Mineral and Bone Disorder and Management in the China DOPPS

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Mineral and Bone Disorder and Management in the China Dialysis Outcomes and Practice Patterns Study

The management of mineral and bone disorder (MBD) in hemodialysis (HD) patients is a critical aspect of care globally, yet significant regional disparities exist in monitoring practices, treatment approaches, and clinical outcomes. The China Dialysis Outcomes and Practice Patterns Study (DOPPS) provides a comprehensive evaluation of MBD markers—hypocalcemia, hyperphosphatemia, and secondary hyperparathyroidism—among HD patients in three major Chinese metropolitan areas (Beijing, Guangzhou, and Shanghai). This analysis highlights the prevalence of these conditions, current management practices, and opportunities for improvement within China’s rapidly expanding dialysis population.

Epidemiological Profile of MBD in China

The China DOPPS cohort included 1,186 patients from 45 randomly selected HD facilities. Compared to other DOPPS regions (Japan, North America, and Europe), Chinese patients were younger (mean age: 58.6 years) and less likely to have diabetes as the primary cause of end-stage renal disease (18% vs. 35–56% in other regions). Despite shorter dialysis vintage (median 3.5 years vs. 6.4 years in Japan), Chinese patients exhibited higher rates of severe hyperphosphatemia (serum phosphorus >7 mg/dL in 27% of patients) and secondary hyperparathyroidism (parathyroid hormone [PTH] >600 pg/mL in 21%). These figures starkly contrast with data from Japan, where only 10% had phosphorus >7 mg/dL and 1% had PTH >600 pg/mL. Hypocalcemia (albumin-adjusted calcium <8.4 mg/dL) was also prevalent in China (25%), though comparable to Japan (26%).

Dialysis Prescription and Biochemical Markers

Dialysis practices in China differed notably from other regions. While most patients received HD three times weekly, 25% underwent two sessions per week—a rarity in other DOPPS regions. Treatment duration (242 minutes/session) aligned with Japanese and European standards but exceeded North American practices (220 minutes). Despite comparable session lengths, Chinese patients had lower standardized Kt/V (2.05 vs. 2.14–2.28 in other regions), reflecting suboptimal dialysis efficiency. Higher dialysate calcium concentrations (73% used ≥1.500 mmol/L) likely contributed to relatively normal serum calcium levels (mean 9.12 mg/dL), though 25% remained hypocalcemic.

Hyperphosphatemia was disproportionately severe in China. The mean serum phosphorus level (6.00 mg/dL) exceeded values from Japan (5.42 mg/dL), North America (5.11 mg/dL), and Europe (4.87 mg/dL). Elevated phosphorus correlated with lower dialysis frequency (1 cup/day) and longer dialysis sessions were protective against hyperphosphatemia. Secondary hyperparathyroidism showed strong associations with prolonged dialysis vintage, higher phosphorus, and higher calcium levels, while diabetes and residual kidney function were inversely related.

Monitoring and Treatment Practices

Laboratory monitoring of MBD markers in China lagged behind global standards. Only 14.9% of patients underwent monthly phosphorus testing, compared to >70% in other regions. PTH monitoring was particularly infrequent, with 3.2% tested monthly versus 15–23% elsewhere. These gaps in surveillance likely contributed to delayed interventions.

Phosphate binder use was lower in China (59%) than in Japan (84%), North America (66%), and Europe (79%). Calcium-based binders dominated prescriptions (53%), while non-calcium-based agents like sevelamer were rare (1%). Active vitamin D (calcitriol or analogs) was prescribed to 57% of patients—similar to Europe but lower than Japan (75%) and North America (79%). Cinacalcet use was negligible (2%) compared to 16–24% in other regions. Facility-reported targets for PTH and phosphorus revealed discordance between goals and practice: 47% of Chinese facilities aimed for PTH 7 mg/dL.

Predictors of Treatment Prescription

Multivariable analyses revealed incongruities between biochemical markers and therapeutic responses. Elevated phosphorus or PTH levels did not reliably predict phosphate binder or vitamin D prescriptions. Instead, vitamin D use correlated with congestive heart failure and concurrent phosphate binder use, while binder prescriptions were linked to higher albumin levels and vitamin D co-administration. This suggests clinical decision-making in China may prioritize comorbid conditions over MBD severity.

Regional Comparisons and Cultural Context

The high prevalence of MBD in China contrasts with dietary and physiological factors that might predict better control. Traditional Chinese diets contain less phosphorus than Western or Japanese diets, and racial differences in PTH regulation (lower levels in Asians at equivalent kidney function) have been reported. However, systemic challenges—such as infrequent dialysis, limited access to non-calcium-based binders, and cost barriers for cinacalcet—likely override these advantages. Additionally, normalized protein catabolic rate (nPCR), a surrogate for dietary protein intake, was lower in China (0.82 vs. 0.98–1.02 g/kg/day elsewhere), yet hyperphosphatemia rates remained high, possibly implicating processed food additives or underestimation of protein intake.

Opportunities for Improvement

The China DOPPS underscores critical gaps in MBD management:

  1. Standardized Monitoring Protocols: Implementing monthly phosphorus and PTH testing, as practiced in other regions, could enable timely interventions.
  2. Expanded Therapeutic Options: Increasing access to non-calcium-based phosphate binders and cinacalcet, now available but underutilized due to cost, may improve biochemical control.
  3. Dialysis Adequacy: Optimizing session frequency and duration, alongside high-flux dialyzers, could enhance phosphorus clearance.
  4. Guideline Development: China-specific MBD guidelines, addressing local practices and resource constraints, may harmonize treatment targets and monitoring practices.

Limitations and Future Directions

The study’s focus on metropolitan areas limits generalizability to rural China, where dialysis access and treatment quality may differ. Cross-sectional design precludes causal inferences, and missing data (e.g., 11–40% missingness for PTH and Kt/V) may affect accuracy. Longitudinal assessments in future DOPPS phases could track progress as China expands dialysis access and refines MBD management strategies.

Conclusion

The China DOPPS reveals a high burden of poorly controlled MBD markers among HD patients, driven by infrequent monitoring, therapeutic inertia, and resource limitations. While dietary and demographic factors offer theoretical advantages, current practices fall short of international standards. Addressing these challenges requires multifaceted strategies: reinforcing laboratory surveillance, expanding medication access, optimizing dialysis prescriptions, and developing context-appropriate clinical guidelines. As China’s dialysis population grows, prioritizing MBD management will be essential to reducing cardiovascular morbidity and improving quality of life.

doi.org/10.1097/CM9.0000000000000533

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