Mortality after deliberate self-poisoning. A prospective follow-up study of 587 persons observed for 5279 person years: risk factors and causes of death.

A follow-up study of mortality and factors associated with death from various causes were done on two unselected groups of patients surviving deliberate self-poisoning in 1978 and 1987. The persons were studied up to the end of 1993. In 1978 the group included 152 female and 101 male subjects and in 1987 the group included 190 female and 144 male subjects. By the end of 1993 a total of 37 (24%) of the female and 33 (33%) of the male patients admitted in 1978 had died (n.s.) and 18 (10%) of the female and 29 (20%) of the male patients admitted in 1987 had died (P < 0.01). The main causes of death were suicide and death from cardiovascular disease. The 5-year follow-up mortality more than doubled in males from 1978 to 1987 but decreased in females. In female subjects, the total follow-up mortality was 3.6 times the expected ratio, with a 95% confidence interval (95% CI of 2.7-4.6); in male subjects it was 5.0 times the expected ratio (95% CI = 3.8-6.4). The cause-specific mortality ratio was highest for deaths from suicide--in the female group it was 65.5 (39.4-102.3) times the expected and in the male group 41.5 (26.0-62.8)--and from accidental poisoning--for females 50.0 (6.1-180.6) times the expected and for males 66.7 (24.5-145.1). In the female group none of the variables examined reached significance as predictors for subsequent suicide or death from unnatural causes. In the male group being aged 30 years or more came out as a predictor for subsequent suicide [relative risk (RR) = 5.66 (1.05-30.37)], while imprisonment came out as a protective factor [RR = 0.08 (0.01-0.64)]. Significant predictors for death from unnatural causes were: having been convicted (but not been in jail) [RR = 34.01 (1.07-1078.15)] and a serious suicidal intent [RR = 138.62 (1.38-13,946.79)]. It is concluded that patients who survive deliberate self-poisoning are at increased risk of death. The predictors for death are not very specific and are considered difficult to apply in the clinical work with these patients.