Composite Abuse Scale (CAS)
The Composite Abuse Scale (CAS) is a widely used self report of partner behaviours that women describe as abusive. It has been published in the Centers for Disease Control and Prevention compendium of intimate partner violence measures. It is an easily administered self-report measure that provides standardized sub scale scores on four dimensions of intimate partner abuse. It consists of 30 items presented in a six point format requiring respondents to answer “never”, “only once”, “several times”, “monthly”, “weekly” or “daily” in a twelve month period. The Severe Combined Abuse Factor has 8 items that represent severe physical abuse items, all sexual abuse items, and physical isolation aspects of emotional abuse. The Emotional Abuse factor has 11 items that include verbal, psychological, dominance and social isolation abuse items. The Physical Abuse factor has 7 of the less severe physical abuse items and the Harassment factor has 4 items that are about actual harassment. The strength of the scale is the ability to measure different types and severity of abuse, although a limitation is the reduced number of sexual abuse items. Some researchers have changed the sexual abuse items from ‘raped’ to ‘forced to have sex’ to reflect the more recent language that is used around sexual assault.
The original scale, developed in 1995, contained 74 items comprising the four sub-scales (Severe Combined Abuse, Physical Abuse, Emotional Abuse and Harassment) and was validated on a convenience sample of nurses (n=427). Further validation on a sample of general practice patients (n=1896) and emergency department patients (n= 345) has resulted in the current 30 item version. The language has been updated from raped to forced to have sex to align with contemporary language.
In clinical settings, the CAS can provide prevalence figures and associations with other physical and emotional co-morbidities. It has been used as a research tool in general practice, antenatal clinics, emergency departments, mental health and drug and alcohol clinics. Administered over time, it can provide valuable information about changes in abuse and response to interventions. It has also been administered and validated in a large community cohort study, Women’s Health Australia and a community version of the CAS was developed.
The CAS has been translated into Vietnamese, Arabic, Dutch, Bengali, Russian, Spanish, Malaysian, Japanese, German. It has been used with men (although has limited validity in this population) and also for child exposure to adult IPV.
Recent developments include a ‘Think aloud’ study with survivors that have made some suggestions for better language and a shorter version of the CAS developed by a Canadian group of researchers.
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Definitional issues
There are still key areas of debate within the literature about how domestic violence is defined. Inconsistent definitions of domestic or intimate partner violence and abuse in research and practice have resulted in varying information about its prevalence and associations. Some of the issues that need to be considered include: “which relations should be included as domestic or intimate?” and “how should violence or abuse be defined?”
What is intimate partner abuse?
Domestic violence is sometimes used to refer to violence and abuse that occurs in any relationship within households. An alternative term, family violence also refers to violence occurring between family members. However, domestic violence is mainly used to refer to violence and abuse between partners.
Intimate Partner Violence and Abuse is any behavior within an intimate relationship that causes physical, psychological or sexual harm to those in the relationship, includes: physical aggression, psychological abuse, forced intercourse & other forms of sexual coercion, various controlling behaviors (World Health Organization)
The CAS attempts to measure aspects of what is now known as coercive control.
Coercive control by partners is defined as ‘an ongoing pattern of domination by which partners interweave repeated physical and sexual violence with intimidation, sexual degradation, isolation and control. The primary outcome is a condition of entrapment that can be hostage-like in the harms it inflicts on dignity, liberty, autonomy and personhood as well as to physical and psychological integrity.
From a health perspective, intimate partner abuse can be best understood as this chronic syndrome that is characterised not by the episodes of physical violence that punctuate the problem but by the emotional and psychological abuse that the perpetrator uses to maintain control over his partner. Furthermore, as most survivors of partner abuse report, the physical violence is the least damaging abuse she suffers: it is the relentless psychological abuse that cripples and isolates the woman. Thus the term “violence” is too limiting, instead the term “abuse” is preferable because it is inclusive of the varying actions that perpetrators use to control their partners. Alexander suggests a comprehensive definition that takes into account the varying types of abuse (emotional, physical and sexual), severity and frequency of the abuse, and the intention and meaning of the abuse.
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The CAS has mostly been used in written self-report format in individual and group settings and has been used with women 16 years of age and over (13-15) and pregnant women. The clinical settings it has been used in include general practice, hospital emergency departments and antenatal clinics, where trained research assistants have given the questionnaire to participants to fill in by themselves. It has been used in telephone and face-to face interviews in several studies and this requires additional selection and training of interviewers. It has also been used in iPad format in the waiting room.
The following instructions and testing conditions are recommended to ensure the safety of participants:
The introductory information alerts participants that the questionnaire contains questions about emotional well being, including domestic violence.
It is best for administration to be conducted in a private setting. If respondents are mailed it at home it is vital that some checking beforehand has occurred as to whether this is safe or not for the woman e.g. during the recruitment and consent procedures.
There should be an opportunity given to respondents to ask clarifying questions either by phoning or speaking to a research assistant.
The research assistant should be trained in a distress protocol.
All participants (regardless of whether abused or not) should be given a resource card to access available counselling services.
Most women can complete the CAS in 5 minutes, or in less than 15 minutes with associated questions about socio-demographics and lifetime abuse.
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There are five key steps in the CAS scoring and categorisation process.
These include calculation of:
1) item scores; 2) subscale scores; 3) total score; 4) cut-offs points;
and then categorisation of 5) abuse type.
1/ Item Scores
There are 30 items in the CAS, each of which is scored between 0 and 5, as follows:Never = 0
Only Once = 1
Several times = 2
Once/month = 3
Once/week = 4
Daily = 5
None of the items are weighted.
2/ Subscale Scores
The CAS is made up of 4 subscales:
Severe Combined Abuse (8 items; possible score 0-40), Physical Abuse (7 items; possible score 0-35), Emotional Abuse (11 items; possible score 0-55) and Harassment (4 items; possible score 0-20). The items in each subscale are listed below in Table 13/ Total Score
A total score on the CAS can be obtained by adding scores for all items in the scale (or total scores for each subscale). As there are 30 items in the CAS, each scored from 0-5, this gives a possible total score of 0-150.
4/ Cut-off Scores
Suggested cut-off scores
Once subscale scores have been calculated, these should be compared with a pre-decided cut-off score for each subscale. If a participant’s score is equal to or greater than the cut-off score, they are determined to have experienced that type of abuse. Suggested cut-off scores for each subscale, and for the total scale, are listed in the table below.These cut-off scores aim to maximise true positives, while minimising false positives. They were developed through the study outlined in Appendix 5). The level of sensitivity and specificity required, and thus the cut-off score chosen for use with the CAS, may vary depending on the reason the scale is being used and the setting. The outline presented below aims to assist with these cut-off score decisions.Suggested cut-off scores for the CAS were developed by comparing scores for women “known to be abused” with scores of women “known not to be abused” in order to determine suitable cut-off scores for each subscale. This allowed estimation of the proportion of women who would be misclassified by using particular cut-off scores.
As with any screening tool, there are two ways in which respondents may be misclassified on the CAS. Respondents may be classified as not experiencing abuse when in fact they are (false negative). Alternatively they may be classified as experiencing abuse when in fact they are not (false positive). A perfect screen would have a 0% false negative and a 0% false positive rate. All respondents who have experienced abuse would be classified as abused, giving a 100% true positive rate. While this level of accuracy is rarely achievable in reality, the aim is use a cut-off score that is as close to this ideal as possible.
Recommended cut-off scores for Composite Abuse Scale
Despite limitations with any known group analysis, preliminary recommendations for case finding in clinical practice can be made: -a cut-off score of 3 for the Total scale, and for the individual sub-scales - Severe Combined Abuse, Physical Abuse, Emotional Abuse, and Harassment. These cut-off scores have face validity, in that there are more items required to occur in a twelve month period in the Harassment and Emotional Abuse sub-scales than the Physical Abuse and Severe Combined Abuse dimension. If however, screening was occurring in a different setting it may be better to use the higher cut-off score of 7 for the total score to minimise the false positives. Alternatively the individual sub- scale cut off scores can be used to identify the abused group.
Final recommendations on cut-off scores are based on a limited known group analysis with CAS appearing to have quite high sensitivity and specificity. From this analysis, a cut-off total score of 3 would most likely result in no abused women missed and only a very small percentage (<5%) of false positives. A cut-off total score of 7 would miss four women in every one hundred but have no false positives. Which of the total cut-off scores should be used would depend on the aim and the setting of the individual research project. Preliminary recommended cut-off scores for the individual sub-scales are as follows: - Severe Combined Abuse, Physical Abuse, Emotional Abuse, and Harassment. Some studies have used these cut offs to classify women as abused or not rather than the total score. Which of these total cut-off scores should be used would depend on the aim and the setting of the individual research project.5/ Abuse Categorisation
Once cut-off scores have been implemented, the type of abuse experienced by each respondent can be categorized.
Using the four subscales above, there are 15 possible combinations of abuse type that participants may experience (e.g. SCA + Physical; SCA + Emotional; SCA + Physical + Emotional; and so on…). These 15 combinations can be reduced to four major categories of abuse experienced by women.
In this categorisation process, SCA takes precedence over the other forms of abuse, so that any participant who has experienced SCA falls into the SCA category (Category 1). The second category includes all participants who have experienced Physical Abuse in combination with Emotional Abuse and/or Harassment. Participants who have experienced at least one episode of Physical Abuse, but no other forms of abuse, fall into the third category, Physical Abuse Alone. The final category contains all participants who have experienced Emotional Abuse and/or Harassment, but not any other form of abuse. -
The Composite Abuse Scale has the ability to classify women according to type and severity of abuse, a common criticism of other current measures of abuse. The original scale, developed in 1995, contained 74 items comprised four sub-scales (Severe Combined Abuse, Physical Abuse, Emotional Abuse and Harassment) and was validated on a convenience sample of nurses (n=427). Further validation on a sample of general practice patients (n=1896) and emergency department patients (n= 345) has resulted in the current 30 item version. The second study confirmed the four CAS sub-dimensions i.e. the same four factors as in the preliminary validation study on a nurses sample, although the order of the factors was different with the Emotional Abuse factor rather than the Severe Combined Abuse factor accounting for the majority of the variance in this sample.
These four factors would seem to exhibit good internal reliability i.e. the items reflect common underlying constructs. Bland and Altman (1997) discusses how for comparing groups, Crohnbach’s alpha values of 0.7 to 0.8 are regarded as satisfactory but that for clinical applications much higher values of alpha are needed (>0.9). The internal consistency reliability of the CAS was 0.85 or above and for the majority of sub-scales greater than 0.9 and the corrected item-total correlations were generally high (more than 0.5).
The Composite Abuse Scale has demonstrated face, content, criterion, and construct validity. There is strong evidence in the literature that to weight items for multi item scales does not produce advantages in measurement accuracy. The second CAS validation study investigated how upset women were by the individual acts by their partners. As the degree of upset was found to be highly correlated with the frequency of the behavior, it is recommended that CAS not be weighted by the upset scale. -
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Hegarty K, Bush R, Sheahan M. The Composite Abuse Scale: Further development and assessment of reliability in two clinical settings. Violence and Victims. 2005;20(5):529-47.
Hegarty K, O'Doherty L, Chondros P, Valpied J, Taft A, Astbury J, et al. Effect of type and severity of intimate partner violence on women's health and service use: findings from a primary care trial of women afraid of their partners. J Interpers Violence. 2013;28(2):273-94.
Loxton D, Powers J, Fitzgerald D, Forder P, Anderson A, Taft A, et al. The Community Composite Abuse Scale: Reliability and validity of a measure of intimate partner violence in a community survey from the ALSWH. J Womens Health, Issues Care. 2013;2(4).
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Da Rocha RWG, de Oliveira DC, Liebel VA, Pallu PHR, Hegarty K, Signorelli MC. Translation and Cross-Cultural Adaptation Protocol of Abuse Questionnaires: The Brazilian Portuguese Version of the Composite Abuse Scale (CAS). Violence Against Women. 2022 Apr;28(5):1171-1187. doi: 10.1177/10778012211013901. Epub 2021 Jun 1. PMID: 34074162.