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Number Need to Treat. remember to round it to whole numbers. Clinical questions. Matching the strongest design to clinical question. Prevalence. Prevalence. Cohort study, case control study. Cohort study. Clinical trial. Clinical trial. Cohort study, case control study.
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Number Need to Treat remember to round it to whole numbers
Clinical questions Matching the strongest design to clinical question Prevalence Prevalence Cohort study, case control study Cohort study Clinical trial Clinical trial Cohort study, case control study
The Six Ds Outcome of Disease • Death • Disease/Illness • Discomfort • Disability • Dissatisfaction • Destitution
All patients with the condition of interest Internal validity Sampling Sample Sample Selection bias Measurement, confounding bias ??? External validity Conclusion
The story of selling bug-killer Well, if this does not kill every of the bug, I will give you $1000000000000000 in return!
Oh! I have forgotten to told you, you have to put the drug into every bug’s mouth! If it does not kill it, don’t hesistate to come back!
Efficacious treatment One that has the desired effects among those who receive it Effective treatment One does more good than harm in those to whom it is offered
Intention to Treat analysis Drop out analyze according to treatment assigned i.e. effectivness Population of patients with the condition sample Cross over Drop out Drop out analyze according to treatment recieved i.e. efficacy Population of patients with the condition Cross over sample Per treatment analysis Drop out
Efficacy Trial Noncompliance Less selected patient Less selected clinician Costs Impracticality Other Internal validity Generalizability Effectiveness Trial Fletcher 3rd
Examination paper 2000/5/30 A randomised clinical trial was carried out with sample size of 500 patients to determine whether drug A or B is better at reducing the number of complications in a particular disease. Both drugs were compared to placebo.
B1a: Calculate the NNT Both drug A and B are more effective than placebo, though drug B is more efficacious than drug A
B1a: Calculate the NNT Drug B is also more effective than drug B as patient more likely to be helped than harmed when they use drug B rather than drug A
B1c: Potential benefits for using NNT • Impact of treatment is related to the baseline risk of the adverse outcome it is designed to prevent • easier to derive risk-benefit analysis before making clinical decision. • easier to interpret than relative risk, odds ration and relative risk reduction and thus easier to communicate with colleagues, nurses and general public. • it is a measure of therapuetic effort required to obtain one beneficial event. Consequently, it is useful in comparing utility of treatments when we have comparable trials with comparable outcomes in comparable patients.