Serum phosphate and social deprivation independently predict all-cause mortality in chronic kidney disease

Solbu, M. D., Thomson, P. C., Macpherson, S., Findlay, M. D., Stevens, K. K., Patel, R. K., Padmanabhan, S. , Jardine, A. G. and Mark, P. B. (2015) Serum phosphate and social deprivation independently predict all-cause mortality in chronic kidney disease. BMC Nephrology, 16, 194. (doi: 10.1186/s12882-015-0187-1) (PMID:26627078) (PMCID:PMC4666082)

Abstract

Background: Hyperphosphataemia is linked to cardiovascular disease and mortality in chronic kidney disease (CKD). Outcome in CKD is also affected by socioeconomic status. The objective of this study was to assess the associations between serum phosphate, multiple deprivation and outcome in CKD patients. Methods: All adult patients currently not on renal replacement therapy (RRT), with first time attendance to the renal outpatient clinics in the Glasgow area between July 2010 and June 2014, were included in this prospective study. Area socioeconomic status was assessed as quintiles of the Scottish Index of Multiple Deprivation (SIMD). Outcomes were all-cause and cardiovascular mortality and commencement of RRT. Results: The cohort included 2950 patients with a median (interquartile range) age 67.6 (53.6–76.9) years. Median (interquartile range) eGFR was 38.1 (26.3–63.5) ml/min/1.73 m 2 , mean (±standard deviation) phosphate was 1.13 (±0.24) mmol/L and 31.6 % belonged to the most deprived quintile (SIMD quintile I). During follow-up 375 patients died and 98 commenced RRT. Phosphate ≥1.50 mmol/L was associated with all-cause (hazard ratio (HR) 2.51; 95 % confidence interval (CI) 1.63-3.89) and cardiovascular (HR 5.05; 95 % CI 1.90–13.46) mortality when compared to phosphate 0.90–1.09 mmol/L in multivariable analyses. SIMD quintile I was independently associated with all-cause mortality. Phosphate did not weaken the association between deprivation index and mortality, and there was no interaction between phosphate and SIMD quintiles. Neither phosphate nor SIMD predicted commencement of RRT. Conclusions Multiple deprivation and serum phosphate were strong, independent predictors of all-cause mortality in CKD and showed no interaction. Phosphate also predicted cardiovascular mortality. The results suggest that phosphate lowering should be pursued regardless of socioeconomic status.

• Item Type: Articles
• Additional Information: The Renal Research Group at the University of Glasgow is funded by Darlinda’s Charity for Renal Research. MDS was funded by the Northern Norway Regional Health Authority. The funders had no role in study design or analysis.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Patel, Dr Rajan and Findlay, Dr Mark and Stevens, Dr Kathryn and Thomson, Dr Peter and Macpherson, Dr Sarah and Mark, Professor Patrick and Solbu, Dr Marit Dahl and Padmanabhan, Professor Sandosh and Jardine, Professor Alan
• Authors: Solbu, M. D., Thomson, P. C., Macpherson, S., Findlay, M. D., Stevens, K. K., Patel, R. K., Padmanabhan, S., Jardine, A. G., and Mark, P. B.
• Subjects: R Medicine > R Medicine (General)
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health; College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
• Journal Name: BMC Nephrology
• Publisher: BioMed Central
• ISSN: 1471-2369
• ISSN (Online): 1471-2369
• Copyright Holders: Copyright © 2015 Solbu et al.
• First Published: First published in BMC Nephrology 16: 194
• Publisher Policy: Reproduced under a creative commons license