Patients with porphyria cutanea tarda (PCT) have a higher risk for all-cause mortality, a study in the Journal of the American Academy of Dermatology suggests.

Danish patients who received a PCT diagnosis from September 1989 to December 2012 were included in this historical cohort study (n=637). A biochemical diagnosis of PCT was defined as a urine urocarboxylporphyrin/creatinine of >6 μmol/mol creatinine, plasma fluorescence emission peak at 615 to 620 nm, or fecal heptacarboxylporphyrin of >2 nmol/g (dry weight).

Random control individuals from the general population were matched to the PCT cohort by sex, age, and birth year (n=6519). For each patient with PCT, a total of 10 control individuals were matched. A 94-year-old woman with PCT was matched with only 6 control individuals. In analyses adjusted for alcohol-related diseases, hepatitis, hemochromatosis, HIV, diabetes, acute myocardial infarction, stroke, cancer, chronic obstructive pulmonary disease, and cirrhosis, survival and cause-specific mortality outcomes were compared among patients with PCT and control individuals.

The 20-year survival probability was lower for patients in the PCT group vs the control group (42.9% [95% CI, 36.9%-48.7%] vs 60.5% [95% CI, 58.6%-62.4%], respectively). In the analysis adjusted for comorbid diseases, the all-cause mortality hazard ratio (HR) for patients with PCT vs control individuals was 1.22 (95% CI, 1.04-1.44), suggesting a 1.22-fold higher mortality risk in this patient population. The study investigators note this finding likely indicates that the excess mortality in patients with PCT was partially attributed to comorbid disease and residual confounding from lifestyle factors.

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A noticeable increase in cause-specific mortality was associated with nonmalignant gastrointestinal diseases (HR, 5.32; 95% CI, 2.71-10.41), as well as 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 of the study were the inclusion of only Danish patients, as well as the lack of data on patients’ lifestyle factors.

The study found that “a large part of the excess mortality in patients with PCT was due to lifestyle factors and comorbidity, and this conclusion is corroborated by their higher risk of death from alcohol-related causes, accidents, and suicide.” According to the researchers, the findings from this study emphasize “that patients with PCT and clinicians treating these patients must pay special attention to lifestyle and lifestyle-related comorbidities.”

Disclosure: None of the study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

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Reference

Christiansen AL, Brock A, Bygum A, Rasmussen LM, Jepsen P. Increased mortality in patients with porphyria cutanea tarda – a nationwide cohort study [published online July 30, 2019]. J Am Acad Dermatol. doi:10.1016/j.jaad.2019.07.082