Antihypertensive prescribing: do we have reason to celebrate?
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Antihypertensive Agents↗
Biomedical subjects
Barry L Carter
Publications and source records attributed to Barry L Carter.
Thiazide diuretics, potassium, and the development of diabetes: a quantitative review.
National guidelines and a recent clinical trial have supported the use of thiazide diuretics as the preferred initial pharmacological treatment for hypertension. However, evidence from this and other clinical trials have also found an increased incidence of new onset diabetes among those patients receiving thiazide diuretics. The mechanisms responsible for the increased incidence of diabetes with thiazide diuretics have not been fully elucidated. This article provides a review of intervention studies that included data on the relation between thiazide-induced hypokalemia and glucose intolerance. We conducted a literature search from 1966 to June 2004 to identify clinical trials using thiazide diuretics where the metabolic effects on potassium and glucose are reported. A total of 59 clinical trials constituting 83 thiazide diuretic study arms were identified. Trial size, length, type of thiazide diuretic, and dose varied substantially among the studies. The association between average changes in potassium and glucose in the study arms is considered jointly in a weighted statistical model. The Pearson's correlation coefficient, weighted by study sample size, for the relationship between glucose and potassium was -0.54 (95% CI, -0.67 to -0.36; P < 0.01). A sensitivity analysis, which considered subset analyses and effect of covariates, as well as inverse-variance weighting, supported this finding. These data suggest that thiazide-induced hypokalemia is associated with increased blood glucose. Treatment of thiazide-induced hypokalemia may reverse glucose intolerance and possibly prevent the future development of diabetes.
Blood Glucose↗
Comparative antihypertensive effects of hydrochlorothiazide and chlorthalidone on ambulatory and office blood pressure.
Low-dose thiazide-type diuretics are recommended as initial therapy for most hypertensive patients. Chlorthalidone has significantly reduced stroke and cardiovascular end points in several landmark trials; however, hydrochlorothiazide remains favored in practice. Most clinicians assume that the drugs are interchangeable, but their antihypertensive effects at lower doses have not been directly compared. We conducted a randomized, single-blinded, 8-week active treatment, crossover study comparing chlorthalidone 12.5 mg/day (force-titrated to 25 mg/day) and hydrochlorothiazide 25 mg/day (force-titrated to 50 mg/day) in untreated hypertensive patients. The main outcome, 24-hour ambulatory blood pressure (BP) monitoring, was assessed at baseline and week 8, along with standard office BP readings every 2 weeks. Thirty patients completed the first active treatment period, whereas 24 patients completed both. An order-drug-time interaction was observed with chlorthalidone; therefore, data from only the first active treatment period was considered. Week 8 ambulatory BPs indicated a greater reduction from baseline in systolic BP with chlorthalidone 25 mg/day compared with hydrochlorothiazide 50 mg/day (24-hour mean = -12.4+/-1.8 mm Hg versus -7.4+/-1.7 mm Hg; P=0.054; nighttime mean = -13.5+/-1.9 mm Hg versus -6.4+/-1.8 mm Hg; P=0.009). Office systolic BP reduction was lower at week 2 for chlorthalidone 12.5 mg/day versus hydrochlorothiazide 25 mg/day (-15.7+/-2.2 mm Hg versus -4.5+/-2.1 mm Hg; P=0.001); however, by week 8, reductions were statistically similar (-17.1+/-3.7 versus -10.8+/-3.5; P=0.84). Within recommended doses, chlorthalidone is more effective in lowering systolic BPs than hydrochlorothiazide, as evidenced by 24-hour ambulatory BPs. These differences were not apparent with office BP measurements.
Adult↗
Relationship between physician knowledge of hypertension and blood pressure control.
The purpose of this study was to evaluate the cross-sectional relationship between physician knowledge of hypertension guidelines and blood pressure (BP) control. The authors evaluated a sample of primary care faculty (n=32) and a sample of their patients (n=613). When treating patients as independent observations, the authors found an inverse relationship (r=-0.524; p=0.002) where higher knowledge scores were associated with lower BP control. The authors conducted a multivariate analysis to accommodate the nonindependence due to random physician effects and found that there was no longer a significant association between knowledge and BP control, but there was still a trend (odds ratio=0.84; p=0.130). This study demonstrates that there is no evidence that high knowledge of hypertension guidelines will improve BP control rates and that higher knowledge may actually be associated with lower BP control. Strategies that are designed only to improve knowledge of hypertension guidelines are insufficient to improve BP control rates.
Adult↗
Antihypertensive drug interactions.
There are many drug interactions with antihypertensive agents and some of these are highly significant. Patients with hypertension frequently take multiple medications and may be at increased risk for drug interactions. Nearly every elderly patient with multiple medical problems will have the potential for one drug interaction in their regimen. These drug interactions can lead to morbidity or even mortality if appropriate steps are not taken to minimize this risk. Drug interactions may occur due to pharmacokinetic (i.e., absorption, distribution, metabolism, elimination) or pharmacodynamic interactions. Physicians and pharmacists must remain vigilant in their monitoring of potential drug interactions and make appropriate dosage or therapy adjustments.
Antihypertensive Agents↗
Development of diabetes with thiazide diuretics: the potassium issue.
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Diabetes Mellitus↗
Hypertension outcomes through blood pressure monitoring and evaluation by pharmacists (HOME study).
OBJECTIVE: To evaluate the effectiveness of a community pharmacist-based home blood pressure (BP) monitoring program. DESIGN: Trial of a high-intensity (HI) versus low-intensity (LI) intervention randomized in 12 community pharmacies. The HI intervention comprised 4 face-to-face visits with a trained pharmacist. Pharmacists provided patient-specific education about hypertension. Following the first and third visits, patients were provided with a home BP monitoring device and instructed to measure their BP at least once daily for the next month. Home BP readings were used by the pharmacists to develop treatment recommendations for the patient's physician. Recommendations were discussed with the physician and, if approved, implemented by the pharmacist. In the LI intervention, pharmacists measured patients BP in the pharmacy and referred them to their physician for evaluation. PARTICIPANTS: Patients with uncontrolled BP at baseline. MEASUREMENTS: The main outcomes were the differences in systolic and diastolic BP (SBP and DBP) from baseline to follow-up between the HI and LI patients. RESULTS: The study enrolled 125 patients, 64 in the HI and 61 in the LI group. From baseline, SBP declined 13.4 mmHg in the HI group and 9.0 mmHg in the LI group. At the final visit, the difference in SBP/DBP change between the HI and LI group was -4.5/-3.2 mmHg (P=.12 for SBP and P=.03 for DBP). CONCLUSIONS: The HI intervention achieved a lower DBP and this model could be a strategy for patients with hypertension.
Aged↗
Antihypertensive drug interactions.
There are many drug interactions with antihypertensive agents and some of these are highly significant. Patients with hypertension frequently take multiple medications and may be at increased risk for drug interactions. Nearly every elderly patient with multiple medical problems will have the potential for one drug interaction in their regimen. These drug interactions can lead to morbidity or even mortality if appropriate steps are not taken to minimize this risk. Drug interactions may occur due to pharmacokinetic (i.e., absorption, distribution, metabolism, elimination) or pharmacodynamic interactions. Physicians and pharmacists must remain vigilant in their monitoring of potential drug interactions and make appropriate dosage or therapy adjustments.
Absorption↗
Measuring adherence to practice guidelines for the management of hypertension: an evaluation of the literature.
Adherence to practice guidelines is frequently used as a measure of quality of care. Numerous studies have evaluated physician adherence to hypertension guidelines by prescription data, physician survey data, or medical record review. However, most have methodological limitations that might underestimate physician adherence. Accurate and meaningful characterization of adherence rests on evaluation of varied components of hypertension care, use of explicit validated performance measures, incorporation of implicit and explicit review, and linkage of process measures to blood pressure outcomes.
Guideline Adherence↗
Influential characteristics of physician/pharmacist collaborative relationships.
BACKGROUND: A theoretical model of physician/pharmacist collaborative relationships, driven by 3 groups of relationship characteristics termed participant, context, and exchange, has been developed. There are no studies that have examined the types of characteristics which most influence development of collaborative relationships between physicians and pharmacists. OBJECTIVE: To test the model and determine which drivers most influence physician/pharmacist collaboration. METHODS: Data on the relationship drivers and collaborative practice were collected via a mailed survey of a random sample of 1000 primary care physicians in Iowa. Participant variables include demographics; context drivers refer to the practice environment and professional interactions between physicians and pharmacists. Exchange characteristics describe the nature of social exchange and were elicited using scores from 3 domains (relationship initiation, trustworthiness, role specification) of the Physician/Pharmacist Collaboration Instrument (PPCI). Five additional questions asked about the physician's collaborative practice with a pharmacist. Hierarchical linear regression analysis was performed with collaborative practice as the dependent variable and measures of participant, context, and exchange drivers as independent variables. RESULTS: Three hundred forty usable surveys (34%) were returned. Almost 70% of the respondents were male and aged 45.8 +/- 9.9 years (mean +/- SD). The majority were family practice physicians (72.1%) in private practice (67.3%). Regression analyses produced an R2 = 0.804 (p < 0.001). Significant predictors in the model were internal medicine physicians, professional interaction with a pharmacist, and the 3 domains of exchange drivers from the PPCI (p < 0.05). CONCLUSIONS: Although participant and context factors influenced physician/pharmacist collaborative relationships, exchange characteristics were the most influential relationship drivers. Role specification, trustworthiness, and relationship initiation were positively associated with physician/pharmacist collaborative practice. Recognition of these drivers may help pharmacists who are developing collaborative working relationships with physicians. But, studies are needed to delineate other factors that may influence physician/pharmacist relationships.
Adult↗
A longitudinal analysis of antihypertensive drug interactions in a Medicaid population.
BACKGROUND: Drug interactions are a frequent cause of adverse drug events. We evaluated whether the frequency of previously reported antihypertensive drug-drug interactions could be reduced by pharmaceutical case management. METHODS: Patients >30 years of age with hypertension who were enrolled in the Iowa Pharmaceutical Case Management (PCM) program were evaluated. All prescription claims for patients were obtained on their date of eligibility and again 9 months later. A drug interaction database was developed to examine potential drug interactions in each patient's regimen. RESULTS: Antihypertensive drugs were taken by 1377 patients at baseline and at 9-month follow-up. Highly significant antihypertensive drug interactions were observed at baseline in 35% of patients (0.47 per patient), and interaction prevalence did not change over time. Decreases in the number of drug interactions tended to occur more commonly among patients of pharmacies that provided the highest intensity of service (11.5% in high-intensity pharmacies v 9% in low- or zero-intensity pharmacies, but this did not achieve statistical significance). Nearly 75% of patients had an interaction of any significance level, and the total number of interactions increased over time (P =.0067). CONCLUSIONS: This Medicaid population with hypertension had a very high prevalence of potential drug interactions. The prevalence of interactions did not change, but the mean number of all interactions actually increased over time. There was some suggestion that higher-intensity pharmacies might be more successful in minimizing the risk of clinically significant drug interactions when compared with lower-intensity pharmacies.
Adrenergic beta-Antagonists↗
Implementing the new guidelines for hypertension: JNC 7, ADA, WHO-ISH.
BACKGROUND: The new guidelines issued by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) emphasize that aggressive blood pressure (BP) control is essential to reducing morbidity and mortality. Additionally, guidelines issued by the American Diabetes Association (ADA) and the World Health Organization-International Society of Hypertension (WHO-ISH) emphasize the critical need for lowering BP levels. Achieving BP goals is a challenge for patients and their physicians, and most patients are not at goal. Poor BP control is even more of a challenge for patients with diabetes and chronic kidney disease since their goals are even lower. The strategies for lowering BP levels include patient lifestyle changes, adherence to therapy, and regular monitoring of BP levels. OBJECTIVE: To summarize the antihypertension guidelines recommended by WHO-ISH, JNC 7, the ADA, and the Hypertension in African Americans Working Group (HAAW Group) of the International Society on Hypertension in Blacks and evaluate the pharmacist.s collaborative role in the management of hypertension by examining the results of programs designed to include pharmacist counseling. METHODS: The relevant literature was evaluated and reviewed. Emphasis was placed on literature that evaluated strategies to improve BP control. RESULTS: Results from several programs and studies showed positive effects of pharmacist collaboration. A program that provided pharmacist academic detailing to physicians at 5 Veterans Affairs facilities resulted in significant increases in patients receiving beta-blocker therapy or thiazide diuretics and angiotensin-converting enzyme inhibitor or angiotensin receptor blocker therapy. Another study in which hypertensive patients received clinical services from pharmacists showed significant improvement in patients. knowledge of hypertension and its management and in patient adherence, and also showed a significant increase in the number of patients whose BP stayed in the normal range. A 6-month, controlled, single-blind, parallel-group study of 51 hypertensive patients showed significant improvements in BP control, quality of life, and overall patient satisfaction in the study group that received treatment through a primary care team that included pharmacists. Among patients at a Veterans Administration medical center, results suggested that the intervention of a clinical pharmacist improved documentation of drug therapy and estimated patient compliance. A study of the effectiveness of comanagement in 197 hypertensive patients with physician-pharmacist collaboration using an evidence-based, systematic approach showed that a significantly larger number of patients in the study group achieved BP control than in the control group. CONCLUSIONS: The expanded role of clinical pharmacists in programs for evaluating, monitoring, and treating patients with hypertension can result in improved adherence to therapy and established guidelines. As members of interdisciplinary health care teams, pharmacists should utilize the JNC 7 guidelines and scientific evidence to consult with physicians about medications, design effective formularies, and collaborate with physicians in evaluating and comanaging patients with hypertension.
Black or African American↗
Hydrochlorothiazide versus chlorthalidone: evidence supporting their interchangeability.
Thiazide diuretics are one of the preferred pharmacologic treatments for hypertension. Hydrochlorothiazide and chlorthalidone have been the 2 most commonly used diuretics in major clinical trials. Treatment guidelines and compendia often consider these 2 drugs interchangeable agents within the class of thiazide or thiazide-like diuretics. Many sources list them as equipotent. Despite these beliefs, there is some suggestion that cardiovascular outcomes are not necessarily the same with these 2 drugs. We conducted a literature search from 1960 to 2003 to identify studies that evaluated the pharmacokinetic and blood pressure-lowering effects of these 2 agents. There are significant pharmacokinetic and pharmacodynamic differences between these diuretics. Chlorthalidone is approximately 1.5 to 2.0 times as potent as hydrochlorothiazide, and the former has a much longer duration of action. Whether these pharmacokinetic and pharmacodynamic features cause differences in outcomes is not known.
Antihypertensive Agents↗
Development of a computer algorithm for defining an active drug list using an automated pharmacy database.
BACKGROUND AND OBJECTIVE: Increasingly, pharmacy databases are being used to assist in evaluating the appropriateness of drug therapy. Such determinations often require the creation of a drug regimen at a particular point in time. The objective of this study was to develop a computer algorithm for defining a cross-sectional active drug list. METHODS: Electronic pharmacy data were obtained as part of the Iowa Medicaid Pharmaceutical Case Management Program. The active drug lists generated by the computer algorithm were compared with active drug lists generated by independent pharmacist review of the pharmacy refill data. RESULTS: In a sample of 25 patients who received 379 potentially active medications, the interrater reliability between pharmacist reviewers was excellent (kappa=0.94). In a second sample of 100 patients who received 1476 potentially active medications, the computer algorithm had a sensitivity of 93.8% and specificity of 91.7%, using pharmacist review as the comparison standard. CONCLUSION: The computer algorithm was found to be a valid method of processing electronic pharmacy data to yield a characterization of drug exposure at a point in time. The potential benefits and limitations of using this approach are discussed.
Adult↗
Pharmaceutical care services for patients with hypertension.
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Antihypertensive Agents↗
Hypertension: a review of therapeutic options.
Excellent clinical trial data support the use of several classes of drugs for reducing and controlling hypertension. This review covers the classes discussed by JNC-7, including angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, beta blockers, calcium channel blockers, and diuretics.
Antihypertensive Agents↗
The extent of potential antihypertensive drug interactions in a Medicaid population.
BACKGROUND: Drug interactions are a frequent cause of adverse drug events and these might be avoided by computer alerts to physicians or pharmacists. We evaluated the frequency of potential drug-drug interactions in patients receiving medications commonly used for hypertension. METHODS: Patients more than 30 years of age with hypertension who were receiving Medicaid and who were enrolled in the Iowa Pharmaceutical Case Management (PCM) program were evaluated. All prescription claims for patients were obtained on their date of eligibility. A drug interaction database was developed to examine potential drug interactions in each patient's regimen. RESULTS: There were 1574 patients who received a drug typically used for hypertension. Depending on age and sex, 23% to 48% of patients had a potential interaction of high significance and 55% to 84% had at least one potential interaction. Both increasing age (P =.0007, odds ratio [OR] 1.012 [1.005,1.019]) and number of drugs (P <.0001, OR 1.120 [1.092,1.150]) were significantly associated with the potential for a highly significant drug interaction in the univariable models. Female sex was not significant (P =.56, OR 1.074 [0.845,1.364]). The multivariable model found that there was a significant interaction between age and the number of drugs in the regimen (P <.0001). CONCLUSIONS: This study found a very high frequency of potential drug interactions with agents typically used for hypertension. Because of the large volume of potential interactions, these data raise the concern that any attempt to provide physicians and pharmacists with computer alerts about these interactions will result in alerts for the vast majority of patients.
Adult↗
Blood pressure as a surrogate end point for hypertension.
OBJECTIVE: To review relevant literature and provide opinions regarding the use of blood pressure as a surrogate measure to predict cardiovascular risk. DATA SOURCES: Primary and review articles were identified by MEDLINE search (1990-January 2001) and through secondary sources. STUDY SELECTION AND DATA EXTRACTION: Studies and review articles that related to the interpretation of blood pressure as a surrogate measure were reviewed. Information that was relevant to this topic was included. DATA SYNTHESIS: The measurement of blood pressure is subject to numerous sources of error and bias. Patients who perform home blood pressure testing and self-report these values frequently leave out high values and add ghost values into logbooks. Additionally, analysis of recent data suggests that at any given level of blood pressure that is achieved, cardiovascular risk reduction may not be the same with different therapeutic agents. It is also now recommended that systolic blood pressure be used in preference to diastolic blood pressure to determine risk and to assess management strategies. Although 24-hour blood pressure measurements may be the best predictors of cardiovascular risk, this has not been demonstrated in a long-term morbidity trial. CONCLUSIONS: Blood pressure is a relatively poor surrogate measure. Unfortunately, no alternatives are available at this time. Therefore, every attempt must be made to accurately determine blood pressure and to assess risk and benefit from specific antihypertensive agents. Systolic blood pressure should be the predominant blood pressure measure used to evaluate patients, especially middle-aged and elderly individuals.
Antihypertensive Agents↗