“Endpoints are the quantitative measurements implied or required by the trial objectives.
An endpoint is determined in each study subject, whereas the
objectives are met by the aggregate of endpoints.”
Piantadosi (1997), p 127
For example
Asthma trial
objective: “reduced rate of treatment related adverse events such as asthma attacks”
endpoint:
number of attacks suffered?
(In what time-frame?
How diagnosed? How/when followed-up?)
“hard” preferred:
well defined and reliable
no subjectivity: objectively measured
examples: death, presence of ulceration, laboratory measurements (e.g blood pressure, serum cholesterol, weight etc)
“soft”
difficult to define
subjective measures
examples: degree pf satisfaction with treatment, amount of pain (Visual Analogue Scales, VAS), severity of depression (numerical score: 0 - 10, MADRS, HAMD etc.)