Medication adherence before an increase in antihypertensive therapy: A cohort study using pharmacy claims data

Factors influencing adjudicative competence and length of time to restoration

Few studies on adjudicative competence explore the relationship between diagnosis, treatment, and restorability. Most focus on demographics and major psychiatric diagnosis with very few exploring the diagnoses common to the forensic population (i.e., personality disorders and substance abuse). Our study of 365 defendants who were incompetent to stand trial at a state psychiatric facility indicates that non-restored defendants have a greater likelihood of cognitive disorders, misdemeanor charges, and histories of prior hospitalization, and less likelihood of personality disorders. In addition, the odds of having a substance use disorder and being medication non-adherent was greater among restored defendants. The mean length of time to restoration (LOR) of 56 days was significantly different from the mean length of time to adjudication (LOA) for those not restored (88 days). This study supports prior literature on restorability while distinguishing those treated for psychosis from those treated for substance use and personality disorder. In its novel focus on medication adherence, the study expands the remediable factors available to clinical and forensic professionals and supports interventions that improve treatment and shorten the time to restoration.

Medication Adherence and the Risk of Cardiovascular Mortality and Hospitalization Among Patients With Newly Prescribed Antihypertensive Medications

The importance of adherence to antihypertensive treatments for the prevention of cardiovascular disease has not been well elucidated. This study evaluated the effect of antihypertensive medication adherence on specific cardiovascular disease mortality (ischemic heart disease [IHD], cerebral hemorrhage, and cerebral infarction). Our study used data from a 3% sample cohort that was randomly extracted from enrollees of Korean National Health Insurance. Study subjects were aged ≥20 years, were diagnosed with hypertension, and started newly prescribed antihypertensive medication in 2003 to 2004. Adherence to antihypertensive medication was estimated as the cumulative medication adherence. Subjects were divided into good (cumulative medication adherence, ≥80%), intermediate (cumulative medication adherence, 50%–80%), and poor (cumulative medication adherence, <50%) adherence groups. We used time-dependent Cox proportional hazards models to evaluate the association between medication adherence and health outcomes. Among 33 728 eligible subjects, 670 (1.99%) died of coronary heart disease or stroke during follow-up. Patients with poor medication adherence had worse mortality from IHD (hazard ratio, 1.64; 95% confidence interval, 1.16–2.31; P for trend=0.005), cerebral hemorrhage (hazard ratio, 2.19; 95% confidence interval, 1.28–3.77; P for trend=0.004), and cerebral infarction (hazard ratio, 1.92; 95% confidence interval, 1.25–2.96; P for trend=0.003) than those with good adherence. The estimated hazard ratios of hospitalization for cardiovascular disease were consistent with the mortality end point. Poor medication adherence was associated with higher mortality and a greater risk of hospitalization for specific cardiovascular diseases, emphasizing the importance of a monitoring system and strategies to improve medication adherence in clinical practice.

Utilization patterns of antihypertensive drugs among the chronic kidney disease population in the United States: a cross-sectional analysis of the national health and nutrition examination survey

PURPOSE

Antihypertensive drugs are prescribed to patients with chronic kidney disease (CKD) for their cardioprotective and renoprotective effects. Nationally representative information on the use of antihypertensive drugs among CKD patients is limited. The purpose of this study was to assess the utilization patterns of antihypertensive drugs among the CKD population (stages I-IV) in the United States.

METHODS

We conducted a retrospective cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) panels from 2005-2006, 2007-2008, and 2009-2010. The estimated glomerular filtration rate was calculated and kidney damage was assessed to identify participants with CKD. The demographic and clinical characteristics of the participants with CKD were reported, as were the antihypertensive drugs they used.

FINDINGS

A total weighted sample of 116,231,361 participants representative of the CKD population in the United States (stages I-IV) was identified. Less than one half of the participants with CKD in the NHANES were using antihypertensive drugs. β-blockers were the most commonly used and angiotensin II receptor blockers were the least used antihypertensive agents among participants with CKD. Age (≥70 years), awareness of hypertension or diabetes, and higher stage of CKD were associated with an increased likelihood of antihypertensive drug use among participants with CKD.

IMPLICATIONS

The results of our analyses suggest that antihypertensive drugs are underused in the CKD population, and the use of preferred agents (ie, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers) is low. Efforts should be directed toward emphasizing the importance of using antihypertensive drugs in the CKD population.

Relation of statin nonadherence and treatment intensification

Failure to intensify medication and failure to adhere to medication have been shown to contribute to suboptimal low-density lipoprotein cholesterol goal attainment. To examine whether nonadherence to statins in 126,903 patients on stable statin therapy is associated with subsequent treatment intensification, we conducted a retrospective analysis using an integrated pharmacy and medical claims database. Pharmacy claims were analyzed to determine whether nonadherence, as measured by proportion of days covered on statins <80%, was associated with intensification of statin treatment over a 360-day follow-up. Of 11,361 patients who had treatment intensification, 44% were previously nonadherent to statins. Patients whose treatment was intensified had slightly lower adherence to statin therapy than those without intensification (76% vs 78%, p <0.0001) and were more likely to be nonadherent as defined by proportion of days covered <80% (44% vs 37%, p <0.0001). After controlling for confounding factors, patients nonadherent to statins were 30% more likely to have treatment intensification compared to adherent patients (odds ratio 1.30, 95% confidence interval 1.25 to 1.36). In addition, patients with statin intensification were more likely to be younger, women, and have coronary artery disease, diabetes, hypertension, dyslipidemia, stroke, peripheral arterial disease, heart failure, or depression. Primary care physicians were more likely to escalate therapy than cardiologists. In conclusion, nearly 1/2 of patients with therapy escalation were nonadherent to statins. Clinicians should inquire about adherence and consider adherence before escalating statin therapy.

Factors influencing antihypertensive medication compliance in Taiwan: a nationwide population-based study

BACKGROUND

Poor medication compliance with antihypertensive drugs may have a significant impact on clinical outcomes, hospitalisation and healthcare expenditure. This study aims to assess medication compliance and its underlying factors in patients receiving antihypertensive drugs in Taiwan.

METHODS

This retrospective population-based study was based on data from Taiwan's Longitudinal Health Insurance Database (LHID). All patients (n = 78,558) were aged 30 years or more and had received at least one antihypertensive prescription between January 2004 and December 2007. We used the medication possession ratio (MPR) as an index to measure the level of medication compliance.

RESULTS

Approximately 53% of the patients had high compliance with antihypertensive medication. Factors that were positively associated with medication compliance included patients being aged 30-44 years, higher comorbidity scores (odds ratio (OR): 1.18; 95% confidence interval (CI): 1.08-1.28), the same prescribing physician being visited and a single-drug therapy being prescribed. Female sex (OR: 0.92; 95% CI: 0.89-0.95) and higher socioeconomic status (OR: 0.91; 95% CI: 0.86-0.96) were negatively associated with drug compliance. In addition, high-compliance patients were less likely to be treated at medical centres, corporations (OR: 0.89; 95% CI: 0.84-0.93) or rural (OR: 0.88; 95% CI: 0.83-0.94) institutions.

CONCLUSION

Several patient- and institution-related factors may influence medication compliance. Therefore, for optimal outcomes, patients' awareness of the need for compliance with antihypertensive therapy must be enhanced, and effective intervention strategies should be developed.

Does an increase in non-antihypertensive pill burden reduce adherence with antihypertensive drug therapy?

Objectives

Hypertensive patients often are prescribed multiple medications for their hypertension as well as for other chronic conditions. Poor adherence has been both positively and negatively associated with increasing numbers of medications or required daily doses. We sought to determine whether adherence with antihypertensive drugs changes in response to a change in non-antihypertensive pill burden.

Methods

This retrospective cohort analysis used 2006–2007 US MarketScan Medicare Supplemental and Coordination of Benefits administrative data. The study sample comprised 471 359 beneficiaries diagnosed with hypertension. We measured monthly proportion of days covered (PDC) with antihypertensive medications and average number of daily doses with non-antihypertensive drugs (pill burden). We assessed the effect of changes in pill burden on subsequent changes in antihypertensive PDC using difference equations with sensitivity tests for the sign and magnitude of monthly change in pill burden and the presence of physician visits.

Key findings

Changes in monthly non-antihypertensive pill burden had essentially no impact on antihypertensive adherence rates for Medicare beneficiaries in retiree health plans. A monthly addition of one non-antihypertensive pill/day resulted in a statistically significant reduction in the following month's antihypertensive medication PDC of approximately one percentage point (−0.98). Similar results were obtained in a 3-month lag model (−0.88). These findings were insensitive to changes in model parameters.

Conclusions

while physicians should pay close attention to individual factors that may affect their patients' adherence to antihypertensive medications, our findings indicate that changes in medications used to treat concomitant diseases should have little short-term impact on antihypertensive adherence.

A High Level of Patient Activation Is Observed But Unrelated to Glycemic Control Among Adults With Type 2 Diabetes

OBJECTIVE

To measure patient activation and its relationship to glycemic control among adults with type 2 diabetes who had not participated in a formal diabetes self-management education program as a baseline assessment for tailoring diabetes education in a primary care setting.

RESEARCH DESIGN AND METHODS

Patient activation was assessed in a stratified, cross-sectional study of adults with controlled (n = 21) and uncontrolled (n = 27) type 2 diabetes, who were receiving primary care at a unique family practice center of Baylor Health Care System in Dallas, Tex.

RESULTS

The mean patient activation was 66.0 (95% confidence interval [CI] 60.8-71.2) among patients with uncontrolled diabetes and 63.7 (55.9-71.5) among those with controlled diabetes (P = 0.607). A significant association was observed between the self-management behavior score and activation among patients whose glycemia was under control (ρ = 0.73, P = 0.01) as well as among patients with uncontrolled glycemia (ρ = 0.48, P < 0.001).

CONCLUSIONS

Although activation is correlated with self-management and may be important in tailored patient-centered approaches to improving diabetes care outcomes, the highest stage of activation may be necessary to achieve glycemic control. These findings reinforce the importance of conducting prerequisite needs assessments so diabetes educators are able to tailor their educational interventions to individual patients' needs and readiness to take action.

Differences in adherence to antihypertensive medication regimens according to psychiatric diagnosis: results of a Korean population-based study

OBJECTIVE

To identify the relationship between various types of psychiatric disorders and adherence to antihypertensive medication.

METHODS

We obtained data from claims submitted to the National Health Insurance, which covers almost the entire Korean population. Of the total of 2,454,844 patients who received prescriptions for antihypertensive medication during 2004, the study used data from 158,982 patients diagnosed with psychiatric disorders and 2,295,862 patients without psychiatric disorders according to International Classification of Diseases 10th Revision. We measured cumulative medication adherence (CMA) and compared the rates of appropriate level of adherence, defined as CMA > or =80%, between individuals with and without psychiatric disorders. We used multiple logistic regression to identify differences in antihypertensive medication adherence according to the type of psychiatric disorder.

RESULTS

Adherence to antihypertensive medication regimens was lower among patients with dementia, alcohol use disorders, psychotic disorders, and mood disorders-accounting for 15.4% of the patients with psychiatric disorders. On the other hand, the majority of patients (82.8%) who had substance use disorders, anxiety disorders, neurotic and somatoform disorders, and behavioral syndromes showed greater adherence. Overall adherence was higher in those with psychiatric disorders than in those without psychiatric disorders after adjusting for sociodemographic and clinical factors (odds ratio = 1.03, 95% Confidence Interval = 1.02-1.04).

CONCLUSIONS

Adherence to medication is reduced in patients with various types of psychiatric disorders, usually those accompanied by functional impairment. Effective strategies for improving medication adherence should be tailored to individual levels of function and psychopathology.

First Things First: Difficulty with Current Medications Is Associated With Patient Willingness to Add New Ones

BACKGROUND: Inadequate blood pressure (BP) control remains prevalent. One proposed explanation is "clinical inertia," often defined as the failure by providers to initiate or intensify medication therapy when otherwise appropriate. However, patients could contribute to clinical inertia by signaling an unwillingness to consider medication intensification. OBJECTIVE: To explore covariates of patient attitudes regarding medication intensification. STUDY DESIGN: Cross-sectional survey. SETTING: 9 Midwestern U. S. Veterans' Administration medical facilities. PARTICIPANTS: 1,062 diabetics identified as having BP>= 140/90 mm Hg as part of a prospective cohort study of clinical inertia in hypertension treatment. MEASUREMENTS: Primary outcome was participants' indicated willingness to intensify BP medications if their provider noted elevated BP levels. Potential covariates assessed included BP control (actual and perceived), perceived importance of BP control, BP management self-efficacy, competing demands, medication factors (adherence and management issues), trust in provider, and sociodemographic factors. RESULTS: While 64% of participants reported complete willingness to intensify BP medications, 36% of participants expressed at least some unwillingness. In ordered logistic regression analysis, willingness to intensify was negatively associated with medication concerns, particularly concern about side effects (OR=0.49, 95% CI: 0.42, 0.59) and adherence or management problems (OR=0.72, 95% CI: 0.57, 0.91), and positively associated with perceived dependence of health on BP medications (OR=1.50, 95% CI: 1.26, 1.79) and trust in provider (OR=1.30, 95% CI: 1.10, 1.54). Importance of BP control had a weaker, non-significant association with willingness to intensify as well (OR=1.17, 95% CI: 0.99, 1.40). Neither competing demands, current BP control, current number of medications prescribed, nor self-efficacy was associated with willingness to intensify medications. CONCLUSIONS: Patients' willingness to consider intensification of BP medications appears primarily determined by how well patients are managing their current medications, rather than patients' perceived importance of BP control, their self-efficacy, or their prioritization of BP control versus other health demands. Greater attention to patients' pre-existing medication issues may improve providers' ability to intensify BP medication therapy when medically appropriate while simultaneously improving patient satisfaction with care.

Can adherence to antihypertensive therapy be used to promote adherence to statin therapy?

OBJECTIVE

To compare adherence with statin therapy in patients switching to single-pill amlodipine besylate/atorvastatin calcium with patients adding a separate statin to their amlodipine regimen.

METHODS

We identified hypertensive patients prescribed amlodipine who switched to amlodipine/atorvastatin (switch) or added a statin to their amlodipine regimen (add-on) from July 2004 to June 2007. Propensity score matching (1 switch:3 add-on) was applied based on 'nearest neighbor' approach. The primary adherence measure was patients with proportion of days covered (PDC) >/=0.80 at 180 days; secondary measures included mean PDC and persistence. A sensitivity analysis was performed, accounting for total statin/amlodipine exposure.

RESULTS

Among 4556 matched patients (n = 1139 switch; n = 3417 add-on), mean age was 53.9 years and 52.1% were male. After 180 days, adherence with statin therapy was higher for the switch vs add-on cohort (50.8% vs 44.3%; P < 0.001). After adjusting for pre-index amlodipine adherence, the switch cohort was more likely to be adherent than the add-on cohort (odds ratio: 1.64 [95% confidence interval: 1.42 to 1.89]). Persistence was higher in the switch than the add-on cohort (127.6 vs 117 days; P < 0.001).

CONCLUSION

Hypertensive patients taking amlodipine who initiated statin therapy via single-pill amlodipine/atorvastatin were more likely to remain adherent to their statin than patients adding a separate statin to their antihypertensive regimen.

First-year treatment adherence among outpatients initiating antihypertensive medication in Korea: results of a retrospective claims review

BACKGROUND

Patients' adherence to antihypertensive drug therapy-especially at the beginning of treatment-is essential for preventing serious cardiovascular complications over the long term.

OBJECTIVES

This study was conducted to assess adherence among hypertensive patients who initiated antihypertensive pharmacotherapy and to identify whether it was related to the medical provider, dispensing patterns, or comorbidities.

METHODS

We reviewed the computerized claim records submitted to Korea's Health Insurance Review Agency (which maintains data for all medication prescriptions for Korean residents) between July 2004 and December 2006. We processed the claims of adult hypertensive patients who initiated therapy with an antihypertensive medication in 2005. Medication adherence was assessed by the cumulative medication adherence (CMA), calculated by dividing the sum of a day's supply (obtained over a series of intervals) by the total number of days in the time period. Good adherence was defined as CMA > or =80%.

RESULTS

The records of 725,220 antihypertensive patients aged > or =20 years were included in the analysis. The mean CMA value of the study group was 59.6% (median, 67.6%), and 39.2% of the patients had good adherence (CMA > or =80%). In multiple logistic regression analysis, the likelihood of a good adherence rate was greater when the medical provider was from a public health center (adjusted odds ratio [AOR], 2.71) or private clinic (AOR, 1.99) than a general hospital (ie, a hospital with >100 beds and > or =9 major departments) (AOR, 1.00). The likelihood of good adherence was greater when the medical provider's specialty was internal medicine (AOR, 1.00) versus family medicine (AOR, 0.96) or another specialty (AOR, 0.85). The odds of good adherence were greater among patients prescribed an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (AOR, 1.00) or combined drugs without a diuretic (AOR, 1.01) as the first-line drug rather than other drugs (AOR, < or =0.92). The likelihood of good adherence was also better when the mean daily number of antihypertensive pills was >1 to 2 (AOR, 1.22) or >2 to 3 (AOR, 1.34) than when it was < or =1 (AOR, 1.00). The likelihood of good adherence was lower among patients without target organ disease or metabolic syndrome (AOR, 1.00) and highest among those with > or =4 relevant comorbidities (AOR, 1.85).

CONCLUSIONS

The overall CMA of these hypertensive Korean patients who started antihypertensive therapy for the first time was <60%, and the rate of good adherence (CMA > or =80%) was <40%. Good medication adherence appeared to be related to the type of medical provider who prescribed the medication, the type of antihypertensive agent prescribed, the number of agents used, and the number of related comorbidities that a patient had.

Intensifying therapy for hypertension despite suboptimal adherence

More intensive management can improve control blood pressure (BP) in hypertensive patients. However, many would posit that treatment intensification (TI) is not beneficial in the face of suboptimal adherence. We investigated whether the effect of TI on BP varies by adherence. We enrolled 819 patients with hypertension, managed in primary care at an academically-affiliated inner-city hospital. We used the following formula to characterize TI: (visits with a medication change-visits with elevated BP)/total visits. Adherence was characterized using electronic monitoring devices ("MEMS caps"). Patients who returned their MEMS caps (671) were divided into quartiles of adherence, whereas patients who did not return their MEMS caps (148) had "missing" adherence. We examined the relationship between TI and the final systolic blood pressure (SBP), controlling for patient-level covariates. In the entire sample, each additional therapy increase per 10 visits predicted a 2.0 mm Hg decrease in final SBP (P<0.001). After stratifying by adherence, in the "best" adherence quartile each therapy increase predicted a 2.1-mm Hg decrease in final SBP, followed by 1.8 for the "next-best" adherence quartile, 2.3 in the third quartile, and 2.4 in the "worst" adherence quartile. The effect size for patients with "missing" adherence was 1.6 mm Hg. The differences between the group with "best" adherence and the other 4 groups were not statistically significant. In this observational study, treatment intensification was associated with similar BP improvement regardless of the patient's level of adherence. A randomized trial could further examine optimal management of patients with suboptimal adherence.

Comparing methods of measuring treatment intensification in hypertension care

BACKGROUND

Greater treatment intensification (TI) improves hypertension control. However, we do not know the ideal way to measure TI for research and quality improvement efforts. We compared the ability of different TI measures to predict blood pressure (BP) control.

METHODS AND RESULTS

We enrolled 819 hypertensive outpatients from an urban academic hospital. Each patient was assigned 3 scores to characterize TI. The any/none score divides patients into those who had any therapy increases during the study versus none. The norm-based method models the chance of a medication increase at each visit, then scores each patient based on whether they received more or fewer medication increases than predicted. The standard-based method is similar to the norm-based method but expects a medication increase whenever the blood pressure is uncontrolled. We compared the ability of these scores to predict the final systolic blood pressure (SBP). The any/none score showed a paradoxical result: any therapy increase was associated with SBP 4.6 mm Hg higher than no increase (P<0.001). The norm-based method score did not predict SBP in a linear fashion (P=0.18); further investigation revealed a U-shaped relationship between the norm-based method score and SBP. However, the standard-based method score was a strong linear predictor of SBP (2.1 mm Hg lower for each additional therapy increase per 10 visits, P<0.001). Similarly, the standard-based method predicted dichotomized blood pressure control, as measured by SBP <140 mm Hg (odds ratio, 1.30; P<0.001).

CONCLUSIONS

Our results suggest that standard-based method is the preferred measure of treatment intensity for hypertension care.

Disparities in antihypertensive medication adherence in persons with disabilities and without disabilities: results of a Korean population-based study

OBJECTIVE

To determine disparities in antihypertensive medication adherence between persons with disabilities and those without disabilities in South Korea.

DESIGN

The study compared antihypertensive medication adherence between persons with disabilities and those without disabilities using medical claims data of the National Health Insurance (NHI).

SETTING

We obtained data from claims submitted to the NHI, which covers almost the entire Korean population. Persons who were prescribed antihypertensive medication during the calendar year 2004 were identified.

PARTICIPANTS

The study comprised data from persons with disabilities (n=85,098) and persons without disabilities (n=2,368,636).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A cumulative medication adherence (CMA) greater than or equal to 80% was defined as an appropriate medication adherence. Multiple logistic regression was used to identify differences in antihypertensive medication adherence between persons with disabilities and without disabilities. Estimates were adjusted for demographic characteristics (sex, age), type of medical insurance, insurance contribution a month as a proxy for household income, residential area, and clinical characteristics (medication duration, comorbid conditions).

RESULTS

People with disabilities had lower CMAs than those without (median CMA, 83.6% vs 85.7%; appropriate medication adherence, 54.5% vs 57.5%). Results of the multiple logistic regression adjusting other factors indicated that people with disabilities had decreased probabilities of appropriate adherence.

CONCLUSIONS

Medication adherence is reduced by various types of disability and impairment such as those involving mobility and communication. Much effort should be made to investigate how and why these disparities take place and develop health policies to remove these disparities if they exist.

Predictors of persistence with antihypertensive therapy: results from the NHANES

BACKGROUND

More than 40% of treated hypertensives in the United States do not have their blood pressure under control. This is partly owing to non-persistence with prescribed medication, which occurs within 1 year in 32-53% of newly treated patients. Knowledge of factors related to non-persistence is limited, partly because previous studies have being conducted mostly in elderly patients enrolled in a single health insurance.

METHODS

Weighted logistic regression was used to identify factors associated with non-persistence in hypertensive patients from National Health and Nutrition Examination Surveys III (NHANES III) and NHANES 1999-2002 who had been prescribed antihypertensive medication.

RESULTS

Of 6100 participants, 903 were non-persistent (sampling weighted national prevalence of 12.5%), even though they had elevated blood pressure. Non-persistence was 12 times higher in patients <30 years than in those > or =50 years old (P < 0.001), 31% higher in men than in women (P = 0.01), and 43% higher in Hispanics, as compare to other racial groups (P = 0.03). Patients with low income were almost two times more likely to be non-persistent (P < 0.001). Having no health insurance increased non-persistence by 88% (P = 0.002), and patients who did not visit their doctor during the last year were 10 times more likely to be non-persistent than those who made at least one medical visit (P < 0.001).

CONCLUSIONS

In addition to young age, factors related to access to health care and medications (low income, health insurance, and visits to the doctor) were the main predictors of non-persistence. Policies that improve access to health care and patient follow-up may be of great impact in maintaining persistence.

Overcoming barriers: the role of providers in improving patient adherence to antihypertensive medications

PURPOSE OF REVIEW

To provide an overview of recent research assessing the role of physicians and other healthcare providers in facilitating improvements in patient adherence to antihypertensive medications, to provide a framework for addressing patient adherence to antihypertensive therapy, and to propose future directions for assessing the risk of poor adherence in clinical settings.

RECENT FINDINGS

Several recent studies have highlighted the role of the healthcare provider in improving patient adherence to antihypertensive therapy. Opportunities exist for providers to improve communication that enhances patients' understanding of their disease and its treatment, to tailor interventions based on whether patients are intentionally or unintentionally non-adherent, to assess and treat side-effects such as erectile dysfunction, to switch to less costly generic alternatives, and to reduce the complexities of medication regimens.

SUMMARY

Poor adherence to prescribed therapies is common in patients with hypertension, and should be considered in the evaluation of the hypertensive patient with poor blood pressure control. When initiating treatment in patients newly diagnosed with hypertension and when monitoring patients with existent disease, providers should identify barriers to medication adherence and actively engage patients in shared decision-making regarding their treatment. These activities will facilitate adherence, which may lead to improved outcomes for patients with hypertension and other chronic cardiovascular diseases.

Antihypertensive drug medication adherence and its affecting factors in South Korea

CONTEXT

Uncontrolled hypertension attributable to low medication adherence may cause such serious complications as cardiovascular disease and stroke.

OBJECTIVES

To estimate adherence to antihypertensive drug medication of the nation's representative sample in South Korea and to identify factors affecting medication adherence.

DATA SOURCES

We obtained claims data and qualification data of compulsory from the National Health Insurance, which covers almost all Korean, and identified those who got a prescription of antihypertensives during calendar year 2004.

PATIENTS

A total of 2,455,193 patients were included as study subjects. Cumulative medication adherence (CMA) was used as an index of medication adherence. Above 80% of CMA was defined as appropriate medication adherence.

RESULTS

Average CMA in the total of 2,455,193 patients was 81.4%. Appropriate adherence (CMA >or=80%) rate was 54.7% and those whose CMA is below 50% occupied 17.9%. In multiple logistic regression analysis, probability of appropriate medication adherence decreased in female gender, as age decreased, when patients have disability, when patients' residential area were from metropolitan city to city (OR: 0.91-0.92), to rural area (OR: 0.76-0.78), to extreme rural area (OR: 0.72-0.74), prescription days per visit decreased, and the number of prescribing physicians increased.

CONCLUSIONS

Identifying these factors in a target population or community, followed by developing intervention programs to increase antihypertensive medication adherence is needed. Also, medication adherence rate produced in this study can be used as a national health index and performance indexes of various hypertension control programs.

Hypertension treatment in a medicare population: Adherence and systolic blood pressure control

BACKGROUND

Despite substantial trial evidence that demonstrates the effectiveness of pharmacologic treatment for reducing blood pressure (BP) and cardiovascular events, many patients are nonadherent to their hypertension treatment.

OBJECTIVES

The purpose of this study was to examine patient adherence to hypertension medications using pharmacy data (ie, outpatient, inpatient, and mail-order prescriptions) and the association between adherence measures and systolic BP (SBP) control.

METHODS

The study included Medicare + Choice beneficiaries (aged > or = 65 years) who were continuously enrolled in an integrated delivery system in 2003, and who had documented hypertension and received > or = 1 hypertension drug in 2002. This analysis used automated clinical data and the 2000 US Census. We estimated 2 measures of hypertension treatment adherence in 2003 using the supply of dispensed drugs in days (proportion of days covered > or = 80%): (1) adherence to > or = 1 hypertension drug; and (2) adherence to the full hypertension treatment regimen. We defined the regimen by the number of hypertension drugs used concurrently in 2002. We assessed adherence annually and during the 30, 60, and 90 days before an SBP measurement. Logistic regression was used to examine the association between adherence and the number of drugs in the hypertension regimen, as well as the association between adherence and elevated SBP ( > or = 140 mm Hg). We adjusted for patient sociodemographic and clinical characteristics.

RESULTS

The majority (52.8%) of patients had multidrug hypertension regimens. In 2003, 87.3% of subjects were adherent to > or = 1 hypertension drug; 72.1% were adherent to their full regimen. After adjustment, we found that subjects with multidrug regimens were significantly more likely to be adherent to > or = 1 drug and significantly less likely to be adherent to their full regimen, compared with patients on a 1-drug regimen. Over one-third of subjects had elevated SBP in 2003. Both adherence measures were associated with lower odds of having elevated SBP (eg, odds ratio = 0.87 [95% CI, 0.84-0.89] for adherence to the full regimen). For subjects with multidrug regimens, partial adherence and nonadherence to the regimen were associated with higher odds of having elevated SBP.

CONCLUSIONS

Adherence measures using automated pharmacy data can identify patients who are nonadherent to their drug treatment regimen and who are more likely to have inadequately controlled BP. Adherence measures that account for the number of drugs in a patients' drug regimen might help identify additional patients at risk for poor BP outcomes due to partial treatment adherence.

Contemporary analysis of secondary failure of successful sulfonylurea therapy

OBJECTIVE

To revise older estimates of secondary failure that may no longer describe the contemporary pattern of sulfonylurea (SU) monotherapy and to identify predictors of such failure.

METHODS

We identified 4,091 patients who achieved hemoglobin A1c (A1C) <8% within 1 year after initiation of SU therapy as their first-ever antihyperglycemic drug after January 1, 1996. The study subjects underwent follow-up until they added or switched antihyperglycemic medication, had A1C > or =8%, or terminated health plan membership or until December 31, 2004. We defined secondary failure by using two separate but overlapping approaches: (1) the addition of or switch to another antihyperglycemic drug after 6 months of SU therapy or (2) the first A1C measurement > or =8.0%.

RESULTS

The level of A1C achieved within 1 year after initiation of SU treatment was the most powerful predictor of secondary SU failure. About 50% of patients whose best A1C was 7.0% to 7.9% added or switched antihyperglycemic drugs within 40 months, whereas it took nearly 60 months for those in the 6.0% to 6.9% A1C category and 74 months in the A1C <6.0% category to reach a 50% failure rate. Similarly, more than half of those patients whose best A1C was 7.0% to 7.9% had an A1C value > or =8% within 24 months, whereas it took nearly 60 months for study subjects in the 6.0% to 6.9% A1C category and 86 months for those in the <6.0% category to have SU failure. Younger age and weight gain were also predictive of failure.

CONCLUSION

Secondary failure of SU therapy is inversely associated with the level of A1C achieved within the first year of SU monotherapy. Clinicians should quickly consider therapeutic adjustments to lower the A1C level rapidly if initial success is not achieved.

Antihypertensive Drug Medication Adherence of People with Disabilities and its Affecting Factors in Korea

OBJECTIVES

The aims of this study were to estimate the antihypertensive medication adherence in people with a disability and a history of taking antihypertensive medication, and to identify the factors affecting medication adherence.

METHODS

The National Health Insurance claims data were linked with the National Disability Registry. People with a disability, who received a prescription of antihypertensives, were identified from a total of 85,098 cases. Cumulative medication adherence (CMA) was used as an indicator of medication adherence. A CMA>80% was defined as appropriate medication adherence. Multiple logistic regression analysis was used to identify the factors affecting medication adherence.

RESULTS

The average CMA in a total of 85,098 patients was 79.5%. The appropriate adherence (CMA>or=80%) rate was 54.5% and 20.5% of patients had a CMA<50%. Multiple logistic regression analysis revealed that the probability of appropriate adherence decreased with decreasing number of prescription days per visit, increasing number of providers, the patients' residential area moving from urban to rural areas, and when patients have an internal organ disability, auditory impairment, mobility impairment.

CONCLUSIONS

The adherence to antihypertensive medication in people with a disability is influenced by various socio-economic, clinical and regional factors. In particular, the disabled who have locomotive and communication disabilities and internal organ impairments have a higher probability of under-adherence to antihypertensive medication adherence in Korea.