Elderly patients with deliberate self-poisoning treated in an Australian general hospital

To examine the demographic, prescription, ingestion, and psychiatric diagnostic factors that distinguished elderly from nonelderly patients treated for deliberate self-poisoning (DSP).

A prospective case series study of 2,667 patients presenting to a regional referral center for poisoning (Newcastle Mater Hospital, NSW, Australia), January 1991 to July 1998. The sample was stratified into two groups, 65 years or greater (n = 110) and 64 years or less (n = 2,557) at the time of index admission. The groups were compared using a forward stepwise logistic regression model. Uncontrolled comparisons were analyzed by chi-square statistic with Bonferroni-adjusted p values and controlled comparisons by odds ratio (OR) with 95% confidence interval (CI).

The elderly group represented 4.1% of the total. The logistic regression analysis found the elderly DSP group was more likely to have a longer length of stay (OR 5.90, CI 3.87-9.00), to have been prescribed "other" drugs (neither benzodiazepines, mood treatment drugs, nor paracetamol) before admission (OR 5.32, CI 3.34-8.48), to have been prescribed benzodiazepines (OR 3.15, CI 2.03-4.89), and to be diagnosed with major depression (OR 2.17, CI 1.41-3.36) than the younger group. The elderly group was less likely to have ingested paracetamol (OR 0.28, CI 0.14-0.54) or "other" drugs (neither benzodiazepines nor mood treatment drugs) in the DSP episode (OR 0.33, CI 0.20-0.54).

Elderly DSP patients differ in several important respects from younger patients. They have higher morbidity as a result of the DSP. Major depression plays a more important role. The strong relationship between benzodiazepine prescription and DSP in the elderly raises questions and possible prevention strategies.