What conclusion is supported by a hazard ratio of 0.80 with a 95% confidence interval of 0.73-0.87 in a heart failure study?

A hazard ratio (HR) of 0.80 indicates a 20% reduction in the risk of the event occurring in the treatment group compared to the control group. This is an important finding, especially in a heart failure study where reducing risk factors is crucial for patient outcomes.

The confidence interval (CI) of 0.73 to 0.87 provides further insight into the precision and reliability of the hazard ratio. Since the entire interval is below 1.0, it suggests that there is a statistically significant reduction in the risk of the combined endpoints. If the confidence interval had crossed 1.0, it would have indicated that there could be no significant difference. Thus, the CI supports the conclusion that the observed reduction in risk is not only likely to be real but also statistically significant.

In summary, a hazard ratio of 0.80 with a confidence interval of 0.73-0.87 indicates a statistically significant reduction in the risk of an event occurring, making the conclusion of a statistically significant reduction in combined endpoints well supported by the data.