Factors related to intentional and unintentional medication nonadherence in elderly patients with hypertension in rural community

Abstract

Purpose: We assessed medication nonadherence, categorized as intentional or unintentional, and related factors in elderly patients with hypertension, correlating the data with measurement of blood pressure as the final target of medication adherence and other possible influencing factors, such as lifestyle.

Patients and methods: Subjects were aged ≥65 years, resided in a rural area, and were taking antihypertensive drugs. The survey was conducted in July 2014. Participants were divided into the following three groups: "Adherence", "Unintentional nonadherence", and "Intentional nonadherence". Individual cognitive components, such as necessity and concern as well as self-efficacy and other related factors, were compared according to adherence groups. The interrelationships between those factors and nonadherence were tested using structural equation modeling analysis.

Results: Of the 401 subjects, 182 (45.6%) were in the adherence group, 107 (26.7%) in the unintentional nonadherence group, and 112 (27.9%) in the intentional nonadherence group. Necessity and self-efficacy were found to have a significant direct influence on unintentional nonadherence behaviors (necessity β=-0.171, P=0.019; self-efficacy β=-0.433, P<0.001); concern was not statistically significant (β=-0.009, P=0.909). Necessity was found to have significant direct and indirect impact on intentional nonadherence (direct β=-0.275, P=0.002; indirect β=-0.113, P=0.036). Self-efficacy had no significant direct effect on intentional nonadherence though it had the only significant indirect effect on intentional nonadherence (direct β=-0.055, P=0.515; indirect β=-0.286, P<0.001). Concern had no significant influence on intentional or on unintentional nonadherence (direct β=0.132 0.132, P=0.151; indirect β=-0.006, P=0.909).

Conclusion: Unintentional nonadherence should be regularly monitored and managed because of its potential prognostic significance. Interventions addressing cognitive factors, such as beliefs about medicine or self-efficacy, are relatively difficult to implement, but are essential to improve medication adherence.

Keywords: aged; hypertension; medication adherence; self-control; self-efficacy.

Figure 1

Framework of current study. Abbreviation: BMQ, beliefs about medicines questionnaire.

Figure 2

Blood pressure according to medication adherence groups. Left is systolic blood pressure and right is diastolic blood pressure. Note: *P<0.05.

Figure 3

Standardized coefficients of structural equation model. Notes: χ²=122.644, GFI =0.998, AGFI =0.997, TLI =0.972, CFI =0.903, WRMR =0.775 and RMSEA =0.045, *P<0.05, **P<0.01, ***P<0.001. Abbreviations: AGFI, adjusted goodness of fit index; CFI, comparative fit index; GFI, goodness of fit index; RMSEA, root mean square error of approximation; TLI, Tucker-Lewis index; WRMR, weighted root mean square residual.