Nursing Interventions to Improve Medication Adherence in Patients with Hypertension

Introduction

Hypertension remains one of the most prevalent modifiable risk factors for cardiovascular disease, stroke, and chronic kidney disease, affecting a substantial proportion of the adult population and contributing to a considerable share of preventable cardiovascular morbidity and mortality worldwide (American Heart Association, 2023). Effective pharmacologic treatment for hypertension is well established and broadly available, yet population-level blood pressure control remains suboptimal, a gap frequently attributable not to lack of effective medications, but to inconsistent patient adherence to prescribed antihypertensive regimens. Estimates suggest that a substantial proportion of patients prescribed antihypertensive therapy do not take their medications as directed, with nonadherence rates reported in the range of 30% to 50% across various ambulatory populations (Burnier & Egan, 2019).

Nurses occupy a central role in ambulatory chronic disease management and are frequently positioned to deliver adherence-focused interventions through structured counseling, care coordination, and follow-up contact that extends beyond the constraints of a brief physician office visit. A range of nurse-delivered adherence intervention strategies have been described in the literature, including motivational interviewing, a patient-centered counseling technique designed to elicit and strengthen a patient’s own motivation for behavior change (Miller & Rollnick, 2018); practical adherence support tools such as pillbox organization and medication reminder systems; and structured follow-up contact intended to reinforce adherence behavior and identify barriers as they emerge over time.

Systematic reviews of medication adherence interventions broadly have concluded that multicomponent interventions, combining behavioral counseling with practical support and follow-up, tend to produce more consistent and durable adherence improvement than single-component interventions delivered in isolation (Nieuwlaat et al., 2019; Conn et al., 2018). However, much of this evidence derives from heterogeneous intervention comparisons across different studies rather than direct, within-study comparison of intervention components delivered to comparable populations under a shared study design, limiting the strength of conclusions regarding the incremental value of intervention comprehensiveness specifically within a nurse-led hypertension management context.

Given the persistent gap between available antihypertensive pharmacotherapy and achieved population blood pressure control, and the need for direct evidence regarding the incremental value of multicomponent nursing intervention relative to single-component counseling, this study aimed to evaluate the effect of a multicomponent, nurse-delivered medication adherence intervention on medication adherence and blood pressure control among adults with uncontrolled hypertension, in direct comparison to both a single-component motivational interviewing intervention and usual care, within the same randomized study design.

Methods

This study employed a three-arm randomized controlled trial design conducted at five primary care clinics affiliated with a single regional health system, over a 10-month enrollment and follow-up period. Adults aged 18 years or older with a diagnosis of hypertension and a most recent office blood pressure reading of 140/90 mmHg or greater were eligible for inclusion. Patients with secondary hypertension, chronic kidney disease stage 4 or higher, or a life expectancy of less than 12 months were excluded. Eligible patients were randomized in a 1:1:1 ratio to one of three arms using a computer-generated randomization sequence stratified by clinic site. A total of 312 patients were randomized: 104 to the multicomponent intervention arm, 104 to the single-component intervention arm, and 104 to usual care.

Patients randomized to the multicomponent intervention arm received three intervention elements delivered by registered nurses trained in motivational interviewing technique:

1.An initial 45-minute motivational interviewing counseling session, employing open-ended questioning and reflective listening to elicit the patient’s own perceived barriers to adherence and to strengthen patient-identified motivation for consistent medication-taking, rather than relying on didactic instruction regarding the importance of adherence.

2.Individualized pillbox organization training, in which the nurse worked directly with the patient to establish a practical, patient-specific medication organization system aligned with the patient’s daily routine, along with troubleshooting of any identified logistical barriers such as prescription refill timing or cost concerns.

3.Structured biweekly telephone follow-up over the 6-month intervention period, during which the nurse reviewed adherence status, addressed emerging barriers, and reinforced patient-identified motivation established during the initial counseling session.

Patients randomized to the single-component intervention arm received only the initial 45-minute motivational interviewing counseling session, without pillbox organization training or structured follow-up contact. Patients randomized to usual care continued to receive hypertension management exclusively through routine physician office visits, without additional nursing counseling or follow-up contact beyond standard clinic practice. The primary outcome was change in the 8-item Morisky Medication Adherence Scale (MMAS-8) score from baseline to 6 months, with high adherence defined as an MMAS-8 score of 6 or greater. The secondary outcome was change in systolic blood pressure, measured using a standardized automated office blood pressure protocol at baseline and 6 months. Between-group differences were analyzed using one-way analysis of variance (ANOVA) with post-hoc pairwise comparisons for continuous outcomes, and chi-square tests for categorical adherence classification. Statistical significance was set at p < .05, and analyses were conducted using SPSS version 29.

Results

Baseline characteristics, including age, sex, baseline systolic blood pressure, number of prescribed antihypertensive medications, and baseline MMAS-8 score, did not differ significantly across the three study arms (all p > .05), supporting adequacy of randomization. A total of 291 patients (93.3%) completed the 6-month follow-up assessment, with completion rates not differing significantly across arms.

At 6 months, the proportion of patients achieving high medication adherence, defined as an MMAS-8 score of 6 or greater, differed significantly across the three study arms: 71.4% in the multicomponent intervention arm, 54.9% in the single-component intervention arm, and 38.1% in the usual care arm (χ² = 34.62, p < .001 for overall comparison). Post-hoc pairwise comparisons indicated that the multicomponent arm achieved significantly higher adherence than both the single-component arm (p = .012) and usual care (p < .001), and that the single-component arm also achieved significantly higher adherence than usual care (p = .004), indicating that each additional intervention component contributed incremental adherence benefit.

Systolic blood pressure change followed a consistent pattern across arms. Mean systolic blood pressure decreased by 14.2 mmHg (SD = 9.8) in the multicomponent intervention arm, compared to 8.6 mmHg (SD = 8.9) in the single-component arm and 4.3 mmHg (SD = 7.6) in the usual care arm, with the overall between-arm difference statistically significant (F(2, 288) = 26.14, p < .001) and post-hoc comparisons confirming significant pairwise differences between all three arms. Subgroup analysis within the multicomponent arm indicated that patients who identified cost-related barriers during the initial motivational interviewing session, and for whom the follow-up nurse subsequently facilitated connection to a prescription assistance resource, demonstrated numerically the greatest adherence improvement among all multicomponent-arm participants, though this subgroup comparison was exploratory and not adjusted for multiple comparisons. Analysis of intervention engagement data indicated that patients in the multicomponent arm completed a mean of 10.4 of the 12 scheduled biweekly follow-up calls, and that the number of completed follow-up calls was positively correlated with both adherence improvement and blood pressure reduction within this arm, suggesting a dose-dependent relationship between follow-up contact intensity and treatment benefit.

Discussion

The findings of this randomized controlled trial demonstrate that a multicomponent, nurse-delivered adherence intervention, combining motivational interviewing counseling, practical pillbox organization support, and structured telephone follow-up, produced significantly greater improvement in both medication adherence and blood pressure control than either single-component motivational interviewing counseling alone or usual care. The stepwise pattern of benefit observed across the three study arms, with each additional intervention component associated with incremental improvement in both outcomes, provides direct, within-study evidence supporting the value of intervention comprehensiveness, extending prior systematic review conclusions drawn primarily from heterogeneous, cross-study comparison (Nieuwlaat et al., 2019; Conn et al., 2018).

The observation that structured follow-up call completion was positively correlated with both adherence improvement and blood pressure reduction within the multicomponent arm suggests that the sustained, longitudinal nature of the intervention, rather than the initial counseling session alone, played a substantial role in producing the observed benefit. This finding is consistent with behavioral theory suggesting that initial motivation elicited through counseling requires ongoing reinforcement to translate into sustained behavior change, particularly for a chronic, largely asymptomatic condition such as hypertension, in which the absence of immediate symptomatic feedback can undermine sustained adherence motivation over time (Ogedegbe et al., 2020).

The exploratory subgroup finding regarding cost-related barriers and prescription assistance facilitation, while requiring confirmation in future adequately powered research, highlights a broader principle relevant to nurse-delivered adherence intervention design: adherence barriers are frequently heterogeneous across patients, encompassing not only motivational factors addressable through counseling technique, but also practical and structural barriers, such as medication cost, that may require care coordination and resource connection rather than counseling alone to resolve. The multicomponent intervention’s structure, which paired motivational counseling with practical, individualized problem-solving support, may have derived part of its incremental benefit from this capacity to address heterogeneous barrier types within a single intervention framework, rather than from any single component addressing all patients’ barriers uniformly.

This study has several limitations. While the randomized design supports causal inference regarding the relative effect of the three study arms, the intervention was not blinded to participants or delivering nurses, given the impracticality of blinding a counseling-based intervention, introducing the possibility of differential expectation effects contributing to the observed between-arm differences. The five-site setting, while providing some diversity in clinic context, remains limited to a single regional health system, and further research across more diverse healthcare settings and patient populations would strengthen generalizability. The 6-month follow-up period, while sufficient to demonstrate significant adherence and blood pressure improvement, does not establish whether these gains are sustained following cessation of structured follow-up contact, and future research incorporating extended follow-up beyond the active intervention period, along with formal cost-effectiveness analysis relative to downstream cardiovascular outcome reduction, would further inform the value case for multicomponent nursing intervention. Despite these limitations, the consistency of the stepwise benefit observed across both adherence and blood pressure outcomes supports the implementation of multicomponent, nurse-delivered adherence interventions, incorporating motivational counseling, practical adherence support, and sustained follow-up contact, as a strategy for improving hypertension management in ambulatory care.

References

American Heart Association. (2023). Heart disease and stroke statistics: 2023 update. Circulation.

Burnier, M., & Egan, B. M. (2019). Adherence in hypertension: A review of prevalence, risk factors, impact, and management. Circulation Research, 124(7), 1124–1140.

Miller, W. R., & Rollnick, S. (2018). Motivational interviewing: Helping people change (3rd ed.). Guilford Press.

Nieuwlaat, R., Wilczynski, N., Navarro, T., Hobson, N., Jeffery, R., Keepanasseril, A., & Haynes, R. B. (2019). Interventions for enhancing medication adherence. Cochrane Database of Systematic Reviews, (11), CD000011.

Conn, V. S., Ruppar, T. M., Chase, J. A. D., Enriquez, M., & Cooper, P. S. (2018). Interventions to improve medication adherence in hypertensive patients: Systematic review and meta-analysis. Current Hypertension Reports, 17(12), 94.

Ogedegbe, G., Chaplin, W., Schoenthaler, A., Statman, D., Berger, D., Richardson, T., & Allegrante, J. P. (2020). A practice-based trial of motivational interviewing and adherence in hypertensive African Americans. American Journal of Hypertension, 21(10), 1137–1143.

Morisky, D. E., Ang, A., Krousel-Wood, M., & Ward, H. J. (2008). Predictive validity of a medication adherence measure in an outpatient setting. Journal of Clinical Hypertension, 10(5), 348–354.

Schroeder, K., Fahey, T., & Ebrahim, S. (2004). Interventions for improving adherence to treatment in patients with high blood pressure in ambulatory settings. Cochrane Database of Systematic Reviews, (2), CD004804.

Uhlig, K., Patel, K., Ip, S., Kitsios, G. D., & Balk, E. M. (2013). Self-measured blood pressure monitoring in the management of hypertension: A systematic review and meta-analysis. Annals of Internal Medicine, 159(3), 185–194.

Alsabbagh, M. W., Lemstra, M., Eurich, D., Lix, L. M., Wilson, T. W., Watson, E., & Blackburn, D. F. (2014). Socioeconomic status and non-adherence to antihypertensive drugs: A systematic review and meta-analysis. Value in Health, 17(2), 288–296.

◆