[Instrument to measure adherence in hypertensive patients: contribution of Item Response Theory].

Objective: To analyze, by means of "Item Response Theory", an instrument to measure adherence to t treatment for hypertension.

Methods: Analytical study with 406 hypertensive patients with associated complications seen in primary care in Fortaleza, CE, Northeastern Brazil, 2011 using "Item Response Theory". The stages were: dimensionality test, calibrating the items, processing data and creating a scale, analyzed using the gradual response model.