Tuesday, May 29, 2007

About the Cohort Definition Tool

As promised, some details about the project...

My original application was for the Clinical Data Visualization Tool, but a slight re-allocation happened and I'll be working with the Cohort Definition Tool.

First of all, the defining the term Cohort is important. At least for me it was, since I wasn't familiar with it. According to the trustful Wikipedia:

"In statistics and demography, a cohort is a group of subjects — most often humans from a given population — defined by experiencing an event (typically birth) in a particular time span. (...)"

Even though this is a very general definition, it's quite applicable to this context. Medically speaking, and particularly in OpenMRS, a cohort is a set of patients with common characteristics. These can be very diverse, from gender, age, types of drugs taken, etc... After defining a cohort, one should be able to act on that set of patients as appropriate, e.g. scheduling an encounter for all male subjects with CD4 count<350.

Darius, who will be mentoring me for the Summer has made very significant progress with the Cohort Builder, as seen on OpenMRS demo website:
A user can already search cohorts according to many variables, conveniently organized in categories and available through the tabbed interface. Cohorts can also be combined with AND and OR operators, or by defining a more complex expressions. The searches can be saved for later use and are stored with cached results (which may not be always accurate, but guarantee a fast UI response to user queries and a good estimate of the number of patients).

As complete as the described tool may be, there's always room for improvement, as with any piece of software. Currently the patients' names are listed together with their age and sex. My work will focus on graphical cohort visualization alternatives. One of the main goals is to have this data organized in one or several plots, customizable by the user. The exact way in which this will be done is still to be decided, but the adopted solution should provide a clean, fast and useful way of viewing cohort data.

More on this to come...


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