Abstract No. 1 Epidemiology of erythropoietic protoporphyria: the U.K. experience

Abstract

Erythropoietic protoporphyria (EPP) is a rare inherited photodermatosis that causes lifelong painful photosensitivity. Neither its full clinical spectrum nor its impact on quality of life (QOL) have been investigated in a large group of patients. We sought to document the epidemiology of EPP and its impact on QOL in a high proportion of all patients with EPP resident in the U.K. Subjects with EPP were identified from U.K. clinical databases and were assessed by the same clinical investigator over a 7-month period using a standardized proforma and Dermatology Life Quality Index questionnaires. Three hundred and eighty-nine living subjects with EPP were identified, giving a minimum U.K. prevalence of 1 in 136 000. Of these, 223 (114 females, 109 males; median age 34 years, range 5–87) were investigated. Mean total erythrocyte porphyrin (TEP) was higher in males (29·3 μmol L-1) than females (23·1 μmol L-1). The median age at onset (1·1 years) preceded that at diagnosis by 10·9 years. Median times to onset of symptoms after sun exposure, onset of signs (oedema, erythema) and resolution of signs were 20 min, 6 h and 3 days, respectively. Most subjects reported priming (85%), absence of protection by glass (92%), exacerbation by wind (68%), no family history of photosensitivity (58%), no symptoms during winter (56%) and had chronic skin lesions (79%). Symptoms changed little with age but improved during pregnancy in 47% of gravid women. Most subjects used protective clothing and a sunscreen; 28% were taking beta-carotene and a further 56% had taken it; 29% were not under regular medical care. Two subjects (0·9%) had liver failure and 8% had gallstone disease. QOL was markedly impaired with scores similar to those in severe dermatological disease. QOL scores correlated weakly with TEP (r = 0·215) and time to onset of symptoms (r = –0·267), but not with age at onset. In conclusion, we have reported the epidemiology of EPP. It is a persistent, socially disabling disease with a marked impact on QOL. Its diagnosis is often overlooked. Neither TEP, age at onset nor time to onset of symptoms are useful predictors of impaired QOL in individual patients.