Mineral bone disorder and its management among hemodialysis patients in the Gulf Cooperation Council: Initial findings from the dialysis outcomes and practice patterns study (2012-2015)

Abstract

The prospective cohort Dialysis Outcomes and Practice Patterns Study (DOPPS) initiated data collection in national samples of hemodialysis (HD) units (total of 41 study sites) in all six Gulf Cooperation Council (GCC) countries (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates) in late 2012. Here, we report initial results regarding mineral bone disorders (MBDs) and its management in the GCC countries. Forty-one randomly selected HD facilities, treating >23 HD patients each, were sampled and represent care for >95% of GCC HD patients. Descriptive results for the GCC countries based on a random sample of 20-30 HD patients in each study facility. Initial results for the GCC are from 931 HD patients treated at 41 dialysis units (ranging from 1 unit in Bahrain to 21 in Saudi Arabia). Results are presented as weighted estimates, accounting for the sampling fraction in each unit. Baseline descriptive statistics (e.g., mean, median, or percentage), weighted by facility sampling fraction were calculated for the study sample. For analyses examining the percent of facility patients having (a) serum phosphorus >6.0 mg/dL or (b) parathyroid hormone (PTH) >600 pg/mL, analyses were restricted to facilities having at least 10 HD patients with a reported serum phosphorus or PTH measurement, respectively. Logistic regression analyses of the indicated binary outcomes were based on the use of generalized estimating equations and were adjusted for GCC country, patient age category (65 years old), sex, and whether the patient was diagnosed with diabetes mellitus. Logistic models accounted for clustering of patients within facilities, assuming an exchangeable working correlation matrix. Mean age of HD patients in the GCC countries was 53 years vs. 61-64 years in the three other DOPPS regions. MBD markers showed slightly lower mean serum Calcium in the GCC countries, similar mean serum phosphorus, and intermediate median PTH levels compared with the three other DOPPS regions. Among GCC countries, the country mean value of MBD markers ranged from 8.6-9.0 mg/dL for serum calcium, 4.4-5.4 mg/dL for serum phosphorus, whereas median PTH ranged from 163-389 pg/mL. Similar to other DOPPS regions, PTH was higher among patients who were younger or without diabetes, and serum phosphorus was lower with older age (P <0.001 for each). History of parathyroidectomy was lower in the GCC countries versus other regions but did not differ when adjusted for age and dialysis vintage. Among treatments used for managing MBD, the GCC countries showed one of the highest uses of cinacalcet (24%) and phosphorus binder use (81%), whereas intravenous Vitamin D use (24%) was slightly higher than that in EURANZ. A much larger fraction of HD patients in the GCC countries had a dialysate calcium bath ≥3.5 mEq/L (43%) versus 0-4% in the three other DOPPS regions. Although many aspects of MBD management and MBD marker achievement are similar in the GCC countries to that seen in other DOPPS study regions, large variability was seen across countries and facilities in the GCC. Mean serum calcium was lower in the GCC despite the much greater use of dialysate Ca of ~3.5 mEq/L which may be due to the relatively low use of vitamin D and higher cinacalcet use, meriting further study. Future work will focus on GCC facility HD practices and patient characteristics most strongly related to the achievement of MBD target levels and associated outcomes.