Starting in April 2011, NHS hospitals in England will not be paid for “avoidable” readmissions occurring within 30 days of discharge.  As Trust finance officers begin steeling themselves for this change, they may be interested in a Canadian project designed to predict and avoid such readmissions. 

Known as the Toronto Post-Discharge Virtual Ward, the project borrows a concept first developed at Croydon PCT in South London.  Virtual wards use the daily routines and staffing of a hospital ward to deliver care at home to patients at high predicted risk of unplanned hospital admission.  The key difference in Toronto is that the team focuses specifically on readmissions within 30 days.

On the day they are due to go home, patients at St. Michael’s Hospital and Toronto General Hospital are seen by a discharge coordinator who calculates their LACE score.  This score, which ranges from 0-19, reflects each patient’s risk of death or readmission within the next 30 days.

Virtual ward team

File 221
Members of the Toronto post-discharge virtual ward team

Any patient with a LACE score of ten or higher is offered care on a virtual ward for the post-discharge period.  Virtual ward patients are managed by a team led by a consultant physician.  Other staff include a ward clerk, a pharmacist, care coordinators and nurse practitioners.  Medical consultants rotate onto the virtual ward team for three-week blocks at a time.  During this period, they are contactable 24 hours a day by virtual ward patients.  Lucky the European Working Time Directive does not apply in Canada…

Every morning at 8.30am, the virtual ward team meets for an office-based ward round.  Jobs for different members of the team are recorded on a large whiteboard together with the date when each patient will next be reviewed on a ward round.  Any patients with mental health issues are scheduled for discussion on Thursday morning ward rounds, when mental health specialists supplement the usual team. 

Virtual ward patients may be visited at home by various members of the team, and are encouraged to telephone the ward clerk with any concerns, who can pass on messages as required.  Patients are “discharged” from the virtual ward once their health and social care management plan has been optimised, and ongoing care by the GP and community-based teams has been fully established.

Patients with a LACE score of 10 or higher have a 21.5% chance of readmission to hospital within 30 days, with an average readmission costing $11,000.  The key questions then are whether the virtual ward can successfully mitigate this risk, and what the net cost of an averted readmission is.

In the UK, the Nuffield Trust is currently evaluating the virtual wards in Croydon, Devon and Wandsworth using a technique called propensity score matching.  We are also conducting an economic analysis.  In contrast, the Toronto post-discharge virtual ward is being evaluated by means of a randomised controlled trial.  There will be 1,500 patients in each arm of the study with data collection due to finish in May 2012.

Already, however, there is anecdotal evidence that the project is having an effect on behaviour.  Physicians returning to the hospital wards after their block on the virtual ward, report that they are taking much more care over their discharge planning than hitherto.

The Nuffield Trust is planning to validate the LACE tool on NHS data.  Keep an eye on our website for further details. Details of the existing NHS predictive models – which make predictions about hospital (re)admissions over the next 12 months, rather than the 30 days post-discharge – can be found here.

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Comments (11)

Hi I am interested in the phrase "Already, however, there is anecdotal evidence that the project is having an effect on behaviour." Is this what constitutes robust evidence derived health care planning errrrr, hmmnm, I think not Anecdotally, I'd rather overcharge pct's for admissions, as this'll focus their mind on sending patients up in the first place Though, must be said, rather glad that we can now use anecdotal data to challenge health care policy.....

04 March 2011

You state: Starting in April 2011, NHS hospitals in England will not be paid for “avoidable” readmissions occurring within 30 days of discharge. Please advise if this is within 30 days of an elective or emergency admission and what does "avoidable" mean? Advice in this area is vague and conflicting!! thanks

Mark Temple
07 March 2011

Hi Mark, I agree that it has been a bit confusing as the policy developed, but the definitive guidance has now been published by the Department of Health. See pages 21-24 of the Payment by Results Guidance for 2011-2012 (

Geraint Lewis
24 March 2011

Fair point: I probably should have said that "there are anecdotes" rather than "there is anecdotal evidence". The real evidence will only come from the randomised controlled trial - but for that we'll need to wait quite a while longer.

Geraint Lewis
24 March 2011

I am interested to know if the Toronto model of Virtual Wards is very different from the Croyden model?
And, is the LACE score that is quoted here very different from the PARR score / tool that the Croyden and other UK virtual wards models use?

04 August 2011

Hi Rahul

Thanks very much for your comment.

The two projects are very similar. Both use a predictive model to identify which patients should receive multidisciplinary preventive care in the community.

The main difference between them is that the predictive model used in Croydon identifies patients at risk of admission to hospital in the next 365 days, whereas the LACE model used in Toronto identifies patients at risk of admission in the next 30 days.

Hope this helps.

Geraint Lewis
08 August 2011

Thanks for the reply Dr Lewis.

Another quick Query - have any models of VWs helped in early supported discharge or in pulling patients out of the rehab wards in the hospitals? and has there been any evidence if VWs could be more effective (and cost-efficient) in doing this?

18 August 2011

Hi Rahul,

Not that I'm aware of, but you might want to ask my colleague Lorraine ( who is keeping track of virtual ward developments across the UK and overseas.


19 August 2011

Can you clarify for me please if the PARR-30 is the same as the LACE (and if so, why the different name)?
I have been looking at the predictive effect of the LACE in an older NHS population.

Paul Cotter
28 October 2011

Hi Paul,

Thanks for your query. LACE and PARR-30 are both designed to predict readmission to hospital within 30 days of discharge but they differ in the following ways:

1. The LACE tool was built using Canadian data, whereas PARR-30 was built using English NHS data.
2. LACE stands for "length of stay (“L”); acuity of the admission (“A”); comorbidity of the patient (measured with the Charlson comorbidity index score) (“C”); and emergency department use (measured as the number of visits in the six months before admission) (“E”).
3. PARR-30 stands for "Patients At Risk of Readmission within 30 days"
4. LACE only contains four variables (L, A, C and E)
5. PARR-30 contains about 15 variables, and the score can either be calculated using a spreadsheet, an "app", or run automatically off a hospital's PAS system
6. The added complexity of PARR-30 results in more accurate predictions than those generated by LACE.

Hope this helps,


Geraint Lewis
31 October 2011

Hi Dr. Lewis

Do you have mental health practitioners in your VW teams and what is their role?

26 February 2012

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