This goal of this paper was to explore the extent to which psychiatric factors as reflected in DSM-IV anxiety and depressive diagnosis and severity of self-reported anxiety and depressive symptoms play a significant role in how young people with asthma function in terms of both asthma related and psychosocial adjustment.. These data from this large epidemiological study of adolescents with asthma in an HMO revealed that self-report of depressive and anxiety symptoms and presence of ≥ DSM-IV anxiety or depressive diagnosis each independently are associated with more impaired psychosocial and asthma related functional status. Each of these depression and anxiety measures were more significantly associated with all four functional outcomes than the modified HEDIS asthma risk measure. After controlling for a host of demographic variables (age, gender, parental employment, parental education, family median income, race and whether the family lived in a more urban (west) or rural (east) part of the state) youth who endorsed more symptoms of depression or anxiety also reported greater psychosocial and asthma related functional impairment. The fact that a similar degree of additive impairment based on having ≥1 anxiety or depressive disorder was seen at each level of asthma severity suggests that this effect is not due to greater severity of asthma in youth with psychiatric disorders. It is possible that some overlap in content on the symptom and behavioral function measures would explain the stronger association observed between depression and anxiety and psychosocial versus asthma related function. Furthermore, anxiety and depression were not significantly related to asthma severity as reflected in the modified HEDIS scoring system. These findings suggest that identification and treatment of psychiatric comorbidities may be one promising strategy to improve asthma outcomes.
These findings complement the significant body of work that has been conducted with adults. Large epidemiologic studies of patients with illnesses such as diabetes mellitus [31
] and coronary artery disease [32
] have also shown that depression is associated with increased functional impairment after controlling for severity of disease. Studies of adults have consistently found that comorbid depressive and anxiety disorders are associated with increased symptom burden in patients with chronic medical illness, potentially worsening the disability associated with these illnesses [33
]. Wells and colleagues [34
] demonstrated that when major depression is comorbid with medical illness, there is additive functional impairment. Studies have also demonstrated that major depression and anxiety disorders have an adverse impact on adherence to self-care regimens (i.e., diet, exercise, quitting smoking) in adult patients with chronic medical illness [31
]. A recent meta-analysis of the effect of depression and anxiety on adherence by Dimatteo and colleagues [38
] showed that, compared to nondepressed/nonanxious patients, the odds were three times greater that depressed and anxious patients would be nonadherent with medical treatment recommendations. Nonadherence may cause increased complications, health utilization and medical costs as well as worsen the course of symptoms and physical impairment due to medical illness [39
Less research has been reported on the impact of mental health problems on the functional status of asthmatic youth. However, in a recent study of adolescents, Kean and colleagues [40
] found that, even after accounting for asthma severity, asthma functional morbidity was significantly associated with anxiety, depressive and asthma related Post Traumatic Stress symptoms. Anxiety and depression may be more common in youth with asthma because the same neurotransmitters that regulate affect may be involved in processes such as bronchoconstriction and inflammation [11
] Others propose that experience with asthma may generate fearful or catastrophic beliefs about respiratory symptoms which provoke and sustain anxiety and over time, depressive symptoms [41
]. Furthermore, because children with asthma have a higher level of intrinsic airway resistance, negative stressors and mood states may be much more likely to result in significant airway changes in resistance undermining self-confidence in learning to master these situations [43
]. Decreased confidence and sense of control to manage illness symptoms may, in turn, undermine active behavioral self-management strategies such as taking medication regularly, monitoring peak expiratory flow and quitting smoking. Decreased self-management may then worsen asthma symptom burden, increase medical utilization and costs and lead to increased functional impairment.
The cross sectional design of this study precludes causal interpretations of the findings. Inclusion of only adolescents with health insurance limits the ability to generalize to the large population of youth who do not have ready access to health care.. As pointed out by Goodwin and colleagues (1 2) the association between asthma, anxiety, and depression, and in turn the impact of anxiety and depression on functional status, may also reflect the effects of common familial (poverty, childhood abuse) or environmental factors (exposure to secondhand smoke or pollution). Another limitation is the reliance on self-reports for anxiety and depression as well as asthma related functional status. While self-report of depression has been shown to have good reliability [44
], depression and anxiety can affect response style such that youth who report more symptoms of depression or anxiety may see themselves and their ability to function in a more negative light.
In addition, the use of the HEDIS as an independent measure of asthma severity is limited by its lack of a biological measure. We are able to corroborate some of our findings via medical record data but a multimethod, multisource, longitudinal approach is needed to more fully explore the relations among these key variables over time. The strengths of this study included sampling from a large community-based sample using a physician-based definition of asthma, youth representing a wide range of asthma severity, and an interview based DSM-IV diagnostic assessments as well as self-reported mood and anxiety symptoms.