Hurricane Florence and suicide mortality in North Carolina: a controlled interrupted time-series analysis

Abstract

Background: Natural disasters are associated with increased mental health disorders and suicidal ideation; however, associations with suicide deaths are not well understood. We explored how Hurricane Florence, which made landfall in September 2018, may have impacted suicide deaths in North Carolina (NC).

Methods: We used publicly available NC death records data to estimate associations between Hurricane Florence and monthly suicide death rates using a controlled, interrupted time series analysis. Hurricane exposure was determined by using county-level support designations from the Federal Emergency Management Agency. We examined effect modification by sex, age group, and race/ethnicity.

Results: 8363 suicide deaths occurred between January 2014 and December 2019. The overall suicide death rate in NC between 2014 and 2019 was 15.53 per 100 000 person-years (95% CI 15.20 to 15.87). Post-Hurricane, there was a small, immediate increase in the suicide death rate among exposed counties (0.89/100 000 PY; 95% CI -2.69 to 4.48). Comparing exposed and unexposed counties, there was no sustained post-Hurricane Florence change in suicide death rate trends (0.02/100 000 PY per month; 95% CI -0.33 to 0.38). Relative to 2018, NC experienced a statewide decline in suicides in 2019. An immediate increase in suicide deaths in Hurricane-affected counties versus Hurricane-unaffected counties was observed among women, people under age 65 and non-Hispanic black individuals, but there was no sustained change in the months after Hurricane Florence.

Conclusions: Although results did not indicate a strong post-Hurricane Florence impact on suicide rates, subgroup analysis suggests differential impacts of Hurricane Florence on several groups, warranting future follow-up.

Keywords: mortality; natural disaster; suicide/self?harm; surveillance; time series.

Figure 1

Categorisation of hurricane exposure among North Carolina counties based on FEMA designation, September 2018. FEMA, Federal Emergency Management Agency; IA, individual assistance; PA, public assistance.

Figure 2

Suicide rates among people living in counties designated as exposed and unexposed during the period before Hurricane Florence and after Hurricane Florence, North Carolina 2014–2019. Lines and confidence bands represent LOESS (locally estimated scatterplot smoothing) curves based on the observed monthly data and 95% confidence bands around the LOESS curves.

Figure 3

Suicide rates among people living in counties designated as exposed and unexposed not including counties designated as either IA or PA but not both during the period before Hurricane Florence and after Hurricane Florence, North Carolina 2014–2019. Lines and confidence bands represent LOESS (locally estimated scatterplot smoothing) curves based on the observed monthly data and 95% confidence bands around the LOESS curves. IA, individual assistance; PA, public assistance.