Event breakdown for outcomes in incidence rate analysis

This is a request for new data / new functionality in Strategus that is sometimes of-interest; to be clear this is "nice to have" and likely low-priority relative to other submitted Strategus issues. A frequent request from those using evidence generated by Strategus is to describe the breakdown of clinical concepts that contribute to the outcome definition. More specifically, the analysis that would be of interest would be to provide the frequency of occurrence of any concept from a concept set used in the highest level (i.e. not nested) events that qualify for cohort entry. It would be of interest to see the breakdown: 1) by person and by record; and 2) by standard codes and source codes. To the extent possible, it would be nice for the display and statistics to align as closely as possible with the current "index event breakdown" functionality within Strategus.

It is straightforward to provide this breakdown for the entire outcome cohort (i.e. not subset to target or indication) if we enter the outcome cohort as a target in CohortDiagnostics and inspect the "index event breakdown" tab. However, the limitation of such an approach is that this breakdown will not subset to patients who are in our target (e.g. exposure) cohort or in our indication/age/calendar time subsets applied within Strategus. In particular, we can imagine drawbacks to that approach when the outcome is extremely common (e.g. infections occurring in the inpatient setting) outside of our population of interest and may have a notably different breakdown of qualifying events once we subset to the target/indication cohorts.

For the few occasions where this analysis is requested, the current the approach that we use is that we produce a derivation of the outcome cohort which subsets to patients with prior target/indication/continuous enrollment/1st in history requirements. With enough tweaking you can often get the numbers to align exactly with the incidence rate analysis in Strategus but doing so requires time-consuming iteration. This cohort, when indexed on the outcome occurrence, can be used in conjunction with a characterization analysis (with features for 0d to 0d) to get an approximate breakdown of codes included in key outcome concept sets.

So to be clear, there are approximate / time consuming approaches to getting this information with the current functionality. However, I think it would be a relatively low-lift to produce this automatically and include the information in the Characterization tab of Strategus. Please reach out to me (mconove1@its.jnj.com) if I can provide more clarity.

Start by reviewing the existing "index event breakdown" functionality in CohortDiagnostics and the Characterization tab, then compare it with the incidence rate analysis subsets described here. Done should provide outcome concept-set frequencies restricted to the Strategus target and indication populations, broken down by person versus record and standard versus source codes.