Background: The public health significance of mixed anxiety-depressive disorder (MADD) and the distinctiveness of its phenomenology have yet to be established.
Aims: To determine the public health significance of MADD, and to compare its phenomenology with ICD-10 anxiety, depressive, and comorbid anxiety and depressive disorders.
Method: Weighted analysis of data from the Great Britain National Psychiatric Morbidity survey was conducted with a representative household sample of 8580 persons aged 16-74 years.
Results: The 1-month prevalence of MADD was 8.8%. A fifth of all days off work in Britain occurred in this group. The symptom profile of MADD was similar to 'pure' ICD-10 anxiety and depression, but with a lower overall symptom count. The disorder was associated with significant impairment of health-related quality of life. Differences in health-related quality of life measures between diagnostic groups were accounted for by overall symptom severity, which remained strongly associated with health-related quality of life measures after adjusting for diagnostic group. The finding that half of the anxiety, depression and MADD cases and a third of the comorbid depression and anxiety cases grouped into a single latent class challenges the notion of these conditions as having distinct phenomenologies. Mixed presentations may be the norm in the population.
Conclusions: The data support the pathological significance of MADD in its negative impact upon population health. Dimensional approaches to classification may provide a more parsimonious description of anxiety and depressive disorders compared with categorical approaches.