Prevalence of psychiatric morbidity in a difficult asthma population: relationship to asthma outcome.

INTRODUCTION

Psychiatric morbidity appears common in fatal and near-fatal asthma and may be a factor in difficult to control asthmatic subjects. We examined the prevalence of psychiatric morbidity (using psychiatric interview) in a cohort of sequentially referred poorly controlled asthmatics and related this to (a) asthma outcome (b) assessing chest physician opinion and (c) Hospital Anxiety Depression Scale (HADS).

METHODS

Patients were evaluated using a systematic evaluation protocol to identify and manage all co-morbidity. Psychiatric assessment was performed by experienced liaison psychiatrists and ICD10 diagnosis and treatment programme assigned. Subjects completed HADS at presentation and follow-up. Asthma was managed according to BTS/SIGN Guidelines.

RESULTS

Of 65 subjects who attended for psychiatric interview, 32 (49%) had an ICD10 diagnosis, (6 (9%) previously identified) with depression most common (59%). Physician assessment had poor discrimination for psychiatric illness. Anxiety scores (13.4+/-0.8 vs. 8.5+/-0.7) and depression scores (10.2+/-0.7 vs. 4.8+/-0.5) scores were significantly higher in subjects with ICD10 diagnosis (P<0.001), who were also more likely to be current smokers (P<0.01). HADS had a poor positive predictive value for psychiatric illness but a good negative predictive value for depression. There was no relationship between ICD10 diagnosis and asthma outcome. Subjects identified as therapy-resistant asthma after systematic evaluation, had significantly lower depression scores after treatment (P<0.05).

CONCLUSION

In difficult asthmatics, there is a high prevalence of undiagnosed psychiatric morbidity, with depression being particularly prevalent. A simple screening questionnaire such as HADS, has a high false positive rate when compared to psychiatric interview, but may be useful in excluding depressive illness. There appears to be little association between identification and management of co-existent psychiatry morbidity and asthma outcome.