BACKGROUND: Porphyria cutanea tarda (PCT) is a rare hepatocutaneous disease whose prognosis is largely unknown.

OBJECTIVES: To compare all-cause and cause-specific mortality between a nationwide cohort of patients with PCT and a matched population sample.

METHODS: We included all Danish patients diagnosed with PCT from 1989-2012. Each patient was matched by age and gender to ten random population controls. We compared survival and cause-specific mortality between patients and controls and adjusted for confounding from alcohol-related diseases, hepatitis, hemochromatosis, HIV, diabetes, AMI, stroke, cancer, COPD, and cirrhosis.

RESULTS: The 20-year survival was 42.9% (95% CI 36.9-48.7%) for patients with PCT compared to 60.5% (95% CI 58.6-62.4%) for matched controls. All-cause mortality hazard ratio (HR) was 1.80 (95% CI 1.56-2.07) before adjustment and 1.22 (95% CI 1.04-1.44) after adjustment. The cause-specific mortality was markedly increased for non-malignant gastrointestinal diseases (HR 5.32, 95% CI 2.71-10.43) and cancers of the gut (HR 2.05, 95% CI 1.24-3.39), liver/gallbladder (HR 11.24, 95% CI 4.46-28.29), and lungs (HR 2.17, 95% CI 1.41-3.33).

LIMITATIONS: We had no data on lifestyle factors.

CONCLUSIONS: Patients with PCT have increased mortality, primarily explained by an increased mortality from gastrointestinal diseases and from cancers of the gut, liver/gallbladder, and lungs.