Higher Suicide Death Rate in Rocky Mountain States and a Correlation to Altitude

To the Editor:

In 2002, the author presented limited data suggesting a higher suicide death rate in the Rocky Mountain states (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, and Wyoming). ¹ The data were expanded to cover 1979 to 2006, as well as to address gender, race, and socioeconomics factors. Finally, a correlation coefficient diagram between altitude and suicide death rate was developed.

Using the International Classification of Diseases (ICD)-9 (1979-1998) and ICD-10 (1999-2006) Centers for Disease Control (CDC) data for age-adjusted compressed mortality for suicide death rate, a comparison was made between mountain states and the national average. The breakdown of overall mortality, gender-specific mortality, and race-specific mortality is shown in Table 1. In Table 2, we compared mountain suicide death rate to the group mean suicide death rate of the top 5 non-mountain states with the least population density (Alaska, North Dakota, South Dakota, Nebraska, and Kansas), highest household gun ownership percentage (Alaska, South Dakota, West Virginia, Arkansas, and Mississippi), highest population below poverty levels percentage (Louisiana, Mississippi, West Virginia, Alaska, and Texas), highest population without heath insurance percentage (Texas, Louisiana, California, Florida, and Alaska), lowest psychiatrist availability (Alaska, Iowa, Mississippi, Arkansas, and Oklahoma), as well as to states bordering the Rocky Mountains (California, Kansas, Nebraska, North Dakota, Oklahoma, Oregon, South Dakota, Texas, and Washington) and the states with the lowest altitude (Delaware, Louisiana, Florida, Rhode Island, and New Jersey).

Table 1

ICD-9 (1979-1998) and ICD-10 (1999-2006) suicide mortality

	Rocky Mountain states suicide death per 100,000	National United States suicide death per 100,000
Overall mortality	18.4 (ICD-9)	12.2 (ICD-9)
	16.7 (ICD-10)	10.8 (ICD-10)
Male mortality	30.5 (ICD-9)	20.5 (ICD-9)
	27.3 (ICD-10)	18.0 (ICD-10)
Female mortality	7.3 (ICD-9)	5.0 (ICD-9)
	6.6 (ICD-10)	4.2 (ICD-10)
White race mortality	18.6 (ICD-9)	13.0 (ICD-9)
	17.1 (ICD-10)	11.8 (ICD-10)
Black race mortality	10.5 (ICD-9)	6.7 (ICD-9)
	9.1 (ICD-10)	5.4 (ICD-10)
Other race (Hispanic, Asian, etc)	14.8 (ICD-10)	7.8. (ICD-10)
Hispanic race mortality	9.8 (ICD-9)	5.7 (ICD-9)

Table 2

Suicide rates by state groups

State groups	Suicide death rate per 100,000 1979-1998 (ICD-9)	Suicide death rate per 100,000 1999-2006 (ICD-10)
Rocky Mountain	18.4	16.7
Least population density	13.0	13.9
Highest gun ownership	13.5	14.5
Highest poverty	13.4	13.5
Highest non-insured	14.1	13.6
Lowest psychiatric availability	12.5	12.4
Bordering neighbors	13.3	12.5
Lowest altitude	11.4	9.8

Our data show that the suicide death rate in the Rocky Mountain states remains higher and that the greatest differential was between the mountain states and the lowest altitude states. We then plotted state altitude to state suicide death rate and performed regression analysis to get a correlation coefficient of r = 0.76 (Figure). A literature search shows that mood state is worsened with incremental hypobaric hypoxia, and that the higher the altitude the lesser the duration needed to produce mood change. ^{2 -}4 Also, literature shows that oxygen supplementation improves mood at altitude. ⁵ While altitude-induced hypoxia can worsen mood leading to an increased suicide death rate in mountain states, the exact biochemical mechanism for producing this association between altitude and suicide death rate remains unknown.

Figure

State suicide death rate and altitude.