Impact of psychiatric illness upon asthma patients' health care utilization and illness control. Are all psychiatric comorbidities created equal?

The impact of psychiatric illnesses upon asthma patients' functioning is not well understood. This study examined the impact of psychiatric comorbidity upon illness management in asthma patients using empirically-derived psychiatric comorbidity groups. Participants were a clinic sample of Greek-speaking asthma patients (N=212) assessed using the Patient Health Questionnaire (PHQ) Somatoform, Depression, Panic Disorder (PD), Other Anxiety Disorder, Eating Disorder (ED) and Alcohol sub-scales. The associations between sub-scales were examined using multiway frequency analysis. The following groups were derived: Somatoform disorder and/or Any Depressive disorder (n=63), Somatoform disorder and/or Other Anxiety disorder (n=51), Somatoform disorder and/or Any ED (n=60), and Any Anxiety group including PD and/or Other Anxiety disorder (n=24). Across all groups, psychiatric illness was associated with significantly worse asthma control (p<.01). Participants in Any Anxiety group, OR=4.61, 95% CI [1.90, 11.15], Somatoform and/or Any Depressive disorder, OR=2.06, 95% CI [1.04, 4.09] and Somatoform and/or Other Anxiety disorder, OR=2.75, 95% CI [1.35, 5.60] were at higher risk for asthma-related Emergency Room (ER) visits compared to controls. However only Somatoform and/or Any Depressive disorder, OR=3.67, 95% CI [1.60, 8.72], Somatoform and/or Other Anxiety disorder, OR=5.50, 95% CI [2.34, 12.74], and Somatoform and/or Any ED, OR = 4.98, 95% CI [2.14, 11.60] group membership were risk factors for asthma-related hospitalizations. Results suggest that while comorbid psychiatric disorders generally negatively impact asthma illness management, different psychiatric comorbidities appear to have disparate effects upon illness management outcomes.