RESEARCH WEEKLY: What we can learn from Sweden

(March 29, 2016) Collecting and reporting national statistics for more than 100 years, Sweden’s National Patient Register (NPR) is a virtual mother lode of statistical gold for health researchers.

For example, county governments in Sweden have been required to submit statistics on inpatient psychiatric care to the NPR since 1987 and on outpatient psychiatric treatment from both public and private caregivers since the early 2000s. Such a wealth of longitudinal data makes it possible to identify trends and patterns that might be undetectable in local data alone or in data collected over shorter periods.

Seena Fazel, MD, of the University of Oxford department of psychiatry in the United Kingdom, and Paul Lichtenstein, PhD, of the Karolinska Institute in Sweden, have worked with a variety of collaborators to examine the NPR for associations between psychiatric disease and specific negative outcomes, including criminal violence. Following are three examples of their findings.

Medication and Violence

• “Antipsychotics, mood stabilisers, and risk of violent crime” (2006-2009)
  
  Premise: The authors aimed to “establish the effect of antipsychotics and mood stabilisers on the rate of violent crime committed by patients with psychiatric disorders in Sweden.”
  
  Finding: Mentally ill individuals were substantially less likely to commit violent crimes when taking psychiatric medication. Among the estimated 83,000 Sweden patients prescribed antipsychotics or mood stabilizers during the study period, violent crime fell by 45% in patients who were receiving antipsychotic medications and 24% in patients with bipolar disorder who were prescribed mood stabilizers. Reductions in violence were greater in patients who were prescribed higher drug doses.
  
• “Depression and violence: A Swedish population study” (2001-2009)
  
  Premise: The authors aimed “to determine the risks of violent crime in patients with depression and to investigate the association between depressive symptoms and violent crime in a cohort of twins.”
  
  Findings: Individuals with depression were significantly more likely to commit violent crimes than the general population even after discounting for factors such as substance abuse and prior violent conviction. When the additional risk factors were present, risk increased further.
  
• “Violent crime, suicide, and premature mortality in patients with schizophrenia and related disorders: a 38-year total population study in Sweden” (1972-2009)
  
  Premise: The authors investigated to what extent conviction of a violent crime, suicide and premature death were specific to schizophrenia and related disorders. 
  
  Findings: Over the 38-year study period, male patients were 7.5 times more likely and female patients 11.1 times more likely to suffer the three adverse outcomes than control subjects matched by age and sex from the general population. The analysis of nearly 25,000 individuals with schizophrenia and related disorders found that 13.9% of the men and 4.7% of the women were convicted of a violent offence, died from suicide or died from other causes within the first five years following diagnosis. Substance abuse disorders, previous criminal conviction and a history of self-harm increased risk further

The authors noted that, while Sweden’s incarceration rate is low compared to other countries, the prevalence of psychiatric and substance abuse disorders is “largely similar to those in the USA and other high-income countries.” Unlike the Swedes, the United States systematically overlooks the role of mental illness in a host of social and health conditions. Whether the Swedish findings would be replicated in the US will remain unknown until we begin collecting similar statistics.

References:
Fazel, S., Zetterqvist, J., Larsson, H., Langstrom, N., Lichtenstein, P. “Antipsychotics, mood stabilisers, and risk of violent crime.” (7 May 2014). The Lancet.
Fazel, S., Wolf, A., Chang, Z., Larsson, H., Goodwin, G.M., Lichtenstein, P. (March 2015). “Depression and violence: A Swedish population study.” The Lancet Psychiatry.
Fazel, S., Wolf, A., Palm, C., Lichtenstein, P. (June 2014). “Violent crime, suicide, and premature mortality in patients with schizophrenia and related disorders: a 38-year total population study in Sweden.” The Lancet Psychiatry.