Posttraumatic stress disorder (PTSD) has been consistently reported as a major determinant of asthma morbidity among rescue and recovery workers and other populations exposed to the debris generated by the collapse of the World Trade Center (WTC) towers.^1–3 Epidemiological studies have shown that up to one-third of WTC-exposed populations with asthma have comorbid PTSD.^4,5 Among WTC workers, PTSD has been associated with increased risk for airway hyperactivity, worse asthma control, worse quality of life, and increased risk of emergency room visits and hospitalizations.⁶

While the substantial negative impact of PTSD on asthma outcomes in WTC workers has been explored, the underlying mechanisms remain unclear. Several complex self-management behaviors such as medication adherence, inhaler technique, use of action plans, and trigger avoidance are key determinants of asthma control.^7,8 Unfortunately, the literature consistently shows that up to one-half of patients, including WTC workers with asthma, are nonadherent to their medication regimens.^9,10 Patients also frequently have difficulty performing all the tasks required for correct inhaler use, despite the critical nature of proper inhaler technique for adequate medication delivery.¹¹ Allergen avoidance is similarly only adhered to by a subset of patients, making environmental exposures that can trigger asthma symptoms and/or exacerbations more common, particularly in atopic patients.⁹ Given the known association between lower rates of self-management behaviors and mental health conditions,^12–14 it is possible that lower adherence to asthma self-management may explain, in part, the relationship between PTSD and worse asthma control. Immunological mechanisms may also explain the relationship between PTSD and asthma control.

Posttraumatic stress disorder has been strongly associated with low treatment adherence in multiple chronic diseases.^15–18 However, there are limited data on the relationship between PTSD and asthma self-management behaviors in the general population or among WTC workers. It is possible that those with PTSD have different health beliefs about asthma or emotional responses to the disease, factors that, according to the Self-Regulation Model (SRM), can be strong determinants of self-management behaviors.¹⁹ The SRM provides a helpful framework to identify factors that may influence low treatment adherence in individuals with PTSD. According to the model, patients with chronic illness, like asthma, compare their somatic sensations (ie, symptoms) with their normal self, and interpret deviations from normal in relation to their mental model of their illness (based on cognitive representations of illness), which in turn guides their self-management behaviors. Emotional responses to asthma (ie, worry, upset, or anxious) also influence self-management according to the SRM. The framework of the SRM is highly useful for identifying the modifiable beliefs and emotional mechanisms, which underlie behaviors worth targeting for self-management support interventions. Accordingly, in this study, we used data from a well-characterized cohort of WTC workers to understand the potential mechanisms underlying worse asthma outcomes by evaluating the association of PTSD with asthma self-management.

Between February 2017 and January 2020, we contacted potential participants; of these, 177 were found ineligible during screening (23% reported no history of asthma, 23% had a history of COPD, 14% were non‒English or ‒Spanish speakers, and 39% due to other reasons) and 360 eligible WTC workers were enrolled into the study. Of these 360 WTC workers, 3 were found to be ineligible after enrollment, 13 withdrew after recruitment, 52 were excluded because they were not prescribed a controller medication, and 16 did not complete the SCID-5-CV assessment and were excluded. Our final cohort included 276 WTC workers with asthma who were prescribed at least 1 controller medication.

Overall, 84 (30%) WTC workers in the study had PTSD based on SCID-5-CV results (Table I). A greater percentage of WTC workers with PTSD had very poorly controlled asthma (69% vs 46%; P = .001) and poorer asthma-related quality of life (60% vs 30%; P < .0001), whereas a greater percentage of those without PTSD had well-controlled asthma (35% vs 17%; P = .001). Posttraumatic stress disorder was also associated with greater acute resource utilization (28% vs 11%; P = .0006), and greater prevalence of comorbid major depression (64% vs 10%; P < .0001).

Unadjusted analyses showed no significant differences in medication adherence based on MARS scores in WTC workers with or without PTSD (34% vs 41%; P = .4; Table II). However, Ask-12 scores showed lower rates of adherence among WTC workers with versus without PTSD (24.0 ± 5.9 vs 22.1 ± 5.5, respectively; P = .01). Inhaler technique scores (6.6 ± 1.7 vs 6.5 ± 1.6; P = .6) as well as the proportion of WTC workers who showed adequate technique (80% vs 75%; P = .4) were not significantly different among the 2 groups. Similarly, we found no significant differences in the proportion of WTC workers who used an asthma action plan (49% vs 42%; P = .2), avoided asthma triggers (55% vs 47%; P = .2) or received the influenza vaccine (62% vs 59%; P = .7) in those with or without PTSD.

Adjusted analyses showed that PTSD was not associated with MARS scores (mean difference −0.15; 95% CI −0.5 to 0.2), percentage adherence based on MARS scores of 4.5 or greater (odds ratio [OR] 2.5; 95% CI 0.9 to 6.8), or Ask-12 scores (mean difference 1.7; 95% CI −0.3 to 3.6; Table III) after controlling for age, sex, race and ethnicity, education, income, asthma onset pre-vs post-9/11, depression, and other comorbidities. Similarly, WTC workers with and without PTSD did not have significant differences in inhaler technique scores (mean difference −0.11; 95% CI −0.7 to 0.5) or in odds of showing an adequate inhaler technique (OR 0.9; 95% CI 0.4 to 2.3). Use of asthma action plans (OR 0.8; 95% CI 0.4 to 1.8), trigger avoidance (OR 0.9; 95% CI 0.4 to 1.8), and influenza vaccination (OR 0.7; 95% CI 0.3 to 1.5) were not significantly different according to PTSD status after controlling for potential confounders.

Whereas self-management was similar in both groups, we evaluated potential differences in illness and medication beliefs known to be associated with adherence among WTC workers with and without PTSD (Table IV). The WTC workers with PTSD were significantly more likely to have emotional responses to their asthma, such as reporting that thinking about asthma makes them sad (4.5 vs 1.4; P < .0001), worried about their future (3.0 vs 2.3; P < .0001), feeling that nothing will ever improve their asthma (4.6 vs 2.6; P < .0001), and reporting that asthma affects them emotionally (5.6 vs 2.9; P< .0001). They also were more likely to report asthma consequences, such as that asthma affects their lives (6.3 vs 4.8; P = .0001) and they experience a lot of asthma symptoms (5.9 vs 5.2; P = .04). Beliefs about medication necessity (3.1 vs 2.9; P = .1) and concerns (3.0 vs 2.9; P = .2) were not significantly different in those with or without PTSD.

Posttraumatic stress disorder is a major risk factor for poor asthma control and increased resource utilization among WTC workers with asthma. In this study, we evaluated whether differences in adherence to guideline-recommended self-management behaviors may explain this association. Consistent with prior studies, we found that many participants reported low rates of asthma controller adherence and other self-management behaviors^38–42; however, the rates of controller medication adherence, use of action plans, and trigger avoidance were not statistically different between WTC workers with and without PTSD. Inhaler technique was also not significantly different across groups. These results suggest that other mechanisms may lead to worse asthma morbidity in WTC workers with PTSD.

Accordingly, we also found that WTC workers with PTSD reported different illness beliefs. In particular, WTC workers with PTSD were significantly more likely to be emotionally affected by their asthma. They also were more likely to report feeling a lack of control over their health and worried about their future because of their asthma. According to the SRM and empirical data, disease beliefs are strong modifiable predictors of self-management adherence.¹⁹ Thus, these data can help physicians identify and address potential barriers to medication adherence in WTC workers with asthma. In addition, these beliefs could be the target of behavioral interventions to improve asthma self-management, given that almost half of participants reported low adherence to self-management.

Long-term follow-up studies show that approximately one-third of workers exposed to WTC contaminants developed asthma, and thus, achieving good control of symptoms and decreasing exacerbations are important goals for improving the health of this population. Many WTC workers with asthma have comorbid PTSD, which remains a major risk factor for increased asthma morbidity.^4,6,43 Self-management behaviors are a frequent focus of behavioral and/or educational interventions to improve outcomes of patients with chronic diseases such as asthma.⁴⁴ In addition, PTSD has been linked to lower self-management adherence in several chronic diseases,^45,46 raising concern about its potential role in WTC workers with asthma. A study by the WTC Health Registry Cohort evaluated the relationship between mental health conditions (including depression, PTSD, or anxiety), adherence to asthma medications, and asthma control.⁴⁷ The presence of any mental health condition was associated with lower adherence scores, which is consistent with prior studies showing a strong association between depression and asthma controller medication adherence.⁴⁷ Conversely, we did not find a relationship between PTSD and medication adherence; however, we controlled for depression in our study, which may explain the differences in findings from prior studies.^5,12 Regardless, both studies showed that self-management is unlikely to explain the association between PTSD and asthma control, suggesting that other mechanisms should be considered in future research.

There is a growing literature about the important role played by symptom perception among patients with asthma.^48–50 Delays in seeking care for worsening asthma due to symptom under-perception has been proposed as a potential risk factor for emergency room visits or hospitalizations. Asthma symptom under-perception has also been linked to decreased adherence to chronic controller medications.^50–52 Conversely, overperception of asthma symptoms can lead patients to interpret and report that their disease is poorly controlled.⁵³ Prior studies have found that PTSD is more strongly associated with self-reported (eg, Asthma Control Questionnaire scores) compared with objective (eg, lung function) measures of asthma control.^54,55 Thus, it is possible that overperception may partially mediate the relationship between PTSD and asthma morbidity.

Posttraumatic stress disorder has a multisystem impact, leading to changes in the hypothalamic-pituitary axis, the immunological system, and the autonomic nervous system.⁵⁶ Indeed, prior studies have shown persistent, systemic low-grade inflammation in patients with PTSD.⁵⁷ Increased airway inflammation is the hallmark of asthma, with levels of sputum eosinophilia correlating with asthma symptoms, level of control, and exacerbations. Posttraumatic stress disorder may modulate the airway inflammatory response, suggesting a potential mechanism for the association between these conditions. Thus, a better understanding of potential differences in airway inflammatory markers in asthma patients with and without PTSD may unveil new therapeutic targets for these patients. The autonomic nervous system imbalance typically described in patients with PTSD is characterized by decreased parasympathetic activation coupled with a hyperactive sympathetic nervous system.^58,59 Given that these changes should induce bronchodilation, it is unlikely that autonomic nervous system dysregulation explains the association between PTSD and decreased asthma control.

Our study has a number of strengths and limitations. We used detailed data from a cohort of WTC workers with asthma who underwent extensive in-person interviews. Posttraumatic stress disorder was diagnosed using the SCID-5-CV, the gold standard for psychiatric interviews in research. We used validated instruments to evaluate a broad range of self-management behaviors that are recommended by current guidelines and have been linked to asthma outcomes. However, these measures were based on self-report and, thus, may be subject to reporting and social desirability biases. Participant bias is also possible because there may have been systematic differences among WTC workers who were willing to participate in our study compared with those who declined enrollment. We limited our study to WTC workers who are part of the general WTC responder cohort. Consequently, our finding may not be representative to other populations exposed at the WTC site, including local residents, firefighters, and other service members.

The lack of pulmonary function assessments and biomarkers are additional limitations to our study. Whereas we had a relatively robust sample of participants, we may have lacked power to detect small differences in adherence among WTC workers with and without PTSD.

In summary, our study showed that PTSD was not associated with adherence rates to key self-management behaviors in WTC workers with asthma. These findings suggest that behavioral pathways are unlikely to explain the relationship between PTSD and increased asthma morbidity. Nevertheless, we found that many WTC workers were not adherent to asthma self-management, suggesting a potential target for future interventions to improve asthma control.