Hazard Ratio
A measure of how quickly an event (such as death or disease progression) occurs in the treatment group compared to the control group. A hazard ratio below 1 indicates the treatment reduces the risk. Hazard ratios are commonly reported in cardiovascular outcomes trials for metabolic peptide drugs.
Technical Context
The HR is derived from Cox proportional hazards regression and reflects the instantaneous risk ratio between groups. HR = 0.80 means the treatment group has 20% lower hazard (instantaneous risk) of the event at any given time point. Key assumptions: proportional hazards (the HR remains constant over time) and non-informative censoring (censored patients don't differ systematically from those remaining). The SELECT trial reported HR 0.80 (95% CI 0.72-0.90) for 3-point MACE with semaglutide 2.4mg, indicating a 20% cardiovascular risk reduction. Kaplan-Meier curves visualise the event-free survival over time and allow assessment of whether the proportional hazards assumption holds (curves should not cross).