Evidence Based Urology


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An essay on principles of research, evidence based medicine, more specifically with regards to urology.

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  • P:The patient’s characteristics, including age, gender, and condition, plus other relevant clinical or medical history featuresI: What intervention are you considering evaluating or using? Describe the main intervention, exposure, test, or prognostic factor under consideration. In the case of treatment, this might be the standard of care or a placebo, or a “gold standard” diagnostic test. A Comparison is not always needed. Describe what is hoped to be achieved, measured or affected
  • This is ur example.Say wat picot stands for.
  • After formulating the question.. The search begins.
  • Begins with: synthesized (campbell, aua/eau guidelines, e-medicine) + cochrane library – db of SR.. Under urology: subcateg (cancer, stones, incontinence) SR of all relevant articles pertaining to topic so back to ex. Urology: obstructive: prostate: different reviews for finasteride, tamsulosin, terazosin ttt for bphThen search databases ie BMJ EBM for relevant articles (case reports, cohorts, etc) which are peer-reviewed by a panel of clinical experts who rate the importance of each studyIf unsatisfactory results, fallback is larger database of journal articles (pubmed – over 5000 internation med journals)
  • Descriptive studies give us a picture of what is happening in a population.Analytic studies attempt to establish a link btwn an exposure and an outcome.
  • Descriptive shows incidence (# of new cases in time interval), prevalence (# of cases at point in time OR % as cases/population)Analytical observational: researcher measures the outcome Experimental: researcher manipulates outcome<> Evidence is stronger when studies can show relation btwn cause & effect ( e as consequence of c)
  • Surveys give a general outlook on a population ie questionnaire, Case reports or series (individual and collection of similar reports)
  • Types of analytic observationalEach has an objective as we will see later
  • (in direction of time: cross sec – same point in time, case cont – retrospective, cohort – prospective)
  • Snapshot in time. Exposure & outcome measured simultaneously. Impossible to distinguish which came first.
  • Descriptive value shows prevalence. Also can establish association, but not cause & effect.This is usually confirmed by longitudinal studies..
  • Cohort is example of longitudinal study. This study Follows subjx over time to see who will develp outcome and who will not (incidence)<>(prospective or retro)Looksfwd in time exposure to outcome.. Or when data is already collected or exposure would be unethical (smoking) is done retro.
  • Since cohort studies measure potential causes before the outcome has occurred.. Exposure precedes outcome. Cause is somewhat established. CFVIncidence is new cases that develop over time interval.RR is probability of developing outcome if exposed vs if not exposed
  • Risk factor = exposureDisease = outcome<> To calc RR..RR =1 no diff RR <1 = exposed group less likely to develop disease RR >1 = exposed group more likely to develop
  • CFV = all other factors that differ btwn groups (exp and nonexp) Ex. Asthma (exp)  lung cancer (outcome)…. Protects? Don’t think so. Asthmatics don’t smoke. Smoking is CFV.Selection = sample is not representative of the pop. (employed ppl better health than unemployed)Losing contactRecall = in retro, ppl more likely to remember certain events they believe to be risk factors
  • Works backwards. Starts with outcome. Compares to control group w/o outcome. Then determines retro whether exposure prevalence is higher in cases than controls. So take for example pts w prostate cancer .. And lets say for example dietary factors in carcinogenesis.
  • Simple = questionnaireIn rare cases, ie new variant CJD, limited cases present; and long latency time to develop disease; preferrable to work retrospectiveCase control studies gives researcher clues as to which factors are assoc w disease (predictor variable) OR = probability of even happening vs not happening (odds of exposed group developing outcome vs odds of non exposed gp developing outcome)1 = no diff. btwnppl in group w event and group w/o event
  • Gold stand. = in establishing causal effects in studies of therapyRandomly assigning subjx to groups prevents selection biasPrevents CFV by a randomised controlled trial (RCT)—the investigator experiments with the effect of the exposure by assigning exposure to a random sample of the study subjects.the randomisation process allows the investigator to assume that not only known, but also unknown, potential confounders are distributed evenly among the exposed and the unexposed. Therefore, they are not associated with the exposure, hence they cannot be confounders.
  • Several ways rcts guard against biasRndm: to balance btwn known & unknown factorsSimple = coin toss Urn= drawing balls Blinding:pts or researcher: pts AND researcher: subjct, researcher, person treating
  • One of most important safeguards is choosing sample size necessary to detect clinically significant data.
  • Optimal size is calc by comp. balance btwn type I and II errors. Sample size shud be so that Max prob of making type 1; 5% or less. Max false negative; 20% or lessImp bc more subjx r needed to lower error rate of type II. Inadequate sample size can show no diff. when in fact there is.<>Relates to (Pvalue) Prob H0 is rejected. 1/20 or less = statistically significant = 1/20 that difference is dt chance thus rejecting null hypothesis H0 (no diff)
  • 95% level corresponds to hypothesis testing with p-values less than 0.05Means that 95% of time we expect true value to be between upper & lower confidence limitsEx. If the value is mean age of first birth in women w bleeding disorders; CI = 25.5 and 28.4; there4 we are 95% confident that the true mean age lies btwn 25.5 and 28.4
  • Large trials can cost millions of dollars. Can take a long period to conduct. Also exposing pts to inferior ttt is thought to be unethical.Can not be generalized to broader community.. Usually dt strict selection criteria.
  • Reviews all study designs, but focuses mostly on RCTs as they are gold standard, and give most unbiased outcome
  • Quality…. And quantity.
  • Uses hierarchy of evidence and grades them in levelsThis scheme was developed at the centre for EBM at oxford university and uses the GRADE system.For studies of therapy/prognosis/aetiology.. This is brief description.
  • Evidence Based Urology

    1. 1. Principles of Urologic Research& Evidence Based UrologyA PresentationbyFarouk Ashraf Hammoud
    2. 2. First and foremost I would like to thank Allahfor giving me the power to accomplish thiswork.I would also like to express my gratitude to mysupervisors, Prof. Dr. Mohammed Shoeb,Dr. Tarek Osman, and Dr. Diaa Abdelftah,for their continuous supervision andirreplaceable guidance. Also Prof. Dr. Amr ElShorbagy and Prof. Dr. Khaled El Gamal,thank you for attending, I know I put youthrough some difficulties.Finally my deep thanks goes out to my familyand friends for their constant support.
    3. 3. Brief History of Medicine
    4. 4. Ancient medicine:Based on superstitionand medical theoriesRenaissance period:(14th to 17th century)Revolutionary scientificchanges
    5. 5. Medicine & Statistics Change ResearchBradford Hill Archie CochraneFirst modern randomized clinical Founding father of EBM
    6. 6. What is EBM?  “The conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients.” The integration of individual clinical expertise with the best available external clinical evidence from systematic research.
    7. 7. Conducting Research
    8. 8. Conducting Research The EBM process can be summarized by four steps:(1) Formulate a sensible, focused clinicalquestion: PICOT(2) Search the medical literature for evidencerelated to the focused, clinical question.(3) Rate the quality of the available studies.(4) Apply the evidence to a particular patientor clinical situation.
    9. 9. PICOT P = Population. I = Intervention. C = Comparison. O = Outcome. T = Type of study. Choose the best study design
    10. 10. PICOT P = 63 year old with BPH I = medical therapy C = surgery O = reducing lower urinary tract symptoms T = in a randomized controlled trial or systematic review of randomized controlled trials
    11. 11. Search for Evidence
    12. 12. Where to Search Synthesized sources: textbooks, guidelines Selected sources: research that is filtered and published as database Ex. BMJ EBM Bibliographic database of published journal articles. Ex. PubMed
    13. 13. Type Name URL InfoDatabase Cochrane Library http://www.thecochranelibrary.com Database of systemic reviews Medline/Pubmed http://www.pubmed.gov Major source of biomedical publications EMBASE http://www.embase.com/ European equivalent of Medline TRIP: Turning Research Into http://www.tripdatabase.com/ Searches E-Medicine, Practice guidelines, & other evidence-based publicationsGuidelines American Urological http://www.auanet.org/guidelines/ Practice guidelines for Association Guidelines patient management and current standard European Association of http://www.uroweb.org/ of care Urology/guidelinesPreappraised Evidence-base Medicine http://ebm.bmj.com/ Providessources ACPJC: American College of http://www.acpjc.org structured abstract of articles selected from Physicians Journal Club journals by an editorial board, plus critical appraisal of the validity, importance, and applicability CENTRAL: Cochrane Central http://www.mrw.interscience.wiley.com/coch Non English studies Register of Controlled Trials rane/cochrane_clcentral_articles_fs.html included
    14. 14. Understanding Study Design
    15. 15. Types of Studies Descriptive Studies Observational Analytic Studies ◦ Cross Sectional studies ◦ Case Control studies ◦ Cohort studies Experimental Studies ◦ Randomized controlled trials
    16. 16. Hierarchy of Study Types Descriptive Analytic •Case report •Case series •Survey Observational Experimental •Cross sectional •Randomized •Case-control controlled trials •Cohort studiesStrength of evidence for causality between a risk factor and outcome
    17. 17. Descriptive Studies
    18. 18. Descriptive Studies Surveys  “How many men in the U.S. filled Viagra prescriptions in 2004?” Case reports or case series  Sildanefil-associated serous macular detachment.
    19. 19. Descriptive Studies Cannot establish causal relationships Play an important role in generating hypotheses to be tested Alerting physicians to a new disease ◦ Squamous cell carcinoma in sexual partner of Kaposi sarcoma patient. Lancet. 1982 Jan 30;1(8266):286. ◦ New outbreak of oral tumors, malignancies and infectious diseases strikes young male homosexuals. CDA J. 1982 Mar;10(3):39-42. ◦ AIDS in the "gay" areas of San Francisco. Lancet. 1983 Apr 23;1(8330):923-4.
    20. 20. Hierarchy of Study Types Descriptive Analytic •Case report •Case series •Survey Observational Experimental •Cross sectional •Randomized •Case-control controlled trials •Cohort studiesStrength of evidence for causality between a risk factor and outcome
    21. 21. Analytic Studies
    22. 22. Analytic Studies Attempt to establish a link between a predictor/risk factor and an outcome Cross Sectional Cohort Case Control
    23. 23. Cross Sectional Study
    24. 24. Cross Sectional Study: Structure Exposure Outcome time
    25. 25. Cross Sectional Study: Descriptive value: ◦ How many medical students smoke cigarettes? ◦ What is the age and sex distribution of medical students who smoke cigarettes? Analytic value: ◦ Is there an association between regular cigarette smoking and test scores among med students?
    26. 26. Cohort Study
    27. 27. Cohort Study: Structure• Prospective• Retrospective Exposure Outcome time
    28. 28. Cohort Study: Strength  Exposure variable was present before outcome variable  Incidence  Multiple outcomes of a single exposure  Retrospective cohorts where available are cheaper and quicker.  Analyse predictors (risk factors) thereby enabling calculation of relative risk.
    29. 29. Measuring Relative Risk Risk ratio Disease (relative risk) Yes No A A+B C C+D Yes A B RiskFactor No C D
    30. 30. Cohort Study: Weakness Confounding variables Selection bias Loss to follow up Recall bias
    31. 31. Case Control Study
    32. 32. Case-Control Study Retrospective Exposure Outcome time
    33. 33. Case-Control Study: Structure TARGET CASES ACTUAL CASES Males with prostate cancer Males with prostate cancer confirmedDietary Zinc intake by biopsyYESDietary Zinc intakeNO ACTUAL CONTROLS TARGET admitted to hospital for non- Males CONTROLS Males withoutand non-hormone related neoplastic prostate cancer disease time
    34. 34. Case Control Study: Strength• Simple, fast and inexpensive• Rare outcome & long latency period• Determines the strength of the association between each predictor variable and the presence or absence of disease• Determines odds ratio
    35. 35. Case Control Study: Weakness Can only look at one outcome Confounding variables Bias is a major problem ◦ Selection ◦ Recall
    36. 36. Hierarchy of Study Types Descriptive Analytic •Case report •Case series •Survey Observational Experimental •Cross sectional •Randomized •Case-control controlled trials •Cohort studiesStrength of evidence for causality between a risk factor and outcome
    37. 37. Randomized Controlled Trials
    38. 38. RCTs: Gold standard: Causality Investigator controls the predictor variable (intervention or treatment) Randomization: ◦ The only way to avoid selection and confounding bias
    39. 39. Guarding against Bias: Design Randomization ◦ Simple ◦ Urn method ◦ Computer generated Equal treatment Blinding ◦ Single ◦ Double ◦ Triple
    40. 40. Guarding against Bias: Analysis Sample size Reporting effect size Intention to treat principle
    41. 41. Sample Size Optimal sample size ◦ Type I Error: False positives < 5%P-value < 0.05  Probability that H0 is rejected ◦ Type II Error: False negatives > 20%  Less than 1/20 = statistically significant
    42. 42. P-value & CI Confidence Interval relates to P-value ◦ Confidence level = 95% ◦ Confidence limits = Range Wider CI reflects higher confidence level ◦ Ex. 99% CI when mean age CI = 25 and 29
    43. 43. Effect Size The observed relationship between an intervention and an outcome is statistically expressed as an “estimate of effect” ◦ Odds ratio (OR) or a ◦ Relative risk (RR) True effect size lies within confidence interval
    44. 44. Intention-to-treat analysis: Including and analysing all randomised patients according to their original treatment allocation, irrespective of whether they actually received or completed the treatment. This preserves the unbiased comparison of treatment groups afforded by randomization.
    45. 45. RCTs: Weakness Expensive Legnthy External validity
    46. 46. Systematic Review
    47. 47. Systematic Review Attempts to review all of the relevant articles in the field Uses study design based on the hierarchy of evidence ◦ Most use RCTs (gold standard) Uses clearly defined parameters
    48. 48. Systematic Review Accurate and reliable Reduces large quantities of information into manageable size External validity is more applicable than populations from single studies
    49. 49. Meta-analysis
    50. 50. Meta-analysis Type of systematic review that focuses on numerical results ◦ Uses statistics to integrate findings Can detect small effects across a group of studies that individually lack statistical power to detect the effect Common problem is heterogeneity of studies ◦ Noncompatibility
    51. 51. Rating Quality of Studies
    52. 52. Hierarchy of Evidence
    53. 53. Evidence Based Medicine
    54. 54. EBM Level Therapy/Prognosis/Aetiology 1a SR (with homogeneity) of RCTs 1b Individual RCT (with narrow Confidence Interval) 1c All or none case report/series 2a SR (with homogeneity) of cohort studies 2b Cohort study 3a SR (with homogeneity) of case-control studies 3b Case-Control Study 4 Case-series 5 Expert opinion without explicit critical appraisal, or based on physiology, bench research or "first principles"GRADE system: Grading of Recommendations Assessment, Development & Evaluation
    55. 55. EBM - What is it? Clinical Expertise Research Patient Evidence Preferences
    56. 56. EBM MethodAsk clinical questions Acquire the Appraise best evidence the evidence Apply evidence to patient care
    57. 57. Ask Clinical Questions P I C O Patient/ Intervention/ Population Comparison Outcome Exposure doesIn patients with compared to decrease LUTS? treatment BPH surgery with alpha blocker
    58. 58. Acquire the Best Evidence Where do you find high-quality evidence? ◦ Textbook (print or online) ◦ Pre-appraised evidence  Best Evidence  Clinical Evidence (Therapy only)  Cochrane Collaboration (Therapy only)  UpToDate ◦ Medline or PubMed search: find and review articles
    59. 59. Appraise the Evidence Are the results valid? What are the results? Can we apply the results to our patient?
    60. 60. Appraise the Evidence Determine if evidence is unbiased or flawed ◦ Critically appraise articles yourself ◦ Used a source that appraises trials for you  Best Evidence  Clinical Evidence  Cochrane Library  UpToDate
    61. 61. Apply the Evidence Evidence must be applied to each individual patient ◦ Is your patient similar enough to those studied? ◦ Do benefits outweigh harms? ◦ Cost ◦ What are your patient’s values and preferences?
    62. 62. Take Home Message Research is like riding a bicycle ◦ It needs practice Research needs planning ◦ If you fail to plan, you plan to fail Not all of us need to do research ◦ But all of us should practice EBM
    63. 63. Thank You