A multicenter retrospective survey on a suicide trend using hydrogen sulfide in Japan

In Japan, suicide by inhaling hydrogen sulfide (H2S) by mixing commercial products escalated into a nationwide trend in April 2008.

We conducted a multicenter retrospective survey on the demographics, clinical features, treatments, and outcomes of patients exposed to H2S suicide attempts.

Subjects included patients transported to emergency facilities in Japan from January 2005 to December 2011 following H2S suicide attempts. Among 277 facilities to which a letter requesting data collection was sent, questionnaires were sent to and filled out by the 47 (18%) facilities that agreed to provide data. Questionnaires were collected and data were extracted at Kitasato University.

A total of 156 patients were included in this survey. Patients involved in an H2S suicide attempt increased from 1 in 2007 to 51 in 2008, and gradually decreased from 44 in 2009 to 37 in 2010 and 23 in 2011. Ninety-two patients attempted H2S suicide (primary exposure group), and 64 were secondarily affected by the suicide attempt (secondary exposure group). Patients in the primary exposure group were young (mean, 30.3 years (10.9)), and male patients (n = 62) were approximately two times more likely to attempt H2S suicide than females (n = 30). Forty-eight patients in cardiopulmonary arrest at the scene did not survive. Five non-cardiopulmonary arrest patients died, and five patients who presented with a Glasgow coma scale (GCS) < 8 and lactic acidosis had neurological or cardiac signs or symptoms at discharge. Antidote therapy was performed on 26 of the primary group patients, but with poor outcomes. None of the secondary group patients were in cardiopulmonary arrest at the scene, five received antidotal therapy after arriving at the hospital, and all completely recovered from H2S exposure.

Mortality (58%) among patients who attempted H2S suicide was very high, likely resulting from inhaling high concentrations of H2S after mixing commercial products in a sealed and confined space.