Retrospectives: Edgar Sydenstricker: Household Equivalence Scales and the Causes of Pellagra

In the early part of the 20th century the disease pellagra, now almost unknown, affected and killed thousands of people in the United States. Some claimed it was an infection, while others maintained it was due to a dietary deficiency. The economist Edgar Sydenstricker (1881-1936), who was a member of a US Public Health Service team examining the disease, argued it was critical to understand how pellagra varied by levels of income. Collecting survey data, he realized equivalence scales were needed to adjust household incomes. His research demonstrated that there was a strong negative correlation between the incidence of pellagra and equivalized household income. Further analysis of the dietary differences between households suggested that a dietary deficiency associated to a restricted availability of animal protein food was the cause of pellagra. This was confirmed more than a decade later when a deficiency of vitamin B-3 was identified as the cause.