Psychiatry and Clinical Neurosciences 2014; 68: 804–811

doi:10.1111/pcn.12194

Regular Article

Cross-cultural measurement equivalence of the Japanese version of Revised Conflict Tactics Scales Short Form among Japanese men and women Maki Umeda, PhD, MPH* and Norito Kawakami, MD, DMSc Department of Mental Health, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan

Aim: The Revised Conflict Tactics Scales Short Form (CTS2SF) is an instrument used to measure intimate partner violence (IPV) perpetration and victimization over the past 12 months. Methods: The CTS2SF was translated into Japanese, and the reliability (internal consistency and 4-week test–retest reliability) and the concurrent and factorbased validity were examined using two waves of Internet surveys over an interval of 4 weeks. Participants of the survey were 393 Japanese men and women who were registrants of an Internet survey company. Results: Cronbach’s α was greater than 0.5 for most scales, while it was low (α = 0.18) for sexual coercion by partner. The test–retest reliability of the binary variable for the presence or absence of IPV was high (Yule’s Q, 0.79–1.00), and moderate between the

HE PREVALENCE OF intimate partner violence (IPV) varies across countries: the lifetime prevalence of IPV against women ranged from 15% to 71% in a multinational study across 10 countries,1 which implies the complex nature of causes, where individual and interpersonal properties interact with social norms and structures to increase the risk of IPV.2,3 In Japan, 32.9% of women and 18.3% of men experienced physical, psychological, and/or sexual violence repeatedly by their spouses or ex-spouses in their lifetime.4 IPV can be the cause and consequences of mental health problems, being associated with dep-

T

*Correspondence: Maki Umeda, PhD, MPH, Department of Mental Health, Graduate School of Medicine, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Email: [email protected] Received 6 January 2014; accepted 11 April 2014.

804

scores (Spearman’s rank correlation, 0.38:0.70). Concordance with the Buss–Perry Aggression Questionnaire, Violence Against Women Screen, and Kessler 6 generally indicated good concurrent validity. The results of the exploratory factor analysis confirmed the three-factor structure of the Japanese version of the CTS2SF.

Conclusion: Although the internal consistency reliability was limited for some sub-scales, its moderate internal consistency and test–retest reliability and good factor-based validity highlighted the benefit of using the Japanese version of the CTS2SF in a largescale community survey where a shorter scale is required to assess IPV. Key words: cultural characteristics, domestic violence, Japan, reproducibility of result.

ressive disorders, anxiety disorders, post-traumatic stress disorder, substance abuse, suicide ideation, and child maltreatment among victims and perpetrators.5–7 In Japan, the Act on the Prevention of Spousal Violence and the Protection of Victims was enforced in 2001, and national and local governments are obligated to implement the policies that enhance the prevention of IPV and the support for victims. However, in Japan, an epidemiological community survey on the mental health impact of IPV is still limited in number, and existing studies were conducted only among women with the focus on female victimization.8,9 To promote the development and evaluation of IPV policies in Japan, a standardized measurement of IPV perpetration and victimization needs to be administered both among men and women. The Revised Conflict Tactics Scales Short Form (CTS2SF) is a 20-item scale that measures IPV victim-

© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology

Psychiatry and Clinical Neurosciences 2014; 68: 804–811

Japanese version of CTS2SF 805

ization and perpetration among men and women during the past 12 months.10 The CTS2SF is a short version of the Revised Conflict Tactics Scales (CTS2), which is a dominant research instrument validated in over 20 languages,11–15 including the Japanese.16 The CTS2SF has five sub-scales, each of which consists of two items that corresponds to a different type/level of act: negotiation (cognitive/emotional), psychological aggression (minor/severe), physical assault (minor/ severe), injury (minor/severe) and sexual coercion (minor/severe). Based on the respondent’s selfreport, 10 items measure the respondent’s act and perpetration of violence (self/perpetration), while the other 10 items measure their partner’s act and the respondent’s victimization of violence (partner/ victimization). The CTS2SF has the following advantages over other research scales for use in community surveys. First, it is a standardized scale that can reduce the burden of responding to the 78 items on the full CTS2, many of which are related to issues that may not have been experienced by the respondents participating in the community surveys.10 Second, the CTS2SF can reduce refusal and negative reactions from respondents, due to its conceptual framework, which defines IPV as couple conflicts, rather than abuse.15 Third, the CTS2SF can assess both perpetration and victimization in male-to-female and female-to-male violence, while other scales focus on the victimization of women17–19 or are only validated among women.20,21 The aim of the current study was to develop the Japanese version of CTS2SF (J-CTS2SF) and examine its reliability and validity. The original English version was translated by the authors. Then, an Internet survey was conducted to examine the reliability and validity of the J-CTS2SF among Japanese men and women. To the best of our knowledge, this is the first study that examined the test–retest reliability of the CTS2SF in any language. In addition, this study would contribute to cross-cultural research on IPV by examining the cultural adaptability of the scale developed in the USA.

with the original English scale in terms of literal and general meaning. Accordingly, two items of the Japanese version were revised.

METHODS Translation of the CTS2SF The authors translated the original English version of the CTS2SF into Japanese. The Japanese version was back-translated by an independent translator, and sent to the original author to assess the equivalence

Internet survey on the reliability and validity of the J-CTS2SF Participants and data collection Two waves of Internet surveys were conducted in October and in November 2011. Invitations were sent via emails to the registrants of an Internet company who were over the age of 18 years. The survey was kept open until 100 respondents were obtained for each of the marital status categories by sex (married and not-married by male and female). As a result, 412 respondents were included in the first survey (103 respondents for each category of each sex). Four weeks after the first survey, the second survey was conducted and data were obtained from 393 respondents (retention rate = 95.4%). Analysis was conducted on the data of those who responded to the first and the second surveys (n = 393). The Research Ethics Committee of the University of Tokyo Graduate School of Medicine approved the research procedure for this study (No. 3403). Measurements J-CTS2SF The full-set of the J-CTS2SF was administered, and scored on an 8-point scale (1 = once, 2 = twice, 3 = 3–5 times, 4 = 6–10 times, 5 = 11–20 times, 6 = more than 20 times, 7 = not in the past year, but it did happen before, and 8 = never happened).10 The acts conducted by the respondents and resulting injury of the partner were defined as ‘self /perpetration’ and the acts conducted by their partners and resulting injury of the respondents were defined as ‘partner/victimization’. In the second survey, the J-CTS2SF was assessed by looking back at the past 12 months, from the time of the first survey, to make the duration of assessment comparative between the two surveys. Buss–Perry Aggression Questionnaire The Japanese version of the Buss–Perry Aggression Questionnaire (BAQ) measures personal traits of aggression with 24 items on a five-point Likert scale (1 = strongly disagree to 5 = strongly agree).22,23 The

© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology

806 M. Umeda and N. Kawakami

Psychiatry and Clinical Neurosciences 2014; 68: 804–811

total scores of the sub-scales were added together to yield a general total score from 24 to 120. A higher score means a higher degree of aggression.

Household income was measured by 10 income categories, and divided into quartile (low, low–average, average–high, and high).

Violence Against Women screen The Violence Against Women (VAW) is a Japanese screening instrument to detect IPV victimization among women during the prenatal period.24 While the VAW was validated in a female prenatal population, its items were assumed to be applicable to the general female and male population without the items associated with pregnancy-related experiences or gender-laden incidences as in other validated screening instruments. The VAW consists of seven items on physical violence (two items), psychological violence (six items), and sexual violence (one item) with three response options on the frequency of incidents (1 = never, 2 = sometimes, and 3 = often). Each score was added together to yield a total score and a total score of 9 or higher was defined as indicating IPV victimization. We measured the VAW only at the second wave. To examine the association with J-CTS2SF at the same second wave of the survey, respondents were asked to look back at the past 12 months from the time of the first survey.

Statistical analysis

Kessler 6 Kessler 6 (K6) assesses psychological distress that is not specific to certain types of mental disorders.25 It asks about the frequency of listed psychological states in the past 30 days with six items on a five-point scale (0 = none of the time, 1 = a little of the time, 2 = some of the time, 3 = most of the time, and 4 = all of the time). The total score of 13 and above is defined as having a serious mental disorder.26,27 K6 was validated in a Japanese population and showed good concordance with the diagnosis by Composite International Diagnostic Interview on mood and anxiety disorders.28 Demographic variables Demographic variables included in the analysis were sex, marital status (married and not married), age (18–29 years old, 30–39 years old, 40–49 years old, and 50 years old or older), educational attainment (high school, college, and university), employment status (employed and not employed), and having one or more children (none, and one or more).

Reliability was assessed on the basis of internal consistency and test–retest reliability. Standardized Cronbach’s α coefficients were computed using the data from the first survey for each type/level of the subscale by self/perpetration and partner/ victimization status. Test–retest reliability was assessed by Spearman’s correlation coefficients for each type/level of the subscale by self/perpetration and partner/victimization status. The J-CTS2SF scores were re-ordered as a rank (0 = never happened, 1 = not in the past year, but it did happen before, 2 = once, 3 = twice, 4 = 3–5 times, 5 = 6–10 times, 6 = 11–20 times, 7 = more than 20 times). Yule’s Q was also calculated for a bivariate variable of the presence/absence of an IPV-related act (0 = no incidence, and 1 = one or more incidences), considering the frequent use of this binary definition in community surveys. Intra Class Correlation Coefficients were not calculated because of the highly skewed distribution of items (Appendix S1). The criterion-related validity was assessed by the bivariate association of each J-CTS2SF subscale with aggression (BAQ) and IPV victimization (VAW). The negotiation items related to self were expected to have an inverse association with aggression, as were those related to the partner with IPV victimization.11,14 The self/perpetration items of psychological, physical, sexual violence and injury were hypothesized to have positive associations with aggression, and the partner/victimization items were thought to have positive associations with IPV victimization. Logistic regression analyses were conducted, having dichotomous variables of CTS2SF subscales (0 = never, 1 = one or more instances) in either type/ level as the dependent variables. The BAQ, for which no cut-off point was available to define the level of aggression, was entered in the logistic models as a continuous variable. VAW was dichotomized at the cut-off points of 9 as a criterion of victimization.24 Criterion-related validity was also tested on the association between the J-CTS2SF at the first survey and psychological distress measured by K6 at the second survey. Dichotomous variables on ‘IPV perpetration and/or victimization’ were created from the J-CTS2SF items. The responses to each item were

© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology

Psychiatry and Clinical Neurosciences 2014; 68: 804–811

Table 1. Standardized Cronbach’s α coefficients for the subscales of the J-CTS2SF calculated from the first wave of Internet surveys (two items for each subscale by self/ perpetration and partner/victimization)

Negotiation Psychological Physical Injury Sexual

Self/perpetration

Partner/victimization

0.67 0.53 0.85 0.85 0.52

0.69 0.47 0.83 0.53 0.18

Japanese version of CTS2SF 807

second surveys as to control psychological distress at the first survey. All models were adjusted for sex, age, marital status, having one or more children, household income, and employment status. The construct validity was examined by exploratory factor analysis based on the maximum likelihood method with promax rotation.

RESULTS

J-CTS2SF, Japanese version of the Revised Conflict Tactics Scales Short Form.

dichotomized into ‘0’ and ‘once or more times’, and having experienced any instances in the subscale was coded as having experienced IPV (0 = neither by respondents nor their partners and 1 = one or more instances by respondents and/or their partners). K6 was dichotomized at the cut-off point of 13 for having psychological distress at the level of severe mental disorders.26,27 Greater psychological distress at the second survey was hypothesized to have positive associations with psychological, physical, and sexual violence and injury at the first survey, while negotiation was assumed to have a negative association. Generalized estimating equations models were applied to the longitudinal data from the first and the

Reliability of the J-CTS2SF Standardized α was generally higher for items that measured the respondents’ acts (0.52–0.85) than for those of partners (0.18–0.83) (Table 1). The items on physical assault had the highest internal consistency (0.85 for respondents; 0.83 for partners), and those on sexual coercion had the lowest (0.52 for respondents; 0.18 for partners). Test–retest reliability assessed by Spearman’s correlation coefficients was low, especially among sexual coercion items (0.38– 0.68) and injury items (0.48–0.65), while Yule’s Q coefficients were considerably high (0.99–0.78) (Table 2).

Validity of the J-CTS2SF Higher BAQ was positively associated with psychological aggression (odds ratio [OR] = 1.06;

Table 2. Test–retest reliability of the J-CTS2SF for the Internet survey conducted over the interval of 4 weeks Yule’s Q† (SE)

Spearman correlation coefficient (SE)

Negotiation Psychological Physical Injury Sexual

Cognitive Emotional Minor Severe Minor Severe Minor Severe Minor Severe

Self/perpetration

Partner/victimization

Self/perpetration

Partner/victimization

0.56 0.57 0.68 0.55 0.66 0.67 0.48 0.63 0.38 0.47

0.52 0.51 0.70 0.52 0.69 0.53 0.65 0.61 0.63 0.42

0.83 0.83 0.90 0.99 0.99 0.99 0.98 1.00 0.98 1.00

0.81 0.79 0.89 0.93 0.96 0.97 0.98 0.97 0.96 0.98

(0.04) (0.04) (0.04) (0.09) (0.06) (0.08) (0.08) (0.14) (0.12) (0.20)

(0.04) (0.04) (0.04) (0.08) (0.05) (0.09) (0.06) (0.12) (0.07) (0.15)

(0.04) (0.04) (0.03) (0.01) (0.01) (0.01) (0.01) (0.00) (0.02) (0.00)

(0.04) (0.04) (0.03) (0.04) (0.02) (0.02) (0.01) (0.03) (0.02) (0.02)



Concordance of binary variables for the J-CTS2SF between the two surveys (with or without an intimate partner violence incident). J-CTS2SF, Japanese version of the Revised Conflict Tactics Scales Short Form.

© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology

808 M. Umeda and N. Kawakami

Psychiatry and Clinical Neurosciences 2014; 68: 804–811

Table 3. Association between any incidences of conflict tactics in the past 12 months by BAQ, VAW, and K6† using the data from Internet surveys BAQ‡ and self (perpetration)

Negotiation Psychological Physical Injury Sexual

VAW 9+§ and partner (victimization)

K6 13+¶ and either self or partner (victimization/perpetration)

OR

95% CI

P value

OR

95% CI

P value

OR

95% CI

P value

1.00 1.06 1.07 1.07 1.01

0.99–1.02 1.04–1.09 1.03–1.10 1.03–1.12 0.91–1.11

0.782

Cross-cultural measurement equivalence of the Japanese version of Revised Conflict Tactics Scales Short Form among Japanese men and women.

The Revised Conflict Tactics Scales Short Form (CTS2SF) is an instrument used to measure intimate partner violence (IPV) perpetration and victimizatio...
70KB Sizes 0 Downloads 3 Views