Amy Dickey, MD, Assistant Professor of Medicine at Harvard Medical School, and a patient with erythropoietic porphyria (EPP), discusses the development and testing of a wearable device for light exposure measurements for patients with EPP.
EEP is a rare type of porphyria characterized by deficiency of the enzyme ferrochelatase. This deficiency allows for build-up of protoporphyrin in bone marrow, plasma, and red blood cells. Common symptoms include phototoxicity or light sensitivity, tingling, itching, or burning of the skin. These often lead to redness, blistering, and swelling. EEP is caused by changes in the UROS gene.
The study objective was to develop and validate a wearable device that measures light exposure to predict and prevent EPP symptoms. Participants included five patients with EPP who wore two light dosimeters, one as a watch and one as a shirt clip, for three weeks.
Results indicated that daily exposure measured by the watch device was a stronger predictor of symptom risk than self-reported time spent outdoors or exposure to light. An increase of one standard deviation from the mean in the watch device dose increased the odds ratio for symptom risk more than the shirt clip. Additionally, the watch device suggested a 78% predictive accuracy.
