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DALLAS -- Socioeconomic status and race and ethnicity were, and were not, found to be correlated with serum phosphorus levels among incident hemodialysis patients, researchers said here.

Two studies presented at the National Kidney Foundation annual meeting, using different methods, came down on opposite sides of the question of whether race is a factor in risk of abnormal phosphorus levels with hemodialysis.

One of the studies, led by Natasha Tilluckdharry, MD, from the Kaiser Permanente health system in California, looked at the phosphorus levels of more than 5,500 patients and found that the unadjusted levels did not differ by race.

And when they adjusted for age, sex, body mass index, and other factors, Hispanic patients on hemodialysis had lower levels than did non-Hispanic whites or Asians (4.33 mg/dL, 95% CI 4.27-4.40 versus 4.54, 95% CI 4.45-4.64 and 4.48, 95% CI 4.43-4.54, respectively, P=0.0005). African Americans had roughly the same level as whites.

In the other study, by Ravi Manglani, MD, at the Lincoln Medical Center in Bronx, N.Y., and colleagues, Hispanics living in the inner-city on hemodialysis had significantly higher phosphorus levels than non-Hispanics regardless of how well they adhered to a diet or responded to phosphate bonding therapy.

Tilluckdharry told MedPage Today that her team had hypothesized that they would, in fact, find a racial association.

"The results were different than what we expected," she said. "But there were no differences in terms of race even though there were marked differences in other aspects."

Those differences were significant at baseline for vitamin D levels, mean serum albumin, mean serum calcium, and median parathyroid hormone.

The cohort studied was selected from an end-stage renal disease (ESRD) database at Kaiser Permanente. All patients had at least one year of membership with the system during the period from January 2007 to June 2013. Nearly 60% of the patients were male.

The mean follow-up was around 2 years and the mean age was 65.8. Serum phosphorus levels were averaged over time. Limitations of the Kaiser study included the reliance on GPS coordinate data for socioeconomic status data. There was also a lack of information about the type of phosphate binder used, adherence rate to medication, and diet.

Hispanic Ethnicity a Factor?

In the Bronx study, data were gathered on 88 patients with end-stage renal disease. Hispanics with poor diet adherence had higher levels of phosphorus than did non-Hispanics (6.82 versus 6.19, 95% CI 6.64-7.00 and 95% CI 5.96-6.42; P=0.0009).

In addition, Hispanics with good diet adherence had higher phosphorus levels (4.87 versus 4.65; P=0.0064) as did those with good adherence to phosphate binding therapy (5.11 versus 4.78; P=0.0003) and those with poor adherence to therapy (7.00 versus 6.37; P=0.0029). The measurements were taken over a 2-year period, ending in December 2012. All patients had been on dialysis for at least a year.

"We need to increase awareness among physicians that phosphorous levels need to be aggressively managed among the Hispanic population, because there's evidence that higher phosphorus levels lead to a higher morbidity and mortality for dialysis patients," Manglani told MedPage Today. "Whether it's more emphasis on diet restrictions or more aggressive phosphate binding therapy, it could be a big help."

But Tilluckdharry said -- for those in the Kaiser system, at least -- there was no need to change existing treatments. One possible reason for the different findings was the nature of Kaiser's system and those who use it, she said.

"Our population is a little bit different because they're in a managed care system," Tilluckdharry said. "Your access to dietitians, your access to social workers, your access to medication, is pretty standard, regardless of race or socioeconomic status."

One of the goals of the Kaiser study was to figure out who to target. But, said Tilluckdharry, given the results there was no good reason to change clinical practice and target specific populations.

Researchers disclosed no relevant relationships with industry.

• Reviewed by F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine and Dorothy Caputo, MA, BSN, RN, Nurse Planner

last updated 03.27.2015

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Sunitinib represents an acceptable option in first line treatment for metastatic papillary renal cell carcinoma (mPRCC), a recent study published early online in the journal Annals of Oncology has shown.

Because there is currently no standard first line treatment for mPRCC, researchers designed a prospective phase II study to evaluate sunitinib in first line treatment of patients with mPRCC.

Researchers enrolled 15 patients with type 1 and 46 patients with type 2 mPRCC. Of those, 12 were in the favorable risk group, 33 were in the intermediate risk group, 9 were in the poor risk group, and 7 were undetermined.

Results showed that at a median follow-up time of 51.4 months, 13% (95% CI: 0.1 - 30.5) of those with type mPRCC achieved a partial response, 67% had stable disease with 33% of patients having stable disease at least 12 weeks.

For those with type 2, 11% (95% CI: 1.9 - 20.3) achieved a partial response, 54% had stable disease with 22% of patients having stable disease at least 12 weeks.

Median progression-free survival was 6.6 months (95% CI: 2.8 - 14.8) and 5.5 months (95% CI: 3.8 - 7.1) for type 1 and type 2, respectively. Median overall survival was 17.8 months (95% CI: 5.7 - 26.1) for type 1 and 12.4 months (95% CI: 8.2 - 14.3).

The findings suggest that sunitinib shows activity in both types of mPRCC, but lower activity than in clear cell metastatic renal cell carcinoma (mRCC).

Reference

1. Ravaud A, Oudard S, De Fromont M, et al. First-line treatment with sunitinib for type 1 and type 2 locally advanced or metastatic papillary renal cell carcinoma: a phase II study (SUPAP) by the French Genitourinary Group (GETUG). Ann Oncol. 2015. doi: 10.1093/annonc/mdv149.

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