Instrumento mensurador de adesão para hipertensos: contribuição da Teoria da Resposta ao Item

Abstract

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. A study of the dimensionality of the instrument was conducted by analyzing the polychoric correlation matrix and factor analysis of complete information. Multilog software was used to calibrate items and estimate the scores. RESULTS:Items relating to drug therapy are the most directly related to adherence while those relating to drug-free therapy need to be reworked because they have less psychometric information and low discrimination. The independence of items, the small number of levels in the scale and low explained variance in the adjustment of the models show the main weaknesses of the instrument analyzed. The "Item Response Theory" proved to be a relevant analysis technique because it evaluated respondents for adherence to treatment for hypertension, the level of diffi culty of the items and their ability to discriminate between individuals with different levels of adherence, which generates a greater amount of information. CONCLUSIONS:The instrument analyzed is limited in measuring adherence to hypertension treatment, by analyzing the "Item Response Theory" of the item, and needs adjustment. The proper formulation of the items is important in order to accurately measure the desired latent trait.

Measuring the quality of life in hypertension according to Item Response Theory

“…This characteristic enables us to understand the meaning of the score, and not only as an indicator of QOL, as presented by the CTT 17 . Its values should be between -5 and 5 as a way to allow the measurement of the QOL on its good and bad aspects 1 .…”

“…The following levels qualitatively showed the worsening points of the QOL that start with symptoms related to the somatic factor, followed by the impairment of the mental state. This interpretation of the levels is a property of IRT models, which enables the creation of a care plan for the patient according to the individual score 17 . Thus, the instrument is suitable for the identification of worsening of the QOL in hypertension.…”

“…The difference in the proportion of patients with hypertension in these two levels should be, at least, 30% 1 . Because it is hard to satisfy all conditions 17 , the categories of items were positioned to achieve the proportion of 65% of response, called almost anchor levels.…”

“…Unlike CTT, which makes assumptions at the test level, IRT makes assumptions at the item level 1 . The IRT is considered a modern theory of psychometrics, as it focuses on each item of the measuring instrument and assumes that the performance of a particular test can be explained by individual characteristics, which are not directly observable, called latent traits 1,17 . Its growth has sophisticated theoretical background about the fundamentals of measurement in behavioral and social sciences, which must be studied and applied to improve the tests produced by CTT and formulate new tests 1 .…”

Translation, cultural adaptation and validation of the Diabetes Attitudes Scale - third version into Brazilian Portuguese

“…In the analysis of the reliability of the instrument, the Polychoric Correlation Coefficient was used, as the response scale is of the categorical ordinal type 16 . As with the Pearson’s linear correlation coefficient, the polychoric correlation coefficient can have values ​​between -1 and 1.…”