Rural-urban differences in factors associated with poor blood pressure control among outpatients.

Background: The purpose of this study was to determine which patient-related factors are most strongly associated with having uncontrolled hypertension among outpatients.

Methods: A sample of 300 outpatients with diagnosed hypertension from three different settings was reviewed, focusing on demographics, comorbidity, adherence, and treatment factors. Regression analyses were conducted to determine which factors were associated with poor BP control (>140mmHg systolic or >90mmHg diastolic).

Results: Those most strongly associated with blood pressure control were men (OR 2.04, 95% CI 1.17-3.55) living in a rural setting (OR 0.30, 95% CI 0.16-0.55). Age, race, total number of medicines, number of visits, and the number of comorbidities were not significantly associated with poor blood pressure control in this population.

Conclusions: Being urban and male are strongly associated with uncontrolled hypertension. Public health blood pressure control efforts in the Southeast region should be directed toward this population.

Key Words: hypertension, control, adherence, men's health, urban, rural, blood pressure

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Hypertension remains poorly controlled among outpatients despite substantial public health measures directed at detection and treatment. Many patient-oriented factors are thought to contribute to this poor control, including lack of awareness of blood pressure diagnosis and goals, lack of awareness of the consequences of hypertension, and a lack of understanding that high blood pressure is a serious medical condition. (1) Furthermore, a lack of adherence to a medical regimen, lack of adherence to medication, and difficulty accessing healthcare are contributors. (2,3) In addition, providers may contribute to poor blood pressure control through clinical inertia and by failing to adequately address competing demands in the clinical encounter. (4,5) Gender and rural/urban status also appear to play a role. (6)

Determining which patient-oriented factors play the biggest part in poor blood pressure control among people in the Southeast is an important public health priority. The purpose of this study was to determine which demographic, comorbidity, and treatment factors were most strongly associated with having uncontrolled hypertension among outpatients.

Methods

The Institutional Review Board of the Medical University of South Carolina reviewed and exempted the study protocol. We reviewed the medical records of a consecutive sample of 300 outpatients with diagnosed hypertension, 100 from each of three different settings: an urban university family practice center, a suburban residency practice, and a rural private practice. The urban center is located in a downtown area and has a racial mix of 35% whites and 65% African-Americans, and serves a mixed socioeconomic population of urban poor, students, and university employees. The suburban practice serves a largely working poor population and has 39% African-Americans. The rural practice serves a varied socioeconomic population with an ethnic mix that includes 15% African-Americans. All three practices have a large public insurance (Medicaid/Medicare) population (49-64%).

The record review focused on the demographics, comorbidity, adherence, and treatment factors. The medical records existed on paper in the rural practice, and in an electronic medical record system in the urban and suburban practices. Age, race, sex, blood pressure, number of medicines, type of BP medicine, number of visits in the last 12 months, time since most recent visit, presence of comorbidities, rural/nonrural status, and adherence information were recorded. Blood pressure, number of medicines, and type of blood pressure medicine were determined from the most recent visit. The presence of comorbidities was extracted from the problem lists in the record by counting other nonhypertension chronic diagnoses, including diabetes, hyperlipidemia, and obesity. Adherence information was extracted from the most recent progress note. Adherence was dichotomized into "adherent" or "nonadherent." Participants were considered adherent if their behavior was characterized in the medical record as "excellent" (or similar), "good," "adequate," or "OK," and charts with the words "fair," "poor," or similar were designated nonadherent, similar to validated self-report scales used in previous studies. (7)

We analyzed the results using SAS to perform descriptive statistics. Next, logistic regression analyses were conducted to determine which factors were associated with poor BP control (>140mmHg systolic or >90mmHg diastolic). Standardized betas, P-values, odds ratios, and 95% confidence intervals were obtained from the logistic regression output. Statistical significance was defined as P [less than or equal to] 0.05 without correction for multiple-comparisons, since there are relatively few factors and the specific analyses were planned in advance. (8)

Results

The charts of 300 individuals were reviewed, 100 from each practice. The average age of participants was 55.4 years. The study population included 42% African-Americans, and 39% of the sample were male. Further demographic characteristics of the sample are displayed in Table 1.

In the individual factor analysis, the only significant factor was male sex (P = 0.05). Adherence was not significantly associated with blood pressure control, although it was assessed and recorded in fewer than half of the medical records reviewed. In the multivariate model containing all of the variables available (age, race, sex, number of visits, number of medicines, presence of comorbidities, and rural status), the only factors that were significantly associated with blood pressure control were being male (OR 2.04, 95% CI 1.17-3.55) and being from the rural practice (OR 0.30, 95% CI 0.16-0.55) (Table 2). Age, race, total number of medicines, number of visits, and the number of comorbidities were not significantly associated with blood pressure control in this population when other variables were taken into account. Adherence was rated good or better in only 23% of patients, but was recorded in the medical record in only 27% of the most recent visits and thus was not included in the final model.

Discussion

In this study of factors associated with control of blood pressure, we found that being male and being from a nonrural area were associated with an increased likelihood of poor control. These factors surpassed several factors that we suspected would be associated with control before the study, including age, race, comorbidities, and number of medicines.

The study findings are consistent with previous studies documenting the high prevalence of poorly controlled hypertension in urban men, particularly African-American men. (9,10) Shea and colleagues have found that not having a primary care physician and not having health insurance were the factors most strongly associated with poor control in a group of minority patients visiting emergency rooms with severe hypertension. African-American men have higher rates of hypertension, and poorer levels of control in several studies. (6,11-13) Blood pressure control is a complex issue, however, and may not be explained by such commonly assessed factors as race, age, adherence, and comorbidities. In a recent VA study of 20 factors related to blood pressure control among people with good access to care and medications, African-American men still had a higher rate of uncontrolled hypertension (63% versus 50%, OR = 1.70; 95% CI 1.20-2.41). (14) Social support and stress, factors that are difficult to assess and measure, may also have an impact on blood pressure control and may possibly have a greater impact on urban males. (15)

The question of why men would be differentially affected compared with women cannot fully be explained by access to care, since previous studies have shown that even when access is the same, women have better blood pressure control than men. (16) The explanation is elusive, but may be related to priorities, a feeling of invincibility, or the stress of being a male in today's society. (17) The male preponderance of poor hypertension control is not unique to the United States; a recent study of the determinants of blood pressure control in a French population found that male gender was one of the two main variables independently associated with poor blood pressure control. (18) These findings support the main results of the current study, that male gender is an important determinant of blood pressure control.

The association of being urban with poor blood pressure control is consistent with some studies (11) and at odds with others. (6) The rural population studied in the current project has a high level of provider continuity and may partially account for the better control in that environment. (19) Another possible explanation is that unknown factors unique to the particular population studied are playing a role, consistent with previous analyses of the high variation in blood pressure control rates in rural practices. (20)

The implications of this study for clinical practice are that urban men may need greater attention and new approaches to achieve good blood pressure control. Public health programs and policies in the Southeast may need to focus more closely on urban men to reach the Healthy People 2010 blood pressure goals (http://hin.nhlbi.nih.gov).

Limitations of the study include a relatively small sample size in only one geographic area of the United States. As such, the data are not generalizable to other areas of the U.S. Furthermore, adherence was not assessed in the majority of records, inhibiting our ability to assess that factor and draw conclusions regarding its comparative importance. The lack of assessment/documentation of adherence may point to a quality improvement opportunity.

In conclusion, this study demonstrated that being urban and male are strongly associated with uncontrolled hypertension. This association remained while controlling for demographics, comorbidity, and treatment factors. If these results are confirmed in other studies, the findings provide a target for clinical and public health blood pressure control efforts in the region.

References

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2. Schroeder K, Fahey T, Ebrahim S. How can we improve adherence to blood pressure-lowering medication in ambulatory care? Systematic review of randomized controlled trials. Arch Intern Med 2004;164:722-732.

3. Rehman SU, Hutchison FN, Hendrix K, et al. Ethnic differences in blood pressure control among men at Veterans Affairs clinics and other health care sites. Arch Intern Med 2005;165:1041-1047.

4. Grant RW, Cagliero E, Dubey AK, et al. Clinical inertia in the management of Type 2 diabetes metabolic risk factors. Diabet Med 2004;21:150-155.

5. Jaen CR, Stange KC, Nutting PA. Competing demands of primary care: a model for the delivery of clinical preventive services. J Fam Pract 1994;38:166-171.

6. Mainous AG 3rd, King DE, Garr DR, et al. Race, rural residence, and control of diabetes and hypertension. Ann Fam Med 2004;2:563-568.

7. Brooks CM, Richards JM, Kohler CL, et al. Assessing adherence to asthma medication and inhaler regimens: a psychometric analysis of adult self-report scales. Med Care 1994;32:298-307.

8. Rosner B, ed. Fundamentals of Biostatistics. 5th ed. Pacific Grove, Thomson Learning, 2000.

9. Hill MN, Han HR, Dennison CR, et al. Hypertension care and control in underserved urban African American men: behavioral and physiologic outcomes at 36 months. Am J Hypertens 2003;16:906-913.

10. Burt VL, Whelton P, Roccella EJ, et al. Prevalence of hypertension in the US adult population. Results from the Third National Health and Nutrition Examination Survey, 1988-1991. Hypertension 1995;25:305-313.

11. Teitelbaum BA, Roberts DK, Ecklund Winters J, et al. Blood pressure control in an African American sample with diabetes mellitus in an urban eye clinic. Optometry 2005;76:653-656.

12. Gadegbeku CA, Lea JP, Jamerson KA. Update on disparities in the pathophysiology and management of hypertension: focus on African Americans. Med Clin North Am 2005;89:921-933.

13. Riehle JF, Lackland JT, Okonofua EC, et al. Ethnic differences in the treatment and control of hypertension in patients with diabetes. J Clin Hypertens (Greeenwich) 2005;7:445-454.

14. Bosworth HB, Dudley T, Olsen MK, et al. Racial differences in blood pressure control: potential explanatory factors. Am J Med 2006;119:70.e9-15.

15. Strogatz DS, Croft JB, James SA, et al. Social support, stress, and blood pressure in black adults. Epidemiology 1997;8:482-487.

16. Kotchen JM, Shakoor-Abdullah B, Walker WE, et al. Hypertension control and access to medical care in the inner city. Am J Public Health 1998;88:1696-1699.

17. Ludescher G, Nishiwaki R, Lewis D, et al. Black male college students and hypertension: a qualitative investigation. Health Educ Res 1993;8:271-282.

18. Roux O, Chapellier M, Czernichow S, et al. Determinants of hypertension control in a large French population of treated hypertensive subjects. Blood Press 2006;15:6-13.

19. Devroey D, Coigniez P, Vandevoorde J, et al. Prevention and follow-up of cardiovascular disease among patients without a personal GP. Fam Pract 2003;20:420-424.

20. Goldstein AO, Carey TS, Levis D, et al. Variations in hypertension control in indigent rural primary care clinics in North Carolina. Arch Fam Med 1994;3:514-519.

Dana E. King, MD, MS, and Jeremy R. Crisp, BS

From the Department of Family Medicine, Medical University of South Carolina, Charleston, SC.

Reprint requests to Dana E. King, MD, MS, Department of Family Medicine, Medical University of South Carolina, 295 Calhoun Street, Charleston, SC 29425. Email: [e-mail]

This study was presented as a poster at the Annual Meeting of the North American Primary Care Research Group, Quebec City, Quebec, Canada, October 16, 2005.

The project was supported in part by grant number 1D12HP00023 from the Health Resources and Services Administration and grant number 5T35 DK007431 from the National Institutes of Health.

Accepted April 5, 2006.

RELATED ARTICLE: Key Points

* Being male and being from an urban setting are two of the most important patient-related factors associated with poor control of hypertension.

* Public health measures in the southeastern United States may need to target urban men to reach Healthy People 2010 goals for blood pressure control.

Table 1. Descriptive characteristics of the sample (N = 300)

Age (mean)                             55.4
Race (% African Americans)             41.7
Sex (% males)                          39.4
Systolic BP (mean)                    142.5
Diastolic BP (mean)                    81.0
Number of medications (mean)            5.3
Number of visits in 12 months (mean)    5.7
Comorbidity present (%)                74
Rural (%)                              33
Adherent (%)                           23.1

BP, blood pressure.

Table 2. Likelihood of having uncontrolled blood pressure (odds ratios,
95% confidence intervals)

Independent variables              Lower 95% limit  Upper 95% limit
and effects            Odds ratio  odds ration      odds ration

Age                    0.9950      0.976            1.014
Male#                  2.0387#     1.171#           3.551#
Black                  0.754       0.427            1.333
Number visits          0.979       0.9167           1.046
Number meds            0.990       0.905            1.084
Co-Morbidities         0.876       0.494            1.551
Rural#                 0.297#      0.160#           0.546#

Significant odds ratios in bold.

Note: Significant odds ratios indicated with #.