COMHON Index Design and validation of a new rating scale to ...

COMHON Index
Design and validation of a new rating scale
to estimate the risk of pressure ulcer in
patients attended in critical care units
Authors: Cobos Vargas, A.; Garófano Jerez, JR.; Guardia Mesa, MF.; Carrasco Muriel,C;
López Pérez, F.; Gonzalez AR.; Aranda Salcedo, T.

Introduction
Aim: To create a specific scale for critical care patients and
study its reliability and validity.
• High cost problem:
• (Prevention:1,38 € / patient in one day)
• (Treatment: 24 -6800 € / patient)
• Incidence: 6-33%. Prevalence: 41%
Why a specific scale?
• Most of scales used are not designed for CCU (Braden, Norton)
• Risk factors linked to CCU are not included
• The specific ones (Cubbin-Jackson) didn´t have enough
reliability and validity studies in Spanish, or are difficult to use
because they contain too many items.

Material and methods
� Multicentre observational study, transversal to study the reliability
and prospective for the study of predictive validity.
� During 2010 at San Cecilio and Virgen de las Nieves University
Hospitals Granada. Spain
Phases:
1. Definition of working groups and design of the new scale.
2. Piloting: 30 patients in each hospital.
3. Evaluation of the validity and reliability of the scale.

Phase 3: Evaluation of the validity and reliability
of the scale
Reliability:
• The internal consistency. ( Cronbach alpha )
• The interobserver reliability ( Kappa Coefficient )
Validity:
• Content validity.
• Construct validity: Discriminant validity. (Pearson)
• Criterion validity:
• Convergent validity (Gold Standard)
• Predictive validity: Sensitivity, specificity,
Positive Predictive Value (PPV) and Negative
Predictive Value(NPV)

Results
The internal consistency: α : 0,723 – 0,796
First draft with 8 items:
Good consistency
• Level of consciousness
INTEROBSERVER
• Mobility
• Hemodynamic
• Oxigenation
• Nutrition
RELIABILITY
LEVEL OF
CONSCIOUSNESS
• Humidity
• Past medical history
:Reliability
Minimum Kappa index Maximum Kappa index
K CI 95% K CI 95%
0,813 0,7509 – 0,8749 0,892 0, 8335 – 0,9503
MOBILITY 0,821 0,7546 – 0,8877 0,883 0,823 – 0,9417
HEMODYNAMIC 0,979 0,9554 – 1,000 1,000 -
OXIGENATION 0,923 0,8828 – 0,9633 0,979 0,9554 – 1,000
NUTRITION 0,910 0,8683 – 0,9529 0,965 0,9375 – 0,9925
COMHON INDEX 0,8860 0,8281-0,9437 0,930 0,8839-0,9770
• Time of stay
K >0,80: Good Concordance K >0,90: Very Good Concordance

Results: Validity
Content V.: We selected scientifically corroborated items
Construct V.: Pearson Correlations: r > 0,30 and p

Predictive V..
SCALE N SENS SPEC PPV NPV
CUBBIN-JACKSON SCALE 112 89,0% 61,0% 51,0% 92,0%
BRADEN SCALE 112 97,0% 26,0% 37,0% 95,0%
DOUGLAS 112 100,0% 18,0% 34,0% 100,0%
EVARUCI 62 100,0% 68,6% 40,7% 100,0%
BRADEN SCALE 429 79,2% 39,8% 45,1% 74,9%
CUBBIN-JACKSON SCALE 426 85,6% 52,0% 30,3% 94,8%
WATERLOW 1001 83,1% 26,4% 9,1% 95,2%
COMHON INDEX 496 88,2% 79,2% 40,0% 97,7%

Predictiv
validity
Cutoff point SENS(%) SPEC(%) PPV (%) NPV(%)
6 100,0 37,0 20,0 100,0
7 97,1 49,5 23,2 99,1
8 97,1 60,2 27,7 99,2
9 97,1 73,2 36,3 99,4
10 88,2 79,2 40,0 97,7
11 81,3 83,3 41,9 96,8
12 82,4 83,3 43,8 96,8
13 47,1 88,0 38,1 91,4
14 23,5 90,7 28,6 88,3
15 20,6 91,2 26,9 88,0
16 17,7 91,7 25,0 87,6
17 14,7 94,0 27,8 87,5
18 5,9 97,2 25,0 86,8
19 2,9 98,2 20,0 86,5
20 2,9 98,2 20,0 86,5

Conclusions:
COMHON index is defined as a scale for assessing risk of pressure
ulcers in critical care patients. It consists of 5 items or subscales
that measure the level of consciousness, mobility, hemodynamic,
oxygenation and nutrition.
It uses a direct scoring system, with each item scored from 1 to 4
points.
Flexible scale. It can set different cutoff points depending on
available resources.
This scale fulfils the criteria for:
Validity, Reliability, Specificity and Viability

COMHON Index
1
2
3
4
LEVEL OF
CONSCIOUSNESS
Awake and alert
(RASS: 0, +1)
Agitated, Restless,
Confused
(RASS: >+1)
Sedated but
responsive
(RASS: -1…..-3 )
Coma, Sedated
and unresponsive.
(RASS: -4, -5)
MOBILITY HEMODYNAMIC OXIGENATION NUTRITION
Independent
Walking with
help
Limited
Bed-armchair
activity
Very limited but
tolerates
change
position
Unable to
change
position.
Lying prone
No hemodynamic
support
Volume
expanders
Dopamine or
Norepinephrine or
IABP
Needing two of
previous ones
Spontaneous
breathing and
FiO2 < 40%
Spontaneous
breathing and
FiO2 >40%
Noninvasive
Mechanical
Ventilation
Invasive
Mechanical
Ventilation
LOWER RISK: 5 -9. MODERATE RISK: 10-13. HIGH RISK: 14 - 20
Full oral diet
Enteral or
Parenteral
feeding
Oral fluids.
Incomplete
oral feeding
No feeding