Meta-analysis may help identify targets for interventions, treatment trials

A range of potentially modifiable risk factors was associated with self-harm in prisoners, a meta-analysis found.

In data synthesized from nearly 50 years of research on more than a half million prisoners, the strongest associations with self-harm were past and current suicidality and markers of psychiatric morbidity, reported Seena Fazel, PhD, of the University of Oxford, UK, and coauthors in Lancet Psychiatry.

“Overall, we found strong effects for modifiable clinical and custodial variables, moderate effects for historical variables, and smaller effects for sociodemographic and criminological variables,” Fazel and colleagues wrote. “Our findings could identify appropriate targets for interventions and future treatment trials and assist decision-makers in allocating scarce prison resources.”

Many risk factors for self-harm in prisoners are similar to those for self-harm in the general population, noted Amanda Perry, PhD, of the University of York in England, in an accompanying editorial.

“Unlike self-harm behavior in the community, the culture of the prison environment provides exposure to experiences that are unique to being in prison,” she pointed out. The findings “support other research that has focused on the general impact of the prison environment and the effect of this environment on mental health.”

Self-harm is a leading cause of morbidity in prisoners, with an estimated annual prevalence of self-harm in prison of 5%–6% in men and 20–24% in women, compared with less than 1% in the general population.

Prisoners who self-harm are at increased risk of suicide while incarcerated and after release, and the effects of self-harm extend throughout the institution, including other prisoners and staff.

“Previous research has examined a range of individual and environmental correlates of self-harm in prisoners, although findings are inconsistent across primary studies,” the authors noted.

To better understand risk factors for self-harm in prisoners, Fazel and colleagues searched databases for observational studies through October 2019. They included 35 studies from 20 countries in their analysis: 18 studies were judged to be of high quality and 4 of low quality.

Of the 35 studies, 15 included solely men and 5 included solely women. In 15 studies, the sample included both male and female prisoners (average proportion of women was 12.3%), but only two provided data by sex.

The total sample comprised 663,735 prisoners. Of this group, 24,978 prisoners (3.8%) self-harmed in prison.

The strongest associations with self-harm in prison included current or recent suicidal ideation (OR 13.8, 95% CI 8.6–22.1), a lifetime history of suicidal ideation (OR 8.9, 95% CI 6.1-13.0), and previous self-harm (OR 6.6, 95% CI 5.3-8.3).

Any current psychiatric diagnosis was strongly associated with self-harm (OR 8.1, 95% CI 7.0–9.4), especially major depression (OR 9.3, 95% CI 2.9–29.5) and borderline personality disorder (OR 9.2, 95% CI 3.7–22.5). History of antisocial personality disorder was nonsignificant (OR 1.0; 95% CI 0.5-2.1).

Custody-specific risk factors for self-harm included solitary confinement (OR 5.6%, CI 2.7–11.6), disciplinary infractions (OR 3.5, 95% CI 1.2–9.7), and experiencing sexual or physical victimization while in prison (OR 3.2, 95% CI 2.1–4.8).

Sociodemographic and criminological factors were modestly associated with self-harm in prison. Risk factor estimates did not change substantially in strength or significance of effects when low-quality studies were excluded in sensitivity analysis.

“A range of modifiable individual and prison-related factors increase the risk of self-harm in prisoners,” the researchers noted.

“Strategies to address these risk factors will potentially require interventions at all levels of the criminal justice system, including diverting people before prison, improvements to mental health care in prison, purposeful activities, and social support, and maintaining these approaches on release,” they said. “Implementing these interventions will require a multisectorial approach across health, social care, and criminal justice.”

Limitations include small amounts of data on risks by sex. The authors noted that their finding of a non-significant increased risk of self-harm in female prisoners (female sex showed a small but non-significant increase in risk with OR 1.3, 95% CI 0.7-2.2) contrasts with findings in the general population and with a high-quality population study of U.K. prisoners that reported odds of self-harm four times higher in women than in men.

“We were not able to include data from the 13 studies (n=169,806) that combined sexes,” the authors acknowledged. “This limitation meant that examining many informative risk factors (e.g., those in the historical domain) by sex was not possible.”

The analysis also did not account for confounding factors, and generalizability beyond the country the study was conducted in may be limited.

  1. In a meta-analysis that spanned nearly 50 years of research and more than a half million prisoners, the strongest associations with self-harm were past and current suicidality and markers of psychiatric morbidity.

  2. The findings may help identify appropriate targets for interventions and future treatment trials and assist decision-makers in allocating scarce prison resources, the researchers noted.

Paul Smyth, MD, Contributing Writer, BreakingMED™

Research was supported by Funding Wellcome Trust.

The researchers had no competing interests. The editorialist had no competing interests.

Cat ID: 146

Topic ID: 87,146,254,585,730,192,146,52,55,925