Are we undercounting the true burden of mortality related to suicide, alcohol use, or drug use? An analysis using death certificate data from Colorado veterans

Knowledge regarding deaths due to suicide or alcohol- or drug-related causes may be limited by inconsistent and/or restrictive case definitions, resulting in concerns regarding validity of findings and underestimates of burden. In this proof-of-concept study, we assessed varying case definitions (suicide, alcohol-related, and drug-related mortality using underlying-cause-of-death (UCOD) versus multiple-cause-of-death (MCOD) International Classification of Diseases, Tenth Revision (ICD-10) codes) on the basis of counts and rates among Colorado veterans who died (2009–2020). Suicide, alcohol-related, or drug-related ICD-10 codes were identified, and 2 case definitions were compared: UCOD (qualifying ICD-10 code listed as the UCOD) and MCOD (qualifying ICD-10 code in any cause-of-death field). Of 109,314 decedents, the number of deaths and the age-adjusted mortality rate (per 100,000 persons) significantly increased when MCOD codes were included: n = 4,930 (110.3 deaths/100,000 persons) for UCOD versus n = 6,954 (138.4 deaths/100,000 persons) for MCOD. While rates of suicide mortality did not change, rates of alcohol-related mortality doubled with the more inclusive case definition: 1,752 (27.3 deaths/100,000 persons) for UCOD versus 3,847 (59.8 deaths/100,000 persons) for MCOD. Alcohol-use disorder codes accounted for 71% of additional alcohol-related deaths captured with the MCOD definition. Studies that rely on UCOD codes may be underestimating the burden of deaths, especially alcohol-related deaths. Increased effort is required to reevaluate current classifications of deaths associated with suicide, alcohol use, or drug use.