This guide is fully aligned with the Gravity SDOH IG, in that it uses individual Observations to capture key assessment information.  The only difference is that the Physical Activity IG does not require support for the use of Questionnaire/QuestionnaireResponse and extraction of the Observations from a QuestionnaireResponse.  Doing so is certainly allowed .  However, given the small number of assessment questions and their stability, requiring Questionnaire seemed an unnecessary burden.   The differences between the SDOH Assessment profile and the PA vital sign profiles are as follows: SDOH requires an SDOH category, while PA requires a PA category   SDOH binds Observation.code to an preferred value set of codes that don't include physical activity.  PA binds to a specific set of PA codes tied to national guidelines SDOH allows 'Group' as a subject, which is not a use-case that makes sense for the physical activity space SDOH does not constrain Observation.effective.  PA does, because the measures used are always date-specific and cannot apply to a period of time SDOH doesn't constraint Observation.value.  PA does because all PA assement observations are quantities   PA also defines specific profiles for each of our 4 assessment observations because there are a small (and finite) number.  SDOH cannot do this because the set of assessment observations in the SDOH space is much larger and is not fixed.  Therefore they must use spreadsheets to define what the Observation.value constraints are for each different LOINC code.   In short, every PA vital sign observation will pass validation as an SDOH assessment if you choose to put an "SDOH" category on it.  And you can treat the physical activity IG as just additional entries in the SDOH spreadsheet, so long as you add the "physical activity" category.   The physical activity category is important as it allows distinguishing which observations are appropriate for sharing with physical activity professionals from those that are not.   After discussion, have come to the conclusion that, for physical activity, having a grouping observation is not essential and that requiring the use of one would add complexity to implementers that is unnecessary.  We can always revisit this question in the future if there proves to be a new use-case where standardized grouping would be helpful.