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Fundamentals of Clinical Trials Endpoints Betsy Garofalo MD Michigan Technology and Research Institute. Clinical Trial Features. Study objective – hypothesis testing Type of study comparisons Primary and secondary endpoints Measures taken to minimizing bias
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Fundamentals of Clinical Trials Endpoints Betsy Garofalo MD Michigan Technology and Research Institute
Clinical Trial Features • Study objective – hypothesis testing • Type of study comparisons • Primary and secondary endpoints • Measures taken to minimizing bias • Treatment groups (drug & control), • dosage and dose regimen
Endpoint Definition “Results, condition or events associated with individual study patients that are used to assess study treatments”
Characteristics of Endpoint Measures • Easy to diagnose • Easy to identify no evaluator judgment needed • Free of measurement error • Reliable with repeated measure • Internal validity • Directly linked to property of interest • External validity • Ability to generalize to a wider population
Characteristics of Endpoint Measures • Clinically relevant • Influence Rx choices by physicians and patients • “How” and “When” to prescribe the drug
Surrogate Endpoint • Surrogate endpoint – used instead of direct endpoint – ex BP or Cholesterol LDL • Reduction as 1˚ endpoint as opposed to a reduction in CV morbidity or mortality
“The difference between a surrogate and a true endpoint is like the difference between a check and cash. You often get the check earlier but then, of course, it may bounce.”
Primary, Secondary, Tertiary….. • Primary – single (may be co-endpoint) endpoint parameter for rejection of the null hypothesis – regulatory implication in PhIII • Secondary- other endpoints pre-specified, may be powered for hypothesis testing • Tertiary – exploratory and all other
Example • Epilepsy “Event” of interest: Seizures • Maintain seizure diary for study • Video EEG in infants for accurate counts • Global Impression of Change • QOL scales
Example • Depression/Anxiety “Result” of Interest: Functional improvement/ symptom relief • Hamilton Scale for Depression (HAM-D) • Hamilton Scale for Anxiety (HAM-A) • Global Impression of Change • Suicide rates (small numbers of events, efficacy and safety issue)
Example • Multiple Sclerosis – Relapsing Remitting “Result” of interest: Neurological Disability • “Episodes” of focal Neuro signs and symptoms • Disability rating scales • MRI changes • CSF changes
Example • Diabetic Neuropathy “Event” of Interest: Foot ulcers, foot injuries • Nerve conduction velocity changes • Surrogate measurement • Sensory changes • Rating scales
Conclusions - Endpoints Critical and challenging study design decision • Consider • Phase of development • Disease under study • Characteristics of measure • Question to be answered by trial