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The Hospital Frailty Risk Score

Andrew Street

Laia Maynou

Simon Conroy

lse.ac.uk/health-policy

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Overview

Explain importance of identifying frailty

Introduce the Hospital Frailty Risk Score (HFRS)

    • Lancet 2018
    • Lancet Health Longevity 2021

Apply HFRS to all adults admitted to hospital

Show preliminary results applied to primary care data in Catalunya

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Frailty – clinical relevance

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Frailty identification – micro level

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Frailty identification – why?

  • Micro level

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Frailty identification – meso level

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CGA allows a care plan to be generated that can modify trajectories

  • At 6 months, NNT of:
    • 17 (1 unnecessary death or deterioration);
    • 20 (1 institutionalisation)
  • NNT 25 at 12 months

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Frailty identification – macro level

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Frailty registries?

Frailty registry

Primary care

eFI(2)

Clinical validation

CFS

Opportunistic

CFS scores

Secondary care

HFRS

Holistic assessment

Examine or develop Urgent Care Plan

Determine treatment paradigm – palliative or curative?

Address admission or readmission risk

What matters to me (PROM)? Shared decision making

Plan

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Emerging ideas - PROMs

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https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(18)30668-8/fulltext

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Hospital Frailty Risk Score (HFRS) – Lancet 2018

  • weighted set of 109 3-character ICD-10 codes recorded during the current admission and any previous emergency admissions occurring in the prior two years

  • values range from 0 (no frailty risk) to 173·2

  • Patients 75+ categorised into three frailty risk groups:
    • low (HFRS <5),
    • intermediate (5≥ HFRS <15)
    • high (HFRS ≥15)

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National validation cohort

In the national validation cohort (n=1 013 590)

    • Low risk - 42·4%
    • Intermediate risk - 37·6%
    • High risk - 20·0%

Compared with those low HFRS, patients with high HFRS had increased odds of:

  • Long hospital length of stay (OR 6·03, 95% CI 5·92–6·10)
  • 30-day mortality (OR 1·71, 95% CI 1·68–1·75)

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Econometric Model

 

Outcomes – Long LoS, in-hospital mortality

Patient and pathway characteristics, temporal effects

Hospital fixed-effects

Intermediate risk DV

High risk DV

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1183 citations as of 8/1/25

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Inconsistent applications

  1. weighted set of 109 3-character ICD-10 codes recorded during the current admission and any previous emergency admissions occurring in the prior two years

  • Inconsistencies in application
    • Any previous admission
      • patients might be censored by when data window opens

Internal inconsistency

    • Prior two years
      • some studies only current adm … one study prior 15 years

External inconsistency

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https://www.thelancet.com/journals/lanhl/article/PIIS2666-7568(21)00004-0/fulltext

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Trade-off between …

  1. Value of information: more information increases likelihood that the HFRS captures the true effect of frailty risk on patient outcomes
  2. Costs of obtaining information: obtaining historical data might incur costs which might not be worth incurring if the extra data do not offer substantial additional information

When we have a stable estimate, we have enough information

How much diagnostic information is enough?

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As we account for more ICD10 codes …

  1. More people will be classified into the high risk category

  • There may be a change in size of effect of frailty risk on the outcomes

  • Those newly classified as high risk will be marginally less frail than those originally classified

  • Hence, effect size of high frailty risk reduced

How much diagnostic information is enough?

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HFR Score

n

Low

Int

High

Adding ICD10 information increases the HFRS

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HFRS(a) – use diagnostic information from current admission only

HFRS(a+1,1) – add info from previous admission in past year

HFRS(a+2,1) add info from previous two admissions in past year

HFRS(a+1,2) – add info from previous admission in past two years

HFRS(a+n,t)

Various constructions of HFRS

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Data

  • Setting: Yorkshire and Humble region

  • 4 linked datasets

NHS 111 & 999 calls

Ambulance

Emergency Department

Hospital admissions

  • Population 75+

  • 282 091 patients had 675 155 emergency hospital admissions between April 1, 2013, and March 31, 2017

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% in each HFRS category

Low

Intermediate

High

HFRS(a)

55.4

37.2

7.4

HFRS(a+1,1)

44.7

40.1

15.1

HFRS(a+2,1)

42.1

38.9

19.1

HFRS(a+2,2)

39.1

39.1

21.8

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Econometric Model

 

Outcomes – Long LoS, in-hospital mortality

Patient and pathway characteristics, temporal effects

Hospital fixed-effects

Intermediate risk DV

High risk DV

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High risk group: impact of additional diagnostic information

High frailty risk based on ICD in current adm only

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How much diagnostic information is enough?

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Key message

Previously: ICD-10 codes recorded during the current admission and any previous emergency admissions occurring in the prior two years

Now: ICD-10 codes recorded during the current admission and previous two emergency admissions occurring in the prior two years

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LoS more than 10 days

Frailty risk is the biggest predictor of long LoS.

People with HIGH frailty risk were 4 times more likely to have LoS>10d than those with LOW frailty risk

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In-hospital deaths

Charlson comorbidy index biggest predictor of in-hospital death

Frailty risk is also a very important predictor

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Readmissions

Previous admissions most important predictor

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Costs – HRG tariff (1,000 pounds)

Frailty risk important predictor of cost

Hospital adm most important predictor

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Data

  • 5% random sample from the Hospital Episode Statistics (HES) of adults admitted to hospital as emergencies in England.

  • Analytical time period: 1 April 2013 until 31 March 2019.

  • 1,478,554 emergency admissions for 653,294 patients

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HFRS – 75+ v 18+

  • Patients 75+ categorised into three frailty risk groups:
    • low (HFRS <5),
    • intermediate (5≥ HFRS <15)
    • high (HFRS ≥15)

  • Patients 18+ categorised into four frailty risk groups:
    • Zero (HFRS = 0)
    • low (0> HFRS <5)
    • intermediate (5≥ HFRS <15)
    • high (HFRS ≥15)

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HFRS distribution by age band (n=1,478,554)

As age increases, we have higher proportions in the high HFRS category.

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For adults 18-24, an individual with high HFRS will stay 4.5 days longer than an individual with Zero HFRS.

For adults 95+, an individual with high HFRS will stay 15.3 days longer than an individual with Zero HFRS.

LoS (count data)

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Compared to those�with Zero frailty risk, the three HFRS categories have significant explanatory power in all groups except�for those aged 95+

For adults 65-74, an individual with high HFRS have a 2.3% higher probability of dying than an individual with Zero HFRS.

In-hospital deaths

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For adults 18-24, an individual with high HFRS costs will be £1,217 higher than an individual with Zero HFRS.

For adults 95+, an individual with high HFRS costs will be £2,557 higher than an individual with Zero HFRS.

Hospital costs

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HFRS applied to Spanish data

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HFRS applied to Catalan data

Hospital patients 55+ categorised into four frailty risk groups (n=118k):

    • Zero (HFRS = 0) – 67.7%
    • low (0> HFRS <5) – 17.6%
    • intermediate (5≥ HFRS <15) – 12%
    • high (HFRS ≥15) – 2.7%

Primary care patients 55+ categorised into four frailty risk groups (n=156k):

    • Zero (HFRS = 0) – 11.4%
    • low (0> HFRS <5) – 38.8%
    • intermediate (5≥ HFRS <15) – 42.7%
    • high (HFRS ≥15) – 7.1%

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Conclusion

  • The HFRS has become a widely used tool to identify frailty risk

  • Different forms of the HFRS are used capture diagnostic information from previous admissions

  • High frailty risk is associated with longer LoS, higher costs and greater likelihood of in-hospital mortality

  • This is association is evident across all adult age groups, not just those 75+

  • Exploring applicability to primary data in contexts where ICD10 used to code diagnoses

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Conclusion

  • Identifying frailty is important at micro, meso and macro levels

  • The HFRS has become a widely used tool to identify frailty risk

  • Different forms of the HFRS are used capture diagnostic information from previous admissions

  • High frailty risk is associated with longer LoS, higher costs and greater likelihood of in-hospital mortality

  • This is association is evident across all adult age groups, not just those 75+