In this course we discussed the critical importance of a clear case definition. For national and state statistics on disease morbidity and mortality in the US, as well as around the world, the International Classification of Disease 10 (ICD-10-CM) codes are often used. The CDC regularly posts updates on the ICD classifications here (https://www.cdc.gov/nchs/icd/icd10cm.htm#10update). Given the previous case study topic of high blood pressure among cooks using traditional cook stoves, let's start with the example of high blood pressure (i.e. hypertension).

1. What ICD-10-CM code would you use for a case definition of primary hypertension?

2. Define an incident case of hypertension in the context of a 5-year time period.