Safety Net Health Care Systems Can Deliver Equitable Care and Good Hypertension Outcomes

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Patients with CKD who rely on safety net health care systems may receive more equitable and effective care, concludes a study that compared one such system, the Community Health Network San Francisco (CHNSF), with a representative sample of the U.S. population.

Delphine Tuot, MDCM, of the University of California, San Francisco, and her colleagues observed that patients with mild CKD receiving care from CHNSF demonstrated better control of hypertension among racial and ethnic minorities than a similar cohort from the National Health Examination and Nutrition Survey (NHANES) (1). Yet despite these encouraging results, Tuot also reported that African Americans have an increased risk for uncontrolled hypertension when compared to whites, even in the public health care setting. Tuot spoke at Kidney Week 2012 in San Diego.

Although the study shows the potential of systems such as CHNSF to act as front-line agents to reduce disparities of care for a population that may have higher risks for developing CKD and progression to ESRD, it also raises the question of how their success could be translated to improve hypertension control among at-risk minorities with more severe CKD.

Research has shown that racial and ethnic minorities have a higher risk for developing CKD and progressing to ESRD than whites, yet the reasons behind this are unclear. Most likely, this may be due to a combination of factors, and uncontrolled hypertension could be a major contributor to the accelerated and early rate of disease progression that these at-risk populations exhibit.

Efrain Reisin, MD, FACP, FASN, professor of medicine and chief of the section of nephrology and hypertension at the Louisiana State University Health Science Center, New Orleans, who was not involved in the study, said there are congenital, behavioral, and health access factors that contribute to higher rates of uncontrolled hypertension among minorities.

“African Americans, with or without CKD, have a higher rate of associated conditions than Caucasians (e.g., diabetes in men and diabetes and obesity in women),” he said. They also have some congenital characteristics that increase the incidence of hypertension, including lower plasma renin activity (PRA) levels with expansion of fluid volume, and higher prevalence of salt-dependent hypertension. Other barriers to controlling BP in African Americans include low access to medical care and poor adherence to treatment. Also, more populations of African Americans live in communities that lack safe environments for walking or exercising and less neighborhood grocery stores that may offer easy access to a fresh and healthy food supply.”

Because public health care delivery systems act as safety nets and deliver care for vulnerable populations, including minorities, they have the potential to reduce disparities and improve the outcomes of those who are at highest risk for kidney disease. To assess their performance in BP control, Tuot compared the prevalence and odds of uncontrolled hypertension among patients with CKD in CHNSF—an integrated health care delivery system that cares for San Francisco’s uninsured and publically insured residents—with national estimates using data from NHANES.

A total of 6681 patients with CKD who received care at CHNSF between 2010 and 2012 and 3108 NHANES participants with CKD who saw a physician between 2003 and 2010 were included in the study. Although the cohorts differed in age, racial composition, number of non-English speakers, and uninsured individuals, both had similar rates of diabetes. Diagnosis of CKD was confirmed by an eGFR 15–59 mL/min/1.73 m2 or a dipstick albuminuria test result >30 mg/g, with uncontrolled hypertension defined as a mean systolic BP >140 mm Hg or a mean diastolic BP >90 mm Hg. Prevalence of uncontrolled BP in the both cohorts was calculated, as well as odds ratios for uncontrolled hypertension among racial minorities as compared to whites with CKD, controlling for age, gender, insurance status, and presence of diabetes.

In mild CKD (stages 1 and 2), African Americans in the CHNSF cohort had an 8 percent higher odds for uncontrolled hypertension compared with whites. This contrasted strongly with the results from NHANES, in which odds for uncontrolled BP were 153 percent higher among African Americans compared to whites. In CKD stages 3 and 4, the odds for uncontrolled BP in the CHNSF were 11 percent higher for African Americans and 6 percent higher for Hispanics versus whites, compared with a 27 percent higher odds but a 43 percent lower odds for those in NHANES, respectively. Overall adjusted rates of uncontrolled hypertension were higher in the CHNSF cohort compared to NHANES (25.42 percent versus 21.72 percent). When stratified by severity of CKD, rates remained higher for CHNSF in stage 3 and 4 CKD (28.06 percent versus 23.08 percent) but were lower for stage 1 and 2 CKD (18.00 percent versus 22.13 percent) compared to NHANES.

The results revealed that “differences in BP control among patients with CKD of different races/ethnicities were smaller in the CHNSF compared to the national average, and that CHNSF appears to provide more equitable care to patients with CKD,” said Tuot.

Were the higher rates of uncontrolled hypertension among African Americans unexpected? Reisin didn’t think so. “They have a higher rate of hypertension and resistant hypertension than Caucasians due to genetic and behavioral factors. In fact, previous reports from the VA Health Care sites have also shown a lower rate of hypertension control in African Americans when compared with Caucasian subjects, despite the fact that in the VA system both groups have the same access to medications and health care.”

Reisin added that the better performance of CHNSF in managing hypertension in CKD 1 and 2 was also unsurprising given that “previous studies have proven that effectiveness of care may vary among providers. Some health providers may be slow to follow recommended treatment guidelines, or may not have all the resources needed to treat low-income populations or those with special needs, conditions that make it more difficult to control BP.”

The higher rates of uncontrolled hypertension in patients with stage 3 and 4 CKD reported in this study are indicative of the difficulties in managing this population. “According to previous publications, the rate of resistant hypertension increases from 5 percent in general practice to 50 percent or higher in nephrology clinics that treat African Americans or Caucasian CKD patients. The decrease in GFR increases BP and impairs the maintenance of sodium balance and body fluid homeostasis,” he said. “Also, the presence of associated diseases like diabetes, obesity, and sleep apnea are very important factors that increase the rate of resistant hypertension in more advanced CKD stages.”

The work demonstrates that “public health delivery systems, similar to the CHNSF, may provide more equitable care for patients with CKD than national averages and do a good job of controlling BP in patients with early CKD, despite caring for a population with high rates of poverty, limited health literacy, and non-English speakers,” Tuot said. Yet she noted more research is needed to better understand why results differed in patients with mild CKD compared to patients with moderate/severe CKD. “This may reflect challenges in timely and appropriate care for those with more severe disease, including access to nephrologists, but at this point, we do not know,” she said. “But I would like to challenge our community to translate these results in mild stages of CKD to improve care for our patients with more moderate and severe stages of the disease.”

Reisin agreed that more research is needed to “further investigate the pathogenesis of resistant hypertension in African Americans, Hispanics, and other minority communities. In addition, clinical studies should include higher minority participation in the enrolled population to facilitate the assessment of safety and efficacy of different therapeutic approaches in these subjects.”

Reference

1. Tuot DS, et al. Blood pressure control among CKD patients in a public health system. (Abstract)