BACKGROUND: A previous cross-sectional study found that poor control of post-9/11-onset asthma was associated with concurrent mental health conditions. One potential explanation for this finding is that poor mental health could lead to decreased adherence to asthma treatment. We hypothesized that the relationship between mental health conditions and poor control of post-9/11-onset asthma was mediated by poor medication adherence.
METHODS: We studied 1651 adult WTC Health Registry enrollees with self-reported asthma first diagnosed by a clinician between 9/11/2001 and 12/31/2003 who completed baseline (2003-2004) and two follow-up questionnaires (2011-12 and 2015-16). Asthma diagnosis was assessed on all surveys, and control at both follow-ups. Asthma was considered controlled, poorly controlled, or very poorly controlled based on modified National Asthma Education and Prevention Program criteria. Posttraumatic stress disorder (PTSD), depression, and generalized anxiety disorder (GAD) were assessed with validated scales in 2011-12. A score <6 on the 8-item Morisky Medication Adherence Scale (measured 2015-16) was considered poor medication adherence. The Cochran-Armitage test was used to assess trends across levels of asthma control. Multinomial logistic regression was used to examine associations with poor or very poor control, and logistic regression was used to assess associations with poor medication adherence.
RESULTS: In 2015-16, 30% of participants had poor asthma control and 41% had very poor control. Between the two follow-up surveys, control improved for 16%, declined for 25%, and was unchanged for 60%. Comorbid PTSD, depression, or GAD in 2011-12 were each associated with an increased odds of poor or very poor control in 2015-16. In 2015-16, most participants (61%) reported having been prescribed long-acting asthma control medications (e.g. inhaled corticosteroids). Of these, however, 56% reported poor adherence. Poor adherence was reported by 64% of participants with controlled asthma, 62% of those with poorly-controlled asthma, and 50% of those with very poorly-controlled asthma (P for trend <0.001). Poor medication adherence was not associated with any of the mental health conditions.
CONCLUSIONS: These results substantiate previous findings by establishing a temporal relationship between poor mental health and poor control of post-9/11-onset asthma. Contrary to our hypothesis, we did not identify a relationship between mental health conditions and poor adherence. Furthermore, adherence was better in participants with poorer asthma control compared to those with good control, suggesting that more severe symptoms were an incentive for improved adherence. Additional study of the relationship between mental health and asthma control in this population is needed.