Cochrane for Clinicians

Putting Evidence into Practice

Interventions to Improve Blood Pressure Control in Patients with Hypertension

KATHRYN K. HOLDER, lT COL, USAF, MC, David Grant Medical Center
Family Practice Residency Program, Travis Air Force Base, California

The Cochrane Abstract is a summary of a review from the Cochrane Library. It is accompanied by an interpretation that will help clinicians put evidence into practice. Dr. Holder presents a clinical scenario and question based on the Cochrane Abstract, followed by an evidence-based answer and a critique of the review. The practice recommendations in this activity are available at http://www.cochrane.org/reviews /en/ab005182.html.

Clinical Scenario

A 53-year-old man with idiopathic hypertension has not achieved blood pressure control after three years of treatment.

Clinical Question

What interventions are effective in improving blood pressure control in patients with hypertension?

Evidence-Based Answer

One large study of adults with hypertension showed that a rigorous, systematic program including regular patient review and aggressive antihypertensive drug therapy improved systolic and diastolic blood pressure and reduced all-cause mortality (7.8 to 6.4 percent at five years; number needed to treat = 71). A pooled analysis of six randomized controlled trials (RCTs) on organizational interventions to improve care showed heterogeneous results. Self-monitoring of blood pressure, educational interventions directed at the patient or health professional, health professional-led care, and appointment reminder systems each had variable and clinically insignificant effects on blood pressure control. Educational interventions alone were unlikely to produce clinically important reductions in blood pressure.1

Practice Pointers

It is estimated that only 25 to 40 percent of treated patients with hypertension achieve blood pressure goals. Poor compliance with medications and patients not having a primary care physician each have been associated with uncontrolled blood pressure.

This Cochrane review provides some support that an aggressive, stepped approach to providing antihypertensive medications effectively reduces mortality risk. The
largest clinical trial on organizational interventions aimed at improving delivery of care in patients with hypertension (Hypertension Detection and Follow-up study) showed a reduction in systolic and diastolic blood pressure and in all-cause mortality. The study's multifaceted intervention included free care, registration, recall, and regular patient review in addition to an aggressive, stepped approach to therapy. However, it is not possible to distinguish the independent effects of organizational interventions or a stepped approach on blood pressure control.2

Other nonpharmacologic interventions to improve outcomes in patients with hypertension (e.g., salt restriction, body weight reduction, stress management, exercise, alcohol intake reduction) have produced heterogeneous or clinically insignificant results.3 Pooled data from 12 RCTs showed that self-monitoring of blood pressure was associated with a statistically significant reduction in diastolic blood pressure (-2.0 mm Hg); however, it is unclear if this is clinically significant. Although the literature shows that in-office blood pressure readings are higher than ambulatory-based or self-monitored readings, several of the studies in the review did not adjust for this discrepancy.

Twenty-five RCTs reported on educational interventions directed at the patient or a health professional. Although health professional education was associated with a small reduction in systolic blood pressure, individual RCTs had heterogeneous results, making pooled data invalid.

Although health professional-led intervention may be a promising method of delivering care, study results on this topic were heterogeneous. Five out of seven RCTs showed a difference in mean systolic blood pressure ranging from -13 to 0 mm Hg with this method; six out of seven RCTs showed a mean difference in the diastolic blood pressure ranging from -8 to 0 mm Hg. One well-conducted RCT showed that nurse-led intervention was also effective at reducing patient body weight and increasing exercise participation. Five RCTs reviewed appointment reminder systems (mail- or computer-based) and showed an improvement in patient follow-up.

Based on the review, effective hypertension management requires a systematic approach to the identification of patients with hypertension, follow-up, and aggressive treatment with antihypertensive medications. This approach likely leads to modest reductions in cardiovascular mortality and morbidity. Supplemental strategies such as self-monitoring of blood pressure and health professional initiatives require further evaluation. Educational interventions (directed at patients or health professionals) alone are unlikely to lead to clinically significant reductions in blood pressure.

Address correspondence to Kathryn K. Holder, Lt Col, USAF, MC, at kathryn.holder-02@travis.af.mil. Reprints are not available from the author.

Author disclosure: Nothing to disclose.

REFERENCES

1. Fahey T, Schroeder K, Ebrahim S. Interventions used to improve control of blood pressure in patients with hypertension. Cochrane Database Syst Rev 2006;(4):CD005182.

2. Hypertension Detection and Follow-up Program Cooperative Group. Therapeutic control of blood pressure in the Hypertension Detection and Follow-up Program. Prev Med 1979;8:2-13.

3. Ebrahim S, Smith GD. Lowering blood pressure: a systematic review of sustained effects of non-pharmacological interventions. J Public Health Med 1998;20:441-8.

Cochrane Briefs

Alpha-glucosidase Inhibitors May Reduce the Risk of Type 2 Diabetes

Clinical Question

Does acarbose (Precose) decrease the incidence of diabetes when used to treat impaired glucose tolerance or impaired fasting glucose?

Evidence-Based Answer

The literature shows that acarbose can reduce the risk of type 2 diabetes in patients with impaired glucose tolerance or impaired fasting glucose. However, it is unclear whether the drug stops or delays the development of the disease or masks the diagnosis. There is no evidence that acarbose use reduces overall mortality or cardiovascular morbidity. The high incidence of adverse effects may also limit the use of acarbose for the prevention of diabetes.

Practice Pointers

Alpha-glucosidase inhibitors work at the brush border of the small intestine, delaying carbohydrate absorption and subsequently lowering postprandial peaks in glucose levels. Two alpha-glucosidase inhibitors, acarbose and miglitol (Glyset), are approved for use in the United States. Guidelines do not recommend alpha-glucosidase inhibitors as monotherapy for diabetes; however, whether this drug class can prevent overt diabetes in persons with prediabetes has been questioned.

In this Cochrane review, the authors assessed the effects of alpha-glucosidase inhibitor use in persons with impaired glucose tolerance or impaired fasting glucose. The primary outcomes included the incidence of type 2 diabetes, morbidity related to impaired glucose metabolism, and total mortality. Secondary outcomes included glycemic control, blood pressure and lipid effects, fasting and post-carbohydrate load insulin levels, and the incidence of adverse effects. Five studies with 2,360 total patients were included in this review. One study followed patients for one year, two for three years, one for five years, and one for six years. Most of the studies used acarbose, 50 mg orally, three times per day.

The highest-quality study demonstrated that acarbose decreases the incidence of type 2 diabetes; 10 persons need to be treated for three years to prevent one person from developing diabetes. The study also demonstrated that acarbose decreases the incidence of cardiovascular events; 50 patients need to be treated to prevent one cardiovascular event. However, the study results are based on a small number of events and could not be confirmed by other studies.

Two smaller studies also demonstrated that acarbose decreases the risk of type 2 diabetes; however, there are two important concerns about this finding. One of the studies showed that after acarbose was discontinued, more patients who took acarbose became diabetic than patients who took placebo (15.4 versus 10.6 percent). This raises the question of whether acarbose was preventing or merely masking the diagnosis of diabetes. The second concern is adverse effects: 31 percent of participants discontinued acarbose, compared with 19 percent of participants in the placebo arm; one in four participants had gastrointestinal adverse effects. No significant differences between the two groups were found in total mortality, lipid levels, or blood pressure measurements. Patients taking acarbose had a nonsignificant decrease in body weight of 2 lb, 10 oz (1.2 kg). Acarbose had no effect on glycemic control, lipid measurements, or blood pressure.

The incidence of diabetes increased by 54 percent in the United States from 1997 to 2004.1 Diet and exercise remain the mainstays of diabetes prevention. A systematic review showed that diet and exercise reduced the incidence of diabetes by 50 percent over one year without adverse effects.2 One study in the Cochrane review showed that, compared with diet and exercise, five patients need to be treated with acarbose to prevent one patient from developing diabetes in five years. Acarbose, like metformin (Glucophage), is promising but cannot be definitely recommended. The benefits of acarbose must be weighed against the high incidence of adverse effects.

JESSICA T. SERVEY, LT COL, USAF, MC

Author disclosure: Nothing to disclose.

Source: Van de Laar FA, Lucassen PL, Akkermans RP, Van de Lisdonk EH, De Grauw WJ. Alpha-glucosidase inhibitors for people with impaired glucose tolerance or impaired fasting blood glucose. Cochrane Database Syst Rev 2006;(4):CD005061.

REFERENCES

1. National Diabetes Surveillance System. Data and trends. Accessed June 4, 2007, at: http://www.cdc.gov/diabetes/statistics/incidence/fig1.htm.

2. Yamaoka K, Tango T. Efficacy of lifestyle education to prevent type 2 diabetes: a meta-analysis of randomized controlled trials. Diabetes Care 2005;28:2780-6.

Antiretroviral Prophylaxis for Occupational Exposure to HIV

Clinical Question

Should health care workers with occupational exposure to human immunodeficiency virus (HIV) receive postexposure antiretroviral prophylaxis?

Evidence-Based Answer

There are no controlled trials of postexposure prophylaxis for persons with occupational exposure to body fluids potentially infected with HIV. Based on one case-control study, individually selected antiretroviral therapy, initiated soon after exposure, is recommended. Treatment should continue for four weeks or until the source body fluid tests HIV negative.

Practice Pointers

The Centers for Disease Control and Prevention (CDC) defines occupational HIV exposure as a percutaneous injury (e.g., a needlestick, cut from a sharp object) or contact of mucous membranes or nonintact skin (e.g., skin that is chapped, abraded, or affected by dermatitis) with blood, tissue, or other body fluids that are potentially infected with HIV.1 Potentially infectious fluids include cerebrospinal, synovial, pleural, peritoneal, pericardial, and amniotic fluids. Feces, nasal secretions, saliva, sputum, sweat, tears, urine, and vomit are not considered infectious unless visibly bloody. The risk of HIV transmission is approximately 0.3 percent after percutaneous exposure to infected blood and 0.09 percent after mucous membrane exposure. The risk of transmission varies with the type of exposure and infected fluid.1

The authors of this Cochrane review searched the literature from 1985 to May 2005. They found no controlled trials of postexposure prophylaxis, but found one case-control study. Participants were health care workers with occupational, percutaneous exposure to HIV-infected blood. Patients in the case group had HIV seroconversion temporally associated with the exposure and no other reported concurrent exposure to HIV. Participants in the control group remained seronegative six months after exposure.

An increased risk of HIV transmission was associated with deep injury, visible blood on the device, procedures involving a needle placed in the source patient's blood vessel, and terminal illness in the source patient. Zidovudine (Retrovir) use after exposure was associated with a lower risk of HIV transmission. Most patients took at least 1,000 mg of zidovudine per day starting within four hours of exposure.

Of 58 health care workers who received postexposure prophylaxis, 71 percent had adverse effects, including nausea (24 percent), fatigue (22 percent), emotional distress (13 percent), and headache (9 percent). Although patients who received a three-drug regimen reported more adverse effects, the drop-out rate in these patients was similar to that in patients who received fewer drugs.

The CDC recommends postexposure prophylaxis for health care workers who have occupational exposure to blood infected with HIV, and it recommends considering prophylaxis for health care workers with percutaneous injuries from sources with unknown HIV status who have risk factors or who are from settings where HIV exposure is likely.1 Prophylaxis should be initiated as soon as possible, ideally within hours, not days, of exposure. Therapy should continue for four weeks or until the source blood tests HIV negative. Selection of prophylactic medication should be determined in consultation with an expert in antiretroviral therapy and HIV transmission.1 If expert consultation is not immediately possible, more information on prophylactic regimens is available at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5409a1.htm and http://www.ucsf.edu/hivcntr/Hotlines/PEPline.html.

CLARISSA KRIPKE, MD

Source: Young TN, Arens FJ, Kennedy GE, Laurie JW, Rutherford G. Antiretroviral post-exposure prophylaxis (PEP) for occupational HIV exposure. Cochrane Database Syst Rev 2007;(1):CD002835.

REFERENCES

1. Panlilio AL, Cardo DM, Grohskopf LA, Heneine W, Ross CS. Updated U.S. Public Health Service guidelines for the management of occupational exposures to HIV and recommendations for postexposure prophylaxis. MMWR Recomm Rep 2005;54(RR-9):1-17.

The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the U.S. Air Force Department or the U.S. Air Force Service at large.

This clinical content conforms to AAFP criteria for evidence-based continuing medical education (EB CME). See Clinical Quiz on page 339.

The series coordinator for AFP is Clarissa Kripke, MD, Department of Family and Community Medicine, University of California, San Francisco.

Copyright © 2007 by the American Academy of Family Physicians. This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. Contact afpserv@aafp.org for copyright questions and/or permission requests.