Psychology of Addictive Behaviors 2014, Vol. 28, No. 2, 313–321

© 2014 American Psychological Association 0893-164X/14/$12.00 DOI: 10.1037/a0034971

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Alcohol Consumption and Partner Violence Among Women Entering Substance Use Disorder Treatment Vyga G. Kaufmann and Timothy J. O’Farrell

Christopher M. Murphy

VA Boston Healthcare System, Boston, Massachusetts, and Harvard Medical School

University of Maryland, Baltimore County

Marie M. Murphy

Patrice Muchowski

VA Boston Healthcare System, Boston, Massachusetts, and Harvard Medical School

AdCare Hospital of Worcester, Inc., Worcester, Massachusetts

To test the hypothesized role of alcohol consumption as a proximal risk factor for partner violence, a within-subjects analysis compared levels of alcohol consumption in violent versus nonviolent conflict events among substance-abusing women and their male partners. Participants were married or cohabiting women (N ⫽ 145) who had recently begun a substance abuse treatment program and reported both a violent and a nonviolent relationship conflict event with their male partner in the prior 6 months. The average age was 38, and 83% were White. Male partners did not participate in the study. The female participant provided information about the male partner. Women were interviewed regarding a violent conflict event in which physical violence occurred and a nonviolent conflict event in which psychological aggression occurred without physical violence. The interview assessed quantity of alcohol consumed and use of other drugs prior to each conflict. Alcohol consumption was significantly greater prior to violent versus nonviolent conflict events for all measures of women’s alcohol consumption examined: any drinking, heavy drinking, number of drinks in the 12 hr preceding the conflict event, and estimated blood alcohol concentration at time of the event. Male partners’ alcohol consumption showed similar results. Use of other drugs in women, but not men, was significantly more likely prior to physical conflicts. These within-subject comparisons help to rule out individual difference explanations for the alcohol–violence association and indicate that the quantity of alcohol consumption is an important proximal risk factor for partner violence in substance-abusing women and their male partners. Keywords: partner violence, alcohol consumption, female alcoholic patients

Intimate partner violence (IPV) is a major problem among women entering treatment for substance use disorders (SUDs). In various studies, women’s past year prevalence of physical IPV victimization, as reported at the outset of SUD treatment, was in the 50% to 65% range (Burnette et al., 2008; Chase, O’Farrell, Murphy, Fals-Stewart, & Murphy, 2003; Chermack, Walton, Fuller, & Blow, 2001). These studies also found that about two

thirds of women entering SUD treatment have perpetrated physical IPV toward their partners in the past year. These IPV rates among women entering SUD treatment far exceed rates observed in community members without substance use problems (Schumm, O’Farrell, Murphy, & Fals-Stewart, 2009), as well as among those in the community who exhibit substance use problems but have not sought treatment in the past year (Lipsky & Caetano, 2008).

Vyga G. Kaufmann and Timothy J. O’Farrell, Families and Addiction Program, Department of Psychiatry, VA Boston Healthcare System, Boston, Massachusetts, and Harvard Medical School, Boston, Massachusetts; Christopher M. Murphy, Department of Psychology, University of Maryland, Baltimore County; Marie M. Murphy, Families and Addiction Program, Department of Psychiatry, VA Boston Healthcare System, Boston, Massachusetts, and Harvard Medical School; Patrice Muchowski, AdCare Hospital of Worcester, Inc., Worcester, Massachusetts. Vyga Kaufmann is now at the Department of Psychology and Neuroscience, University of Colorado at Boulder. Portions of this article were presented at the Annual Meeting of the Association for Advancement of Cognitive and Behavior Therapies, New York, New York, November, 2009. The data examined in the present investigation were collected as part of a larger study of treatment-seeking women alcoholics. Published results from this larger study have tested a

conceptual model of partner aggression (Schumm, O’Farrell, Murphy, Murphy, & Muchowski, 2011), but the situational conflict data that are examined in this article have not been the subject of any prior publication. This research was supported by Grant R01AA12834 awarded to Timothy J. O’Farrell by the National Institute on Alcohol Abuse and Alcoholism and by the Department of Veterans Affairs. Preparation of this article was part of Vyga Kaufmann’s research project under Timothy J. O’Farrell’s supervision in the psychology internship program at the VA Boston Healthcare System. We gratefully acknowledge assistance from Fay Larkin, Anne Gribauskas, Denise Kwasnik, Leslie Reid, and Lisa Jennings. Correspondence concerning this article should be addressed to Timothy J. O’Farrell, Harvard Medical School Department of Psychiatry at the VA Boston Healthcare System, VAMC-116B1, 940 Belmont Street, Brockton, MA 02301. E-mail: [email protected] 313

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One factor posited to elevate risk for IPV among women SUD patients is the effects of alcohol intoxication on impulsive aggression (Leonard, 1993; Steele & Josephs, 1990). More specifically, alcohol is hypothesized to increase aggression indirectly through its effects on information processing capacity under conditions characterized by a salient impulse to act aggressively combined with less immediately apparent inhibitory cues. For example, a large international study of nearly 35,000 respondents in 13 countries found that IPV severity was significantly higher for IPV incidents in which one or both partners had been drinking compared with incidents in which neither partner had been drinking and that this relationship between drinking and IPV severity did not differ significantly for men and women or by country (Graham, Bernards, Wilsnack, & Gmel, 2011). Nevertheless, it is quite possible that IPV risk derives not from the acute effects of alcohol intoxication, but from correlated personality, relationship, and demographic factors. For example, in comparison to nonviolent alcoholic women, partner-violent alcoholic women have more antisocial personality characteristics, more relationship problems, lower income, and less education (Chase et al., 2003; Schumm, O’Farrell, Murphy, Murphy, & Muchowski, 2011). One research strategy used to infer a proximal role of alcohol consumption in IPV (Leonard, 1993) has been to examine accounts of alcohol use prior to specific violent and nonviolent conflict episodes among individuals who reported both types of conflicts. This research strategy allows for the examination of alcohol consumption and partner aggressive acts while controlling individual difference factors by contrasting different conflict episodes in a within-subjects design. Murphy and colleagues (Murphy, Winters, O’Farrell, FalsStewart, & Murphy, 2005) used this strategy in their study of treatment-seeking alcoholic men. Murphy et al. interviewed alcoholic men and their relationship partners about a conflict event in which physical violence occurred and one in which psychological aggression occurred without physical violence. Results followed study hypotheses. The number of standard drinks consumed by the husband in the previous 12 hr was significantly higher prior to violent versus nonviolent conflicts, as was blood alcohol concentration (BAC) estimated from self-report data. Other drug use did not significantly distinguish violent from nonviolent conflict events. Findings for alcohol consumption by the wife were mixed, with some evidence of greater drinking prior to violent conflict events. These within-subject comparisons helped to rule out individual difference explanations for the alcohol–violence association and indicated that the quantity of alcohol consumed was an important proximal risk factor for IPV in alcoholic men. Whether the Murphy et al. findings generalize to women SUD patients is not known because similar studies of women have not been reported. The present study of treatment-seeking female SUD patients sought to contribute new information on the situational association between alcohol consumption and IPV in female SUD patients. First, it builds on previous research on male alcoholics (Murphy et al., 2005), extending this work to women SUD patients, an understudied clinical group, and using a substantially larger sample size. Second, the current study is important because previous findings on male alcoholics may not generalize to female SUD patients. On one hand, women with alcohol problems may be at risk for IPV independent of alcohol consumption, particularly if their drinking is a coping response to previous abuse and trauma experiences. On

the other hand, the associations of IPV with alcohol consumption may be stronger for women with alcohol problems relative to their male counterparts, because women alcoholic patients are more likely to have relationship partners with SUD or heavy substance use (Greenfield et al., 2007). Third, this is the first study using a within-subjects analysis to examine the association between alcohol use and IPV among treatment-seeking women SUD patients. Two within-subject newlywed studies examined only the husband’s IPV and the husband’s drinking (Leonard & Quigley, 1999; Testa, Quigly, & Leonard, 2003), and most wives in the Murphy et al. (2005) study did not have clinical level alcohol problems. Finally, the data were gathered near the beginning of treatment and therefore reflect naturally occurring associations that are independent of possible treatment effects on the association between alcohol and violence. Data were collected about the quantity of alcohol consumption in the hours preceding conflict events with and without physical violence. The hypothesis was that alcohol consumption would be greater prior to violent versus nonviolent conflict events.

Method Harvard Medical School and VA Boston Institutional Review Boards approved the study.

Participants The sample (N ⫽ 145) derived from the first wave of a longitudinal investigation of IPV among female substance-abusing patients and their male relationship partners. For the larger investigation, participants were 277 women who entered inpatient rehabilitation (n ⫽ 72) or outpatient (n ⫽ 205) substance use treatment at a large addictions treatment center in the northeastern United States. The eligibility criteria for participation were as follows: (1) female patient was between 18 and 49 years of age; (2) female patient met Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM–IV; American Psychiatric Association, 1994) criteria for a current (past 6 months) diagnosis of alcohol abuse or alcohol dependence and/or drug abuse or drug dependence on the Structured Clinical Interview for DSM–IV (SCID-IV; First, Spitzer, Gibbon, & Williams, 1996); (3) female patient had consumed alcohol or illicit drugs in the 6 weeks prior to treatment admission; and (4) female patient and male relationship partner had been married or living together for at least 1 year, with no more than 6 months living apart in the past year; and (5) neither female patient or male partner met DSM–IV criteria for a current (past 6 months) psychotic disorder on the SCID-IV. Male partners did not take part in the study. Information about the male partner was gathered from the female study participant. Participants for the current investigation were those women (N ⫽ 145) from this larger sample who completed a situational conflict interview about both a violent and a nonviolent conflict event that occurred in the prior 6 months. Eligibility for the situational interview was determined on the basis of affirmative reports of male-to-female and/or female-to-male physical aggression in the prior 6 months on the revised Conflict Tactics Scale (CTS-2; Straus, Hamby, Boney-McCoy, & Sugarman, 1996) or the Timeline Followback Spousal Violence Interview (TLFB-SV; Fals-Stewart, Birchler, & Kelley, 2003) administered during the

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ALCOHOL CONSUMPTION AND PARTNER VIOLENCE

baseline assessment. As this investigation focused primarily on within-subject comparisons between conflict events with and without violence, only those participants (N ⫽ 145) who reported both a violent and a nonviolent conflict event were included in the investigation sample.1 The investigation sample of substance-abusing women (N ⫽ 145) averaged 38.3 years of age (SD ⫽ 7.6), 12.9 years of education (SD ⫽ 2.1), and yearly income of $15,000 to $20,000. Female participants were mostly Caucasian (82.8%), and the remainder were African American (7.6%), Hispanic or Latina (4.8%), or of another racial category (4.8%). Their male partners averaged 40.1 year of age (SD ⫽ 9.2), 12.2 years of education (SD ⫽ 2.1), and yearly income of $35,000 –$40,000. The racial composition of male partners was as follows: Caucasian (77.9%), African American (9.7%), Hispanic or Latino (6.2%), and other (6.2%). The participants had been living as a couple for an average of 7.5 years (SD ⫽ 7.4). Sixty-three participants were married (43.4%), and 82 participants were cohabiting but not married (56.6%). The percentage of female participants who met current (i.e., past 6 months) diagnostic criteria for dependence on the following substances were as follows: alcohol (79.3%); cocaine (37.9%); opiates (28.3%); sedatives, hypnotics, or anxiolytics (13.8%); cannabis (11.7%); and stimulants (2.8%). When grouped across the diagnostic categories, 36.6% of female participants had an alcohol use disorder only, 44.1% had both an alcohol and drug use disorder, and 19.3% had a drug use disorder only. Female participants drank heavily (i.e., four or more standard drinks) an average of 68.6 (SD ⫽ 56.5) days out of the past 6-months baseline period and used illicit drugs an average of 66.7 (SD ⫽ 67.7) days. Among the male partners (based on information provided by the female patients), 42.1% of the men met current diagnostic criteria for alcohol dependence. Male partners averaged 42.9 (SD ⫽ 63.2) days of heavy drinking (i.e., 6 or more standard drinks) and 51.6 (SD ⫽ 70.0) days of illicit drug use during the baseline period.

Procedure Study participants provided interview and questionnaire data on substance use and individual and relationship functioning at study entry and at 6-, 12-, and 18-month follow-up. The male relationship partners were not interviewed as part of the study protocol. The female study participants provided the information about their male relationship partners. The present results are from data gathered at study entry2 in a baseline assessment that lasted 3 to 4 hr.3

Measures Measures of SUD and substance use frequency. Women’s reports on the SCID-IV (First et al., 1996) were used to determine for which SUD(s) the female patient met DSM–IV criteria and whether the male partner met criteria for alcohol dependence (the only SUD diagnosed for the man). Women’s reports on the Timeline Followback Interview (TLFB; Sobell & Sobell, 1996) assessed for the past 6 months the number of days of heavy drinking by the woman (four or more standard drinks) and her male partner (six or more standard drinks)4 and the number of days the female and male partner used drugs other than alcohol. The validity of using women’s reports of the male partner’s alcohol use disorder is supported by prior studies showing large, robust correlations

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between individuals’ self-report and collateral reports of their SUD and substance use behaviors, with no difference in the magnitude of correlations between those with and without SUD (Achenbach, Krukowski, Dumenci, & Ivanova, 2005). Measures of occurrence of partner physical and psychological aggression. The first measure was the CTS2 (Straus et al., 1996), which included the 12-item Physical Assault and the eightitem Psychological Aggression subscales. Participants were asked to indicate which of the 12 physical and eight psychological aggressive behaviors on the CTS2 their male partners perpetrated toward them and which of the behaviors they perpetrated toward their male partners in the past 6 months. Evidence of concurrent, content, and construct validity has been presented for the CTS2 subscales (Straus et al., 1996). The second measure was the TLFBSV, a calendar method that assesses daily patterns and frequency of partner violence (Fals-Stewart et al., 2003). The TLFB-SV assessed episodes of male-to-female and female-to-male physical aggression that occurred in the 6 months prior to the baseline assessment. TLFB-SV data have moderate-to-high correlations with other measures of partner violence and general marital distress, but low correlations with a measure of positive impression management (Fals-Stewart et al., 2003). Participants who reported one or more acts of male-to-female or female-to-male physical aggression on the CTS2 or the TLFB-SV were administered the situational interview about the worst violent and worst nonviolent conflict events of the prior 6 months. The validity of relying solely on women’s reports of partner aggression is supported by a prior study of a SUD sample that revealed moderate interpartner agreement on the presence or absence of partner aggression and medium-to-large effect sizes for estimates of interpartner concor1 Demographic comparisons showed that the 145 women who had a violent and nonviolent conflict event in the past 6 months, when compared with the 132 women who did not, had significantly fewer years of education for the woman and her male partner, greater likelihood of living together unmarried, fewer years in relationship, and a trend (p ⬍ .10) toward younger age for the woman and her male partner. Such demographic differences are commonly found between male alcoholic patients with recent (past 6 –12 months) IPV and their counterparts without recent IPV (e.g., Murphy et al., 2001). 2 Study entry occurred when the patient signed the informed consent and completed their baseline interview. These two activities (i.e., signing informed consent and completing the baseline interview) occurred on the same day according to study protocol. On average, study entry occurred about 2.5 weeks after entry into treatment (mean ⫽ 17.7 days, SD ⫽ 17.2 days). 3 Given the sensitive nature of the research interview, there were several crisis intervention resources available during data collection, such as: mature, female interviewers with several years of experience working with the study population; availability of a supervisor and/or clinician-on-call at the research site; a policy to discontinue the interview if distress arose without penalty to the participant; and, in the event of distress, an agreement to have the interviewer remain with the participant until she was no longer distressed. Over the course of the study, no significant distress related to the interview experience was reported by participants or research assistants. 4 These definitions of heavy drinking are based on what was used in the Project MATCH treatment outcome study (Project MATCH Research Group, 1997). More recent guidelines based on epidemiological research (National Institute on Alcohol Abuse and Alcoholism [NIAAA], 2005) define heavy or at risk drinking (a) for women as more than three drinks a day (which is the same definition used in this study) and (b) for men as more than four drinks in a day (which is one drink less than the definition used in this study).

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dance on aggression frequency. When discrepancies were apparent, women in general reported higher rates of aggression by both self and partner in contrast to men (Panuzio et al., 2006). Situational interview about the worst violent and worst nonviolent conflict events. The situational interview about the worst violent conflict event consisted of a series of steps. First, the respondent was asked to pick out the conflict event (in which she or her partner did one or more of the 12 CTS2 violent acts listed on a card given to the respondent) that she considered to be the worst in the past 6 months. “Worst” was defined as the time when the most severe injuries occurred, or, if there were no injuries, the time when the conflict was the most intense or most severe as judged by the respondent. Second, she was asked to describe what happened leading up to the conflict event, during the event, and after the event. Interviewer notes about these subjective event descriptions are not part of the present study. Third, she was asked a series of standard questions about this worst violent conflict event, including (a) the specific acts of physical and verbal aggression exhibited by her male partner and by herself (based on two cards that listed, respectively, the 12 physical assault and eight psychological aggression items from the CTS2), (b) how long ago the conflict event occurred, (c) whether it occurred at home or away from home, (d) the topic of the argument or disagreement, and (e) the total duration of the conflict event. Fourth, the most severely violent act5 that was done by the woman or the man during the conflict event was identified as indicated by responses to Step 3a above. Fifth, a final set of questions examined this most severely violent act, including the length of time between the beginning of the conflict event and the time when the most severely violent act occurred. The respondent was asked to consider the time at which the most severely violent act occurred and to estimate the number of standard drinks consumed by herself and her partner during each of four intervals covering a total span of 12 hr before the violent act: (1) the 2-hr period preceding the violent act, (2) the 2-hr period before the first interval, (3) the 4-hr interval before the second interval, and (4) the 4-hr interval before the third interval. The respondent was also asked whether she or her partner had used other drugs (in nine categories) during the 2-hour period before the target aggressive behavior and the 10-hour period before that. The situational interview about the worst nonviolent conflict event in the past 6 months consisted of the same steps as for the violent conflict event already described. First, the respondent was asked to pick out the worst nonviolent conflict event (in which she or her partner did one or more of the eight CTS2 psychological aggression acts but none of the 12 CTS2 violent acts listed on two cards given to the respondent). “Worst” was defined as the time when an argument between the woman and her partner was the most intense as judged by the respondent without either person becoming violent. After the worst nonviolent conflict event was determined, the steps in the interview continued as they did with the worst violent conflict. With the exception of questions about the number of standard drinks consumed, which required that the respondent provide a numeric response, all interview questions contained structured response options that the interviewer used as prompts. For example, when asked about the topic of disagreement, respondents were shown a card that listed 25 common conflict topics and asked whether the disagreement concerned any of these topics. In addi-

tion, specific follow-up questions inquired whether alcohol use and drug use were topics of the conflict event. Calculation of estimated BAC. BAC was calculated for the female participant using the BACCuS computer program (Markham, Miller, & Arciniega, 1993), which estimates BAC on the basis of gender, body weight, number of standard drinks, and time since first drink.6 Estimated BAC at the time of the conflict event was calculated from the participants’ reports of the number and timing of standard drinks consumed during four preceding assessment intervals (i.e., hours 1–2, 3– 4, 5– 8, and 9 –12 prior to the conflict event). In order to avoid negatively biased BAC estimates, drinking reports from each sequential preceding time interval were included only if they increased the estimated BAC at the time of the conflict event. For example, the estimated BAC for a participant who consumed 10 standard drinks in the 2-hr interval before the conflict event, and had only one drink in the preceding 10 hours, would be calculated from 10 drinks over a 2-hr time frame rather than 11 drinks over a 12-hr time frame, as the latter calculation would severely underestimate BAC at the time of the conflict based on an erroneous assumption about the time available to metabolize the alcohol consumed. Although the individual consumed 11 drinks in a 12-hr time span, at the time of the conflict event she would have had 10 hr to metabolize the first drink, and only 2 hr to metabolize the other 10 drinks. As recommended by the Form 90 protocol used in Project MATCH (Miller, 1996), BAC estimates greater than .60% were recoded to .60%.

Results For the majority of conflict events, aggression was bidirectional, with both partners engaging in aggressive acts. In 62% of violent conflict events, both members of the couple performed one or more of the 12 CTS2 violent acts; in 19% only the man was violent, and in 19% only the woman was violent. In 90% of nonviolent conflict events both members of the couple performed one or more of the eight CTS2 psychological aggression acts; in 7% only the man was aggressive, and in 3% only the woman was aggressive.

Descriptive Information on the Conflict Events Tables 1 and 2 present information on the violent and nonviolent conflict events reported by the female patients. Some participants were unable to recall some of the details of the conflict events, so the number of participants per analysis varied and is provided in the tables. Descriptive data revealed both similarities and differences between violent and nonviolent conflict events. As shown in Table 1, 5 The severity ordering of the 12 CTS2 physical assault items was determined by combining two sources of information. First, items that were retained in the CTS2 from the original CTS were ordered on the basis of the Guttman scaling of this prior version of the measure (Straus, 1979). Then, items new to the revised CTS (CTS2) were placed within the rank order on the basis of item severity ratings provided by members of our research team. The same approach was used to order severity of the 8 CTS2 psychological aggression items. Murphy et al. (2005) used the same method. 6 The BAC was not calculated for the male partners because data on their body weight was not available.

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Table 1 Properties of Violent Versus Nonviolent Conflict Events for Continuous Variables

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Violent conflict events

Nonviolent conflict events

Continuous variable

N

M

SD

M

SD

Length of time since the event (days)a Time from beginning of conflict event to target aggressive behavior (min)b Total duration of conflict event (min)b Number of conflict topics discussedc

129 130 131 145

79.8ⴱ 28.5ⴱⴱ 72.3 6.5ⴱ

52.1 42.3 64.3 4.4

66.0 15.3 65.2 5.8

53.9 30.6 66.7 4.3

a Responses were recoded to the category mean as follows: less than 1 week ⫽ 4 days; 1 week to 1 month ⫽ 15 days; 1–3 months ⫽ 60 days; and 4 – 6 months ⫽ 150 days. b Responses were recoded to the category mean as follows: 5 min or less ⫽ 3; 6 –10 min ⫽ 8; 11–30 min ⫽ 20; 31– 60 min ⫽ 45; 1–2 hr ⫽ 90; and more than 2 hr ⫽ 180. c Responses were the number of conflicts discussed that were endorsed from a list of 25 common couple conflicts. ⴱ Violent events differed from nonviolent events for this variable, p ⬍ .05. ⴱⴱ Violent events differed from nonviolent events for this variable, p ⬍ .001.

both types of conflict events averaged a little more than an hour in duration, and the total duration of the conflict event did not differ significantly between violent and nonviolent conflicts. Location of the event did not differ significantly between violent and nonviolent conflicts because both types of events mainly occurred at home (80%–90% of events; see Table 2). Turning to differences between events, time of the event differed between type of events such that violent conflicts were more likely to occur in the evening and early morning hours (see Table 2; Wilcoxon signed-ranks test Table 2 Properties of Violent Versus Nonviolent Conflict Events for Categorical Variables Violent conflict events Categorical variable Location of the event At home Away from home Time of the eventaⴱ 9 a.m.–4 p.m. 5 p.m.–midnight 1 a.m.–8 a.m. Conflict topics discussedb Woman’s alcohol useⴱ Money Woman’s drug use Communication Jealousy Friends Correct behaviorⴱ Housing Children Amount of time spent together Man’s alcohol use Man’s drug use

Nonviolent conflict events

N

%

N

%

130 15

89.7 10.3

119 23

82.1 15.9

31 75 17

25.2 61.0 13.8

47 66 10

38.2 53.7 8.1

92 78 61 56 56 51 49 41 40 37 37 37

63 54 42 39 39 35 34 28 28 26 26 26

77 73 59 43 51 42 35 40 39 37 33 37

53 50 41 30 35 29 24 28 27 26 23 26

Z ⫽ 2.31, p ⫽ .021). Also the time of escalation to the most severe aggressive act was significantly greater for the violent than nonviolent conflict event, t(129) ⫽ 3.6, p ⬍ .001. The time elapsed since the event was also significantly different such that violent events occurred further back in time from the interview than nonviolent events, t(128) ⫽ 2.3, p ⫽ .02. On average, female patients reported 6.5 different conflict topics in the violent events and 5.8 different conflict topics in the nonviolent events (see Table 1), a difference that is statistically significant, t(144) ⫽ 1.97, p ⫽ .05. The pattern of conflict topics discussed was mainly similar across violent and nonviolent conflict events, as shown in the most frequently discussed conflict topics listed in Table 2. Exceptions to this general pattern were woman’s alcohol use, ␹2 (1, N ⫽ 145) ⫽ 5.94, p ⫽ .015, and correct and proper behavior, ␹2(1, N ⫽ 145) ⫽ 4.45, p ⫽ .035; these topics were more likely to be discussed in violent than in nonviolent conflict events. To summarize, these descriptive data showed that violent and nonviolent events did not differ on location, duration, or most topics discussed. However, time since the conflict, time of escalation to worst aggressive act, and number of topics discussed all were significantly greater for violent than nonviolent events. In addition, the likelihood of the conflict to occur in the evening and in the early morning and the likelihood that the conflict topic discussed would be the woman’s alcohol use or correct and proper behavior also were significantly greater for violent than nonviolent events. These differences in some general properties of the two types of conflict events could serve as potential confounding variables for the tests of alcohol association with physical aggression that are the main purpose of the present study. After presenting results for the main study hypotheses, we will return to this point.

Consumption of Alcohol and Drugs Prior to Violent Versus Nonviolent Conflict Events

a

The N for time of event is 123. The cases missing are those participants who were unable to recall the time of the conflict event. Participants were significantly more likely to be unable to remember the time of a verbal event compared with a physical event (14.5% vs. 2%, p ⬍ .001). b These were the most frequently discussed (i.e., at least 25% of sample mentioned the topic) conflict topics that were endorsed from a list of 25 common couple conflicts. A McNemar chi-square analysis was done separately for each topic to see whether the proportion of respondents who endorsed the topic differed for violent versus nonviolent events. ⴱ Violent events differed from nonviolent events for this variable, p ⬍ .05.

Prevalence of any drinking and heavy drinking. As expected with this clinical sample, alcohol consumption by the female patient was reported prior to a large percentage of conflict events (see Table 3). For example, more than 60% of female patients had consumed alcohol in the 12 hr before the violent event, and nearly 60% met the criterion for heavy drinking (defined as four or more standard drinks). Consistent with the hypothesis, the prevalence of any drinking and of heavy drinking by

KAUFMANN ET AL.

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Table 3 Prevalence of Alcohol Consumption, Heavy Drinking, and Other Drug Use in the 12 hr Before Violent Versus Nonviolent Conflict Events Alcohol or drug use

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By the woman With any alcohol consumption With heavy drinking (ⱖ4 drinks) With other drug use By the man With any alcohol consumption With heavy drinking (ⱖ6 drinks) With other drug use

N

Violent conflict events

Nonviolent conflict events

␹2

p

R

141 141 142

64.5 57.4 45.1

44.0 41.1 36.6

19.1 12.4 4.3

.000 .000 .04

.36 .30 .17

136 136 140

39.7 26.5 26.4

30.1 17.6 25.0

5.3 7.0 0.1

.02 .008 .75

.20 .23 .03

Note. r ⫽ effect size expressed as a correlation coefficient (Rosenthal, 1991), with r ⫽ .10 a small effect, r ⫽ .30 a medium effect, r ⫽ .50 a large effect (Cohen, 1988).

for the woman at the time of the conflict. Results support the hypothesis of greater alcohol consumption by the female patient prior to the violent conflict events. Specifically, number of drinks consumed and estimated BAC were both significantly higher in violent versus nonviolent conflict events. Male partners’ alcohol consumption was measured by the number of drinks he consumed in the prior 12 hr (see Table 4). Number of drinks consumed by the male partner also was significantly higher in the violent versus nonviolent conflict events. Impact of potential confounds on findings of greater alcohol consumption prior to violent conflict events. Time since the conflict, time of escalation to worst aggressive act, number of topics discussed, and the likelihood that the conflict topic discussed would be the woman’s alcohol use or correct and proper behavior all were significantly greater for violent than nonviolent events. In addition, time at which the conflict occurred differed for violent versus nonviolent events. These different properties of the two types of conflict events could serve as potential confounding variables for the tests of alcohol association with physical aggression reported immediately above. To examine these potential confounds, each of these six variables was correlated with the reported level of alcohol consumption (i.e., number of drinks) for both the woman and the man within each conflict event. Correlations for five of the variables were not statistically significant (all ps ⬎ .22), suggesting that drinking reports were not systematically inflated across subjects as a function of these five variables. There were

the female patient were significantly higher in the violent versus nonviolent conflict events. Alcohol consumption by the male partner was reported prior to a substantial percentage of conflict events (see Table 3). For example, nearly 40% of male partners had consumed alcohol in the 12 hr before the violent event, and more than 25% met the criterion for heavy drinking (defined as 6 or more standard drinks). Consistent with the hypothesis, the prevalence of any drinking and of heavy drinking by the male partner were both significantly higher in the violent versus nonviolent conflict events. Prevalence of other drug use. Female patients’ use of drugs other than alcohol was reported in the previous 12 hr for a substantial percentage of conflicts (see Table 3). Following the hypothesis, prevalence of the female patient using drugs other than alcohol was significantly higher in violent versus nonviolent conflict events. Female patients’ most frequently used drug in the 12 hr preceding violent conflict events was cocaine (in 26% of cases). Male partners’ drug use was relatively common (reported for 25% of cases) prior to violent and nonviolent conflict events (see Table 3). However, there were no significant differences in the prevalence of male partner drug use in violent and nonviolent conflict events. Quantity of alcohol consumed. Table 4 displays means and standard deviations for female patients’ alcohol consumption measures, specifically the number of standard drinks in the 12-hr preceding the two types of conflict events and the estimated BAC

Table 4 Quantity of Alcohol Consumed and Estimated BAC Before Violent Versus Nonviolent Conflict Events

Alcohol consumption By the woman No. standard drinks BAC By the man No. standard drinks

Violent conflict events

Nonviolent conflict events

N

M

SD

M

SD

t

p

141 138

9.4 .176

12.8 .205

6.2 .106

11.4 .176

3.2 4.2

.002 ⬍.001

136

6.1

13.0

4.7

11.4

2.5

.015

r

.13 .17 .109

Note. r ⫽ effect size expressed as a correlation coefficient (Rosenthal, 1991), with r ⫽ .10 a small effect, r ⫽ .30 a medium effect, r ⫽ .50 a large effect (Cohen, 1988).

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ALCOHOL CONSUMPTION AND PARTNER VIOLENCE

significant correlations between the topic of woman’s alcohol use and number of female drinks in the violent event (r ⫽ .37, p ⬍ .001) and in the nonviolent event (r ⫽ .38, p ⬍ .001). However, the amount of drinking would not have been affected by discussing the woman’s alcohol use as a conflict topic because the drinking measurement covered the time period before the conflict event. It seems more plausible that greater drinking by the woman led to greater discussion of the woman’s alcohol use as a topic. Therefore, the conflict topic of the woman’s alcohol use does not appear to be a confound in the context considered here.7 Alcohol consumption and drug use. An additional analysis examined whether alcohol use was associated with violence independent of any effects of drug use. Specifically, an ANOVA with matched sample design adjusted for drug use as a repeatedmeasures covariate, indicated that the number of drinks consumed by the woman remained significantly greater in the violent than in the nonviolent event, F(1, 136) ⫽ 9.1, p ⫽ .003. Thus, the amount of alcohol use was associated with violence over and above the effects of drug use. To further address the impact of drug use on study findings, the number of standard drinks consumed by the female patient in the 12-hr preceding the two types of conflict events was examined for each of three diagnostic subgroups: alcohol use disorder only, alcohol and drug use disorder, and drug use disorder only. Each diagnostic subgroup displayed the same level of effect as observed for the overall sample (r ⫽ .13), supporting the finding of greater alcohol consumption by the female patient prior to the violent conflict events.

Discussion As hypothesized, alcohol consumption was significantly greater prior to violent versus nonviolent relationship conflict events for this clinical sample of substance abusing women. This hypothesized finding received consistent support for all four measures of women’s alcohol consumption examined: any drinking, heavy drinking, number of drinks in the 12 hr preceding the conflict event, and estimated BAC at time of the event. Findings for alcohol consumption by the male partner showed a similar pattern of results, with the exception that BAC was not examined for men. Women’s use of drugs other than alcohol also was significantly more likely prior to violent than nonviolent conflict events. However, male partners’ drug use did not differ significantly between violent and nonviolent conflict events. Alcohol consumption was not only associated with greater conflict severity as predicted, but the woman’s alcohol use was also a very common topic of conflicts, reported in half of both violent and nonviolent conflict events. Other drug use by the woman was also a common topic of conflict, reported in roughly 40% of each type of conflict event. The current study findings are consistent with previous findings from a treatment-seeking sample of alcohol-abusing men (Murphy et al., 2005). Using nearly identical research methods, the current study found somewhat stronger support for the hypothesis with female SUD patients in contrast to prior work with male patients (Murphy et al., 2005). Specifically, the present findings were consistent across all (not just some) of the alcohol consumption measures tested and for both the woman patient and her partner (not just the patient). The stronger results may have been due to greater statistical power afforded by the larger sample in the

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present study. It is also likely, however, that other differences in the relationships of male versus female SUD patients help account for the more consistent association in the current sample. Notably, the level of alcohol problems was greater for the male collateral partners in the current study than for female collateral partners in prior research on male patients. Therefore, the association between alcohol abuse and conflict escalation may be stronger with mutual substance use problems. In addition, although the patient’s alcohol use was a very common topic of conflict in both studies, other drug use was a somewhat more common argument topic in the current sample. It is possible that these conflict topics, which are commonly linked to actual consumption at the time of the event, are more volatile in the relationships of women with SUD problems than in the relationships of men with SUD problems. The within-subjects design provided a high level of control over individual difference factors that might otherwise account for associations between alcohol and violence. Important case factors such as antisocial personality characteristics, relationship discord, and demographics were expected to remain relatively stable over the 6-month period during which both conflict events took place and were therefore not likely explanations for increased alcohol consumption prior to violent versus nonviolent conflict episodes. Further, six potentially confounding variables on which violent and nonviolent events differed were subjected to further analyses that suggested that these variables did not affect the tests of alcohol association with physical aggression. Finally, alcohol use was associated with violence independent of any effects of drug use. Nevertheless, other situational factors, memory issues, or reporting biases may have been confounded with aggression level and may thus have accounted in part for the observed differences in alcohol consumption. Other limitations bear noting. First, the BAC calculations were merely estimates, subject to recall errors and not able to account for variation due to individual differences in metabolism. Interpretation of the absolute magnitude of BAC estimates must be made with great caution. Greatest confidence should be placed in convergent findings for which the number of drinks consumed and estimated BAC were both significantly higher in the violent conflicts. Second, an additional consideration is the order of the interview. Situations were not counterbalanced. All respondents described the violent situation first and the nonviolent second. Third, the purpose of the interview may have been transparent to some participants. They may, in response, have produced data in line with the apparent hypothesis of greater alcohol consumption prior to more severe conflict events. Fourth, some important situ7 To further assess the impact of the six potential confounding variables for the tests of alcohol association with physical aggression, a series of ANOVAs with matched sample design adjusted for each confounding variable as a repeated measures covariate were conducted. The results were largely consistent with the correlational analyses. They indicated that the number of drinks consumed by the woman and by the man remained significantly greater in the violent than the nonviolent conflict events for four of the six variables (i.e., time since the conflict, time of escalation to worst aggressive act, likelihood that the conflict topic discussed would be about correct and proper behavior, and time at which the conflict event occurred). The two variables that did not reach significance for either female or male drinking were woman’s alcohol use as a conflict topic (not logically a confound as discussed above), and the number of topics discussed during the conflict event.

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KAUFMANN ET AL.

ational factors associated with the individual conflict events were not examined in this study. For example, from the current study we do not know who initiated the conflict, whether and how selfdefense or retaliation may have been involved, or whether anyone was injured in the conflict. Future research should more fully consider other potentially confounded aspects of situations. Fifth, the predominantly Caucasian study sample of relatively highly educated heterosexual couples living in long-term relationships limits our ability to generalize the present results to other types of partnerships or ethnic groups (Field & Caetano, 2004) and to couples with less education and shorter relationship duration. Finally, data about the male partners was provided by the woman. In summary, the current study contributes to a substantial body of research demonstrating a consistent association between alcohol consumption and IPV (Lipsey, Wilson, Cohen, & Durzon, 1997), with stronger associations observed in clinical than in nonclinical samples (Foran & O’Leary, 2008). The current research strategy—a within-subjects analysis of violent versus nonviolent conflict events—is an important innovation in this line of research because it controls for individual difference and relationship factors that may otherwise account for the alcohol–IPV association. Confounded individual difference and dyadic factors, such as multiple stress exposures, relationship distress, personality dysfunction, and comorbid psychological problems, are particularly relevant to clinical samples. Our literature review uncovered three previous studies that have compared alcohol use in violent versus nonviolent conflicts. Results have been consistent across all four studies. In addition to the current study and the previous study of male SUD patients, two studies found an increased situational risk for physical aggression and severe violence as a function of alcohol consumption among newlyweds in the community (Leonard & Quigley, 1999; Testa et al., 2003). In conclusion, the current results indicate that consumption of a greater amount of alcohol prior to a relationship conflict is associated with increased risk for escalation to physical violence during the subsequent conflict, even among women SUD patients who consume large quantities of alcohol on many occasions. Clinical implications from this research suggest that substance abuse clinicians should screen all female patients for IPV both as victims and perpetrators. Additionally, the conflict topics identified are likely to continue, perhaps even intensify, during the woman’s early recovery. Importantly, clinicians should educate their female patients that “discussions” and arguments with their partner when either of them has been drinking or using drugs may increase their risk for IPV victimization. Many females may experience additional guilt and shame associated with their own acts of violence. Educating females about the direct contributions of alcohol and other substances to this behavior may be a useful intervention. Additionally, such experiences may also be used in a motivational counseling intervention to foster treatment engagement. Finally, the results underscore the necessity of substance abuse clinicians recognizing that many of their women substance abuse patients have experienced the trauma of violent victimization by their male partners, which often is part of a broader pattern of physical, emotional, and sexual abuse experienced in these women’s lives. This is important because clinically influential, trauma-informed substance abuse treatment models (e.g., Harris, 1998; Najavits, 2002), which address both the trauma experiences

and the substance abuse, have been developed for use with this population of women who are substance abuse patients.

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Received November 4, 2012 Revision received July 18, 2013 Accepted September 16, 2013 䡲