Emergency Medicine · Psychiatry

Hack's Impairment Index calculator

Enter the published formula inputs below to calculate and interpret this score.

Clinical inputs

Speech and mentation

4 means unable, 3 an unfinished attempt, 2 poor, 1 imperfect, and 0 perfect. A refusal is left out of the mean.

Gross motor skill

4 means unable, 3 an unfinished attempt, 2 poor, 1 imperfect, and 0 perfect. A refusal is left out of the mean.

Eye tracking and nystagmus

4 means unable, 3 an unfinished attempt, 2 poor, 1 imperfect, and 0 perfect. A refusal is left out of the mean.

Finger-to-target pursuit

4 means unable, 3 an unfinished attempt, 2 poor, 1 imperfect, and 0 perfect. A refusal is left out of the mean.

Tracing between two curves

4 means unable, 3 an unfinished attempt, 2 poor, 1 imperfect, and 0 perfect. A refusal is left out of the mean.

Result

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Primary source

Yakubov S, Hack JB, Goldlust E. Introduction of an electronic mobile device version of an alcohol impairment scale (the Hack's Impairment Index score) does not impair the assessment of patients in emergency departments. Curr Ther Res Clin Exp. DOI: 10.1016/j.curtheres.2021.100630. PMID: 34306270. Five tasks are each scored 0 to 4: speech and mentation, gross motor skill, eye tracking and nystagmus, finger-to-target pursuit, and tracing between two curves. Broadly, 4 means unable to comply, 3 means the attempt was not completed, 2 means the task was done poorly, 1 means it was done but not perfectly, and 0 means it was done perfectly. A refused task is unscored. The index is the sum of the scored tasks divided by the number completed. The 2014 description (PMID: 24555813) introduced the five tasks. This paper does not print a clinical cutoff. (2021)

Scope: Emergency patients being examined for alcohol-related impairment. The index is not returned when every task is refused. Higher means more impairment. No mild, moderate, or severe cutoff is printed.

Last reviewed 2026-10-17

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Professional use only

For qualified clinicians. Independently verify inputs, calculations, source guidance, and applicability before any clinical action. This calculator does not replace clinical judgment.

Source: Yakubov S, Hack JB, Goldlust E. Introduction of an electronic mobile device version of an alcohol impairment scale (the Hack's Impairment Index score) does not impair the assessment of patients in emergency departments. Curr Ther Res Clin Exp. DOI: 10.1016/j.curtheres.2021.100630. PMID: 34306270. Five tasks are each scored 0 to 4: speech and mentation, gross motor skill, eye tracking and nystagmus, finger-to-target pursuit, and tracing between two curves. Broadly, 4 means unable to comply, 3 means the attempt was not completed, 2 means the task was done poorly, 1 means it was done but not perfectly, and 0 means it was done perfectly. A refused task is unscored. The index is the sum of the scored tasks divided by the number completed. The 2014 description (PMID: 24555813) introduced the five tasks. This paper does not print a clinical cutoff. (2021)

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Clinical inputs

Speech and mentation
Gross motor skill
Eye tracking and nystagmus
Finger-to-target pursuit
Tracing between two curves

Primary source

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