes best evidence regarding a specific question. Should have explicit methods to minimize bias. Should be critically appraised by consumers (VOCE). If methodologically well done (low risk of bias) = highest level of evidence. Important tool to evidence based health care as they help handling large amounts of information. Before looking at the meta-analysis look at the risk of bias of the SR. SRs do not make decision, they inform decisions.