J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 10, Number 3, March 2018, pages 247-253

Predicting Difficult Intubation in Emergency Department by Intubation Assessment Score

Figure 2. Discrimination power of the score in the development dataset. AuROC: area under receiver operating characteristic curve; 95% CI: 95% confidence interval.

**Table 1.** Characteristics of Patients With Difficult and Non-Difficult Intubation, and Discrimination Power (AuROC) Under Univariable Analysis
Characteristics	Difficult intubation (n = 157), n (%)	Non-difficult intubation (n = 1,055), n (%)	P-value	AuROC (95% confidence interval)
AuROC: area under receiver operating characteristic curve.
Male gender	117 (74.5)	661 (62.7)	0.004	0.56 (0.52 - 0.60)
Age (year), mean (±SD)	56.5 (± 18.7)	60.4 (± 19.8)	0.020	0.43 (0.39 - 0.48)
Glasgow coma scales
3 - 8	86 (62.8)	575 (61.9)	0.421	0.49 (0.45 - 0.53)
9 - 13	23 (16.8)	126 (13.6)
14 - 15	28 (20.4)	228 (24.5)
Traumatic causes	41 (26.1)	150 (14.2)	< 0.001	0.56 (0.52 - 0.60)
Method of intubation
Rapid sequence	27 (17.2)	235 (22.3)	0.053	0.50 (0.45 - 0.54)
Sedation only, without paralysis	63 (40.1)	323 (30.6)
No-medication assisted	67 (42.7)	497 (47.1)
Used of induction agents	87 (55.4)	555 (52.6)	0.549	0.51 (0.47 - 0.56)
Mean number of attempts (± SD)	2.0 (± 1.2)	1.3 (± 0.7)	< 0.001	n/a
Failed intubation	18 (11.5)	15 (1.42)	< 0.001	n/a
Difficult intubation indicator
Facial trauma	15 (9.6)	27 (2.6)	< 0.001	0.54 (0.51 - 0.56)
Large incisors	12 (7.6)	28 (2.7)	0.003	0.52 (0.50 - 0.55)
Beard or mustache	8 (5.1)	33 (3.1)	0.232	0.51 (0.49 - 0.53)
Large tongue	50 (31.9)	64 (6.1)	< 0.001	0.63 (0.59 - 0.67)
Limited mouth opening	57 (36.3)	71 (6.7)	< 0.001	0.65 (0.61 - 0.69)
Short hypo-mental distance	24 (15.3)	70 (6.6)	0.001	0.54 (0.51 - 0.57)
Short thyro-hyoid distance	22 (14.0)	61 (5.8)	0.001	0.54 (0.51 - 0.57)
Poor neck mobility	63 (40.1)	156 (14.8)	< 0.001	0.63 (0.59 - 0.67)
Presence of obstructed airway	27 (17.2)	15 (1.4)	< 0.001	0.58 (0.55 - 0.61)

Table 1. Characteristics of Patients With Difficult and Non-Difficult Intubation, and Discrimination Power (AuROC) Under Univariable Analysis

Characteristics

Difficult intubation (n = 157), n (%)

Non-difficult intubation (n = 1,055), n (%)

P-value

AuROC (95% confidence interval)

AuROC: area under receiver operating characteristic curve.

Male gender

117 (74.5)

661 (62.7)

0.004

0.56 (0.52 - 0.60)

Age (year), mean (±SD)

56.5 (± 18.7)

60.4 (± 19.8)

0.020

0.43 (0.39 - 0.48)

Glasgow coma scales

3 - 8

86 (62.8)

575 (61.9)

0.421

0.49 (0.45 - 0.53)

9 - 13

23 (16.8)

126 (13.6)

14 - 15

28 (20.4)

228 (24.5)

Traumatic causes

41 (26.1)

150 (14.2)

< 0.001

0.56 (0.52 - 0.60)

Method of intubation

Rapid sequence

27 (17.2)

235 (22.3)

0.053

0.50 (0.45 - 0.54)

Sedation only, without paralysis

63 (40.1)

323 (30.6)

No-medication assisted

67 (42.7)

497 (47.1)

Used of induction agents

87 (55.4)

555 (52.6)

0.549

0.51 (0.47 - 0.56)

Mean number of attempts (± SD)

2.0 (± 1.2)

1.3 (± 0.7)

< 0.001

n/a

Failed intubation

18 (11.5)

15 (1.42)

< 0.001

n/a

Difficult intubation indicator

Facial trauma

15 (9.6)

27 (2.6)

< 0.001

0.54 (0.51 - 0.56)

Large incisors

12 (7.6)

28 (2.7)

0.003

0.52 (0.50 - 0.55)

Beard or mustache

8 (5.1)

33 (3.1)

0.232

0.51 (0.49 - 0.53)

Large tongue

50 (31.9)

64 (6.1)

< 0.001

0.63 (0.59 - 0.67)

Limited mouth opening

57 (36.3)

71 (6.7)

< 0.001

0.65 (0.61 - 0.69)

Short hypo-mental distance

24 (15.3)

70 (6.6)

0.001

0.54 (0.51 - 0.57)

Short thyro-hyoid distance

22 (14.0)

61 (5.8)

0.001

0.54 (0.51 - 0.57)

Poor neck mobility

63 (40.1)

156 (14.8)

< 0.001

0.63 (0.59 - 0.67)

Presence of obstructed airway

27 (17.2)

15 (1.4)

< 0.001

0.58 (0.55 - 0.61)

**Table 2.** Odds Ratio of Predictors and Difficult Intubation From Multivariable Stepwise Backward Elimination Logistic Regression Analysis, and Item Score Assignment
Predictor	Odds ratio	95% confidence interval	P-value	Beta coefficient	Score
Male gender	1.82	1.17 - 2.83	0.008	0.59	1
Large tongue	4.47	2.72 - 7.35	< 0.001	1.49	2
Limited mouth opening	3.93	2.44 - 6.31	< 0.001	1.37	2
Poor neck mobility	2.76	1.81 - 4.19	< 0.001	1.01	2
Presence of obstructed airway	7.54	3.57 - 15.93	< 0.001	2.02	3

Table 2. Odds Ratio of Predictors and Difficult Intubation From Multivariable Stepwise Backward Elimination Logistic Regression Analysis, and Item Score Assignment

Predictor

Odds ratio

95% confidence interval

P-value

Beta coefficient

Score

Male gender

1.82

1.17 - 2.83

0.008

0.59

Large tongue

4.47

2.72 - 7.35

< 0.001

1.49

Limited mouth opening

3.93

2.44 - 6.31

< 0.001

1.37

Poor neck mobility

2.76

1.81 - 4.19

< 0.001

1.01

Presence of obstructed airway

7.54

3.57 - 15.93

< 0.001

2.02

**Table 3.** Distribution of Score Categorized by Difficult and Non-Difficult Intubation
Score	Total (n = 1,212)	Prevalence (%)	Difficult intubation (n = 157)	Non-difficult intubation (n = 1,055)
0	331	27.3	10	3.0	321	97.0
1	516	42.6	30	5.8	486	94.2
2	65	5.3	12	18.5	53	81.5
3	188	15.5	45	23.9	143	76.1
4	28	2.3	13	46.4	15	53.6
5	47	3.9	22	46.8	25	53.2
6	11	0.9	6	54.6	5	45.4
7	14	1.1	9	64.3	5	35.7
8	6	0.5	5	83.3	1	16.7
9	3	0.3	2	66.7	1	33.3
10	3	0.3	3	100	0	0

Table 3. Distribution of Score Categorized by Difficult and Non-Difficult Intubation

Score

Total (n = 1,212)

Prevalence (%)

Difficult intubation (n = 157)

Non-difficult intubation (n = 1,055)

331

27.3

3.0

321

97.0

516

42.6

5.8

486

94.2

5.3

18.5

81.5

188

15.5

23.9

143

76.1

2.3

46.4

53.6

3.9

46.8

53.2

0.9

54.6

45.4

1.1

64.3

35.7

0.5

83.3

16.7

0.3

66.7

33.3

0.3

100

**Table 4.** Score Categorized Probability Groups, Likelihood Ratio and 95% Confidence Interval of Difficult Intubation
Score categorized probability groups	Score	Difficult intubation (n = 157), n (%)	Non-difficult intubation (n = 1,055), n (%)	Likelihood ratio of positive	95% confidence interval	P-value
Low	≤ 1	40 (4.7)	807 (95.3)	0.33	0.25 - 0.44	< 0.001
Intermediate	2 - 3	57 (22.5)	196 (77.5)	1.95	1.53 - 2.49	< 0.001
High	≥ 4	60 (53.6)	52 (46.4)	7.75	5.56 - 10.79	< 0.001
Mean (± SD)	-	3.43 (± 2.3)	1.2 (± 1.3)			< 0.001

Table 4. Score Categorized Probability Groups, Likelihood Ratio and 95% Confidence Interval of Difficult Intubation

Score categorized probability groups

Score

Difficult intubation (n = 157), n (%)

Non-difficult intubation (n = 1,055), n (%)

Likelihood ratio of positive

95% confidence interval

P-value

Low

≤ 1

40 (4.7)

807 (95.3)

0.33

0.25 - 0.44

< 0.001

Intermediate

2 - 3

57 (22.5)

196 (77.5)

1.95

1.53 - 2.49

< 0.001

High

≥ 4

60 (53.6)

52 (46.4)

7.75

5.56 - 10.79

< 0.001

Mean (± SD)

3.43 (± 2.3)

1.2 (± 1.3)

< 0.001