MM20802

• Efficacy


  The extent to which a specific intervention, procedure, regimen, or service produces a beneficial result under ideal conditions
• Effectiveness


  The benefit or utility to the individual or the population of the service, treatment regimen or intervention
• Ideally the determination of efficacy is based on the results of a randomized control trial
• Strategy for deciding whether a treatment is efficacious


  1. Step I: Is efficacy a biologically plausible consequence of the treatment?

  2. Step II: Are other treatments equally good or better candidates for efficacy?

  3. Step III: Is the timing between the initiation of treatment and the achievement of the treatment target correct?

  4. Step IV: Did the patient comply with the treatment?

  5. Step V: Does the treatment target worsen when the treatment is withdrawn?

  6. Step VI: Does the treatment target improve when the treatment is reinitiated?
• Clinical trial


  A planned experiment on human beings which is designed to evaluate the effectiveness of one or more forms of treatment
• Phases of clinical trials within the pharmaceutical industry

  • Phase I: Clinical pharmacology and toxicity
  • Phase II: Initial clinical investigation
  • Phase III: Full scale evaluation of treatment
  • Phase IV: Post-marketing surveillance
• Randomized double-blind controlled trial


  • Usually taken as the 'gold standard' for the design of a clinical trial
• Random allocation


  Gives all subjects the same chance of receiving either treatment in an unbiased way
• Minimization


  A non-random method suitable for smaller trials and for trials where small numbers of patients are recruited from each several centers
• Method of minimization

  1. First patient given treatment at random

  2. For each subsequent patient, determine which treatment would lead to better balance between the groups

  3. Patient then randomized using a weighting in favour of the treatment which would minimize imbalance

  4. Preferable treatment for new patient is that of the smaller total

  5. Process repeated for next patient
• Other methods of treatment allocation

  • Systematic allocation (pseudo-random)
  • Non-random concurrent controls
  • Historical controls
• Blinding


  Both patient and doctor may be affected in the way they respectively respond and observed by knowledge of which treatment was given
• Double-blind


  Neither the patient nor the person evaluating the patient knows which treatment was given
• Single-blind


  Only the patient is unaware of which treatment was given
• Placebo


  Inert dummy or treatment given to control group
• Reasons for using a placebo

  • Placebo effect - the act of taking some treatment may itself have some benefit to the patient
  • To make a study double-blind, the treatment must be indistinguishable from the placebo
• Summary steps in conducting a clinical trial

  1. Criteria for selecting study participants

  2. Measure baseline variables

  3. Randomization

  4. Blinding the intervention

  5. Choice of intervention

  6. Include a comparison with a placebo control