Substance abuse raises violent crime risk in BD patients
MedWire News: Patients with bipolar disorder (BD) who abuse drugs are significantly more likely to commit violent crime than is the general population, study results suggest.
However, the team found that BD patients who do not abuse substances were no more likely to commit violent crime relative to the general population.
"Various adverse health outcomes have been reported in BD, including increased risk of premature death from suicide and other causes, victimization, homelessness, and repeat offending," explain Seena Fazel (University of Oxford, UK) and team
"However, the evidence for interpersonal violence and violent crime is less clear," they add.
To investigate further, the researchers used the Swedish Hospital Discharge Registry to identify 3743 individuals with two or more discharge diagnoses of BD between 1973 and 2004.
National censuses and the Multi-Generation Register were used to identify 37,429 controls without BD from the general population who were matched for age and gender to the BD patients. A second control group of 4059 unaffected siblings of the BD patients was also included in the analysis.
Using data from the National Crime Register, the researchers found that 8.4% (n=314) of the patients with BD committed a violent crime during the study period compared with just 3.5% (n=1312) of general population controls. After accounting for income, marital status, and immigrant status, BD patients were 2.3 times more likely to commit a violent crime than general population controls.
However, further analysis revealed that the risk for committing violent crime was mainly limited to BD patients who abused substances (odds ratio [OR]= 6.4), with the risk attenuated in other BD patients (OR=1.3).
The risk for violent crime among BD patients without substance abuse comorbidity became negligible when unaffected siblings were used as the control group (OR=1.1).
The researchers also assessed the risk for violent crime in bipolar disorder patients in a systematic review and meta-analysis of eight studies published between 1970 and 2009. However, they found high heterogeneity between studies, with ORs ranging from 2.2 to 8.9.
Fazel and team conclude in the Archives of General Psychiatry: "We demonstrated a clear association of bipolar disorder with violent crime in individuals with substance abuse comorbidity.
"The risk associated with a bipolar diagnosis per se appears low; it was minimal compared with that in general population controls when there was no comorbid substance abuse, and there was no association when violence risk in patients was compared with that in unaffected siblings."
They add: "Our findings suggest the need for violence risk assessment and management in patients with bipolar disorder who have substance abuse comorbidity."
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By Mark Cowen