Comorbidity and Trauma Study (CATS)

image - Sydney Alley 280
Date Commenced:
Expected Date of Completion:
Project Supporters:

National Institute of Drug Abuse (Grant R01 DA017305)

Drug Type:
Project Members: 
image - Briony Larance Square
Conjoint Senior Lecturer
Ph 02 9385 0333
image - Sarah Larney
Senior Lecturer
Ph +61 (2) 9385 0333
Project Main Description: 

The Comorbidity and Trauma Study (CATS) is a large retrospective case-control study, which examined the influence of genetics and environmental factors (e.g. childhood trauma) contributing to opioid dependence liability. The present research proposes a new data linkage component, which will link data from the CATS cohort with mortality, opioid substitution therapy, emergency department and hospital data.

Project Collaborators: External: 

Professor Elliot Nelson
Department of Psychiatry, Washington University

Dr Elizabeth Conroy
Centre for Health Research, University of Western Sydney


The aim of the present research is to examine causes and predictors of mortality, and patterns of engagement with opioid substitution therapy among the CATS cohort. The specific aims of this research are to:

  • Estimate overall mortality (both underlying and contributing causes) for the CATS cohort;
  • Explore whether demographic or treatment variables are related to mortality levels during and following cessation of treatment;
  • Estimate mortality risk, according to specific causes of death;
  • Identify patterns and predictors of engagement (e.g. retention) in OST;
  • Identify patterns and predictors of emergency department presentations;
  • Identify patterns and predictors of hospital separations; and
  • Explore neonatal outcomes among opioid dependent women compared with matched controls, and associations of childbirth with engagement with OST among opioid dependent woman.
Design and Method: 

A sample of 1487 opioid dependent cases and 515 non-dependent controls matched on age, sex and socio-economic status participated in face-to-face structured interviews between 2004 and 2008. Cases were recruited from 34 of the 35 available public and private opioid substitution therapy clinics in the greater Sydney region, and through word of mouth and snowballing recruitment methods. Controls were recruited from community and employment centres, open street malls and local press servicing the same geographic area as the clinics.

Data from the CATS cohort will be linked with the following administrative databases:

  1. National Death Index (NDI) at the Australian Institute of Health and Welfare;
  2. Ministry of Health –
    • Pharmaceutical Drugs of Addiction System (PHDAS) at the Pharmaceutical Services, Legal and Regulatory Services Branch (PBS).
    • NSW Admitted Patient Data (APD) at the Health System Information and Performance Reporting Unit.
    • NSW Emergency Department Data Collection (EDDC) at the Health System Information and Performance Reporting Unit.



CATS cohort data has been linked to administrative data from the National Death Index (NDI), Pharmaceutical Drugs of Addiction System (PHDAS), NSW Admitted Patient Data (APD) and NSW Emergency Department Data Collection (EDDC) databases. Data analysis is currently underway.


1.       Maloney, E., Degenhardt, L., Darke, S., Mattick, R.P. & Nelson, E. (2007).Suicidal behaviour and associated risk factors among opioid-dependent persons: A case control study. Addiction,102, 1933-1941.

2.       Conroy, E., Degenhardt, L., Mattick, R.P. & Nelson, E. (2009).Child maltreatment as a risk factor for opioid dependence: Comparison of family characteristics and type and severity of child maltreatment with a matched control group.Child Abuse and Neglect, 33(6), 343-352.

3.       Maloney, E., Degenhardt, L., Darke, S., and Nelson, E., (2009). Are non-fatal opioid overdoses misclassified suicide attempts? Comparing the associated correlates. Addictive Behaviors, 34(9), 723-729. 

4.       Maloney, E., Degenhardt, L., Darke, S., and Nelson, E., (2009). Impulsivity and borderline personality as risk factors for suicide attempts among opioid-dependent individuals.  Psychiatry Research, 169, 15-21.

5.       Shand, F., Degenhardt, L., Slade, T., & Nelson, E. (2009). The structure of polysubstance dependence and its correlates in a heroin dependent sample (abstract). Drug and Alcohol Review, 28, A58-A58.

6.       Shand, F. Slade, T., Degenhardt, L., & Nelson, E.C. (2009). The severity of heroin dependence: does it exist and is it clinically relevant? Drug and Alcohol Review, 28, A58-A58.

7.       Shand, F., Degenhardt, L., Nelson, E. & Mattick, R.P., (2010). Predictors of social anxiety in an opioid dependent sample and a matched control group. Journal of Anxiety Disorders, 24, 49-54.

8.       Maloney, E., Degenhardt, L., Darke, S., & Nelson, E. (2010). Investigating the co-occurrence of self-mutilation and suicide attempts among opioid dependent individuals and matched controls. Suicide and Life Threatening Behavior, 40(1), 50-62.

9.       Shand F, Degenhardt L, Slade T, Mattick RP, Nelson EC. (2010). Comorbidity and severity of heroin dependence: untangling the impact of each on overdose, suicidality, treatment history and criminality. Drug And Alcohol Review, 29, 68-68.

10.    Shand, F., Degenhardt, L., Slade, T., & Nelson, E.N. (2011). Sex differences amongst dependent heroin users: Histories, clinical characteristics and predictors of other substance dependence. Addictive Behaviors, 36(1-2), 27-36.

11.    Shand, F., Slade, T., Degenhardt, L., Baillie, A., & Nelson, E.N. (2011). Opioid dependence latent structure: two classes with differing severity? Addiction, 106(3), 590-598.

12.    Agrawal, A., Nelson, E.C., Littlefield, A., Bucholz, K., Degenhardt, L., Henders, A., Madden, P., Martin, N., Montgomery, G., Pergadia, M., Sher, K., Heath, A., & Lynskey, M. (2012). Cannabinoid receptorgenotype moderation of the effects of childhood physical abuse on anhedonia and depression. Archives of General Psychiatry, 69(7), 732-740. doi:10.1001/archgenpsychiatry.2011.2273

13.    Panagopoulos, V., Trull, T., Glowinski, A., Lynskey, M., Heath A., Agrawal, A., Henders, A., Wallace, L., Todorov, A., Madden, P., Moore, E., Degenhardt, L., Martin, N., Montgomery, G., & Nelson, E. (2013). Examining the Association of NRXN3 SNPs with borderline personality disorder phenotypes in heroin dependent cases and socioeconomically disadvantaged controls. Drug and Alcohol Dependence, 128, 187-193.

14.    Nelson, E., Lynskey, M., Heath, A., Wray, N., Agrawal, A., Shand, F., Henders, A., Wallace, L., Todorov, A., Schrage, A., Saccone, N., Madden, P., Degenhardt, L., Martin, N., Montgomery, G. (2013). ANKK1, TTC12, and NCAM1 Polymorphisms and heroin dependence:Importance of considering drug exposure. JAMA Psychiatry, 70(3), 325-33.

15.    Nelson, E., Lynskey, M., Heath, A., Wray, N., Agrawal, A., Shand, F., Henders, A., Wallace, L., Todorov, A., Schrage, A., Madden, P., Degenhardt, L., Martin, N., Montgomery, G., (2014). Association of OPRD1 Polymorphisms with Heroin Dependence in a Large Case-control Series. Addiction Biology, 19(1) 111-121.

16.    Nelson, E.C., Heath, A., Lynskey, M., Agrawal, A., Henders,A., Todorov, A., Madden, P., Moore, E., Degenhardt, L., Martin, N.G. & Montgomery, G., (2014). PTSD risk associated with a functional DRD2 polymorphism in heroin dependent cases and controls is limited to amphetamine dependent individuals. Addiction Biology. DOI: 10.1111/adb.12062

17.    Shand, F., Rawlinson, W., Degenhardt, L., Day, C., Martin, N., & Nelson, E.N. (2014). Hepatitis C testing and status among opioid substitution treatment clients in New South Wales. Australian and New Zealand Journal of Public Health, 38(2), 160-164.

18.    Hancock, D., Levy, J., Gaddis, N., Glasheen, C., Saccone, N., Page, G., Hulse, G., Wildenauer, D., Kelty, E., Schwab, S., Degenhardt, L., Martin, N., Montgomery, G., Attia, J., Holliday, E., McEvoy, M., Scott, R., Bierut, L., Nelson, E., Kral, A., & Johnson, E., (2015). Cis-Expression Quantitative Trait Loci Mapping Reveals Replicable Association with Heroin Addiction in OPRM1. Biological Psychiatry. doi: 10.1016/j.biopsych.2015.01.003

19.    Schwantes-An, T-H., Zhang, J., Chen, L-S., Hartz, S., Culverhouse, R., Chen, X., Coon, H., Frank, J., Kamens, H., Konte, B., Kovanen, L., Latvala, A., Maher, B., Legrand, L., Melroy, W., Nelson, E., Reid, M., Robinson, J., Shen, P-H., Yang, B-Z., Andrews, J., Aveyard, P., Beltcheva, O., Brown, S., Cannon, D., Cichon, S., Corley, R., Dahmen, N., Degenhardt, al.(in press accepted April 18th 2015). Association of the OPRM1 variant rs1799971 (A118G) with non-specific liability to substance dependence in a collaborative de novo meta-analysis of European-ancestry cohorts. Behavior Genetics.

20.    Carey, C., Agrawal, A., Zhang, B., Conley, E., Degenhardt, L., Heath, A., Li, D., Lynskey, M., Martin, N., Montgomery, G., Wang, T., Bierut, L., Hariri, A., Nelson, E., & Bogdan, R. (accepted June 10th 2015). Endocannabinoid variants and childhood adversity predict cannabis dependence symptoms and amygdala habituation. Journal of Abnormal Psychology.

21.    Nelson, E., Agrawal, A., Heath, A., Sherva, R., Zhang, B., Al-Hasani, R., Bruchas, M., Chou, Y.-L., Fakira, A., Farrer, L., Goate, A., Gordon, S., Henders, A., Hesselbrock, V., Kapoor, M., Lynskey, M., Madden, P., Moron-Concepcion, J., Rice, J., Saccone, N., Schwab, S., Shand, F., Todorov, A., Wallace, L., Wang, T., Wray, N., Zhou, X., Degenhardt, L., Martin, N.,Kranzler, H., Gelernter, J., Bierut, L., Clark, D., & Montgomery, G. (in press accepted June 17th 2015). A genome-wide association study provides evidence of CNIH3 involvement in opioid dependence. Molecular Psychiatry.


The CATS study seeks to provide a better understanding of the genetics of opioid dependence. The data linkage component of the study will examine underlying and contributing causes of death among this cohort of opioid dependent people, in addition to factors (i.e. demographics, childhood and adult victimisation, and psychiatric disorders) that predict mortality and engagement in OST. The analysis of data from opioid dependent cases and non-opioid dependent controls will provide unique insight into the role of opioid dependence and opioid substitution therapy in mortality risk.

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