Improving blood pressure control in hypertensive hemodialysis patients.
Hypertension is very prevalent among patients undergoing chronic
hemodialysis. The purpose of this randomized controlled study was to
determine if home blood pressure (BP) monitoring could improve BP
control in a sample of 34 outpatient hemodialysis patients. Seventeen
participants were randomized to a home BP monitor intervention (HBPM)
plus usual care group and the other 17 participants were randomized to
usual care only. Average weekly BPs and fluid gains were monitored for
both groups over 12 weeks. The results indicated that HBPM significantly
lowered SBP (p=.018) in the HBPM group compared to the usual care group.
No significant differences were found between groups in terms of DBP or
fluid gains. These findings indicate that HBPM could help improve BP
control in the hemodialysis population. Nephrology nurses can be
instrumental in helping hemodialysis patients monitor their BP and
providing education on interventions that may improve BP control.
Key words: home blood pressure monitoring, hypertension, hemodialysis patients
|Article Type:||Clinical report|
(Care and treatment)
Blood pressure (Control)
|Publication:||Name: CANNT Journal Publisher: Canadian Association of Nephrology Nurses & Technologists Audience: Trade Format: Magazine/Journal Subject: Health care industry Copyright: COPYRIGHT 2007 Canadian Association of Nephrology Nurses & Technologists ISSN: 1498-5136|
|Issue:||Date: Oct-Dec, 2007 Source Volume: 17 Source Issue: 4|
|Geographic:||Geographic Scope: United States Geographic Code: 1USA United States|
After reading the article, the reader will be able to:
1. Understand the prevalence, pathophysiology and consequences of hypertension in the hemodialysis population.
2. Discuss possible reasons for uncontrolled blood pressure in the hemodialysis population.
3. Discuss how a nonpharmacologic intervention such as home BP monitoring can help control blood pressure in dialysis patients.
Hypertension is a major factor contributing to increased morbidity and mortality in patients dependent on hemodialysis due to end stage renal disease. Cardiovascular disease (CVD), including hypertension, accounts for almost 50% of deaths in patients with renal failure (U.S. Renal Data System, 2006). Uncontrolled hypertension may result in left ventricular hypertrophy, coronary artery disease, congestive heart failure and cerebrovascular complications (Agarwal et al., 2003; Rocco, Yan, & Heyka, 2001).
The National Kidney Foundation Task Force on cardiovascular disease in chronic kidney disease (CKD) has targeted hypertension as one of the major risk factors in the management of cardiovascular disease (CVD) (National Kidney Foundation, 1998). Targeting a reduction in deaths due to hypertension may lead to a significant reduction in the overall mortality of this population. Controlling hypertension in dialysis patients will help health care providers meet the 2010 Healthy Peoples' goal for Chronic Kidney Disease, i.e., decreasing complications, disability and death in CKD (U.S. Department of Health and Human Services, 2003).
Hypertension is very prevalent among patients undergoing chronic hemodialysis patients. A recent report by the U.S. Renal Data System (2002) estimates that 75% of patients on HD in the United States are hypertensive. Similar findings have been reported in other studies. Morse, Dang, Thakur, Zhang and Reisin (2003) reported the hypertension rate among hemodialysis patients ranged from 80% to 100%. Mettal, Kowalski, Trenkle, MacDonough, Halinski, Devlin, et al. (1999) found that 80% of patients on dialysis had elevated blood pressure (BP) despite being on one or more antihypertensive medications. In a large multicentre study cohort, Agarwal, Nissenson, Batlle, Coyne, Trout and Warnock (2003) reported that 86% of 2,535 clinically stable adult hemodialysis patients were hypertensive as defined by an average pre-dialysis systolic blood pressure > 150 mmHg or diastolic blood pressure > 85 mmHg. Despite the high prevalence of hypertension in this HD population, BP control was poor. Less than 15% of this sample was normotensive and only 30% of those with hypertension had adequately controlled blood pressure, 58% had poorly controlled BP and 12% had untreated hypertension (Agarwal et al., 2003). Systolic hypertension also appeared to be more prevalent in this sample (Agarwal et al., 2003). Eighty-eight per cent of the sample had systolic hypertension, either alone (35%) or in combination with diastolic hypertension (53%). Only 12% of the sample had isolated diastolic hypertension.
The variables that have a strong association with hypertension in the general population have been found to have little influence on BP in the hemodialysis population. Age, gender and ethnicity did not increase the prevalence of hypertension in the HD population (Agarwal et al., 2003; Coresh, Wei, & McQuillan, 2001). Possible reasons may be that age relates to improved adherence to a medication regimen and/or interdialysis fluid gains. Alternatively, elders are more likely to have comorbid cardiac diseases such as heart failure, which could be associated with lower BPs (Agarwal et al., 2003).
The reasons underlying inadequate control of hypertension in the hemodialysis population are poorly understood. Possible reasons include the practice of routinely withholding antihypertensive medications before dialysis, patient noncompliance with medication and dialysis regimens, excessive interdialytic weight gain due to excess fluid intake, poor salt restriction and missed hemodialysis treatments (Agarwal et al., 2003; Horl & Horl, 2002; Rahman et al., 1999).
To date, the majority of studies focusing on hypertension in hemodialysis patients have examined the pharmacological and medical treatment of hypertension. Agarwal et al. (2003) and Horl and Horl (2002) reported that medications alone do not control hypertension in chronic hemodialysis patients. Maintenance of normal BPs in this population has been largely attributed to optimal volume control as well as salt restriction (Horl & Horl, 2002).
Few studies have examined nonpharmacologic interventions to help control hypertension in patients dependant on hemodialysis. Home BP monitoring is an intervention that has been increasingly utilized in a variety of settings to improve BP control. Monitoring is increasingly being seen in the literature as a component of self-management of chronic disease. Self-monitoring has been described as a self-care strategy or approach aimed at facilitating a high level of self-management (Koch & Kralik, 2001; Thorne, Paterson, Russell, & Schultz, 2002).
According to Wilde and Garvin (2007), the concept of selfmonitoring comprises two major components: 1) awareness of bodily symptoms, sensations, daily activities and cognitive processes, and 2) measurements, recording or observation that inform cognition and provide information for independent action or consultation with care providers. According to Wilde (2003), monitoring can increase awareness and transform knowledge to a more cognitive dimension. This may allow individuals to have more ability to think about their needs and plan their self-care. Nurses, in turn, can guide patients to pay attention to their BP measurements and help guide patients in self-monitoring and appropriate interventions for BP control.
Many studies have confirmed that BPs taken at home with automatic BP monitors are more representative of true BPs than BPs measured by a physician in a clinic or office setting (Agarwal, 1999). Agarwal (2006) found that dialysis unit BP measurements are imprecise estimates of ambulatory BPs. Agarwal (2006) found that home BP monitoring was superior to BP obtained in the dialysis unit in determining ambulatory BP and left ventricular hypertrophy. The National Kidney Foundation K/DOQI guidelines have recommended that predialysis and post-dialysis BPs should be < 140/90 mm Hg and 130/80 mm Hg respectively (K/DOQI guidelines, 2005). The Canadian Society of Nephrology (CSN) (2006) recommends a target pre-dialysis BP of < 140/90 mmHg (Jindal, Chan, Deziel, Hirsch, Soroka, Tonelli, & Culleton, 2006).
Although home BP monitoring has improved outcomes in a variety of settings, no studies have been found to validate its use in the chronic hemodialysis population.
Agarwal (1999) postulated that involvement of the hemodialysis patient in managing hypertension could improve adherence and may provide a more reliable method to assess the effects of antihypertensive medications in hemodialysis patients. Home BP monitoring may cue patients to take actions to control their BP by helping them see the effects of increased fluid gains, dietary lapses, missed medications or treatments on their BP.
Purpose and hypotheses
The main purpose of this research study was to determine whether home BP monitoring in chronic hemodialysis patients leads to improved BP control. The specific aims of the study were to: (a) determine if home BP monitoring will lead to a reduction in BP between baseline and three-month follow-up among patients on hemodialysis, and (b) determine if home BP monitoring will decrease average interdialytic fluid gains between baseline and three-month follow-up among patients on hemodialysis.
The following hypotheses were tested:
1. Compared to the usual care group, chronic hemodialysis patients between the ages of 20 and 65 years who receive a home BP monitoring intervention (HBPM) will have a greater reduction in BP between baseline and three-month follow-up.
2. Compared to the usual care group, chronic hemodialysis patients between the ages of 20 and 65 years, who receive HBPM, will have a greater reduction in average weekly interdialytic fluid gains between baseline and three-month follow-up.
The Wayne State University Human Investigation Committee approved the study protocol. Written informed consent was obtained for all participants by the principal investigator.
A randomized two-group experimental longitudinal design was used in this study. Participants were randomly assigned to the HBPM group or to usual care. Randomization assignments were determined prior to the start of data collection using a random numbers table. The assignments were recorded on a 3-by-5 card, sealed in an opaque envelope, and stored in a file box. After baseline data were collected for each participant, the next envelope was drawn indicating that participant's number and group assignment. Data were collected at baseline and weekly for 12 weeks.
Setting and sample
The study was conducted in a 170-chair hemodialysis unit in Detroit, Michigan.
Because of funding limitations and the need to purchase home BP monitors, only 36 participants were enrolled in the study. Eligible patients were between the ages of 20 and 65 years, with an average pre-hemodialysis systolic BP > 150 mmHg and a diastolic BP > 90 mmHg. Exclusion criteria included: on hemodialysis less than six months, scheduled for renal transplantation, history of illicit drug use, mental illness or dementia, lack of orientation to person, time or place, or having a major health problem such as terminal cancer or human immunodefi- ciency virus (HIV).
Usual care involved BP assessment during each hemodialysis treatment, as well as having health care providers deliver ad hoc information and education about BP.
Home blood pressure monitoring
The HBPM group received usual care plus a memoryequipped Omron IC automatic home BP monitor. Patients in the HBPM group were asked to monitor and record their BP twice a day between 6 a.m. and 10 a.m. and then between 6 p.m. and 10 p.m. The first author trained patients on how to use the BP monitor and the patients performed a return demonstration of proper use. After initiation of the study, both study groups were seen weekly by the principal investigator, who answered questions and ensured the HBPM was working correctly (for those assigned to HBPM).
Demographic data were collected by the author on all patients after attaining written consent. Data about systolic and diastolic BP and fluid gains were collected from the medical record at baseline and weekly for 12 weeks.
Data were analyzed by the author using the SPSS software system 13.0 version. Intention to treat analysis was conducted to preserve the baseline comparability between groups achieved by random assignment. All data were analyzed using descriptive statistics. Average weekly pre-hemodialysis BP and interdialytic fluid gains in between hemodialysis treatments were calculated for both groups over a 12-week period. Average BP and fluid gain was used in these analyses.
Independent t-tests were used to compare average baseline
BPs of both groups. The hypotheses were tested using analysis of covariance (ANCOVA) to determine if there was a significant drop in BP between the two groups over a 12-week period. Baseline BPs were used as covariates to control for significant differences between groups in diastolic BP at baseline. Independent tests were run to determine if there were significant differences between the two groups for fluid gains. The significance level was set at 05.
Table One describes the demographic characteristics of the sample. Thirty-six patients were initially enrolled in the study. One died before completion of study and another was not able to continue because of severe illness and hospitalization. The analyses were conducted on a sample of 34 patients. The mean age of the sample was 48.7 + 10.8 years, with a range of 23 to 64 years. Thirty-three patients (97%) of the sample were African American and one patient was of Middle Eastern descent.
Twenty-three of 34 patients (68%) were female and 11 (32%) were male. In terms of education, the entire sample had at least a tenth-grade education or more. Although Table One demonstrates the HBPM group was more educated than the control group, these differences were not significant (p=.176). On average, the majority of the sample was not married and earned an annual income below $10,000/year. There were no significant demographic differences between the groups at baseline.
In terms of baseline BPs, there was no significant difference in systolic BP (SBP) between the two groups (t=-.262, p=.795). Baseline SBP was 161 + 14 mmHg in the HBPM group and 162 + 12 mmHg in the usual care group. However, a statistical difference was found between the two groups in baseline diastolic BP (DBP). The HBPM group had an average baseline DBP of 94 + 7 mmHg and the usual care group had an average DBP of 100 + 10 mmHg (t=-2.077, p=.046). This difference was taken into account when analyzing the first hypothesis.
There were no significant differences between the groups in number of BP medications taken at baseline (t=.15, p=.143). The HBPM group took an average of 2.2 BP medications and the usual care group took an average of 2.3 medications. Figure One demonstrates the average number of medications taken per group at baseline. In terms of medications, three patients (9%) were not on any BP medications, four patients (12%) were only taking one BP medication, 15 (44%) were on two BP medications, and approximately 12 patients (36%) were on three or more BP medications. Within this study, it appeared that withholding BP medications by patients occurs. At least two of the patients assumed they should hold their morning BP medications so their BP would not drop during dialysis.
[FIGURE 1 OMITTED]
Relationships between study variables
Correlation coefficients were conducted to determine the relationships between the variables weight, age, gender, highest education level, number of medications, income, and baseline BP. The only significant relationships that were found were between age and baseline diastolic BP (r=-.486, p=.004) and between income and baseline diastolic BP (r=-.345, p=.050). This indicated that the younger the age of the study participant, the higher the baseline diastolic BP. These findings also indicated that the lower the income of the participant, the higher the baseline diastolic BP.
Our first hypothesis, that home BP monitoring would have a greater reduction in BP between baseline and threemonth follow-up was partially supported. In the HBPM group, SBP fell from 161 + 14 mmHg at baseline to 153 + 16 mmHg at three-month follow-up (t=3.6, p=.003); DBP fell from 94 + 7 mmHg to 90 + 5 mmHg (t=2.1, p=.06). In the usual care group, SBP fell from 162+12 mmHg to 161+14 mmHg at three-month follow-up (t=.419, p=.68); DBP fell from 100+10 mmHg to 97+10 mmHg (t=.97, p=.35). A significant difference (F=6.211, p=.018) was found between the two groups for SBP; the difference was not significant for DBP (F=1.76, p=.195). Figures Two and Three demonstrate these findings.
Our second hypothesis, that home BP monitoring will lead to lower interdialytic fluid gains was not supported. There were no significant differences between the two groups in weekly interdialytic fluid gains at the end of 12 weeks (p=.296). The HBPM group gained an average of 2.56 + 1.0 kg and the usual care group gained 2.93 + 1.0 kg in between hemodialysis treatments.
[FIGURE 2 OMITTED]
[FIGURE 3 OMITTED]
The findings from this study support those reported previously in the literature. Hypertension is common and poorly controlled in the hemodialysis population (Agarwal et al., 2003). Despite the small sample size, the findings in this study did support that self-monitoring BP at home led to a signifi- cant reduction in SBP over a three-month period. This is important since systolic hypertension is more prevalent than diastolic hypertension in the hemodialysis population (Agarwal et al., 2003). Patients assigned to the HBPM group had significantly lower systolic BPs than those assigned to the usual care group. Although not significant, the diastolic BP did drop 4 mm Hg in the monitor group compared to a 3 mm Hg drop in the control group after three months.
Participants in this study were under-medicated in terms of BP medications. Patients in this study received an average of 2.24 + 1.21 BP drugs, yet, at baseline BPs, were uncontrolled. Despite an 8 mmHg drop in BP in the home HMBP, BPs remained uncontrolled at follow-up in both groups. These results are similar to those found in a landmark study by Agarwal et al. (2003), which reported that treated patients on hemodialysis received an average of 2.0 + 1.0 drugs. Approximately 20% of the patients were on one or no BP meds. Future studies to explore possible reasons for this finding need to be conducted. Additionally, future qualitative studies are recommended to explore patient nonadherence to BP management.
Poor control of hypertension may not always be related to under-recognition of hypertension or the lack of use of BP medication. Other possible causes may be excessive interdialytic fluid gains, withholding antihypertensive medications before dialysis, the timing of administration and type of dose used (Rahman, Dixit, Donley, Gupta, Hanslik, Lacson, et al., 1999). As mentioned above, excessive interdialytic weight gain has been postulated as a possible cause of hypertension in the hemodialysis population. This finding was not confirmed in this study. Home monitoring did not reduce interdialytic fluid gain and there were no differences in interdialytic fluid gain between groups, yet SBP was reduced at three-month followup. The HBPM group gained an average of 2.56 + 1.0 kg and the usual care group gained 2.93 + 1.0 kg in between hemodialysis treatments.
Since 68% of the sample was female and 97% of the sample was African American, future studies should aim to include more males and individuals of different ethnic backgrounds to increase the generalizability of findings. Further research with larger samples needs to be conducted to further validate these findings. It is the hope of this author to replicate this study in a Canadian dialysis unit in order to increase generalizability of the findings. Future research is also needed to determine the intensity of the intervention that results in the best BP outcome. A number of patients in this study had indicated that twice daily BP monitoring was too labour-intensive. Perhaps daily readings or two to three times weekly would be more appropriate for these patients and may result in similar findings.
In general, it is difficult to determine "what" in the selfmonitoring of BP had an effect. Perhaps patients were more engaged in their care and took more responsibility to reduce salt, reduce interdialytic weight gains or take medications as prescribed. Some literature on self-care notes that "watching" or knowing that providers and others were focused on one particular outcome led to patients being more attentive and wanting to achieve that outcome. Further exploration of possible reasons BP monitoring may enhance BP control is needed.
Implications for nephrology nurses
Nephrology nurses are frequently the major health caregiver for hemodialysis patients. They can be instrumental in helping hemodialysis patients monitor and understand their BP, as well as play a key role in reinforcing the need for adequate BP control. Nephrology nurses are in a key position to provide valuable education for patients related to reasons for high BP (e.g., increased fluid consumption, too much dietary consumption, missed medications or missed hemodialysis treatments). Nephrology nurses also play a major role in coordinating care with physicians when BP medications need adjustment. Working as a team with the aid of an intervention such as home BP measurement can improve BP control in the hemodialysis population.
In conclusion, despite the small sample size, the findings in this study did lend support for the intervention of home BP measurement in improving blood pressure control in the hemodialysis population. These findings are very encouraging and demonstrate a way to positively engage patients in their care and focuses on an important outcome to reduce cardiovascular morbidity and mortality.
This study is funded by Blue Cross Blue Shield of Michigan Foundation Student Award Program.
Nancy T. Artinian, PhD, RN (advisor).
Agarwal, R. (1999). Role of home blood pressure monitoring in hemodialysis patients. American Journal of Kidney Diseases, 33(4), 682-687.
Agarwal, R., Nissenson, A., Batlle, D., Coyne, D., Trout, J., & Warnock, D. (2003). Prevalence, treatment and control of chronic hemodialysis patients in the United States. American Journal of Medicine, 115(4), 291-297.
Agarwal, R. (2006). Management of hypertension in hemodialysis patients. Hemodialysis International, 10, 241-248.
Coresh, J., Wei, G., & McQuillan, G. (2001). Prevalence of high blood pressure and elevated serum creatinine level in the United States findings from the third National Health and Nutrition Examination survey (1988-1994). Archives of Internal Medicine, 161, 1207-1216.
Horl, M., & Horl, W. (2002). Hemodialysis-associated hypertension: Pathophysiology and therapy. American Journal of Kidney Diseases, 39(2), 227-244.
Jindal, K., Chan, C., Deziel, C., Hirsch, D., Soroka, S., Tonelli, M., & Culleton, B. (2006). Canadian Society of Nephrology: Clinical practice guidelines for management of blood pressure in hemodialysis patients. Journal of American Society of Nephrology, 17, S8-S10.
Koch, T., & Kralik, D. (2001). Chronic illness: reflections on a community-based action research program. Journal of Advanced Nursing, 36(1), 23-31.
Mettal, S., Kowalski, E., Trenkle, J., MacDonough, B., Halinski, D., Devlin, et al. (1999). Prevalence of hypertension in a hemodialysis population. Clinical Nephrology, 51, 77-82.
Morse, S.A., Dang, A., Thakur, V., Zhang, R., & Reisin, E. (2003). Hypertension in chronic dialysis patients: Pathophysiology, monitoring and treatment. American Journal of the Medical Sciences, 325(4), 194-201.
National Kidney Foundation. (2005). K/DOQI clinical practice guidelines for cardiovascular disease in dialysis patients.. American Journal of Kidney Disease, 45, S1-S153.
National Kidney Foundation Task Force on Cardiovascular Disease. (1998). Controlling the epidemic of cardiovascular disease in chronic renal disease. American Journal of Kidney Disease, 32, 853-906.
Rahman, M., Dixit, A., Donley, V., Gupta, S., Hanslik, T., Lacson, E., et al. (1999). Factors associated with inadequate blood pressure control in hypertensive hemodialysis patients. American Journal of Kidney Diseases, 33, 498-506.
Rocco, M., Yan, G., & Heyka, R. (2001). Risk factors for hypertension in chronic hemodialysis patients: Baseline data from the HEMO study. American Journal of Nephrology, 21, 280-288.
Thorne, S., Paterson, B., Russell, C., & Schultz, A. (2002). Complementary/alternative medicine in chronic illness as informed self-care decision making. International Journal of Nursing Studies 39(7), 671-683.
U.S. Renal Data System. (2006). USRDS 2006 annual data report: Atlas of end-stage renal disease in the United States. Bethesda, MD: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases.
U.S. Department of Health and Human Services. (2003). Healthy people 2010. Hyattsville, MD: Office of Disease Prevention and Health Promotion. Wilde, M. (2003). Embodied knowledge in chronic illness and injury. Nursing Inquiry, 10(3), 170-176.
Wilde, M.H., & Garvin, S. (2007). A concept analysis of selfmonitoring. JAN: Theoretical Paper, 339-346.
Zorica Kauric-Klein, MSN, APRN, is a nurse practitioner and adjunct faculty at the University of Detroit Mercy, McCauley School of Nursing, Detroit MI, U.S.A.
Nancy Artinian, PhD, RN, is a professor at Wayne State University, College of Nursing, Detroit, MI, U.S.A.
Address correspondence to: Zorica Kauric-Klein, MSN, APRN, at the University of Detroit, Mercy College of Health Professions, McCauley School of Nursing, 4001 W. McNichols Rd., Detroit, MI 48221-3038 U.S.A.
Submitted for publication: July 4, 2007.
Accepted for publication in revised form: October 8, 2007.
Table One. Demographic characteristics of sample (n=34) Variable Mean+ SD Mean + SD/ t/ Number (%) Number (%) Chi-square HBPM Usual care (p-value) group (n=17) group(n=17) Age 47.8 + 9.9 49.5 + 11.9 0.64 (n.s.) Gender Male 5 (29) 6 (35) -.356(n.s.) Female 12(71) 11(65) Education < 12 yrs 7 (42) 1 (65) 1.72 (n.s.) 13-16 yrs 8 (47) 6 (35) + 17 yrs 2 (12) 0 Marital Status Single/ 9 (53) 8 (53) 30 (n.s.) N. Married Significant 4 (18) 5 (18) Other Divorced/ separated 3 (18) 2 (12) Widowed 1 (6) 2 (12) Income < $5000 3 (17) 6 (36) .15 (n.s.) $5000-$9,999 5 (29) 5 (29) $10,000-$19,999 3 (17) 3 (17) $20,000-$29,999 3 (17) 1 (6) $30,000-$49,999 2 (12) >$50,000 2 (12) 0 Note: SD=Standard Deviation; %=Percent; n.s.=non-significant
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