Assessment of exposure to a flood disaster in a mental-health study

The lasting psychological consequences of disasters are an important public health issue, especially for determining the support needed by victims. One important question in evaluating psychological consequences remains the assessment of individual disaster-related experiences or stressors. This article proposes two approaches towards the construction of cumulative exposure indicators (CEIs) for a disaster and discusses their relevance for other disasters. In 1997, we carried out a cross-sectional study of the association between the severity of exposure to a 1992 flood in southeastern France and the prevalence of psychological symptoms 5 years later. We interviewed 500 randomly selected subjects residing in one of the most affected municipalities and constructed two CEIs: one based on relevant articles in the literature and the second based on the results of a principal component analysis (PCA) of all the items exploring exposure to the flood. We compared these CEIs with a map of flood damage and tested the association between these indicators and a score of post-traumatic stress symptoms. Most of the subjects (79.1%) had been exposed to at least one stressor besides physical presence. The two CEIs were significantly correlated with one another; comparisons with the map showed that both had good ability to discriminate between mild and severe exposure. Multiple regression analyses showed a significant exposure-effect relation, of the same level of magnitude and significance, between the post-traumatic stress disorder score and each CEI. Our results show the appropriateness of such indicators in assessing the effect of cumulative stress from natural disasters. Guidelines should be developed to improve the comparability of instruments and help standardize methods for evaluating cumulative stress from disasters insofar as possible. Further research is nonetheless necessary to assess the consistency and reproducibility of the data collected.