Costs of the police service and mental health care pathways


Is prison the right environment for those with severe mental health issues? Evidence indicates that increasingly people with mental health problems are finding themselves incarcerated (Bradley, 2009). There is a growing consensus that this may not be the best environment for those with mental illness, with custody exacerbating issues, and increasing risk of self-harm and suicide (Bradley, 2009).

Issues relating to mental health and the police service have oft been discussed in the woodland. Today’s post is focussed on the costs related to the interaction between NHS mental health services and the police service for those with enduring mental health issues.

Recent years have seen a number of policy recommendations to improve the pathways and interactions between mental health services and the criminal justice system. The most notable of these was the Bradley Report (Bradley, 2009), which featured a series of recommendations to improve and enhance care pathways to improve ‘diversion’. Diversion in this context refers to services that function at the juncture between the criminal justice system and mental health services. The purpose of diversion is to identify and divert those with mental health issues towards the treatment and care they require, particularly as an alternative to prison (Sainsbury Centre for Mental Health, 2009) with the benefit of reducing further exacerbation of mental health issues.

Little is known about the costs associated with the current pathways between mental health services and the police service for those suffering from mental health conditions, and even less is known about the cost of implementing enhanced care pathways as suggested within policy documents.

The enhanced service pathways considered within this paper include:

  • Street triage
  • A custody link worker
  • Mental Health Act (MHA) assessments for all MHA section 136 detainees. Section 136 of the MHA allows the police to take individuals to a place of safety if they are in a public place and they suspect the individual of having a mental illness.

The purpose of this study can broadly be split into two parts:

  1. Mapping and costing existing service pathways
  2. Decision modelling to estimate the cost of introducing service enhancements.
How much do diversionary services cost?

How much do diversionary services cost?


Mapping and costing existing pathways

To map current pathways between existing services, a case-linkage approach was adopted. Data was obtained from an existing study (Lea et al, 2015). Individuals were identified retrospectively and followed up using police and mental health case records for one year. This data came from a rural county in England. To examine the interaction between mental health services and the police service, it was necessary to focus on individuals who had both, i) a record of police interaction, and, ii) known mental health issues.

To achieve this, a sample of cases were randomly selected from cases where individuals:

  • Had a record on the neighbourhood harm register, or, were recorded on the National Strategy for Police Information Systems (NSPIS) as having interacted with the police in the second quarter of 2011.
  • Had a record from any time period on the RiO (electronic patient record) system with the local mental health trust.

Services were mapped using an iterative case-linkage process. This used the case reports to identify a range of resources and services used by the individuals. Resources included:

  • Mental health care services;
  • Police and other emergency services;
  • Custody services;
  • ‘Other’ services e.g. transport.

To calculate the costs of existing pathways, unit costs were attached to the resource use information identified within the case-linkage study. This allowed the calculation of total costs per client from both the mental health care perspective and the police service perspective for the one-year period. Due to the complexity of the pathways, only the most significant cost drivers were included within the analysis. Costs of the current pathways were reported as means, and predictors of costs were identified using bootstrap OLS (ordinary least squares) regressions.

Modelling the cost of service enhancements

At the time of the study, there were no enhanced services within the region, and as such, a modelling approach was required to estimate costs of enhancements. Decision models provide a transparent and logical way of assessing the impact of a change. In this case they were used to model the impact of introducing the enhanced service pathways. The data from the existing pathway formed the basis for the decision model of the enhanced pathways. Models were validated through a variety of external stakeholders including mental health professionals and senior police officers.

Using the case-linkage data, the existing pathways were modelled. To examine the impact of service enhancements, the models were adjusted to reflect the impact of potential enhancements. The three service enhancements that were modelled included:

  1. Street triage – this involves a mental health nurse attending incidents with officers when there is a suspicion that mental health support is required with the intention of diverting individuals appropriately. The addition of street triage should divert individuals away from unnecessary Section 136 detentions. The case-linkage study suggested 14% of clients needed a section 136. A pilot study of street triage suggested that just 3.2% of clients actually need to go to a section 136 custody suite when street triage is operationalised. Consequently, within the street triage model, there was a conservative 50% reduction in the probability of being referred to a section 136 custody suite following street triage.
  2. MHA assessments for all individuals detained under section 136 of the MHA. From the case-linkage data, it transpired that not all section 136 detainees were receiving an MHA assessment (according to the MHA (1983), this should be compulsory). The authors therefore examined the impact of all section 136 detainees receiving the MHA assessment. The modelled impact of this was the reduction in likelihood of detention, and the removal of the need for forensic medical examiners.
  3. A link worker within custody suites. This enhancement covered the introduction of a link worker for those currently within custody on an arrest. Within this model, probabilities remained the same as in the base case.


The cost of existing pathways

Resource use data was collected for 55 out of the 80 individuals within the case-linkage study. All individuals had at least one contact with mental health services in the 1-year period following the first contact with police.

Mental health care costs

  • The mean mental healthcare cost per person was £10,812 (95% CI £6,055 to £19,726)
  • The biggest driver of mental healthcare costs was inpatient services which accounted for 76% of costs
  • Only 13 of the 55 clients had an inpatient stay, these stays were however typically long in duration with a mean inpatient stay of 90 days (range: 5 to 310 days). Thus, a minority appear to account for the majority of mental healthcare costs in this context.

Police service costs

  • The mean costs associated with the police service use was £4,552 (CI £3,551 to £6,058)
  • The largest cost drivers in relation to police service costs was the attendance at incidents which accounted for 59% of the total police costs
  • The average number of police contacts was 7, of which 59% required at least one police officer in attendance. On average 3 police officers attended each incidence
  • 13% of the contacts required time in custody
  • When custody was required, the mean time spent was 8 hours and 38 minutes. Of those who went into custody, 12% required MHA assessments.

Total costs

  • The total cost to both mental health services and police was £15,364 (95% CI £10,689 to £24,960) per person
  • When considered on a per incident basis, the average cost per incident within the current care pathway was estimated to be £522 per incident
  • The only baseline characteristic found to be associated with cost was whether the client was a non-substantive referral, that is, if they had been on the case load of a care team for less than two months at the time of the police contact
  • Those who had not been on care team’s case load for more than two months costed an additional £12,850 (95% CI £2,945 to £29,192) per person.

The cost of implementing enhanced pathways

Street triage

The cost of implementing street triage increased the cost per incident from £522 to £526. A number of sensitivity analyses were conducted suggesting this value is moderately sensitive to changes. For example, a sensitivity analysis suggested that if street triage reduced the numbers detained for a section 136 MHA assessment to the degree found in the pilot study (3.2%) then costs per incident would fall to £478 per incident.

MHA assessments for all section 136 detainees

Again, there was an identical increase in cost as street triage, with costs rising to £526 per incident.

Link worker at custody suites

The introduction of a link worker again increased costs, this time by 2% to £534 per incident. A sensitivity analysis examined the impact of increasing client contact from one hour to three hours, this led to an increase in cost per incident to £557.

Service enhancements were associated with a small increase in costs per incident.

Service enhancements were associated with a small increase in costs per incident.


It is estimated that the cost of the current pathway was £522 per incident, of which 70% fell on mental health services, and 30% on police services. The introduction of enhanced pathways has little impact on the costs as estimated through the modelling process. Each enhancement under the base-case assumptions were associated with a small increase in cost. The authors note that this small increase per incident could have substantial budgetary impacts if scaled up. In short, the results suggest that there would be small increases in costs per incident due to enhancing service pathways, which could be large when extrapolated. On an individual basis however, these cost increases were relatively minor and did not increase substantially under sensitivity analysis. It is however important to be cautious in terms of generalisability due to a number of limitations: A relatively small sample size in a rural population, and only the short term (1 year) main cost drivers were included.

Having read the paper, the first thing that strikes me as a health economist is, ‘What about the outcomes?’ This article for good reasons has focussed on costs, and makes a good attempt at modelling the costs of service enhancements whilst also recognising significant limitations and assumptions. In relation to outcomes however, it simply acknowledges that there may be parallel benefits to the clients and society of enhanced pathways.

The government reports which suggest service enhancements, do not make these suggestions to reduce costs, they make these suggestions to improve the long term outcomes of those with mental health conditions. It is presumed that the point of the enhanced service pathways is to divert patients with mental health needs towards the care they require. The end result of this process should be fewer mental health patients in inappropriate prison settings, improved mental health, and a reduction in self-harm and suicide (Bradley, 2009). Without any information in relation to outcomes, it is difficult to draw any conclusions around the cost-effectiveness of the service enhancements. Having said that, given minimal increase in individual level costs, any improvement in terms of health-related quality of life would likely be deemed cost-effective.

This study provides a starting point by mapping current resource use and identifying the cost of service enhancements. The next step should be to measure the long term costs and benefits (to both the client, and society) of such enhancements. Once this data has been collected it may then be possible to make firmer decisions regarding the cost-effectiveness of these polices.

The study didn’t consider any outcomes or improvements in quality of life resulting from diversion

The study didn’t consider any outcomes or improvements in quality of life resulting from diversion.


  • The cost per incident without enhancing service pathways is approximately £522
  • Service pathways enhancements as advocated in government and policy reports are associated with a very small increase in cost per incident
  • Evidence on the impact of service enhancements on outcomes is required
  • Future research should focus on examining the impact of diversionary services on outcomes for clients with mental health issues and conducting a full economic evaluation.


Primary paper

Heslin M, Callaghan L, Barrett B, Lea S, Eick S, Morgan J, Bolt M, Thornicroft G, Rose D, Healey A, Patel A. (2016) Costs of the police service and mental healthcare pathways experienced by individuals with enduring mental health needs (PDF). Br J Psychiatry. 2016 Mar 17.

Other references

Bradley K. (2009) The Bradley Report: Lord Bradley’s Review of People with mental Health Problems or Learning Disabilities in the Criminal Justice System. 2009.

Sainsbury Centre for Mental Health. (2009) Diversion: A better way for criminal justice and mental health. London; 2009.

Lea S, Callaghan L, Eick S, Heslin M, Morgan J, Bolt M, et al. (2015) The management of individuals with enduring moderate to severe mental health needs: a participatory evaluation of client journeys and the interface of mental health services with the criminal justice system in Cornwall. Heal Serv Deliv Res. 2015 Apr;3(15):1–232.

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