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Irritability Scale
Please email the author for information about obtaining the instrument: Dr. Anjan Chatterjee,
Supplemental: Huntington's Disease (HD) and Mitochondrial Disease (Mito)
Short Description of Instrument
Summary/Overview of Instrument: The Irritability Scale (IS) consists of 14 items regarding different dimensions of apathetic behavior. The score for each item ranges from 0 to 3. Rating of each item is based on a semi-structured interview.
Construct measured: Irritability
Generic vs. disease specific: Generic
Intended use of instrument/purpose of tool: Assessment of severity of irritability
Means of administration: Paper and Pencil
Location of administration: Clinic or Home
Intended respondent: Patient and Caregiver/Informant
# of items: 14
# of subscales and names of sub-scales: None
Special Requirements for administration: None
Administration Time: Likely 15-30 minutes
Translations available: Available in English, Dutch
Scoring and Psychometric Properties
Scoring: Ratings should be based on both verbal and non-verbal information of the past 4 weeks. For each item ratings should be judged: 4 possible responses for each question: 'not at all', 'slightly', 'somewhat', 'a lot'.
Standardization of scores to a reference population (z scores, T scores, etc.): Using ROC analysis, a score of = 14 points on the IS-self was identified as a robust indicator for irritability (Reedeker, et. al., 2012). The IS cut-off score of = 14 points yielded an acceptable sensitivity and high specificity for all three cut-off points.
If scores have been standardized to a reference population, indicate frame of reference for scoring: First-degree non-carriers.
Psychometric Properties:
Reliability: Test-retest or intra-interview (within rater) reliability (as applicable): Not available.
Inter-interview (between-rater) reliability (as applicable): Inter-rater agreement for the presence of irritability above a median score in a HD population ranged from poor for the most cognitively impaired participants to good for the less cognitively impaired participants.
Agreement between IS-self and IS-inf scores was assessed using one-way random, single measure intraclass correlation coefficients (ICCs). The overall ICC for IS-self and IS-inf scores was 0.61 (95% CI = 0.50-0.72, p<0.001) (Reedeker, et. al., 2012).
Internal consistency: The Cronbach's alphas were 0.90 for the IS-self and 0.93 for the IS-inf (Reedeker, et. al., 2012).
Statistical methods used to assess reliability: Kruskal-Wallis tests were conducted to compare IS-self and IS-inf scores (Reedeker, et. al., 2012).
Content validity: Not available.
Construct validity: Not available.
Sensitivity to Change/ Ability to Detect Change (over time or in response to an intervention):
The IS cut-off score of = 14 points yielded an acceptable sensitivity and high specificity for all three cut-off points.
Known Relationships to Other Variables: Use of medication.
Diagnostic Sensitivity and Specificity, if applicable (in general population, HD population- premanifest/manifest, other disease groups): Not available.
Strengths: Self report and Informant report.
Weaknesses: Presence and severity are roughly scored on a 5-point Likert-scale. The cut-off score is not validated (no external validity).
Key Reference:
Chatterjee A, Anderson KE, Moskowitz CB, Hauser WA, Marder KS. A comparison of self-report and caregiver assessment of depression, apathy, and irritability in Huntington's disease. J Neuropsychiatry Clin Neurosci. 2005 Summer;17(3):378-83. [scoring of the IS in this article is incorrect].
Additional References:
Kloppel S, Stonnington CM, Petrovic P, Mobbs D, Tuscher O, Craufurd D, Tabrizi SJ, Frackowiak RS. Irritability in pre-clinical Huntington's disease. Neuropsychologia. 2010 Jan;48(2):549-57.
Reedeker N, Bouwens JA, Giltay EJ, Le Mair SE, Roos RA, van der Mast RC, van Duijn E. Irritability in Huntington's disease. Psychiatry Res. 2012 Dec 30;200(2-3):813-8.
Document last updated March 2024