How does prescribing for antihypertensive products stack up against guideline recommendations? An Australian population-based study (2006-2014)

Blood pressure—lowering medication prescribing, its adherence to guidelines and relationship with blood pressure control at a family medicine department

Background

In many resource‐constrained countries, control of blood pressure (BP) is low. Antihypertensive drug prescribing practices may influence BP control. However, adherence of prescribing to treatment guidelines may not be optimal in resource‐constrained settings. The aim of this study was to evaluate the pattern of blood pressure‐lowering medication prescribing, and how it adheres to treatment guidelines, and to identify the relationship between medication prescriptions and BP control.

Methods

It was a cross‐sectional study of hypertensive outpatients at the Korle Bu Teaching Hospital (KBTH) Family Medicine department (FMD)/Polyclinic. Data was collected with a validated structured form. Adherence of “prescribing” to recommendations of the 2017 Standard Treatment Guidelines of Ghana and 2018 European Society of Cardiology guidelines was assessed using a composite measure. We analyzed data with SPSS.

Results

About 81% (247/304) of patients received two or more antihypertensive drugs. Most patients (41%; 267/651) received calcium channel blockers (CCB), and 21.8% (142/651), 15.7% (102/651) and 12.7% (83/651) were on diuretics, angiotensin‐receptor blockers (ARBs) and angiotensin converting enzyme (ACE) inhibitors respectively. CCB plus RAS inhibitor (50%) was the most prescribed two‐drug combination. Number of BP drugs per patient had a statistically significant inverse relationship with BP control (beta Coefficient = –0.402; 95% Cl: 1.252–2.470; p = 0.015). The composite adherence score was 0.73 (moderate adherence) but Single‐pill combination (SPC) was poor (3.2%; n = 8).

Conclusion

Most patients received multiple‐pill combination treatment, and overall adherence to guidelines was suboptimal, largely owing to complex drug therapy. Number of drugs predicted BP control. Our findings suggest a need to prioritize simplified treatment, and implement other strategies to improve hypertension guideline adherence. Further research on the influence of SPC on BP control may inform future hypertension guidelines in Ghana and elsewhere in Africa.

Are We There Yet? Exploring the Use of Single-Pill Combination Therapy in the Management of Raised Blood Pressure in Australia

OBJECTIVE

Single-pill combination (SPC) therapy is recommended as first-line therapy for most patients in global hypertension guidelines due to benefits of improved adherence and blood pressure (BP) control. We aimed to understand factors affecting SPC use in the management of raised BP in Australia.

DESIGN

A mixed-method study comprising of qualitative (policy review and interviews) and quantitative (Pharmaceutical Benefits Scheme [PBS] data) approaches.

MAIN OUTCOME MEASURES

Australian and international hypertension guideline recommendations regarding SPC use; the Australian registration and subsidy approval processes of SPCs; use of SPCs on the PBS; cost-analysis of PBS-listed SPCs compared to free-drug combinations; perceptions of healthcare providers towards SPCs.

RESULTS

The 2016 Australian Heart Foundation's "Guideline for the diagnosis and management of hypertension in adults" does not recommend combination therapy (including SPCs) as first-line treatment. Additional challenges in the uptake of SPCs include: (1) the additional PBS requirements and barriers imposed for the listing of SPCs. (2) Script volumes for SPCs have not matched the rise in the number of SPCs listed for subsidy, have plateaued since 2016 and remained significantly lower than single constituent scripts. (3) SPCs are not subsidised by the PBS for initial treatment. Most SPCs provided substantial cost savings for individual patients compared to free-drug combinations. Health care providers were positive about the cost-saving and convenience of SPCs, however perceived negatives included inflexibility of SPCs during dose titration, medicine shortages, and potential adverse effects when initiating treatment with multiple drugs.

CONCLUSION

The safety, efficacy and cost-saving potential of SPCs have been established in the literature but several roadblocks in the existing health system in Australia impede uptake. Interventions addressing these barriers may facilitate improved uptake, which may in turn improve blood pressure control in Australia.

Incidence and risk factors of hypertension therapy in Australian cancer patients treated with vascular signalling pathway inhibitors

BACKGROUND

Clinical trials report systemic hypertension is an adverse effect of vascular signalling pathway inhibitor (VSPi) use. There are limited data from routine clinical practice. We aimed to estimate the real-world incidence and risk factors of new-onset and aggravated hypertension for cancer patients dispensed VSPi in whole-of-population Australian setting.

METHODS

We used dispensing records for a 10% random sample of Australians to identify treatment with subsidised VSPi from 2013 to 2018. We further identified dispensings of oral antihypertensive medicines 6 months before and 12 months after VSPi therapy. We defined (i) new-onset hypertension in people first dispensed antihypertensives after VSPi and (ii) aggravated hypertension in people with prior antihypertensive use dispensed an additional, or higher strength, antihypertensive after VSPi. We applied the Fine-Gray cumulative incidence function and Cox proportional hazard regression.

RESULTS

1802 patients were dispensed at least one VSPi. The mean age of the cohort was 65 years and 57% were male. The incidence of new-onset treated hypertension was 24.3% (95%CI: 21.2-27.8); age ≥ 60 years (HR 1.74; 95%CI: 1.32-2.31) and treatment with oral tyrosine kinase inhibitors compared to bevacizumab (HR 1.96; 95%CI: 1.16-3.31) were risk factors. The incidence of aggravated hypertension was 25.2% (95%CI: 22.0-28.7) and risk was elevated for patients with renal cancer (HR 2.84; 95%CI: 1.49-5.41) and cancers other than colorectal (HR 1.85; 95%CI: 1.12-3.03).

CONCLUSIONS

Our real-world estimates of incident hypertension appear comparable to those observed in clinical trials (21.6-23.6%). Our population-based study provides some insight into the burden of hypertension in patients commencing VSPi in routine practice.

Antihypertensive medication use and blood pressure control among treated older adults

The association of different antihypertensive regimens with blood pressure (BP) control is not well-described among community-dwelling older adults with low comorbidity. We examined antihypertensive use and BP control in 10 062 treated hypertensives from Australia and the United States (US) using baseline data from the ASPirin in Reducing Events in the Elderly (ASPREE) trial. Renin-angiotensin system (RAS) drugs were the most prevalently used antihypertensive in both countries (Australia: 81.7% of all regimens; US: 62.9% of all regimens; P < .001). Diuretics were the next most commonly used antihypertensive in both countries, but were more often included in regimens of US participants (48.9%, vs 33.3% of regimens in Australia; P < .001). Among all antihypertensive classes and possible combinations, monotherapy with a RAS drug was the most common regimen in both countries, but with higher prevalence in Australian than US participants (35.9% vs 20.9%; P < .001). For both monotherapy and combination users, BP control rates across age, ethnicity, and sex were consistently lower in Australian than US participants. After adjustment for age, sex, ethnicity, and BMI, significantly lower BP control rates remained in Australian compared to US participants for the most commonly used classes and regimens (RAS blocker monotherapy: BP control = 45.5% vs 54.2%; P = .002; diuretic monotherapy: BP control = 45.2% vs 64.5%; P = .001; and RAS blocker/diuretic combo: BP control = 50.2% vs 65.6%; P = .001). Our findings highlight variation in antihypertensive use in older adults treated for hypertension, with implications for BP control. Differences in BP control that were observed may be influenced, in part, by reasons other than choice of specific regimens.

Antihypertensive polytherapy in Australia: prevalence of inappropriate combinations, 2013-2018

OBJECTIVES

To estimate the prevalence of inappropriate antihypertensive polytherapy in Australia.

METHODS

We used a nationally representative 10% sample of Pharmaceutical Benefits Scheme (PBS) eligible Australians and their dispensing history to identify people aged 18+ years exposed to at least one PBS-listed antihypertensive between 2012 and 2018. We measured prevalence of antihypertensive polypharmacy (≥40 days concomitant exposure), inappropriate antihypertensive combinations (against guideline recommendations; within-class polytherapy) and combinations to be used with caution.

RESULTS

Almost half (47.5%) of people using antihypertensives in 2018 experienced polytherapy. Among these, 2.4% had an inappropriate combination (1.5% against guidelines; 1.0% within-class polytherapy). Inappropriate combinations were more prevalent in people experiencing polytherapy with three (3.7%) or four (16.1%) antihypertensive medicines than people on dual therapy (0.7%). Inappropriate combinations occurred at a lower rate in people using fixed-dose rather than free-drug combinations for dual therapy (0 vs. 0.7%) and in those using three antihypertensives (2.4 vs. 7.3%); this was not the case for people using four or more antihypertensives (15.5 vs. 16.1%). Between 2013 and 2018, the prevalence of antihypertensive polytherapy was relatively stable (49-47%); however, the prevalence of inappropriate combinations among these patients halved (from 5.1 to 2.4%).

CONCLUSION

Antihypertensive polytherapy in Australia is common, but the prevalence of inappropriate combinations is low and decreasing over time, suggesting strong awareness of Australian clinical guidelines. However, in 2018, approximately 49 000 Australian adults experienced inappropriate polytherapy; prescribing of fixed-dose combinations in patients on dual or triple therapy may further reduce this inappropriate care, although increased vigilance treating patients with more than 3 antihypertensives is required.

Dynamics of switching, adherence, and persistence of dipeptidyl peptidase-4 inhibitors use: A nationwide cohort study

AIMS

To characterise the patterns of switching, adherence, and persistence among adults aged ≥18 years with diabetes prescribed dipeptidyl peptidase-4 inhibitors (DPP-4is) in Australia.

METHODS

The analysis included 15,915 adults newly prescribed DPP-4is (sitagliptin = 9576; vildagliptin = 1130; saxagliptin = 1126; linagliptin = 3560; and alogliptin = 523). Multivariable logistic regression model was used to compare the non-adherence (proportion of days covered [PDC] <0.80) rates whereas Cox proportional hazards regression models were used to compare switching and non-persistence (≥90-day gap) among different DPP4-is over 12-months.

RESULTS

Overall, 36.0% (5722/15,915) of DPP-4i users were non-adherent and 30.0% (4775/15,915) were non-persistent at 12-months. Compared to sitagliptin, vildagliptin, linagliptin, and alogliptin were not associated with higher non-adherence and non-persistence. However, saxagliptin was associated with a higher likelihood of being non-adherent (odds ratio 1.41, 95% confidence interval [CI] 1.23-1.60) or non-persistent (hazard ratio 1.27, 95% CI 1.15-1.42) compared to sitagliptin. Just 3.2% of people switched between different DPP-4is. Compared to sitagliptin, people initiated on vildagliptin, saxagliptin, alogliptin, and linagliptin were more likely to switch.

CONCLUSIONS

We found no significant differences in the adherence and persistence rates between alogliptin, vildagliptin or linagliptin and sitagliptin. However, saxagliptin was associated with higher non-adherence and non-persistence compared to sitagliptin. Switching was lowest amongst users of sitagliptin.

Fixed-dose combination antihypertensive medications, adherence, and clinical outcomes: A population-based retrospective cohort study

BACKGROUND

The majority of people with hypertension require more than one medication to achieve blood pressure control. Many patients are prescribed multipill antihypertensive regimens rather than single-pill fixed-dose combination (FDC) treatment. Although FDC use may improve medication adherence, the impact on patient outcomes is unclear. We compared clinical outcomes and medication adherence with FDC therapy versus multipill combination therapy in a real-world setting using linked clinical and administrative databases.

METHODS AND FINDINGS

We conducted a population-based retrospective cohort study of 13,350 individuals 66 years and older in Ontario, Canada with up to 5 years of follow-up. We included individuals who were newly initiated on one angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II-receptor blocker (ARB) plus one thiazide diuretic. High-dimensional propensity score matching was used to compare individuals receiving FDC versus multipill therapy. The primary outcome was a composite of death or hospitalization for acute myocardial infarction (AMI), heart failure, or stroke. We conducted 2 analyses to examine the association between adherence and patient outcomes. First, we performed an on-treatment analysis to determine whether outcomes differed between groups while patients were on treatment, censoring patients when they first discontinued treatment, defined as not receiving medications within 150% of the previous days' supply. Second, we conducted an intention-to-treat analysis that followed individuals allowing for breaks in treatment to quantify the difference in drug adherence between groups and assess its impact on clinical outcomes. As expected, there was no significant difference in the primary outcome between groups in the on-treatment analysis (HR 1.06, 95% CI 0.86-1.31, P = 0.60). In the intention-to-treat analysis, the proportion of total follow-up days covered with medications was significantly greater in the FDC group (70%; IQR 19-98) than in the multipill group (42%, IQR 11-91, P < 0.01), and the primary outcome was less frequent in FDC recipients (3.4 versus 3.9 events per 100 person-years; HR 0.89, 95% CI 0.81-0.97, P < 0.01). The main limitations of this study were the lack of data regarding cause of death and blood pressure measurements and the possibility of residual confounding.

CONCLUSIONS

Among older adults initiating combination antihypertensive treatment, FDC therapy was associated with a significantly lower risk of composite clinical outcomes, which may be related to better medication adherence.

Prior experience with cardiovascular medicines predicted longer persistence in people initiated to combinations of antihypertensive and lipid-lowering therapies: findings from two Australian cohorts

PURPOSE

Many studies of persistence involving fixed dose combinations (FDCs) of cardiovascular medicines have not adequately accounted for a user's prior experience with similar medicines. The aim of this research was to assess the effect of prior medicine experience on persistence to combination therapy.

PATIENTS AND METHODS

Two retrospective cohort studies were conducted in the complete Pharmaceutical Benefits Scheme prescription claims dataset. Initiation and cessation rates were determined for combinations of: ezetimibe/statin; and amlodipine/statin. Initiators to combinations of these medicines between April and September 2013 were classified according to prescriptions dispensed in the prior 12 months as either: experienced to statin or calcium channel blocker (CCB); or naïve to both classes of medicines. Cohorts were stratified according to formulation initiated: FDC or separate pill combinations (SPC). Cessation of therapy over 12 months was determined using Kaplan-Meier survival analysis. Risk of cessation, adjusted for differences in patient characteristics was assessed using Cox proportional hazard models.

RESULTS

There were 12,169 people who initiated combinations of ezetimibe/statin; and 26,848 initiated combinations of amlodipine/statin. A significant proportion of each cohort were naïve initiators: ezetimibe/statin cohort, 1,964 (16.1%) of whom 81.9% initiated a FDC; and amlodipine/statin cohort, 5,022 (18.7%) of whom 55.4% initiated a FDC. Naïve initiators had a significantly higher risk of ceasing therapy than experienced initiators regardless of formulation initiated: ezetimibe/statin cohort, naïve FDC versus experienced FDC HR=3.0 (95% CI 2.8, 3.3) and naïve SPC versus experienced SPC HR=4.4 (95% CI 3.8, 5.2); and amlodipine/statin cohort naïve FDC versus experienced FDC HR=2.0 (95% CI 1.8, 2.2) and naïve SPC versus experienced SPC HR=1.5 (95% CI 1.4, 1.6).

CONCLUSION

Prescribers are initiating people to combinations of two cardiovascular medicines without prior experience to at least one medicine in the combination. This is associated with a higher risk of ceasing therapy than when combination therapy is initiated following experience with one component medicine. The use of FDC products does not overcome this risk.

How does prescribing for antihypertensive products stack up against guideline recommendations? An Australian population-based study (2006-2014)

AIMS

We describe choice of first-line antihypertensive drug therapy and uptake of fixed-dose combinations (FDCs) in Australia, and investigate the impact of initiation on FDCs and other non-recommended first-line therapies on treatment discontinuation.

METHOD

This was a population-based retrospective cohort study using a random 10% sample of persons dispensed an Australian Pharmaceutical Benefits Scheme listed medicine from 1 July 2005 to 30 June 2014. The primary outcomes were adherence to Australian recommendations at initiation of antihypertensive therapy, discontinuation of initial therapy and discontinuation of any therapy in the first year after initiation.

RESULTS

In our sample of 55 937 persons initiating therapy, 42.0% did so outside Australian recommendations, including not initiating on recommended monotherapy (26.3%) and not initiating on the lowest recommended dose (30.6%). Only 1.7% of individuals who were dispensed an FDC established therapy on the free combination regimen (as recommended) prior to switching. After adjusting for covariates, persons initiating on non-recommended monotherapy (OR = 2.64, 95% CI 2.47-2.83) or FDCs of two or more antihypertensives (OR = 1.42, 95% CI 1.30-1.55), were more likely to discontinue all antihypertensive drug treatment in the first year compared to persons initiating on recommended monotherapy.

CONCLUSION

More than half of antihypertensive initiators conformed to Australian guidelines. Initiation on FDCs and other non-recommended treatments was associated with lower persistence on antihypertensive therapy in the first year. Long-term effectiveness and outcomes may be enhanced by initiating with low dose monotherapy.