Elsevier

Mayo Clinic Proceedings

Volume 88, Issue 10, October 2013, Pages 1099-1107
Mayo Clinic Proceedings

Original article
Characteristics of Resistant Hypertension in a Large, Ethnically Diverse Hypertension Population of an Integrated Health System

https://doi.org/10.1016/j.mayocp.2013.06.017Get rights and content

Abstract

Objective

To evaluate the prevalence of and characterize resistant hypertension in a large representative population with successful hypertension management and reliable health information.

Patient and Methods

We performed a cross-sectional study using clinical encounter, laboratory, and administrative information from the Kaiser Permanente Southern California health system between January 1, 2006, and December 31, 2007. From individuals older than 17 years with hypertension, resistant hypertension was identified and prevalence was determined. Multivariable logistic regression was used to calculate odds ratios (ORs), with adjustments for demographic characteristics, clinical variables, and medication use.

Results

Of 470,386 hypertensive individuals, 60,327 (12.8%) were identified as having resistant disease, representing 15.3% of those taking medications. Overall, 37,061 patients (7.9%) had uncontrolled hypertension while taking 3 or more medicines. The ORs (95% CIs) for resistant hypertension were greater for black race (1.68 [1.62-1.75]), older age (1.11 [1.10-1.11] for every 5-year increase), male sex (1.06 [1.03-1.10]), and obesity (1.46 [1.42-1.51]). Medication adherence rates were higher in those with resistant hypertension (93% vs 89.8%; P<.001). Chronic kidney disease (OR, 1.84; 95% CI, 1.78-1.90), diabetes mellitus (OR, 1.58; 95% CI, 1.53-1.63), and cardiovascular disease (OR, 1.34; 95% CI, 1.30-1.39) were also associated with higher risk of resistant hypertension.

Conclusion

In a more standardized hypertension treatment environment, we observed a rate of resistant hypertension comparable with that of previous studies using more fragmented data sources. Past observations have been limited due to nonrepresentative populations, reliability of the data, heterogeneity of the treatment environments, and less than ideal control rates. This cohort, which was established using an electronic medical record–based approach, has the potential to provide a better understanding of resistant hypertension and outcomes.

Section snippets

Study Population

A cross-sectional study was performed of members of the Kaiser Permanente Southern California (KPSC) health system between January 1, 2006, and December 31, 2007. The KPSC health care system is a prepaid integrated health plan providing comprehensive care to 3.4 million individuals throughout Southern California, from Bakersfield to San Diego, at 14 medical centers and more than 100 satellite clinics. During the study period, there were 2.4 million adult members. The patient population is

Hypertension Cohort

A total of 498,891 individuals in KPSC were identified as having hypertension during the study period. This represented 21% of all adults in the health plan. Secondary hypertension was identified in 642 patients, resulting in 498,249 individuals with nonsecondary hypertension. Another 27,863 patients had BPs missing, leaving 470,386 members in the study analysis (Figure). The average age of the hypertension population was 65 years, with women accounting for 55% (Table 1). The race/ethnicity

Discussion

We found a significant proportion of resistant hypertension, with a prevalence of 12.8% (60,327 out of 470,386 patients) in all hypertensive individuals and 15.3% (60,327 out of 395,482 patients with medications) in those taking medications. Using a stricter criteria, 7.9% of the hypertension population (n=37,061) had uncontrolled BP while taking 3 or more medicines. Hypertensive individuals who were male, of black race, obese, and older were more likely to have resistant hypertension. The

Conclusion

In a large representative hypertension population, we identified and characterized a resistant hypertension cohort that accounted for a substantial proportion (12.8%) of the hypertension population. The resistant hypertension population was older, was more likely to be black, had better adherence, and had more comorbidities. This cohort, established by an electronic medical record–based approach, has the potential to improve our understanding of resistant hypertension by addressing many of the

Acknowledgments

We thank Eric P. Brass, MD, PhD, at Harbor-UCLA Medical Center for his invaluable contributions to methodology and scientific insight into the drafting of this manuscript.

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    Grant Support: This study was partially funded by an investigator-initiated research grant from Novartis Pharmaceuticals (J.J.S.); by KPSC Regional Research; and by a research grant from the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (R01 DK078106 to K.K.-Z).

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