Longitudinal changes in psychological distress in a cohort of people who inject drugs in Melbourne, Australia.
Previous research into psychological distress among people who inject drugs (PWID) is predominantly cross-sectional; we determined longitudinal predictors of change in psychological distress among a cohort of PWID.



We examined Kessler Psychological Distress Scale (K10) scores from 564 PWID (66% male) enrolled in the Melbourne Injecting Drug User Cohort Study. Gender-stratified linear models with fixed effects for each participant were used to examine correlates of change in individual K10 scores. Further linear regressions of adjusted K10 scores were used to measure correlations between demographic variables.



Participants reported higher K10 scores (higher psychological distress) than the general Australian population (mean K10 scores 23.4 (95%CI 22.6-24.2) and 14.5 (95%CI 14.3-14.7) respectively). The cohort's mean K10 score did not significantly differ over time, but individual variations were common. Women reported higher K10 scores than men (mean baseline K10 scores 25.2 (95%CI 23.9-26.6) and 22.4 (95%CI 21.5-23.3) respectively), however no significant differences remained after controlling for temporal factors. Key predictors of increases in K10 scores were being the victim of an assault in the past six months (P<0.001 for women and men) and intentionally overdosing in the past 12 months (P=.010 for women and P<0.001 for men).



PWID experience higher levels of psychological distress than the general population. Temporal rather than individual factors may account for the higher levels of psychological distress reported among women. Interventions to reduce rates of assault and/or intentional overdose should be explored to reduce high levels of psychological distress among PWID.
Centre for Population Health, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia; Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria 3004, Australia.
Nick
N
Scott
Centre for Population Health, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia.
Elise R
ER
Carrotte
Centre for Population Health, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia; Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria 3004, Australia; National Drug Research Institute, Faculty of Health Sciences, Curtin University, Melbourne Office, 6/19-35 Gertrude St, Fitzroy, Victoria 3065, Australia; Department of Public Health, La Trobe University, Bundoora, Victoria 3086, Australia.
Peter
P
Higgs
Centre for Population Health, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia.
Shelley
S
Cogger
Centre for Population Health, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia; Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria 3004, Australia.
Mark A
MA
Stoové
Centre for Population Health, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia; Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria 3004, Australia.
Campbell K
CK
Aitken
Centre for Population Health, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia; Department of Epidemiology and Preventive Medicine, Monash University, The Alfred Centre, 99 Commercial Road, Melbourne, Victoria 3004, Australia. Electronic address: pauld@burnet.edu.au.
Paul M
PM
Dietze
D000328:Adult; D001315:Australia; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D013315:Stress, Psychological / Q000523:psychology*; D015819:Substance Abuse, Intravenous / Q000523:psychology*; D055815:Young Adult
Cohort study; Heroin use; Injecting drug use; Longitudinal research; Mental health; Psychological distress