Rates of Uncontrolled Blood Pressure Higher in Patients with Chronic Kidney Disease Treated in Public Health Setting

A study that looked at patients with chronic kidney disease in a public health setting found that uncontrolled blood pressure was nearly 20% higher than the national average, and somewhat higher among black patients than in white patients.

Controlling blood pressure is a concern among patients with chronic kidney disease (CKD) and little is known about the issue among ethnically diverse patients treated in public health settings, according to Delphine S. Tuot, MD, assistant professor of medicine at the University of California, San Francisco, who presented the findings of the study during Kidney Week 2012, a conference of the American Society of Nephrology held in San Diego.

The UCSF study looked at 6,618 adult patients with CKD who received primary care from 2010 to 2012 at the Community Health Network (CHN), an integrated delivery system that serves San Francisco residents who are either uninsured or publically insured. Tuot and her colleagues examined more than 18,000 clinical blood pressure measurements among a patient population that was 23% white, 34% black, 18% Hispanic, and 21% Asian. Chronic kidney disease for these patients was defined by two values of either the estimated glomerular filtration rate, eGFR<60 ml/min/1.73m² or abnormal dipstick albuminuria.

The results were then compared to weighted and similarly adjusted estimates of uncontrolled blood pressure among 2,404 patients who had seen a doctor in the prior year and were participants in the National Health and Nutrition Examination Survey (NHANES), a government-funded program that tracks national health trends from interviews and physical examination data.

The study found that patients from the public health population were more likely to be younger and from diverse ethnic backgrounds. Nearly one-quarter of that group did not speak English, compared to less than 4% in the national comparison group. Nearly one-fifth were uninsured, compared to roughly 8% nationally.

Overall prevalence of uncontrolled blood pressure among all stages of CKD was 25% in the public health system compared to roughly 22% on the national level, a 20% difference in the public health system, said Tuot.

Interestingly, said Tuot, when the findings were divided by early stage versus later stage CKD, those in the public health group fared better compared to national figures. Among individuals with stages 1 and 2 CKD, prevalence of uncontrolled blood pressure was actually lower in the public health system. “Whereas in individuals with more severe stage kidney disease, the prevalence of uncontrolled blood pressure was higher,” Tout said. “So this overall difference was really driven by more severe CKD.”

Among mild CKD cases, black patients from the San Francisco public health group had 8% greater odds of uncontrolled blood pressure compared to white patients, with no significant differences between Hispanics and whites, and other races and ethnicities, including Asians. But disparities for black patients with mild CKD appeared much greater nationally, according to Tuot. Data from NHANES showed black patients had a 2.5-fold greater risk of having uncontrolled blood pressure compared to white patients.

The data suggests that there are few differences among races and ethnicities treated at the public health level, according to Tuot.

“Overall, what we derive out of this is that, in general, for all stages of CKD, for individuals who receive care in a public health system, the public system seems to provide more equitable care with fewer differences in uncontrolled blood pressure between races and ethnicities compared to national estimates,” she said.

That’s not surprising given that part of the mission of public health facilities is to reduce disparities in health care, Tout said. What still needs to be determined is why that does not translate to individuals with more severe chronic kidney disease, she said.