What is the prevalence of calciphylaxis in dialysis patients?

Prevalence of Calciphylaxis in Dialysis Patients

Calciphylaxis is a rare but life-threatening complication affecting approximately 4.1% of hemodialysis patients, with an incidence rate of 9.0 per 1,000 patient-years in peritoneal dialysis patients. 1, 2

Epidemiology and Risk Factors

Calciphylaxis, also known as calcific uremic arteriolopathy (CUA), is characterized by painful, violaceous skin lesions that can progress to tissue necrosis, nonhealing ulcers, and gangrene. The condition carries a high mortality rate, with an estimated 1-year survival of only 45.8% 3.

Key Risk Factors:

• Demographic factors:

  • Younger patients on dialysis (49 vs. 60 years) 1
  • Female sex (71% of cases in peritoneal dialysis) 2
  • Obesity 3, 2

• Dialysis-related factors:

  • Longer duration of dialysis (80 vs. 20 months) 1
  • Prior hemodialysis before peritoneal dialysis (71% of cases) 2
  • Recurrent hypotension 2

• Laboratory abnormalities:

  • Elevated calcium-phosphate product >70 mg²/dL² 3, 1
  • Higher serum phosphate levels (8.2 vs. 5.7 mg/dL) 1
  • Elevated parathyroid hormone levels (1496 vs. 138 pg/mL) 1
  • Elevated alkaline phosphatase (188 vs. 89 IU/L) 1
  • Serum aluminum >25 ng/mL 3
  • Reduced serum albumin levels 2

• Medications:

  • Vitamin K antagonists (warfarin) - associated with up to 11-fold increased risk 4, 2, 5
  • Systemic corticosteroid use 3

• Comorbidities:

  • Liver disease 3
  • Diabetes 5

Diagnosis

According to KDIGO guidelines, skin biopsy has significant limitations in diagnosing calciphylaxis 4:

• No established features or validated histologic diagnostic criteria
• Standard staining methods alone yield non-specific findings
• 30% of biopsies have inadequate sampling
• Variable sensitivity (20-80%)
• Risk of triggering additional nonhealing ulcers

Treatment Outcomes

Treatment of calciphylaxis is challenging with poor response to conventional therapies:

• Surgical debridement was associated with improved 1-year survival (61.6% vs. 27.4% without debridement) 3

• Parathyroidectomy:

  • No significant difference in survival rates between patients who received parathyroidectomy and those who did not in one study 3
  • However, dramatic healing of ulcers was observed in patients who underwent parathyroidectomy in another study 1

• Sodium thiosulfate:

  • Mixed results reported in the literature 6, 5
  • One study reported no change in poor prognosis despite sodium thiosulfate treatment 5

• SNF472 (hexaphosphate phytate):

  • Promising results in a prospective trial (CALCIPHYX)
  • Improvements in wound healing
  • Fewer deaths and hospitalizations compared to placebo 4

Prevention

Prevention strategies should focus on:

1. Limiting exposure to excess calcium and phosphate 4
2. Avoiding high doses of active vitamin D derivatives 4
3. Avoiding vitamin K antagonists when possible 4
4. Addressing modifiable risk factors such as obesity and liver disease 3
5. Monitoring younger patients who have undergone longer periods of hemodialysis 1

Mortality

Calciphylaxis carries a very high mortality rate:

• Overall estimated 1-year survival rate: 45.8% 3
• 1-year mortality in peritoneal dialysis patients with calciphylaxis: 71% despite multimodal treatment 2

This devastating condition requires early recognition, aggressive management of risk factors, and a multidisciplinary approach to improve outcomes in this vulnerable patient population.