How do you call an outcome if you have multiple endpoints to investigate it?

In the context of clinical research, when you have multiple endpoints to investigate a single outcome, such as exacerbations in asthma, the term often used is "composite endpoint" or "composite outcome." This term is used when multiple individual endpoints are combined into a single, aggregated measure to capture the overall effect on a clinical condition.

However, in your specific case, you are not combining these endpoints into a single measure but rather examining the same outcome (exacerbations in asthma) through different lenses or dimensions. This approach could be described as a "multi-dimensional" or "multi-faceted" analysis of the outcome. Each of the endpoints you mentioned (incidence rate, frequency of patients reporting, and time-to-first-exacerbation) provides a different perspective on the same clinical issue, offering a more comprehensive understanding of the outcome.

So, while "composite endpoint" is a term for combined measures, "multi-dimensional" or "multi-faceted outcome analysis" might be more appropriate for your scenario, where multiple separate endpoints are used to investigate different aspects of the same outcome.