Suicides in Los Angeles County in Relation to the Northridge Earthquake

Abstract

Introduction:Recently, there has been speculation that suicide rates increase after a disaster. Yet, in spite of anecdotal reports, it is difficult to demonstrate a systematic relationship between suicide and disaster. Suicides are fairly rare events, and single disasters rarely have covered geographic areas with large enough populations to be able to find statistically significant differences in such relatively rare events (annual suicide rates in the United States average 12/100,000 population).Hypothesis:Suicide rates increased in the three calendar years (1994–1996) following the Northridge earthquake as compared to the three calendar years (1991–1993) prior to the earthquake. Likewise the suicide rates for 1993 are compared with the rates in 1994. By looking at the suicide rates in a three-year period after the earthquake, the additional disasters that befell Southern California in 1995 and 1996 may have had an additive effect on psychological disorders and suicide rates that can be measured.Methods:Data on suicide mortality were compiled for the years from 1989 through 1996. Differences in rates for 1993 compared with 1994 and for three-year periods before and after the earthquake (1991–1993 vs. 1994 –1996) were analyzed using az-statistic.Results:There is a statistically significant difference in the rates for the years prior to the earthquake (1991–1993) when pooled and compared to the suicide rates for the years after the earthquake (1994–1996). The rates of suicide are lower in the three years following the earthquake (11.85 vs. 13.12/100,000 population) than they are in the three years prior to the earthquake (z= -3.85,p<0.05). Likewise, there is a similar difference when comparing 1993 to 1994 (11.77 vs. 13.84,z= -3.57,p<0.05). The patterns of suicide remain similar over time, with males and non-Hispanic Whites having the highest rates of suicide.Conclusion:It does not appear that suicide rates increase as a result of earthquakes in this setting. This study demonstrates that the psychological impacts of the Northridge earthquake did not culminate in an increase in the rates of suicide.

Long-Term Suicide Mortality Rates Decrease in Men and Increase in Women after the Niigata-Chuetsu Earthquake in Japan

“…Shoaf et al (2004) reported that the 1994 Northridge earthquake in California did not increase suicide rates and suggested some ethnic differences. A study of the 1995 Great Hanshin-Awaji earthquake in Japan, which is comparable to the present study in terms of ethnicity and seismic intensity, showed decreased suicide rates, especially in men, 2 years after the earthquake (Shioiri et al 1999;Nishio et al 2009).…”

“…Krug et al (1998) demonstrated that suicide rates increased after severe earthquakes in the United States, and the 1999 Taiwan earthquake also yielded similar results (Yang et al 2005;Yip 2009). On the other hand, reports from the Northridge and Hanshin-Awaji earthquakes showed that suicide rates did not increase, but rather decreased after the earthquakes (Shioiri et al 1999;Shoaf et al 2004;Nishio et al 2009). Therefore, further studies are needed to address this issue.…”

No Evidence of Suicide Increase Following Terrorist Attacks in the United States: An Interrupted Time‐Series Analysis of September 11 and Oklahoma City

“…Second, we do not have a measure of social cohesion before and after the events. This is important because some scholars argue that disasters increase social cohesion and thus moderate their impact on posttraumatic stress and suicide (Durkheim, 1897/1951; Shioiri et al, 1999; Shoaf et al, 2004; Sweet, 1988). Third, we do not disaggregate suicide by race or socioeconomic status.…”

The influence of a major disaster on suicide risk in the population

“…The suicide counts (the numerator) included only suicides of NYC residents that occurred in the five boroughs of New York City. The NYC population counts (the denominator) were the midyear population estimates published by the United States Census (New York State Data Center, 2008), an approach used by many previous studies of disasters and suicide rates (e.g., de Lange et al, 2004;Liaw et al, 2008;Shoaf et al, 2004). To investigate variation in the association between this event and suicide, we also calculated gender-and race-specific monthly suicide rates (Hawton & van Heeringen, 2009;Institute of Medicine, 2002).…”

“…Overall, however, the evidence concerning the association between disasters and suicide is mixed (Bromet & Dew, 1995;Rezaeian, 2008). In corrected analyses, Krug et al (1999) reported no change in the suicide rate in U.S. counties affected by natural disasters, as did Bourque, Siegel, and Shoaf (2001) and Shoaf, Sauter, Bourque, Giangreco, and Weiss (2004) in their analyses of communities affected by the 1994 Northridge, California earthquake.…”