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Improved Blood Pressure Control With a Physician-Nurse Team and Home Blood Pressure Measurement
ORIGINAL ARTICLE
BP CONTROL BY PHYSICIAN-NURSE TEAM
Improved Blood Pressure Control With a Physician-Nurse Team and Home Blood Pressure Measurement VINCENT J. CANZANELLO, MD; PATRICIA L. JENSEN, RN; LORA L. SCHWARTZ, RN; JOEL B. WORRA, BS; AND LOIS K. KLEIN OBJECTIVE: To assess whether a physician-nurse team model could improve long-term hypertension control rates by active intervention and modification of antihypertensive drug regimens based on home blood pressure (BP) measurements. PATIENTS AND METHODS: This study consisted of patients referred to a hypertension specialty clinic between July 1999 and June 2002 for the evaluation and management of uncontrolled hypertension. Patients were evaluated initially by a physician. A treatment plan was designed and implemented subsequently by a hypertension nurse specialist. Each patient was given an automated digital home BP monitor and requested to provide 42 BP readings taken during 7 days at intervals of 1, 3, 6, 9, and 12 months after dismissal from the clinic. The mean of these weekly values was reviewed by the physician-nurse team, and the treatment regimen was adjusted to achieve a goal BP of less than 135/85 mm Hg. RESULTS: One hundred six consecutively referred patients were enrolled in the study (mean ± SD age, 64±14 years; 58% female; baseline BP, 156±16/85±11 mm Hg). Ninety-four patients submitted BP data after 1 month, and 78 patients completed the entire 12-month study period. Overall, mean BP decreased to 138±17/78±8 mm Hg at 1 month and to 131±9/75±7 mm Hg at 12 months (P<.01 vs baseline). The percentage of patients who achieved BP control to less than 135/85 mm Hg increased from 0% at baseline to 63% at 12 months. Intensification of antihypertensive drug therapy was required, on average, in 24% of patients at each study interval. The mean number of drugs increased from 1.2 at baseline to 2.0 at 12 months (P<.01). CONCLUSION: The use of home BP measurement by a physiciannurse team has the potential to significantly improve long-term hypertension control rates in a geographically dispersed patient population. This model should reduce both cost and inconvenience associated with the treatment of hypertension.
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ypertension is one of the most important public health issues that currently confronts health care practitioners, policymakers, and planners in the United States and many other countries. Approximately 50 million Americans (23% of the population) have hypertension (defined as a blood pressure [BP] ≥140 mm Hg systolic or 90 mm Hg diastolic or requiring treatment).1 In addition, hypertension is one of the most frequent reasons for health care practitioner visits, and the cost of drug therapy now approaches $16 billion annually.2 After several decades of increasing rates of awareness, treatment, and control of hypertension, these rates now appear to have plateaued or are decreasing.3 This is in part related to the aging of the population and the increasing awareness of the importance of systolic hypertension as the major contributor to stroke, congestive heart failure, and renal failure.4 Moreover, aggressive new BP Mayo Clin Proc.
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treatment goals (such as <130/80 mm Hg in patients with diabetes mellitus or renal disease) have recently been promulgated1 and will likely further inflate poor control rates. Currently, the proportion of patients with hypertension who are aware of their diagnosis and whose BP levels are being treated and controlled (ie, BP <140/90 mm Hg) is approximately 31% nationally3 and 17% in Olmsted County, Minnesota.5 In gen- For editorial eral, less than 50% of hypertensive pa- comment, tients receiving drug therapy have well- see page 19 controlled hypertension.3 Interestingly, most patients with treated yet uncontrolled hypertension have health care insurance and have usually been seen by their health care practitioners several times per year. Even access to low-cost or free medications does not ensure successful BP control.3,6-8 Clearly, new paradigms are needed to improve this situation. We previously showed in a relatively small pilot study that use of a physician-supervised, nurse-managed clinic for the initiation and rapid titration of antihypertensive drug therapy could significantly improve long-term hypertension control rates assessed by home BP measurement.9 However, this study was observational in that changes in a patient’s antihypertensive drug regimen were left to the discretion of the local health care practitioner and not the study investigators. The purpose of the current study was to assess whether a similar physician-nurse team model could further improve hypertension control rates by actively intervening and modifying a participant’s antihypertensive drug regimen based on home BP measurements. PATIENTS AND METHODS SHORT-TERM HYPERTENSION CARE CLINIC The study was performed from July 1999 to June 2002. Participants were recruited from the Short-term HypertenFrom the Department of Internal Medicine and Division of Nephrology and Hypertension (V.J.C., P.L.J., L.L.S., L.K.K.) and Research Computing Facility (J.B.W.), Mayo Clinic College of Medicine, Rochester, Minn. This study was funded through a Clinical Practice Initiative Grant from Mayo Foundation. Individual reprints of this article are not available. Address correspondence to Vincent J. Canzanello, MD, Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905 (e-mail: [email protected]). © 2005 Mayo Foundation for Medical Education and Research
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sion Care Clinic in the Division of Nephrology and Hypertension at the Mayo Clinic in Rochester, Minn. The details of this clinic have been described previously.9 This clinic was established in the early 1980s in response to the referral practice in which geographically dispersed hypertensive patients spend limited time in Rochester, Minn. Annually, approximately 7500 patients are referred to 1 of 9 specially trained hypertension nurses after an initial evaluation by a physician. Patients may be referred to the nurse to confirm satisfactory BP control or for changes in medications due to adverse effects; however, most patients are referred for uncontrolled hypertension and the initiation or titration of drug therapy. The initial drug treatment plan is formulated by the physician, reviewed with the nurse, and implemented by the nurse. Adjustment of drug doses is usually at the discretion of the nurse and depends on the patient’s clinical response in terms of BP and drug-related adverse effects. Published guidelines1,10 are used for the selection of most drug classes and doses. Typically, patients are seen 1 to 3 times per day for 3 to 4 days. The initial nurse visit generally takes 30 to 45 minutes, with subsequent visits taking approximately 15 minutes. During the initial visit, educational aspects of hypertension and cardiovascular disease preventive measures (diet, exercise) are reviewed with the patient as are compliance issues and potential drug-related adverse effects. Informational brochures regarding sodium restriction, achieving a healthy weight, and, if necessary, guidelines for lipid lowering are provided. Patients are also encouraged to regularly measure their own BP at home and are provided with an informational brochure on this topic. After dismissal from the clinic, patients are then referred back to their own local health care practitioners. DESIGN AND PROCEDURES The study was open to patients 18 years or older with a systolic BP of 140 mm Hg or greater and/or a diastolic BP of 90 mm Hg or greater, who had no secondary cause of hypertension, and who were willing and able to perform self-measurement of BP with an automated oscillometric sphygmomanometer with proper cuff size (model HEM737, Omron Corp, Kyoto, Japan).11 Simultaneous BP measurements were obtained in each patient with the automated device and a calibrated mercury or aneroid sphygmomanometer (with the nurse unaware of the device measurements).9,11,12 Only devices that agree within 5 mm Hg for both systolic and diastolic BP were used for this study. Three consecutive BP readings were measured simultaneously using the automated device and the reference sphygmomanometer with the patient seated after 5 minutes of rest. These measurements were taken by one of the study nurses (L.L.S., P.L.J.) at baseline referral and at the 32
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time of dismissal from the clinic. On occasion, these visits were the same if the patient had completed his or her Mayo Clinic evaluation on that day. Before dismissal from the clinic, self-measurement of BP by each patient was directly observed by the nurse. Home BP levels were obtained as 3 consecutive measurements (with the patient in the seated position after 5 minutes of rest) twice daily for a 7-day interval at 1, 3, 6, 9, and 12 months after dismissal from the hypertension clinic. These readings were returned to the study nurse by either mail or fax and then reviewed by the physician-nurse team. This team met for approximately 1 hour per week. Patients who did not return follow-up data were contacted by telephone or mail as possible. STUDY INTERVENTIONS If the mean of the submitted 42 readings obtained during each 7-day interval was equal to or greater than a systolic or diastolic BP of 135 or 85 mm Hg, respectively, the patient’s drug regimen was intensified and he or she was notified by telephone or mail of the new recommendation(s). A formal drug-treatment algorithm was not used, although most changes were made in accordance with the guidelines of the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.10 Appropriate laboratory monitoring was arranged, depending on the drug intervention (eg, use of diuretics) and the patient’s local health care practitioner was notified of any proposed treatment changes. A home BP goal of less than 135/85 mm Hg was chosen in accordance with published recommendations for BP measurement at home.10,13 This study was approved by the Mayo Foundation Institutional Review Board, and all patients provided informed consent. STATISTICAL ANALYSES Agreement between the BP level obtained by manual and automated sphygmomanometers was assessed according to the method of Bland and Altman.14 Automated readings underestimated systolic BP by a mean of 0.29 mm Hg (95% confidence interval, –0.93 to 0.35 mm Hg) and overestimated diastolic BP by a mean of 1.5 mm Hg (95% confidence interval, 1.01 to 2.00 mm Hg). As a result of this close agreement, only readings obtained with the automated sphygmomanometer were used in the subsequent statistical analyses. Baseline and follow-up BP data for all subjects were analyzed by 2-way analysis of variance with the timespecific means estimated using a least square means option. Tests for differences between time-specific means were performed with the overall F test for the time factor in this analysis. Categorical data were analyzed by the χ2 test.
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BP CONTROL BY PHYSICIAN-NURSE TEAM
Results are expressed as mean ± SD except as noted. P<.05 was considered statistically significant.
TABLE 1. Baseline Patient Characteristics Characteristic Mean ± SD age (y) Female (%) White (%) Mean ± SD duration of hypertension (y) Diabetes mellitus (%) Dyslipidemia (%) Atherosclerotic vascular disease (%) Mean ± SD blood pressure (mm Hg) Systolic Diastolic No. of blood pressure drugs (range) No. (%) of drugs 0 1 2 3 4 ≥5
RESULTS One hundred six consecutively referred hypertensive patients were enrolled in this study. The baseline patient characteristics are given in Table 1. Patients were generally older than 60 years and had predominantly uncontrolled systolic hypertension. Ninety-four patients submitted BP data after 1 month of follow-up, and 78 patients completed the entire 12-month study period. There were no significant differences at baseline between those who completed the study (n=78) and those who did not (n=28), although there was a trend toward higher BP levels in the nonfinisher group (Table 2). Likewise, there were no significant differences in the prevalence of diabetes mellitus, dyslipidemia, or atherosclerotic vascular disease between the 2 groups. BP CHANGES DURING FOLLOW-UP Blood pressure changes during follow-up are shown in Figure 1. For the entire cohort (N=106), the greatest decrease in BP, compared with baseline, was evident at 1 month: 156±16/85±11 mm Hg at baseline vs 138±17/78±8 mm Hg at 1 month (P<.01), with continued improvement to a mean of 131±9/75±7 mm Hg at 12 months. The percentage of patients who achieved BP control to less than 135/ 85 mm Hg increased from 0% at baseline to 63% at 1 year (Figure 2). In the cohort of patients (n=78) who completed the entire study, mean BP decreased from a baseline of 154±15/84±11 mm Hg to 138±16/78±8 mm Hg and 131±10/ 75±7 mm Hg at 1 and 12 months, respectively (Figure 3) (P<.01). Because this apparent improvement might be explained by the drop out of patients with uncontrolled hypertension, further analysis of the cohort that did not finish the study was performed. Among the 28 patients who did not finish the study, 16 provided follow-up data for a mean of 4.4 months. During this peri od, the mean BP had decreased
Finding (N=106) 64 ±14 58 96 11±12 16 30 25 156±16 85±11 1.2 (0-6) 31 (29) 39 (37) 23 (22) 8 (8) 3 (3) 2 (1)
from 163±17/87±10 mm Hg to 144±14/80±9 mm Hg (P<.01) and was less than 135/85 mm Hg in 4 patients. ANTIHYPERTENSIVE MEDICATION CHANGES DURING FOLLOW-UP Changes in antihypertensive drug therapy during the study are shown in Figure 4. Between the baseline and clinic dismissal visits, antihypertensive drug therapy was initiated or titrated upward in 57 patients (54%). Addition or increases in the following drugs accounted for most medication changes: thiazide diuretics (52%), angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (46%), calcium channel blockers (15%), and β-blockers (12%). On the basis of the home BP data, intensification of antihypertensive drug therapy was necessary, on average, in 24% of patients at each interval. The mean number of drugs per patient increased from 1.2 (range, 0-6) at baseline to 2.0 (range, 0-5) at 12 months (P<.01). DISCUSSION There are many potential barriers to achieving satisfactory hypertension control rates. We recently reviewed the most
TABLE 2. Comparison of Baseline Clinical Characteristics of Patients Who Did and Did Not Complete the Study* Characteristic
Finishers (n=78)
Mean ± SD age (y) Female (%) Mean ± SD blood pressure (mm Hg) Systolic Diastolic No. of blood pressure drugs (range) Diabetes mellitus (%) Dyslipidemia (%) Atherosclerotic vascular disease (%)
Nonfinishers (n=28) 65 ±12 63 154±15 84±11 1.2 (0-4) 15 28 29
62±16 46 160±19 88±10 1.2 (0-6) 19 37 15
*None of the differences were statistically significant. Mayo Clin Proc.
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180 156
180 Systolic 138*
135*
133*
133*
131*
120 Diastolic 78*
77*
75*
75*
Systolic
138*
133*
140
100 85
154
160
BP (mm Hg)
BP (mm Hg)
160
132*
131*
75*
75*
75*
6
9
12
120 100 84
75*
80
132*
140
Diastolic 78*
76*
1
3
80
60 Baseline (N=106)
1 (n=100)
3 (n=88)
6 (n=71)
9 (n=77)
60 Baseline
12 (n=78)
Month
Month
FIGURE 1. Blood pressures (BPs) for the entire study cohort (N=106) after dismissal from the hypertension clinic. Data are presented as mean ± SD. *P<.01 vs baseline.
FIGURE 3. Blood pressures (BPs) for the cohort completing the entire 12-month study (n=78). Data are presented as mean ± SD. *P<.01 vs baseline.
significant factors associated with the poor control rates currently observed in the United States.15 These include both patient-related and physician-related factors. With respect to patient-related factors, lifestyle issues (obesity, high salt intake, excessive alcohol use) can significantly affect BP control. Medical insurance coverage and access to medical care have been considered important barriers to achieving successful BP control; however, recent studies seriously question this concern. Berlowitz et al6 documented inadequate BP control rates for patients followed up in hypertension clinics in the Veterans Administration medical system. In this population, with ready access to care and low-cost drugs, approximately 40% of patients had BP levels higher than 160/90 mm Hg despite a mean of 6 clinic visits per year. In a follow-up study that compared control rates in the Veterans Administration hypertension
population between 1990-1995 and 1999, control rates improved; however, 57% of patients still had mean readings of 140/90 mm Hg or higher.8 In a more recent review of data from the National Health and Nutrition Examination Survey, 95% of patients with treated but uncontrolled hypertension had health insurance, and a similar percentage reported having seen a physician a mean of 6 times in the past year.16 An example of physician barriers to achieving effective hypertension control was explored recently by Oliveria et al.17 In this descriptive survey of salaried primary care physicians in a large multispecialty health system, pharmacological therapy was initiated or changed at only 38% of visits in patients with documented BP levels of 140/90 mm Hg or higher. The most frequently cited reason for this inaction was satisfaction with the observed BP value. The shortcomings of the current traditional approach to managing hypertension, as described herein, highlight the need for new paradigms to improve hypertension control rates with the ultimate goal of reducing the morbidity associated with this disorder. Several approaches to improving BP control rates are being implemented. Efforts are under way to educate both the public and health care practitioners on the importance of systolic BP and the need for tighter BP control in special populations (such as those with diabetes mellitus or renal disease).1 The development of a Clinical Hypertension Specialist Program of the American Society of Hypertension is also important in this regard, especially for physician education and the development of a referral network for the evaluation of patients with complicated and/or resistant hypertension.18 Blood pressure control rates have increased from 26% at baseline to 55% after a period of at least 3 visits to such specialty clinics.19
80 63
Patients (%)
60
54
56
6
9
48 41
40
20 0
0 Baseline
1
3
12
Month
FIGURE 2. Rates of blood pressure control to less than 135/85 mm Hg after dismissal from the hypertension clinic.
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100
No change
Increased
Decreased
81
80
75
72
71
Patients (%)
64
60
54 46
40 29
28
26 22
20
16 7 3
0
Baseline
1
3
6
3
3
0
0
9
12
Month
FIGURE 4. Medication interventions made between the initial and dismissal visit (baseline) and then in response to home blood pressure data after dismissal from the hypertension clinic. Medication increase refers to an increase in drug dose, addition of another medication, or both.
Once awareness of the need for increased hypertension control is raised and a therapeutic plan has been developed, a mechanism must be in place to achieve the desired outcome. It is at this point in which the physician-nurse team and home BP measurement would appear to have the most important role. Nurse-managed algorithmic approaches to several chronic disorders, such as diabetes mellitus, heart failure, asthma, and dyslipidemia, are in place at our institution and elsewhere and have achieved considerable success in terms of clinical outcomes, cost, and patient convenience.20,21 The development of clinical tools to allow selfmeasurement of blood glucose, airways function, oxygen saturation, and BP (eg, LifeLink Monitoring Inc, Bearsville, NY) can provide patients with a convenient means of followup with their health care practitioners whether by telephone, mail, or computer.22,23 We believe that the results of this study confirm and extend the benefits of such an approach to the management of chronic diseases. This study has some limitations. Most study participants had, according to current guidelines,1 stage I hypertension and no identifiable secondary cause of hypertension. Nonetheless, there is no a priori reason to believe our model would not be effective in other patient groups with more severe or complicated hypertension, such as medically treated renovascular hypertension or primary aldosteronism. Another concern is that the reduction of BP levels after dismissal from the clinic could simply reflect the phenomenon of regression to the mean. Although this cannot be excluded completely, it is unlikely because consistently elevated home and/or office BP levels had prompted Mayo Clin Proc.
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initial referral to our clinic. Because this was not a placebocontrolled study, we cannot exclude nonpharmacological aspects, such as weight loss and reduction of dietary sodium intake, as contributing to the observed improvement in BP control, although subsequent clinical benefit should likely accrue regardless of the mechanism of BP reduction. One potential concern is the compliance and accuracy of home BP measurements. All automated devices were proved to be accurate before they were given to patients. The accuracy and reliability of recorded home BP levels have been addressed previously. Mengden et al24 compared automatically stored BP data to patient logbook entries for self-measured readings and found that, although some underreporting and overreporting of values occurred, the overall means for both were identical. Another concern might be the BP status of patients lost to follow-up. Although the information is anecdotal, several of the patients who failed to return BP data were contacted and admitted that after dismissal from the clinic their BP level remained normal and they lost interest in performing and recording additional readings. Finally, the potential costs associated with this study should be considered. Although the automated BP device was provided to the patient at no cost, retail prices vary from $85 to $107, depending on the cuff size required. For physician time, the commitment was approximately 1 hour per week. Nurse time was 3 to 4 hours per week and consisted primarily of recording and formatting the handwritten reports of BP readings and telephoning patients with recommended changes in therapy. The use of telemonitoring with
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BP CONTROL BY PHYSICIAN-NURSE TEAM
receipt of downloaded patient data in a manner that can be expressed automatically in terms of weekly averages would substantially reduce the time investment per patient.23,25 Whether our approach can ultimately reduce the cost associated with treating hypertension is unclear. Although use of home BP monitoring has been associated with reduced medical resource utilization and improved BP control rates,26 there is potential for increased costs associated with intensification of antihypertensive drug therapy. This issue was addressed in a recently published study by Staessen et al.27 They performed a randomized controlled trial of antihypertensive treatment based on either home or office BP measurements. At the end of 1 year, more patients in the home measurement group were able to discontinue the use of antihypertensive drugs (presumably reflecting white coat hypertension), whereas more patients in the office group had their drug regimens intensified. Overall, drug expenditures were lower in the home vs office group, albeit at the expense of significantly higher systolic and diastolic BP of approximately 7 and 4 mm Hg in the home group. That trial differed from the current study in that the patients were significantly younger, diastolic BP control was the only goal, and a formal stepwise drug treatment protocol was used. In the long run, it is likely that even if drug-associated costs increased, this would likely be offset by the savings associated with subsequently reduced rates of hypertensionassociated morbidity and mortality. Although less formally studied, other inconveniences or hidden costs associated with the treatment of hypertension in terms of physician office visits, travel, and time lost from work may be decreased using our model. CONCLUSION The model of a physician-nurse team using home BP measurement has the potential to significantly increase longterm hypertension control rates. This approach should also reduce the cost and inconvenience associated with the treatment of hypertension. REFERENCES 1. Chobanian AV, Bakris GL, Black HR, et al, National Heart, Lung, and Blood Institute Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, National High Blood Pressure Education Program Coordinating Committee. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report [published correction appears in JAMA. 2003;290:197]. JAMA. 2003;289:2560-2572. 2. ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart
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Attack Trial (ALLHAT) [published corrections appear in JAMA. 2003;289:178 and 2004;291:2196]. JAMA. 2002;288:2981-2997. 3. Hajjar I, Kotchen TA. Trends in prevalence, awareness, treatment, and control of hypertension in the United States, 1988-2000. JAMA. 2003;290:199206. 4. Izzo JL Jr, Levy D, Black HR. Importance of systolic blood pressure in older Americans [Clinical Advisory Statement]. Hypertension. 2000;35:1021-1024. 5. Meissner I, Whisnant JP, Sheps SG, et al. Detection and control of high blood pressure in the community: do we need a wake-up call? Hypertension. 1999;34:466-471. 6. Berlowitz DR, Ash AS, Hickey EC, et al. Inadequate management of blood pressure in a hypertensive population. N Engl J Med. 1998;339:1957-1963. 7. Joffres MR, Ghadirian P, Fodor JG, Petrasovits A, Chockalingam A, Hamet P. Awareness, treatment, and control of hypertension in Canada. Am J Hypertens. 1997;10(10, pt 1):1097-1102. 8. Borzecki AM, Wong AT, Hickey EC, Ash AS, Berlowitz DR. Hypertension control: how well are we doing? Arch Intern Med. 2003;163:2705-2711. 9. Canzanello VJ, Jensen PL, Hunder I. Rapid adjustment of antihypertensive drugs produces a durable improvement in blood pressure. Am J Hypertens. 2001;14(4, pt 1):345-350. 10. The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure [published correction appears in Arch Intern Med. 1998;158:573]. Arch Intern Med. 1997;157:2413-2446. 11. Association for the Advancement of Medical Instrumentation. American National Standard for Electronic or Automated Sphygmomanometers. Arlington, Va: Association for the Advancement of Medical Instrumentation; 1992. 12. Canzanello VJ, Jensen PL, Schwartz GL. Are aneroid sphygmomanometers accurate in hospital and clinic settings? Arch Intern Med. 2001;161:729-731. 13. Thijs L, Staessen JA, Celis H, et al. Reference values for self-recorded blood pressure: a meta-analysis of summary data. Arch Intern Med. 1998; 158:481-488. 14. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986;1:307-310. 15. Norby SM, Stroebel RJ, Canzanello VJ. Physician-nurse team approaches to improve blood pressure control. J Clin Hypertens (Greenwich). 2003;5:386-392. 16. Hyman DJ, Pavlik VN. Characteristics of patients with uncontrolled hypertension in the United States [published correction appears in N Engl J Med. 2002;346:544]. N Engl J Med. 2001;345:479-486. 17. Oliveria SA, Lapuerta P, McCarthy BD, L’Italien GJ, Berlowitz DR, Asch SM. Physician-related barriers to the effective management of uncontrolled hypertension. Arch Intern Med. 2002;162:413-420. 18. Krakoff LR, Board of the ASH Specialists Program. The ASH Specialists Program: a progress report [editorial]. Am J Hypertens. 2002;15:577-579. 19. Bansal N, Tendler BE, White WB, Mansoor GA. Blood pressure control in the hypertension clinic. Am J Hypertens. 2003;16:878-880. 20. Gorski LA, Johnson K. A disease management program for heart failure: collaboration between a home care agency and a care management organization. Lippincott’s Case Manag. 2003;8:265-273. 21. Kallenbach A, Ludwig-Beymer P, Welsh C, Norris J, Giloth B. Process improvement for asthma: an integrated approach. J Nurs Care Qual. 2003;18: 245-256. 22. Finkelstein J, Cabrera MR, Hripcsak G. Internet-based home asthma telemonitoring: can patients handle the technology? Chest. 2000;117:148-155. 23. Rogers MA, Small D, Buchan DA, et al. Home monitoring service improves mean arterial pressure in patients with essential hypertension: a randomized, controlled trial. Ann Intern Med. 2001;134:1024-1032. 24. Mengden T, Hernandez Medina RM, Beltran B, Alvarez E, Kraft K, Vetter H. Reliability of reporting self-measured blood pressure values by hypertensive patients. Am J Hypertens. 1998;11:1413-1417. 25. Pickering TG, Gerin W, Holland JK. Home blood pressure teletransmission for better diagnosis and treatment. Curr Hypertens Rep. 1999;1:489-494. 26. Soghikian K, Casper SM, Fireman BH, et al. Home blood pressure monitoring: effect on use of medical services and medical care costs. Med Care. 1992;30:855-865. 27. Staessen JA, Den Hond E, Celis H, et al, Treatment of Hypertension Based on Home or Office Blood Pressure (THOP) Trial Investigators. Antihypertensive treatment based on blood pressure measurement at home or in the physician’s office: a randomized controlled trial. JAMA. 2004;291:955-964.
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Improved Blood Pressure Control With a Physician-Nurse Team and Home Blood Pressure Measurement VINCENT J. CANZANELLO, MD; PATRICIA L. JENSEN, RN; LORA L. SCHWARTZ, RN; JOEL B. WORRA, BS; AND LOIS K. KLEIN OBJECTIVE: To assess whether a physician-nurse team model could improve long-term hypertension control rates by active intervention and modification of antihypertensive drug regimens based on home blood pressure (BP) measurements. PATIENTS AND METHODS: This study consisted of patients referred to a hypertension specialty clinic between July 1999 and June 2002 for the evaluation and management of uncontrolled hypertension. Patients were evaluated initially by a physician. A treatment plan was designed and implemented subsequently by a hypertension nurse specialist. Each patient was given an automated digital home BP monitor and requested to provide 42 BP readings taken during 7 days at intervals of 1, 3, 6, 9, and 12 months after dismissal from the clinic. The mean of these weekly values was reviewed by the physician-nurse team, and the treatment regimen was adjusted to achieve a goal BP of less than 135/85 mm Hg. RESULTS: One hundred six consecutively referred patients were enrolled in the study (mean ± SD age, 64±14 years; 58% female; baseline BP, 156±16/85±11 mm Hg). Ninety-four patients submitted BP data after 1 month, and 78 patients completed the entire 12-month study period. Overall, mean BP decreased to 138±17/78±8 mm Hg at 1 month and to 131±9/75±7 mm Hg at 12 months (P<.01 vs baseline). The percentage of patients who achieved BP control to less than 135/85 mm Hg increased from 0% at baseline to 63% at 12 months. Intensification of antihypertensive drug therapy was required, on average, in 24% of patients at each study interval. The mean number of drugs increased from 1.2 at baseline to 2.0 at 12 months (P<.01). CONCLUSION: The use of home BP measurement by a physiciannurse team has the potential to significantly improve long-term hypertension control rates in a geographically dispersed patient population. This model should reduce both cost and inconvenience associated with the treatment of hypertension.
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ypertension is one of the most important public health issues that currently confronts health care practitioners, policymakers, and planners in the United States and many other countries. Approximately 50 million Americans (23% of the population) have hypertension (defined as a blood pressure [BP] ≥140 mm Hg systolic or 90 mm Hg diastolic or requiring treatment).1 In addition, hypertension is one of the most frequent reasons for health care practitioner visits, and the cost of drug therapy now approaches $16 billion annually.2 After several decades of increasing rates of awareness, treatment, and control of hypertension, these rates now appear to have plateaued or are decreasing.3 This is in part related to the aging of the population and the increasing awareness of the importance of systolic hypertension as the major contributor to stroke, congestive heart failure, and renal failure.4 Moreover, aggressive new BP Mayo Clin Proc.
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treatment goals (such as <130/80 mm Hg in patients with diabetes mellitus or renal disease) have recently been promulgated1 and will likely further inflate poor control rates. Currently, the proportion of patients with hypertension who are aware of their diagnosis and whose BP levels are being treated and controlled (ie, BP <140/90 mm Hg) is approximately 31% nationally3 and 17% in Olmsted County, Minnesota.5 In gen- For editorial eral, less than 50% of hypertensive pa- comment, tients receiving drug therapy have well- see page 19 controlled hypertension.3 Interestingly, most patients with treated yet uncontrolled hypertension have health care insurance and have usually been seen by their health care practitioners several times per year. Even access to low-cost or free medications does not ensure successful BP control.3,6-8 Clearly, new paradigms are needed to improve this situation. We previously showed in a relatively small pilot study that use of a physician-supervised, nurse-managed clinic for the initiation and rapid titration of antihypertensive drug therapy could significantly improve long-term hypertension control rates assessed by home BP measurement.9 However, this study was observational in that changes in a patient’s antihypertensive drug regimen were left to the discretion of the local health care practitioner and not the study investigators. The purpose of the current study was to assess whether a similar physician-nurse team model could further improve hypertension control rates by actively intervening and modifying a participant’s antihypertensive drug regimen based on home BP measurements. PATIENTS AND METHODS SHORT-TERM HYPERTENSION CARE CLINIC The study was performed from July 1999 to June 2002. Participants were recruited from the Short-term HypertenFrom the Department of Internal Medicine and Division of Nephrology and Hypertension (V.J.C., P.L.J., L.L.S., L.K.K.) and Research Computing Facility (J.B.W.), Mayo Clinic College of Medicine, Rochester, Minn. This study was funded through a Clinical Practice Initiative Grant from Mayo Foundation. Individual reprints of this article are not available. Address correspondence to Vincent J. Canzanello, MD, Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905 (e-mail: [email protected]). © 2005 Mayo Foundation for Medical Education and Research
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sion Care Clinic in the Division of Nephrology and Hypertension at the Mayo Clinic in Rochester, Minn. The details of this clinic have been described previously.9 This clinic was established in the early 1980s in response to the referral practice in which geographically dispersed hypertensive patients spend limited time in Rochester, Minn. Annually, approximately 7500 patients are referred to 1 of 9 specially trained hypertension nurses after an initial evaluation by a physician. Patients may be referred to the nurse to confirm satisfactory BP control or for changes in medications due to adverse effects; however, most patients are referred for uncontrolled hypertension and the initiation or titration of drug therapy. The initial drug treatment plan is formulated by the physician, reviewed with the nurse, and implemented by the nurse. Adjustment of drug doses is usually at the discretion of the nurse and depends on the patient’s clinical response in terms of BP and drug-related adverse effects. Published guidelines1,10 are used for the selection of most drug classes and doses. Typically, patients are seen 1 to 3 times per day for 3 to 4 days. The initial nurse visit generally takes 30 to 45 minutes, with subsequent visits taking approximately 15 minutes. During the initial visit, educational aspects of hypertension and cardiovascular disease preventive measures (diet, exercise) are reviewed with the patient as are compliance issues and potential drug-related adverse effects. Informational brochures regarding sodium restriction, achieving a healthy weight, and, if necessary, guidelines for lipid lowering are provided. Patients are also encouraged to regularly measure their own BP at home and are provided with an informational brochure on this topic. After dismissal from the clinic, patients are then referred back to their own local health care practitioners. DESIGN AND PROCEDURES The study was open to patients 18 years or older with a systolic BP of 140 mm Hg or greater and/or a diastolic BP of 90 mm Hg or greater, who had no secondary cause of hypertension, and who were willing and able to perform self-measurement of BP with an automated oscillometric sphygmomanometer with proper cuff size (model HEM737, Omron Corp, Kyoto, Japan).11 Simultaneous BP measurements were obtained in each patient with the automated device and a calibrated mercury or aneroid sphygmomanometer (with the nurse unaware of the device measurements).9,11,12 Only devices that agree within 5 mm Hg for both systolic and diastolic BP were used for this study. Three consecutive BP readings were measured simultaneously using the automated device and the reference sphygmomanometer with the patient seated after 5 minutes of rest. These measurements were taken by one of the study nurses (L.L.S., P.L.J.) at baseline referral and at the 32
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time of dismissal from the clinic. On occasion, these visits were the same if the patient had completed his or her Mayo Clinic evaluation on that day. Before dismissal from the clinic, self-measurement of BP by each patient was directly observed by the nurse. Home BP levels were obtained as 3 consecutive measurements (with the patient in the seated position after 5 minutes of rest) twice daily for a 7-day interval at 1, 3, 6, 9, and 12 months after dismissal from the hypertension clinic. These readings were returned to the study nurse by either mail or fax and then reviewed by the physician-nurse team. This team met for approximately 1 hour per week. Patients who did not return follow-up data were contacted by telephone or mail as possible. STUDY INTERVENTIONS If the mean of the submitted 42 readings obtained during each 7-day interval was equal to or greater than a systolic or diastolic BP of 135 or 85 mm Hg, respectively, the patient’s drug regimen was intensified and he or she was notified by telephone or mail of the new recommendation(s). A formal drug-treatment algorithm was not used, although most changes were made in accordance with the guidelines of the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.10 Appropriate laboratory monitoring was arranged, depending on the drug intervention (eg, use of diuretics) and the patient’s local health care practitioner was notified of any proposed treatment changes. A home BP goal of less than 135/85 mm Hg was chosen in accordance with published recommendations for BP measurement at home.10,13 This study was approved by the Mayo Foundation Institutional Review Board, and all patients provided informed consent. STATISTICAL ANALYSES Agreement between the BP level obtained by manual and automated sphygmomanometers was assessed according to the method of Bland and Altman.14 Automated readings underestimated systolic BP by a mean of 0.29 mm Hg (95% confidence interval, –0.93 to 0.35 mm Hg) and overestimated diastolic BP by a mean of 1.5 mm Hg (95% confidence interval, 1.01 to 2.00 mm Hg). As a result of this close agreement, only readings obtained with the automated sphygmomanometer were used in the subsequent statistical analyses. Baseline and follow-up BP data for all subjects were analyzed by 2-way analysis of variance with the timespecific means estimated using a least square means option. Tests for differences between time-specific means were performed with the overall F test for the time factor in this analysis. Categorical data were analyzed by the χ2 test.
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Results are expressed as mean ± SD except as noted. P<.05 was considered statistically significant.
TABLE 1. Baseline Patient Characteristics Characteristic Mean ± SD age (y) Female (%) White (%) Mean ± SD duration of hypertension (y) Diabetes mellitus (%) Dyslipidemia (%) Atherosclerotic vascular disease (%) Mean ± SD blood pressure (mm Hg) Systolic Diastolic No. of blood pressure drugs (range) No. (%) of drugs 0 1 2 3 4 ≥5
RESULTS One hundred six consecutively referred hypertensive patients were enrolled in this study. The baseline patient characteristics are given in Table 1. Patients were generally older than 60 years and had predominantly uncontrolled systolic hypertension. Ninety-four patients submitted BP data after 1 month of follow-up, and 78 patients completed the entire 12-month study period. There were no significant differences at baseline between those who completed the study (n=78) and those who did not (n=28), although there was a trend toward higher BP levels in the nonfinisher group (Table 2). Likewise, there were no significant differences in the prevalence of diabetes mellitus, dyslipidemia, or atherosclerotic vascular disease between the 2 groups. BP CHANGES DURING FOLLOW-UP Blood pressure changes during follow-up are shown in Figure 1. For the entire cohort (N=106), the greatest decrease in BP, compared with baseline, was evident at 1 month: 156±16/85±11 mm Hg at baseline vs 138±17/78±8 mm Hg at 1 month (P<.01), with continued improvement to a mean of 131±9/75±7 mm Hg at 12 months. The percentage of patients who achieved BP control to less than 135/ 85 mm Hg increased from 0% at baseline to 63% at 1 year (Figure 2). In the cohort of patients (n=78) who completed the entire study, mean BP decreased from a baseline of 154±15/84±11 mm Hg to 138±16/78±8 mm Hg and 131±10/ 75±7 mm Hg at 1 and 12 months, respectively (Figure 3) (P<.01). Because this apparent improvement might be explained by the drop out of patients with uncontrolled hypertension, further analysis of the cohort that did not finish the study was performed. Among the 28 patients who did not finish the study, 16 provided follow-up data for a mean of 4.4 months. During this peri od, the mean BP had decreased
Finding (N=106) 64 ±14 58 96 11±12 16 30 25 156±16 85±11 1.2 (0-6) 31 (29) 39 (37) 23 (22) 8 (8) 3 (3) 2 (1)
from 163±17/87±10 mm Hg to 144±14/80±9 mm Hg (P<.01) and was less than 135/85 mm Hg in 4 patients. ANTIHYPERTENSIVE MEDICATION CHANGES DURING FOLLOW-UP Changes in antihypertensive drug therapy during the study are shown in Figure 4. Between the baseline and clinic dismissal visits, antihypertensive drug therapy was initiated or titrated upward in 57 patients (54%). Addition or increases in the following drugs accounted for most medication changes: thiazide diuretics (52%), angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (46%), calcium channel blockers (15%), and β-blockers (12%). On the basis of the home BP data, intensification of antihypertensive drug therapy was necessary, on average, in 24% of patients at each interval. The mean number of drugs per patient increased from 1.2 (range, 0-6) at baseline to 2.0 (range, 0-5) at 12 months (P<.01). DISCUSSION There are many potential barriers to achieving satisfactory hypertension control rates. We recently reviewed the most
TABLE 2. Comparison of Baseline Clinical Characteristics of Patients Who Did and Did Not Complete the Study* Characteristic
Finishers (n=78)
Mean ± SD age (y) Female (%) Mean ± SD blood pressure (mm Hg) Systolic Diastolic No. of blood pressure drugs (range) Diabetes mellitus (%) Dyslipidemia (%) Atherosclerotic vascular disease (%)
Nonfinishers (n=28) 65 ±12 63 154±15 84±11 1.2 (0-4) 15 28 29
62±16 46 160±19 88±10 1.2 (0-6) 19 37 15
*None of the differences were statistically significant. Mayo Clin Proc.
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180 156
180 Systolic 138*
135*
133*
133*
131*
120 Diastolic 78*
77*
75*
75*
Systolic
138*
133*
140
100 85
154
160
BP (mm Hg)
BP (mm Hg)
160
132*
131*
75*
75*
75*
6
9
12
120 100 84
75*
80
132*
140
Diastolic 78*
76*
1
3
80
60 Baseline (N=106)
1 (n=100)
3 (n=88)
6 (n=71)
9 (n=77)
60 Baseline
12 (n=78)
Month
Month
FIGURE 1. Blood pressures (BPs) for the entire study cohort (N=106) after dismissal from the hypertension clinic. Data are presented as mean ± SD. *P<.01 vs baseline.
FIGURE 3. Blood pressures (BPs) for the cohort completing the entire 12-month study (n=78). Data are presented as mean ± SD. *P<.01 vs baseline.
significant factors associated with the poor control rates currently observed in the United States.15 These include both patient-related and physician-related factors. With respect to patient-related factors, lifestyle issues (obesity, high salt intake, excessive alcohol use) can significantly affect BP control. Medical insurance coverage and access to medical care have been considered important barriers to achieving successful BP control; however, recent studies seriously question this concern. Berlowitz et al6 documented inadequate BP control rates for patients followed up in hypertension clinics in the Veterans Administration medical system. In this population, with ready access to care and low-cost drugs, approximately 40% of patients had BP levels higher than 160/90 mm Hg despite a mean of 6 clinic visits per year. In a follow-up study that compared control rates in the Veterans Administration hypertension
population between 1990-1995 and 1999, control rates improved; however, 57% of patients still had mean readings of 140/90 mm Hg or higher.8 In a more recent review of data from the National Health and Nutrition Examination Survey, 95% of patients with treated but uncontrolled hypertension had health insurance, and a similar percentage reported having seen a physician a mean of 6 times in the past year.16 An example of physician barriers to achieving effective hypertension control was explored recently by Oliveria et al.17 In this descriptive survey of salaried primary care physicians in a large multispecialty health system, pharmacological therapy was initiated or changed at only 38% of visits in patients with documented BP levels of 140/90 mm Hg or higher. The most frequently cited reason for this inaction was satisfaction with the observed BP value. The shortcomings of the current traditional approach to managing hypertension, as described herein, highlight the need for new paradigms to improve hypertension control rates with the ultimate goal of reducing the morbidity associated with this disorder. Several approaches to improving BP control rates are being implemented. Efforts are under way to educate both the public and health care practitioners on the importance of systolic BP and the need for tighter BP control in special populations (such as those with diabetes mellitus or renal disease).1 The development of a Clinical Hypertension Specialist Program of the American Society of Hypertension is also important in this regard, especially for physician education and the development of a referral network for the evaluation of patients with complicated and/or resistant hypertension.18 Blood pressure control rates have increased from 26% at baseline to 55% after a period of at least 3 visits to such specialty clinics.19
80 63
Patients (%)
60
54
56
6
9
48 41
40
20 0
0 Baseline
1
3
12
Month
FIGURE 2. Rates of blood pressure control to less than 135/85 mm Hg after dismissal from the hypertension clinic.
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100
No change
Increased
Decreased
81
80
75
72
71
Patients (%)
64
60
54 46
40 29
28
26 22
20
16 7 3
0
Baseline
1
3
6
3
3
0
0
9
12
Month
FIGURE 4. Medication interventions made between the initial and dismissal visit (baseline) and then in response to home blood pressure data after dismissal from the hypertension clinic. Medication increase refers to an increase in drug dose, addition of another medication, or both.
Once awareness of the need for increased hypertension control is raised and a therapeutic plan has been developed, a mechanism must be in place to achieve the desired outcome. It is at this point in which the physician-nurse team and home BP measurement would appear to have the most important role. Nurse-managed algorithmic approaches to several chronic disorders, such as diabetes mellitus, heart failure, asthma, and dyslipidemia, are in place at our institution and elsewhere and have achieved considerable success in terms of clinical outcomes, cost, and patient convenience.20,21 The development of clinical tools to allow selfmeasurement of blood glucose, airways function, oxygen saturation, and BP (eg, LifeLink Monitoring Inc, Bearsville, NY) can provide patients with a convenient means of followup with their health care practitioners whether by telephone, mail, or computer.22,23 We believe that the results of this study confirm and extend the benefits of such an approach to the management of chronic diseases. This study has some limitations. Most study participants had, according to current guidelines,1 stage I hypertension and no identifiable secondary cause of hypertension. Nonetheless, there is no a priori reason to believe our model would not be effective in other patient groups with more severe or complicated hypertension, such as medically treated renovascular hypertension or primary aldosteronism. Another concern is that the reduction of BP levels after dismissal from the clinic could simply reflect the phenomenon of regression to the mean. Although this cannot be excluded completely, it is unlikely because consistently elevated home and/or office BP levels had prompted Mayo Clin Proc.
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initial referral to our clinic. Because this was not a placebocontrolled study, we cannot exclude nonpharmacological aspects, such as weight loss and reduction of dietary sodium intake, as contributing to the observed improvement in BP control, although subsequent clinical benefit should likely accrue regardless of the mechanism of BP reduction. One potential concern is the compliance and accuracy of home BP measurements. All automated devices were proved to be accurate before they were given to patients. The accuracy and reliability of recorded home BP levels have been addressed previously. Mengden et al24 compared automatically stored BP data to patient logbook entries for self-measured readings and found that, although some underreporting and overreporting of values occurred, the overall means for both were identical. Another concern might be the BP status of patients lost to follow-up. Although the information is anecdotal, several of the patients who failed to return BP data were contacted and admitted that after dismissal from the clinic their BP level remained normal and they lost interest in performing and recording additional readings. Finally, the potential costs associated with this study should be considered. Although the automated BP device was provided to the patient at no cost, retail prices vary from $85 to $107, depending on the cuff size required. For physician time, the commitment was approximately 1 hour per week. Nurse time was 3 to 4 hours per week and consisted primarily of recording and formatting the handwritten reports of BP readings and telephoning patients with recommended changes in therapy. The use of telemonitoring with
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receipt of downloaded patient data in a manner that can be expressed automatically in terms of weekly averages would substantially reduce the time investment per patient.23,25 Whether our approach can ultimately reduce the cost associated with treating hypertension is unclear. Although use of home BP monitoring has been associated with reduced medical resource utilization and improved BP control rates,26 there is potential for increased costs associated with intensification of antihypertensive drug therapy. This issue was addressed in a recently published study by Staessen et al.27 They performed a randomized controlled trial of antihypertensive treatment based on either home or office BP measurements. At the end of 1 year, more patients in the home measurement group were able to discontinue the use of antihypertensive drugs (presumably reflecting white coat hypertension), whereas more patients in the office group had their drug regimens intensified. Overall, drug expenditures were lower in the home vs office group, albeit at the expense of significantly higher systolic and diastolic BP of approximately 7 and 4 mm Hg in the home group. That trial differed from the current study in that the patients were significantly younger, diastolic BP control was the only goal, and a formal stepwise drug treatment protocol was used. In the long run, it is likely that even if drug-associated costs increased, this would likely be offset by the savings associated with subsequently reduced rates of hypertensionassociated morbidity and mortality. Although less formally studied, other inconveniences or hidden costs associated with the treatment of hypertension in terms of physician office visits, travel, and time lost from work may be decreased using our model. CONCLUSION The model of a physician-nurse team using home BP measurement has the potential to significantly increase longterm hypertension control rates. This approach should also reduce the cost and inconvenience associated with the treatment of hypertension. REFERENCES 1. Chobanian AV, Bakris GL, Black HR, et al, National Heart, Lung, and Blood Institute Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, National High Blood Pressure Education Program Coordinating Committee. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report [published correction appears in JAMA. 2003;290:197]. JAMA. 2003;289:2560-2572. 2. ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart
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Attack Trial (ALLHAT) [published corrections appear in JAMA. 2003;289:178 and 2004;291:2196]. JAMA. 2002;288:2981-2997. 3. Hajjar I, Kotchen TA. Trends in prevalence, awareness, treatment, and control of hypertension in the United States, 1988-2000. JAMA. 2003;290:199206. 4. Izzo JL Jr, Levy D, Black HR. Importance of systolic blood pressure in older Americans [Clinical Advisory Statement]. Hypertension. 2000;35:1021-1024. 5. Meissner I, Whisnant JP, Sheps SG, et al. Detection and control of high blood pressure in the community: do we need a wake-up call? Hypertension. 1999;34:466-471. 6. Berlowitz DR, Ash AS, Hickey EC, et al. Inadequate management of blood pressure in a hypertensive population. N Engl J Med. 1998;339:1957-1963. 7. Joffres MR, Ghadirian P, Fodor JG, Petrasovits A, Chockalingam A, Hamet P. Awareness, treatment, and control of hypertension in Canada. Am J Hypertens. 1997;10(10, pt 1):1097-1102. 8. Borzecki AM, Wong AT, Hickey EC, Ash AS, Berlowitz DR. Hypertension control: how well are we doing? Arch Intern Med. 2003;163:2705-2711. 9. Canzanello VJ, Jensen PL, Hunder I. Rapid adjustment of antihypertensive drugs produces a durable improvement in blood pressure. Am J Hypertens. 2001;14(4, pt 1):345-350. 10. The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure [published correction appears in Arch Intern Med. 1998;158:573]. Arch Intern Med. 1997;157:2413-2446. 11. Association for the Advancement of Medical Instrumentation. American National Standard for Electronic or Automated Sphygmomanometers. Arlington, Va: Association for the Advancement of Medical Instrumentation; 1992. 12. Canzanello VJ, Jensen PL, Schwartz GL. Are aneroid sphygmomanometers accurate in hospital and clinic settings? Arch Intern Med. 2001;161:729-731. 13. Thijs L, Staessen JA, Celis H, et al. Reference values for self-recorded blood pressure: a meta-analysis of summary data. Arch Intern Med. 1998; 158:481-488. 14. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986;1:307-310. 15. Norby SM, Stroebel RJ, Canzanello VJ. Physician-nurse team approaches to improve blood pressure control. J Clin Hypertens (Greenwich). 2003;5:386-392. 16. Hyman DJ, Pavlik VN. Characteristics of patients with uncontrolled hypertension in the United States [published correction appears in N Engl J Med. 2002;346:544]. N Engl J Med. 2001;345:479-486. 17. Oliveria SA, Lapuerta P, McCarthy BD, L’Italien GJ, Berlowitz DR, Asch SM. Physician-related barriers to the effective management of uncontrolled hypertension. Arch Intern Med. 2002;162:413-420. 18. Krakoff LR, Board of the ASH Specialists Program. The ASH Specialists Program: a progress report [editorial]. Am J Hypertens. 2002;15:577-579. 19. Bansal N, Tendler BE, White WB, Mansoor GA. Blood pressure control in the hypertension clinic. Am J Hypertens. 2003;16:878-880. 20. Gorski LA, Johnson K. A disease management program for heart failure: collaboration between a home care agency and a care management organization. Lippincott’s Case Manag. 2003;8:265-273. 21. Kallenbach A, Ludwig-Beymer P, Welsh C, Norris J, Giloth B. Process improvement for asthma: an integrated approach. J Nurs Care Qual. 2003;18: 245-256. 22. Finkelstein J, Cabrera MR, Hripcsak G. Internet-based home asthma telemonitoring: can patients handle the technology? Chest. 2000;117:148-155. 23. Rogers MA, Small D, Buchan DA, et al. Home monitoring service improves mean arterial pressure in patients with essential hypertension: a randomized, controlled trial. Ann Intern Med. 2001;134:1024-1032. 24. Mengden T, Hernandez Medina RM, Beltran B, Alvarez E, Kraft K, Vetter H. Reliability of reporting self-measured blood pressure values by hypertensive patients. Am J Hypertens. 1998;11:1413-1417. 25. Pickering TG, Gerin W, Holland JK. Home blood pressure teletransmission for better diagnosis and treatment. Curr Hypertens Rep. 1999;1:489-494. 26. Soghikian K, Casper SM, Fireman BH, et al. Home blood pressure monitoring: effect on use of medical services and medical care costs. Med Care. 1992;30:855-865. 27. Staessen JA, Den Hond E, Celis H, et al, Treatment of Hypertension Based on Home or Office Blood Pressure (THOP) Trial Investigators. Antihypertensive treatment based on blood pressure measurement at home or in the physician’s office: a randomized controlled trial. JAMA. 2004;291:955-964.
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