Contingent Claims Analysis Approach for Modelling Suicide Risk in Later Life

Background: Aective disorder is generally regarded as the prominent risk factor for suicide in the old age population. Despite the large number of empirical studies available in the literature, there is no attempt in modelling the dynamics of an individ- ual's level of suicide risk theoretically yet. In particular, a dynamic model which can simulate the time evolution of an individual's level of risk for suicide and provide quan- titative estimates of the probability of suicide risk is still lacking. Aims and Methods: In the present study we apply the contingent claims analysis approach of credit risk modelling in the field of quantitative finance to derive a theoretical stochastic model for estimation of the probability of suicide risk in later life in terms of a signalling index of aective disorder. Our model is based upon the hypothesis that the current state of aective disorder of a patient can be represented by a signalling index and exhibits stochastic movement and that a threshold of aective disorder, which signifies the occurrence of suicide, exists. Results and Conclusions: According to the numerical results, the implications of our model are consistent with the clinical findings. Hence, we believe that such a dynamic model will be essential to the design of eective suicide prevention strategies in the target population of older adults, especially in the primary care setting.