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 :Reliability
The internal consistency: α : 0,723 – 0,796
First draft with 8 items:
Good consistency
• Level
of consciousness
Minimum Kappa index
INTEROBSERVER
Maximum Kappa index
• Mobility
RELIABILITY
K
CI 95%
K
CI 95%
• Hemodynamic
LEVEL OF
0,813
0,7509 – 0,8749
0,892
0, 8335 – 0,9503
• Oxigenation
MOBILITY
0,821
0,7546 – 0,8877
0,883
0,823 – 0,9417
HEMODYNAMIC
• Nutrition
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
CONSCIOUSNESS
• Humidity
• Past medical history
• 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<0,005
Criterion V.:
Convergent V. ( Kappa)
COMHON/Braden
0,738-0,812 (CI 95%)
COMHON/ Norton
0,721-0,733 (CI 95%)
Good – Very good
Good
Predictive V.
COMHON Sensitivity Specificity
Index
88,2%
79,2%
PPV
NPV
40,0%
97,7%
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
LEVEL OF
CONSCIOUSNESS
1
2
Awake and alert
Independent
(RASS: 0, +1)
Walking with
help
Agitated, Restless,
Confused
Limited
(RASS: >+1)
3
Sedated but
responsive
(RASS: -1…..-3 )
4
MOBILITY
Coma, Sedated
and unresponsive.
(RASS: -4, -5)
Bed-armchair
activity
HEMODYNAMIC
OXIGENATION
NUTRITION
No hemodynamic
support
Spontaneous
breathing and
FiO2 < 40%
Full oral diet
Volume
expanders
Spontaneous
breathing and
FiO2 >40%
Enteral or
Parenteral
feeding
Very limited but Dopamine or
Noninvasive
tolerates
Norepinephrine or Mechanical
change
IABP
Ventilation
position
Oral fluids.
Unable to
change
position.
No feeding
Needing two of
previous ones
Invasive
Mechanical
Ventilation
Incomplete
oral feeding
Lying prone
LOWER RISK: 5 -9. MODERATE RISK: 10-13. HIGH RISK: 14 - 20