later life, although this knowledge is yet to be translated into significant health gains for the population. This
study gathered information about common modifiable and non-modifiable risk factors for depression with
the aim of developing a practical probabilistic model of depression that can be used to guide risk reduction
Methods: A cross-sectional study was undertaken of 20,677 community-dwelling Australians aged 60 years or
over in contact with their general practitioner during the preceding 12 months. Prevalent depression (minor or
major) according to the Patient Health Questionnaire (PHQ-9) assessment was the main outcome of interest.
Other measured exposures included self-reported age, gender, education, loss of mother or father before age
15 years, physical or sexual abuse before age 15 years, marital status, financial stress, social support, smoking
and alcohol use, physical activity, obesity, diabetes, hypertension, and prevalent cardiovascular diseases,
chronic respiratory diseases and cancer.
Results: The mean age of participants was 71.7 ± 7.6 years and 57.9% were women. Depression was present in
1665 (8.0%) of our subjects.Multivariate logistic regression showed depression was independently associated
with age older than 75 years, childhood adverse experiences, adverse lifestyle practices (smoking, risk alcohol
use, physical inactivity), intermediate health hazards (obesity, diabetes and hypertension), comorbid medical
conditions (clinical history of coronary heart disease, stroke, asthma, chronic obstructive pulmonary disease,
emphysema or cancers), and social or financial strain.We stratified the exposures to build amatrix that showed
that the probability of depression increased progressively with the accumulation of risk factors, from less than
3% for those with no adverse factors to more than 80% for people reporting the maximum number of risk
Conclusions: Our probabilistic matrix can be used to estimate depression risk and to guide the introduction of
risk reduction strategies. Future studies should now aim to clarify whether interventions designed to mitigate
the impact of risk factors can change the prevalence and incidence of depression in later life.