Violence among Cocaine and Simultaneous Cocaine and Alcohol Abusers

141 Pages·2017·1.83 MB·English

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Sameer Imtiaz, The University of Western Ontario
Supervisor: Dr. Samantha Wells, The University of Western Ontario
A thesis submitted in partial fulfillment of the requirements for the Master of Science degree in
Epidemiology and Biostatistics
© Sameer Imtiaz 2013
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Imtiaz, Sameer, "Violence among Cocaine and Simultaneous Cocaine and Alcohol Abusers: Results from
a Cross-sectional Study of Treatment Clients" (2013). Electronic Thesis and Dissertation Repository.
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VIOLENCE AMONG COCAINE AND SIMULTANEOUS COCAINE AND ALCOHOL
ABUSERS: RESULTS FROM A CROSS-SECTIONAL STUDY OF TREATMENT
CLIENTS

Thesis format: Monograph

by

Sameer Imtiaz

Graduate Program in Epidemiology and Biostatistics

A thesis submitted in partial fulfillment
of the requirements for the degree of
Master of Science

The School of Graduate and Postdoctoral Studies
The University of Western Ontario
London, Ontario, Canada

© Sameer Imtiaz 2013
Abstract
A population known for substantial violence is the substance abuse treatment population.
This study assessed: (1) extent of violence, (2) personality and mental health correlates of
violence, and (3) sex differences in correlates of violence. Data were obtained from the
Patterns and Consequences of Cocaine and Alcohol Use for Substance Abuse Treatment
Clients Study (N = 403). Logistic regression with backward elimination procedures and
modified Poisson regression were used to assess the study objectives. Violence was reported
by 44% of treatment clients. Furthermore, number of other drugs used per week (RR: 1.124,
95% CI: 1.063 - 1.189) and aggressive personality (RR: 1.043, 95% CI: 1.031 – 1.055) were
significantly associated with an increased likelihood of violence. Finally, there was no
evidence for sex-differences in correlates of violence. These findings suggest that screening
for violence and addressing pertinent risk factors during treatment may be needed to reduce
violence within this population.

Keywords

Violence, physical aggression, substance abuse treatment, substance use disorder treatment,
cocaine, alcohol, simultaneous use, drugs, aggressive personality and sex-differences

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Dedication
“Let me hide in You
From everything that distracts me from You,
From everything that comes in my way
When I want to run to You.”
– Rabia Al-Adawiyya
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Acknowledgments
I am indebted to several individuals whose continued guidance and support made this thesis a
reality. I would like to begin by thanking the faculty in the Department of Epidemiology and
Biostatistics for imparting their years of knowledge and experience. In particular, I am
grateful to my thesis advisory committee, Drs. Greta Bauer, John Koval and Scott
Macdonald, for providing critical feedback that improved the quality of this thesis
substantially. Above all, I am most appreciative of my mentor, Dr. Samantha Wells, for
acting as a constant source of inspiration, guidance and encouragement. Not only have I
benefited from her mentorship, but I have also gained tremendously from the opportunities
she provided me to develop as a scientist.
I would further like to thank all my colleagues and friends in the Department of
Epidemiology and Biostatistics for enriching my graduate experience. In particular, I am
grateful to Ahmed, Alvin, Bryan, Jerry, Joseph, Kariym and Sonia for not only diversifying
my perspective on life, but also making the last two years memorable.
Finally, I would like to thank my family for being the cornerstone of support during this
entire journey. I am forever grateful to my parents for the sacrifices they have made not only
during this graduate experience, but life in general. Additionally, I am thankful to my sister
and brother in law for providing me with two great sources of amusement and happiness that
helped me focus beyond the thesis itself. Last but not least, I am thankful to my wife whose
short presence has quantitatively and qualitatively modified my quality of life. Our marriage
was perhaps the greatest motivation to complete this thesis on time.
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Table of Contents
Abstract ............................................................................................................................... ii
Dedication .......................................................................................................................... iii
Acknowledgments.............................................................................................................. iv
Table of Contents ................................................................................................................ v
List of Tables ................................................................................................................... viii
List of Figures ..................................................................................................................... x
List of Appendices ............................................................................................................. xi
Chapter 1 ............................................................................................................................. 1
1 Introduction .................................................................................................................... 1
Chapter 2 ............................................................................................................................. 3
2 Literature review, rationale and objectives .................................................................... 3
2.1 Violence in substance use disorder treatment population ....................................... 3
2.2 Consequences of violence ..................................................................................... 12
2.3 Correlates of violence ........................................................................................... 13
2.3.1 Primary explanatory variables .................................................................. 13
2.3.2 Control variables ....................................................................................... 19
2.4 Sex differences in correlates of violence .............................................................. 26
2.5 Limitations of existing research ............................................................................ 27
2.6 Thesis rationale ..................................................................................................... 30
2.7 Thesis objectives ................................................................................................... 31
Chapter 3 ........................................................................................................................... 33
3 Methods ........................................................................................................................ 33
3.1 Participants ............................................................................................................ 33
3.2 Exclusion criteria .................................................................................................. 34
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3.3 Data collection procedures .................................................................................... 34
3.4 Questionnaire ........................................................................................................ 35
3.5 Incentives .............................................................................................................. 36
3.6 Response rate ........................................................................................................ 36
3.7 Measures ............................................................................................................... 36
3.7.1 Outcome variable ...................................................................................... 36
3.7.2 Primary explanatory variables .................................................................. 37
3.7.3 Control variables ....................................................................................... 41
3.8 Ethics approval...................................................................................................... 44
3.9 Statistical analyses ................................................................................................ 44
3.10 Analytic strategy ................................................................................................... 44
3.10.1 Modified Poisson regression ..................................................................... 44
3.10.2 Logistic regression .................................................................................... 45
3.11 Preliminary analyses ............................................................................................. 46
3.12 Analyses per study objectives ............................................................................... 46
3.13 Data management and final sample size ............................................................... 49
Chapter 4 ........................................................................................................................... 50
4 Results .......................................................................................................................... 50
4.1 Extent of missingness ........................................................................................... 51
4.2 Sample characteristics ........................................................................................... 53
4.3 Association among study variables ....................................................................... 57
4.3.1 Total sample .............................................................................................. 57
4.3.2 Males ......................................................................................................... 57
4.3.3 Females ..................................................................................................... 58
4.4 Analyses per study objectives ............................................................................... 65
4.5 Sensitivity analysis................................................................................................ 85
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Chapter 5 ........................................................................................................................... 86
5 Discussion .................................................................................................................... 86
5.1 Consideration of findings ...................................................................................... 87
5.1.1 Extent of violence ..................................................................................... 87
5.1.2 Factors associated with violence ............................................................... 88
5.1.3 Sex differences in correlates of violence .................................................. 92
5.2 Clinical implications ............................................................................................. 99
5.3 Study strengths .................................................................................................... 100
5.4 Study limitations ................................................................................................. 101
5.5 Recommendations for future research ................................................................ 105
References ....................................................................................................................... 107
Appendices ...................................................................................................................... 116
Curriculum Vitae ............................................................................................................ 128
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List of Tables
Table 1. Results of studies reporting proportions of any violence in substance use disorder
treatment clients ........................................................................................................................ 5
Table 2. Results of studies reporting proportions of violence in substance use disorder
treatment clients by violence typologies ................................................................................... 6
Table 3. The relationship of licit and illicit substances to violence ........................................ 20
Table 4. Missingness on study variables of interest for treatment clients with valid outcome
data by total sample, males and females ................................................................................. 52
Table 5. Characteristics of total sample, males and females by study variables of interest ... 55
Table 6. Correlation matrix of continuous study variables of interest for total sample (N =
403) ......................................................................................................................................... 60
Table 7. Correlation matrix of continuous study variables of interest for males (N = 195) and
females (N = 207) ................................................................................................................... 61
Table 8. Associations between continuous and ordinal study variables of interest for total
sample, males and females ...................................................................................................... 62
Table 9. Associations between continuous and categorical study variables of interest for total
sample, males and females ...................................................................................................... 63
Table 10. Characteristics of treatment clients associated with violence during the past 12
months by total sample ........................................................................................................... 67
Table 11. Characteristics of treatment clients associated with violence during the past 12
months by males and females ................................................................................................. 68
Table 12. Unadjusted relative risks of violence during the past 12 months associated with
demographics, drug consumption measures, personality traits and mental health indicators by
total sample ............................................................................................................................. 71
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Table 13. Unadjusted relative risks of violence during the past 12 months associated with
demographics, drug consumption measures, personality traits and mental health indicators by
males and females ................................................................................................................... 72
Table 14. Results from logistic regression with backward elimination procedures examining
the associations between each of personality traits and mental health indicators and violence
during the past 12 months while controlling for demographics and drug consumption
measures by total sample ........................................................................................................ 76
Table 15. Results from logistic regression with backward elimination procedures examining
the associations between each of personality traits and mental health indicators and violence
during the past 12 months while controlling for demographics and drug consumption
measures by males and females .............................................................................................. 77
Table 16. Adjusted relative risks of violence during past 12 months associated with
personality traits and mental health indicators while controlling for demographics and drug
consumption measures by total sample................................................................................... 79
Table 17. Adjusted relative risks of violence during past 12 months associated with
personality traits and mental health indicators while controlling for demographics and drug
consumption measures by males and females ........................................................................ 80
Table 18. Results from logistic regression with backward elimination procedures assessing
multiplicative sex interactions between each of demographics, drug consumption measures,
personality traits and mental health indicators and violence during the past 12 months ........ 83

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