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TI Pharma Sep 2010
Transcript of TI Pharma Sep 2010
Medicines Evaluation Board DDC course in individual level Correlational studies Case reports
Case series Cross-sectional surveys Interventional studies Clinical trials in population level What is the main difference between Case-control and Cohort studies? Selection of the groups! is based on patients with and without Adverse Events is based on users and non-users of the medicinal product What about Prospective and Retrospective studies? Adverse Events have already happened before the beginning of the study Adverse Events would happen after the beginning of the study Random error (chance) Systematic error (bias) Sample size Variability Which one is better to use:
P-value or Confidence Interval? shows only the statistical significance,
but NOT the variability of the finding shows both the statistical significance, AND the variability of the finding And what "Power of the study" has to do with it? is a distribution, which dependens on the magnitude of the outcome we expect depends on the variability
of the study samples Meta-analysis Spontaneous Reporting System Signal Detection is more a statistical “detection method”
than an epidemiological “study design” Proportional Reporting Ratio (PRR) I'm confused! How shall I decide which design is better? How common is the outcome? (Adverse Event) How frequent is the exposure? (Medicine Usage) How much money and time do we have? (Resources) Case-control is better for rare events, because we start from all we have, and not waiting! Cohort is better for lower exposure, because we start from all we have, and not digging hopelessly! Cohorts are usually much more expensive and time consuming! Response Bias
Assessment Bias [clinical trials]
Allocation Bias [clinical trials]
Population admixture [genetic epidemiology]
Berksonian Bias (Admission Bias)
Hawthorne effect (Behavior bias)
Loss to follow-up
Healthy worker effect
… Selection Bias Information Bias Confounding Bias Publication Bias (meta-analyses) Recall Bias (case-control studies) effect of a third factor that is related to both the medicine and the adverse event Oral Contraceptive use breakthrough bleeding increased chance of detecting uterine cancer Allocation Bias (clinical trials) higher risk of venous thromboembolism (VTE) women with a baby with a birth defect are more likely to remember having taken a medication Non-response Bias (cohort studies) Assessment Bias (clinical trials)
Diagnosis Bias (cohort studies) younger people are more likely to move to another place and be lost in follow-up ...and what can we do? Sources of error in epidemiological studies Prescription bias (cohort studies) Diagnosis Bias (case-control studies) Analytic studies Descriptive studies e.g. One case of Guillain-Barré Syndrome after Vaccination e.g. Thromboembolic Adverse Events After Use of Human Coagulation Factor VIIa Prospective Retrospective Case-Control Cohort if blindness of a study is broken, the investigator may check the users more thoroughly for adverse events In design: In analysis: Restriction
Matching Multivariate analysis
Stratification Case-control decreased chance of using Oral Contraceptives Obesity Observational studies Cohort Compare outcomes Draw conclusion User group Follow over time Non-user group Case group Control group Take history Compare outcomes Draw conclusion