The OHDSI Phenotype Development and Evaluation Workgroup has made progress in providing guidance on clinical description (note this is still work in progress and in DRAFT stage), however the key idea .
In Phenotype Phebruary 2022 - I introduced the idea of clinical description as the most important step, and now we assert this is a required first step.
Reason for this assertion is: if we dont spend the time to understand the clinical target being phenotyped, then in the absence of the clinical understanding of a) what it is, b) what it is not, c) how does it start, d) how does it stop, e) how is it managed – we cannot recognize measurement errors in our
- entry event (to improve sensitivity and index date timing - by including all relevant events),
- inclusion rules (to improve specificity - by removing ineligible events),
- exit criteria (how long does it take to resolve).
Today there is no debate on the importance of stating upfront the target clinical ideas description, but we are still struggling with focusing the content as needed by the phenotyper. Clinical description is like a case definition but at the population level and required scientific practice.
Clinical description is important for the peer reviewer. As seen in the interactive session - Appendicitis - peer review - because the clinical description stated upfront that the clinical idea of appendicitis included the spectrum of inflammation of appendix - the peer reviewers agreed that ‘Crohns disease of appendix’ was appendicitis. Clinical description justified design choices made by the phenotyper.
It is the clinical description that articulates the target clinical idea we are trying to model with our cohort definition and justifies design choices.