NHANES participants with asthma from 2005 to 2018 were linked to National Death Index records through December 2019 and depressive symptoms measured by PHQ-9 at baseline. Those scoring 10 or above had a restricted mean survival of 155.2 months over 15 years against 165.1 months for the rest, a difference of 9.9 months. An exploratory mediation analysis attributed 23.8% of the association to the poverty-income ratio, with both exposure and mediator measured only at baseline.
Why it is interesting: It puts a survival figure on depressive symptoms within a chronic respiratory population and attempts to separate the income component of that gap.