The Burden of Erythropoietic Protoporphyria ( <scp>EPP</scp> ): Results From the <scp>EPP</scp> Life Impact and Genetic Health Trajectory ( <scp>LIGHT</scp> ) Study

Erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) are rare metabolic disorders causing phototoxicity, potential liver damage, and significant burden in all facets of life. We sought to quantify symptoms, health-related quality of life (HRQoL), work/school productivity, and healthcare utilization (HCU) of individuals with protoporphyria using the EPP Life Impact and Genetic Health Trajectory (LIGHT) study. A cross-sectional, online questionnaire administered to 164 adults and 33 adolescents with protoporphyria aged ≥ 12 years, included validated patient-reported outcome measures and original items assessing symptoms, HRQoL, productivity, and HCU. Prodromal (early warning) symptoms after sunlight exposure, reported by > 50% of participants, included tingling, warmth, itching, sensitivity to touch, and burning; symptoms occurred in ≤ 10 min in 48.8% of adults and 15.2% of adolescents. Symptoms hindered daily activities at least "somewhat" for 62.8% of adults and 87.9% of adolescents, and 23.4% - 41.7% reported school/work absenteeism in past month; 67.1% of adults and 87.9% of adolescents experienced ≥ 1 phototoxic reaction in the previous 12 months. Most adults and adolescents reported feeling depressed (75.0%, 45.5%), anxious (79.9%, 60.6%), isolated (82.9%, 57.6%), frustrated (90.2%, 93.9%), and lonely (75.6%, 39.4%). Fifty-four percent (53.7%; adults) and 16.7% (adolescents) reported work productivity was affected by their EPP at least "a little bit." Adults had a mean number of eight physician visits related to EPP in the previous 12 months, and adolescents had a mean number of 3.2 visits. Adults averaged 5.5 emergency room visits annually. Protoporphyria significantly affects daily life through symptoms, emotional/psychological distress, and HCU.