Co-morbid cardiovascular disease and depression: sequence of disease onset is linked to mental but not physical self-rated health. Results from a cross-sectional, population-based study

Self-rated health has been linked to important health and survival outcomes in individuals with co-morbid depression and cardiovascular
disease (CVD). It is not clear how the timing of depression onset relative to CVD onset affects this relationship. We aimed
to first identify the prevalence of major depressive disorder (MDD) preceding CVD and secondly determine whether sequence
of disease onset is associated with mental and physical self-rated health.

This study utilised cross-sectional, population-based data from 224 respondents of the 2007 Australian National Survey of
Mental Health and Wellbeing (NSMHWB). Participants were those diagnosed with MDD and reported ever having a heart/circulatory
condition over their lifetime. Age of onset was reported for each condition. Logistic regression was used to explore differences
in self-rated mental and physical health for those reporting pre-cardiac and post-cardiac depression.

The proportion of individuals in whom MDD preceded CVD was 80.36% (CI: 72.57–88.15). One-fifth (19.64%, CI: 11.85–27.42) reported
MDD onset at the time of, or following, CVD. After controlling for covariates, the final model demonstrated that those reporting
post-cardiac depression were significantly less likely to report poor self-rated mental health (OR:0.36, CI: 0.14–0.93) than
those with pre-existing depression. No significant differences were found in self-rated physical health between groups (OR:0.90
CI: 0.38–2.14).

MDD is most common prior to the onset of CVD. Further, there is an association between pre-morbid MDD and poorer self-rated
mental health. To our knowledge, this is the first time this has been demonstrated in a national, population-based survey.
As self-rated health has been shown to predict important outcomes such as survival, we recommend that those with MDD be identified
as vulnerable to CVD onset and poorer health outcomes.