Evaluating quality of life tools in North American patients with erythropoietic protoporphyria and X-linked protoporphyria

Background: Erythropoietic protoporphyria (EPP) and X-linked Protoporphyria (XLP) are rare photodermatoses presenting with severe phototoxicity. Although anecdotally, providers who treat EPP patients acknowledge their life-altering effects, tools that fully capture their impact on quality of life (QoL) are lacking. Methods: Adult patients with EPP/XLP were given four validated QoL tools: the Patient Reported Outcomes Measurement Information System 57 (PROMIS-57), the Hospital Anxiety and Depression Scale (HADS), the Illness Perception Questionnaire Revised (IPQR), and an EPP-Specific tool. All patients received the PROMIS-57 while the HADS, IPQR, and EPP-Specific tools were introduced at a later date. Associations between responses and clinical phenotypes were explored. Results: Two hundred and two patients were included; 193 completed PROMIS-57, 104 completed IPQR, 103 completed HADS, and 107 completed the EPP-Specific tool. The IPQR showed that patients strongly believed EPP/XLP had a negative impact on their lives. Mean scores in anxiety and depression domains of both HADS and PROMIS-57 were normal; however, anxiety scores from HADS were borderline/abnormal in 20% of patients. The EPP-Specific tool revealed a decreased QoL in most patients. The PROMIS-57 showed that 21.8% of patients have clinically significant pain interference. Several tool domains correlated with measures of disease severity, most being from the PROMIS-57. Conclusions: Impaired QoL is an important consequence of EPP/XLP. PROMIS-57 was most sensitive in evaluating impaired QoL in EPP/XLP. Further research is needed to compare the effectiveness of it for assessing response to treatment.