Comparative risk assessment for mental disorders
Risk factor definition in the GBD
For the Global Burden of Disease (GBD) study, mental disorders as a risk factor for disease and injury is being investigated. The GBD defines risks according to the following considerations:
- Risk factors should be potentially modifiable;
- Risks should be assessed irrespective of place in a causal chain or scientific discipline that has traditionally analysed the risk factor, as long as evidence of causal effect can be established;
- Risks are defined to be not too broad (e.g. diet or environment as a whole) or too narrow (e.g. every single fruit and vegetable or every toxicant in tobacco smoke) with a relatively specific definition of risk factor exposure;
- Protective as well as hazardous factors are considered. However, the absence of a specific intervention should not be assessed as a risk factor, but rather in measurement of intervention coverage and effectiveness; and
- There exists sufficient data on risk factor exposure and risk-factor disease relationships.
In this brief discussion, an overview of some core possible consequences of mental disorders to be considered in the comparative risk assessment (CRA) analysis for mental disorders as risk factors is presented. The discussion has drawn heavily from the recent paper by Martin Prince and colleagues in their recent extremely comprehensive review of the issue
1.
Overview of possible outcomes to be considered
The table below is taken from the paper and represents the synthesis and conclusions of Prince et al in their recent review. The far left column indicates the level of evidence for a range of mental disorders being a risk factor for the health conditions listed. On the basis of this table, it would appear that the strongest evidence – defined by the authors as “strong evidence from meta-analysis or systematic review” – exists for the following:
1.
Depression as a risk factor for
coronary heart disease
2.
Maternal psychosis as a risk factor for
infant mortality
Two other possible risks of mental disorders, graded as “consistent evidence from several studies”, were:
3.
Depression as a risk factor for
stroke
4.
Maternal depression/common mental disorder as a risk factor for
impaired child growth and development.
Table 1: Summary of evidence for mental disorders as risk factors for other health conditions
Note: Taken from Prince et al.
1
There are several other risks that were not considered in the Prince et al. review to be considered for inclusion in the mental disorders CRA. One obvious one is the risk for
suicide. This was included in the previous GBD estimates and will be in GBD2005 also. The task to be undertaken here will primarily be deciding how to distribute suicide burden to different mental disorders. A recent meta-analytic review considered the role of anxiety disorders, and so on.
Another is the possible link between
mental disorder and
accidental injury and death. This possible link probably requires the greatest amount of review. There is some prospective data suggesting that risk of traumatic and accidental deaths is elevated among people with mental health problems. Several reviews (including meta-analyses) have been conducted examining the link between
ADHD and driving
riskily: they have concluded that there is elevated risk of driving in a hazardous manner.
References
1. Prince M, Patel V, Saxena S, Maj M, Maselko J, Phillips M, et al. Global mental health 1: No health without mental health.
Lancet 2007;370:859-877.