INDIVIDUALS' BELIEFS CONCERNING ADHERENCE TO PRESCRIBED ANTIHYPERTENSIVE MEDICATION REGIMENS (HYPERTENSION).

Description

Literature has documented that lack of adherence to antihypertensive medication is a common problem with individuals who have hypertension. Purposes of this study were to test Fishbein and Ajzen's Theory of Reasoned Action in the prediction of behavioral intention and adherence to antihypertensive medication regimen and to determine if the addition of control to the theory increased predictability of behavioral intention and adherence behavior. Additional analyses were carried out to determine the effects of prior behavior on the prediction of behavioral intention. The convenience sample consisted of 100 individuals (M = 66 years of age) who were receiving antihypertensive medications. An instrument was developed using semantic differential techniques and administered to measure attitude toward taking medication, subjective norms, behavioral intentions and control. Both adherence behaviors (self-report of time since last medication and appointment keeping) and physiological indices (systolic blood pressure, diastolic blood pressure and urine levels of hydrochlorothiazide) were indicators of adherence. Data were analyzed by standard, hierarchical and logistic regressions. When attitude and subjective norm were used in predicting behavioral intention, only attitude was a significant predictor of behavioral intention (F (3,97) = 3.98, p $<$.05), accounting for 11% of the variance. Attitude predicted adherence based on time since last antihypertensive medication, hydrochlorothiazide, and the construct of past behavior (F (1,95) = 8.44, p $<$.01), accounting for 9% of the variance. When control was added to the regression, control accounted for appreciably more variance (21%) in behavioral intention beyond attitude and subjective norm (F (1,94) = 10.64, p $<$.05). Control was also found to be a predictor of urine levels of HCTZ (odds ratio 1.19, p $<$.00) when analyzed by logistic regression. Prior behavior was found to be a significant predictor beyond the theory and control variable in the prediction of behavioral intention (E (3,97) = 7.15, p $<$.01). Results of this study indicate that attitudes and perceptions of control influence behavioral intention and adherence behaviors. Also, prior behavior influences behavioral intention, the mediator of behavior. Further tool development and theoretical extension are needed to increase the amount of variance accounted for in the prediction of medication adherence. Findings suggest an analysis of a longitudinal study of the illness to evaluate the effect of adherence over time.

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