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The impact of detention on the health of asylum seekers

Additional Info

  • Authors: Trine Filges, Edith Montgomery, Marianne Kastrup, Anne-Marie Klint Jørgensen
  • Published date: 2015-09-01
  • Coordinating group(s): Social Welfare
  • Type of document: Title, Protocol, Review, Plain language summary
  • See the full review:

About this systematic review

This Campbell systematic review examines the impacts of on health, including mental health (PTSD, anxiety and depression), physical health and social functioning, of confining asylum seekers in detention centres. The review includes nine studies from the UK, Japan, Canada, and Australia.

What are the main results?

Detention has a negative impact on the mental health of asylum seekers. Levels of post-traumatic stress disorder (PTSD), depression, and anxiety both before and after release were found to be higher among asylum seekers who were detained compared to those who were not detained. The size of the effects were clinically important.

All the studies assessed the mental health of the participants but none reported outcomes related to physical or social functioning.


The last decades of the twentieth century were accompanied by an upsurge in the number of persons fleeing persecution and regional wars. Western countries have applied increasingly stringent measures to discourage those seeking asylum from entering their country. The most controversial of the measures to discourage people from seeking asylum is the decision by some Western countries to confine asylum seekers in detention facilities. In most countries, the detention of asylum seekers is an administrative procedure that is undertaken to verify the identity of individuals, process asylum claims, and/or ensure that a deportation order is carried out. A number of clinicians have expressed concern that detention increases mental health difficulties in asylum seekers, who is already a highly traumatized population, and have called for an end to such practices. This is clearly in conflict with government policies aimed at reducing the numbers of asylum seekers.


The main objective of this review is to assess evidence about the effects of detention on the mental and physical health and social functioning of asylum seekers.

Search strategy

Relevant studies were identified through electronic searches of bibliographic databases, internet search engines and hand searching of core journals. Searches were carried out to November 2013. We searched to identify both published and unpublished literature. The searches were international in scope. Reference lists of included studies and relevant reviews were also searched.

Selection criteria

All study designs that used a well-defined control group were eligible for inclusion. Studies that utilized qualitative approaches were not included.

Data collection and analysis

The total number of potential relevant studies constituted 11,376 hits. A total of nine studies, consisting of 12 papers, met the inclusion criteria and were critically appraised by the review authors. The final selection comprised nine studies from four different countries.

Two studies reported on the same sample of asylum seekers in Australia at different time points after release. The nine studies thus analysed eight different asylum populations. Six studies (all analysing asylum seekers in Australia) could not be used in the data synthesis as they were judged to have too high risk of bias on the confounding item. Three studies were therefore included in the data synthesis. Meta-analysis was used to examine the effects of detention on post-traumatic stress disorder (PTSD), depression and anxiety while the asylum seekers were still detained. Random effects models were used to pool data across the studies using the standardised mean difference. Pooled estimates were weighted using inverse variance methods, and 95% confidence intervals were estimated. It was not possible to perform a meta-analysis after release as only one study providing data after release was included in the data synthesis.


Two studies provided data while the asylum seekers were still detained, and one study provided data less than a year after release. The total number of participants in these three studies was 359. We performed analyses separately for these time points. All outcomes were measured such that a negative effect size favours the detained asylum seekers, i.e. when an effect size is negative the detained asylum seekers are better off than comparison groups of non-detained asylum seekers. The three studies used in the data synthesis were all non randomised studies and only one of them was judged to be of some concern on the confounding item of the risk of bias tool.

Primary study effect sizes for PTSD, depression and anxiety while the asylum seekers were still detained lies in the range 0.35 to 0.99, all favouring the non-detained asylum group. The weighted average effect sizes for PTSD and anxiety are of a magnitude which may be characterised as being of clinical importance: 0.45 [95% CI 0.19, 0.71] and 0.42 [95% CI 0.18, 0.66]. The weighted average effect size for depression is of an even higher magnitude: 0.68 [95% CI 0.10, 1.26]. All effects favour the non-detained; i.e. there is an adverse effect of detention on mental health. The magnitude of the pooled estimates should however be interpreted with caution as they are based on two studies, and for depression there is some inconsistency in the magnitude of effect sizes between the two studies. One study reported outcomes (PTSD, depression and anxiety) after release and the magnitude of the effect sizes were all of clinical importance: 0.59 [95% CI 0.02, 1.17], 0.60 [95% CI 0.02, 1.17] and 0.76 [95% CI 0.17, 1.34]; all favouring the non-detained asylum seekers.

Authors’ conclusions

There is some evidence to suggest an independent adverse effect of detention on the mental health of asylum seekers. All studies used in the data synthesis reported adverse effects on the detained asylum seekers’ mental health, measured as PTSD, depression and anxiety. The magnitude of the effect sizes lay in a clinical important range despite the fact that the comparison groups used in the primary studies faced a range of similar post-migration adversities and had a more or less similar experience of prior traumatic events as the detained asylum seekers. Thus, the current evidence suggests an independent deterioration of the mental health due to detention of a group of people who are already highly traumatised.

Adverse effects on the mental health were found not only while the asylum seekers were detained, but also after release suggesting that the adverse mental health effect of detention may be prolonged, extending well beyond the point of release into the community.

The conclusions should however be interpreted with caution as they are based on only three studies. More research is needed in order to fully investigate the effect of detention on mental health. While additional research is needed, the review does, however, offer support to the view that the detention of already traumatised asylum seekers may have adverse effects on their mental health.

See the full review

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