Periodicity of suicide attempts reported to a poison control center

Suicide attempts make up a significant percentage of intentional overdoses and tend to utilize more poison control center (PCC) resources than any other type of call. In order to determine whether time imparts patterns on these suicide calls, we studied all suicide calls to our PCC over a 2-y period. Particular attention was given to the epidemiology and time of call. Suicide exposures (N = 4031) were extracted from PCC records from January 1988 through December 1989 with particular attention to time of day and age and sex of the patient. Data were computer analyzed using standard ANOVA, cosinor and non-linear regression techniques. Serial frequency and spectral analyses were performed using time series procedures. Significant circadian rhythms were noted for all age ranges with peak time (ie acrophase) for calling the PCC occurring in the early evening. However, individuals over the age of 50 y called earlier than younger aged groups. In addition, the 13 to 19-y age group exhibited a significant annual rhythm by peaking in suicide calls to the PCC on January 28 +/- 12.4 d.