Objective: Vital exhaustion and depression are both independent risk factors for cardiovascular disease, yet the relationship between these highly similar dimensions remains unclear. We have examined the association between depression and vital exhaustion and investigated the extent to which any association is the result of comorbid illnesses.
Methods: Three hundred and five consecutive patients were examined on average 3.6 days following hospital admission with first myocardial infarction (MI). The Maastricht Questionnaire (MQ; vital exhaustion) was administered together with the Hospital Anxiety and Depression Scale (HADS), and details of comorbid physical illness were recorded. The factor structure of the MQ was explored using factor analysis.
Results: Depression and vital exhaustion were highly correlated (r=.61, P<.01). This correlation did not diminish on controlling for age, sex, and comorbidity (r=.59, P<.01). Factor analysis of MQ score gave a four-factor solution: fatigue (18.2% of variance), depression (17.9%), lack of concentration (9.5%), and sleep difficulties (8.1%). The fatigue dimension of the MQ remained highly associated with HADS depression score (r=.50, P<.01), controlling for age, sex, and comorbidity.
Conclusions: Depression and fatigue are highly correlated and their association is not attributable to comorbid physical illnesses or the tendency of the MQ to measure depression. Future studies should investigate fatigue instead of vital exhaustion as a potential risk factor for poor cardiac prognosis independent of the influence of depression.