Income-driven socioeconomic status and presenting illness severity in children with acute respiratory failure.

This was a secondary analysis, not a trial designed to test whether family income causes illness severity. Socioeconomic status was approximated from census tract median family income, not from each family's own income. 63% of consenting parents declined to provide annual income, and 29% did not provide highest level of education, so the analysis relied on neighborhood income. The sample included only children with addresses that could be matched to a U.S. census tract, and 2006 of 2138 consenting subjects were analyzed. The sample's income distribution may not represent the full U.S. income range, with few children from impoverished tracts. The same median income may mean different access to goods and services in different parts of the country. Only about a third of non-survivors had residential addresses included, so the income pattern among children who died is uncertain. Data came from 2009 to 2013, and income values were from 2011, before changes after 2014. Parental consent rates differed by race in the parent study, which may affect who was included.

Do not read the unadjusted PARDS difference across income quartiles as evidence that income caused severity. It was not significant after adjustment for age group, gender, race, ethnicity and primary diagnosis.