Study timeline

The importance of dates

Each of the criteria we’ve discussed so far is also associated with a date. For example, the date a patient fills a prescription is the dispensation date, which is routinely recorded alongside drug codes, duration and other medication information. Similarly, diagnosis codes are also associated with a date. Depending on what kind of data the diagnosis comes from, the associated date may represent a patient’s visit to an emergency room or doctor’s office, or the date of admission and discharge for hospitalization. There are of course other dates available in administrative health data that are not associated with a particular healthcare visit, such as birth dates, death dates, dates when insurance coverage starts and stops etc.

Therefore, it is also important to consider when in time you will be looking for these factors during the cohort creation process.

The study timeline

The study timeline is made up of two types of dates: 

1. Study-specific dates, which apply to all individuals in the cohort, and
2. Patient-specific dates, which relate only to an individual patient in the cohort.

Click on each of the components of the project time frame below to learn more about each one:

Exercises

Question 1. Sort the following timeline components based on whether they refer to the study as a whole, or to an individual patient.

Now that you know the basics, in the next section we will start building our own study cohort using a real CNODES protocol.