Factors associated with mortality after asthma admission in the intensive care unit of a tertiary referral hospital

Sung-Shin Kwon; Min-Hye Kim; Young-Joo Cho

doi:10.4168/aard.2015.3.6.432

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Kwon, Kim, and Cho: Factors associated with mortality after asthma admission in the intensive care unit of a tertiary referral hospital

Original Article

Allergy, Asthma & Respiratory Disease 2015; 3(6): 432-438.

Published online: 30 November 2015

DOI: https://doi.org/10.4168/aard.2015.3.6.432

Factors associated with mortality after asthma admission in the intensive care unit of a tertiary referral hospital

Sung-Shin Kwon^*, Min-Hye Kim^*, Young-Joo Cho

Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul, Korea.

Correspondence to: Young-Joo Cho. Department of Internal Medicine, Ewha Womans University Mokdong Hospital, Ewha Womans University School of Medicine, 1071 Anyangcheon-ro, Yangcheon-gu, Seoul 07985, Korea. Tel: +82-2-2650-5011, Fax: +82-2-2655-2076, yjcho@ewha.ac.kr

Equal contributor:

*These authors contributed equally to this study and should be considered co-first authors.

Received 29 July 2015 Revised 8 September 2015 Accepted 14 September 2015

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/).

Abstract

Purpose

Asthma is a global health concern involving 300 million people, and mortality due to asthma still accounts for a significant proportion of deaths. The purpose of this study was to define risk factors for the mortality of patients admitted to the intensive care unit because of asthma exacerbation.

Methods

A retrospective analysis of 163 severe asthma patients, who were admitted to Ewha Womans University Mokdong Hospital from January 1997 to December 2011 with the need for intensive medical care, was performed. The medical history and laboratory workup at initial visit to hospital were collected by reviewing medical records. To identify risk factors for mortality, data was compared between the survivors (survivor group) and the dead (death group).

Results

As a result, mortality rate was 30.7%. The number of patients 65 years or older was larger in the death group. The number of patients on mechanical ventilation was larger in the death group compared to the survivor group. In arterial blood gas analysis, the levels of pH and PaO₂ were higher and the PCO₂ levels were lower in the death group. In multivariate analysis, the risk of death was higher in patients on mechanical ventilation (odds ratio [OR], 5.327). PCO₂ and O₂ saturation were protective factors for mortality (OR, 0.90 and 0.915, respectively).

Conclusion

Use of mechanical ventilator, low PCO₂, and O₂ saturation are the most important factors for mortality while admitted to the intensive care unit in severe asthma patients. We should pay attention to patients who are on mechanical ventilation and have low PCO₂ and O₂ saturation levels.

Keywords: Asthma, Risk factor, Mortality

Figures and Tables

Table 1

Demographic characteristics of study subjects

Characteristic	Total (n = 163)	Survial (n = 113)	Nonsurvival (n = 50)	P-value
Female sex	83 (50.9)	60 (53.1)	23 (46.0)	0.497
Age (yr)	70.4 ± 13.4	69.5 ± 14.2	72.3 ± 11.4	0.183
≤ 64	47 (28.8)	38 (33.6)	9 (18.0)	0.035^*
65-74	40 (24.5)	22 (19.5)	18 (36.0)
≥ 75	76 (46.6)	53 (46.9)	23 (46.0)
Medical history
Hypertension	69 (42.3)	44 (38.9)	25 (50.0)	0.229
Cardiovascular disease	61 (37.4)	41 (36.3)	20 (40.0)	0.726
Diabetes mellitus	57 (35.0)	45 (39.8)	12 (24.0)	0.074
Tuberculosis	35 (21.5)	25 (22.1)	10 (20.0)	0.838
ESRD	20 (12.3)	15 (13.3)	5 (10.2)	0.795
Chrnoic liver disease	6 (3.7)	5 (4.4)	1 (2.0)	0.668
Smoking (pYR)	19.0 ± 28.6	17.1 ± 27.2	23.8 ± 31.5	0.202
Never smoker	72 (49.3)	54 (51.9)	18 (42.9)	0.064
Ex-smoker	33 (22.6)	18 (17.3)	15 (35.7)
Current smoker	41 (28.1)	32 (30.8)	9 (21.4)
Body mass index (kg/m²)	21.2 ± 4.7	21.4 ± 5.2	20.7 ± 3.1	0.453

Values are presented as number (%) or mean±standard deviation.

ESRD, end stage renal disease; pYR, pack year.

^*P<0.05.

Table 2

Cause of death of severe asthma patient in hospital

Cause of death	No. of patients (%)
Asthma	18 (36.0)
Infection	25 (50.0)
Cardiologic disease	7 (14.0)

Table 3

Comparison of asthma and its treatment history before admission

Variable	Total (n = 163)	Survival (n = 113)	Nonsurvival (n = 50)	P-value
Duration of symptom aggravation (day)	9.6 ± 10.8	3.7 ± 4.7	5.4 ± 8.9	0.116
Duration of asthma diagnosis (yr)	4.2 ± 6.3	9.9 ± 10.2	8.8 ± 12.1	0.555
Admission to general ward within one year due to asthma	59 (37.3)	39 (35.5)	20 (41.7)	0.479
Admission to ICU within 1 year due to asthma	13 (8.1)	9 (8.0)	4 (8.3)	1.000
On asthma therapy within 3 months before admission	89 (58.2)	64 (60.4)	25 (53.2)	0.478

Values are presented as number (%) or mean±standard deviation.

ICU, intensive care unit.

Table 4

Clinical characteristics during hospital course

Variable	Total (n = 163)	Survival (n = 113)	Nonsurvival (n = 50)	P-value
Duration of hospitalizaion (day)	22.8 ± 38.0	17.9 ± 15.3	33.9 ± 63.8	0.086
Duration of ICU admission (day)	7.8 ± 11.5	6.8 ± 9.4	10.0 ± 15.1	0.179
Mechanical ventilation applied	107 (65.6)	66 (58.4)	41 (82.0)	0.004^*
Duration of mechanical ventilator applied (day)	4.4 ± 8.7	3.7 ± 8.7	6.0 ± 8.6	0.139
Combined pneumonia	97 (59.5)	67 (59.3)	30 (60.0)	1.000

Values are presented as mean±standard deviation or number (%).

ICU, intensive care unit.

^*P<0.05.

Table 5

Comparison of initial laboratory finding on admission

Variable	Total	Survival (n = 113)	Nonsurvival (n = 52)	P-value
pH	7.3 ± 0.3	7.3 ± 0.3	7.4 ± 0.1	0.003^*
PCO₂ (mmHg)	51.2 ± 29.2	55.8 ± 33.0	40.5 ± 11.8	< 0.001^*
PaO₂ (mmHg)	66.1 ± 34.8	62.3 ± 26.7	74.7 ± 48.0	0.039
HCO₃ (mmol/L)	23.9 ± 6.4	24.2 ± 6.2	23.2 ± 7.0	0.395
O₂ saturation (%)	82.5 ± 19.5	81.4 ± 19.7	85.0 ± 19.1	0.287
Eosinophil count (/µL)	186.3 ± 539.3	205.1 ± 561.0	139.8 ± 484.5	0.510
ECP (µg/dL)	34.8 ± 35.7	39.9 ± 40.5	22.3 ± 17.4	0.280
IgE (IU/mL)	437.4 ± 820.2	520.1 ± 916.9	214.2 ± 431.7	0.321
CRP (mg/dL)	8.8 ± 11.6	7.8 ± 10.1	10.9 ± 14.4	0.228
BNP (pg/mL)	5,288.8 ± 8,571.7	4,302.9 ± 9,130.4	7,589.0 ± 7,306.2	0.447
EF (%)	56.9 ± 14.8	57.2 ± 15.7	56.1 ± 12.2	0.808
Total cholesterol (mg/dL)	179.3 ± 48.5	176.9 ± 51.3	185.0 ± 41.1	0.350
TG (mg/dL)	81.7 ± 60.6	74.1 ± 45.1	100.0 ± 85.3	0.062
Albumin (g/dL)	3.5 ± 0.6	3.6 ± 0.6	3.5 ± 0.6	0.368
Creatinine (mg/dL)	1.4 ± 3.7	1.5 ± 4.4	1.1 ± 0.5	0.497
CK (IU/L)	209.2 ± 495.3	255.9 ± 601.2	120.0 ± 122.2	0.052
CK-MB (ng/mL)	10.3 ± 33.4	12.6 ± 40.7	5.8 ± 5.4	0.293
Troponin-T (ng/mL)	1.6 ± 15.7	2.3 ± 19.1	0.05 ± 0.08	0.466
LD (IU/L)	858.8 ± 1,434.6	931.7 ± 1,736.6	719.1 ± 475.2	0.474

Values are presented as mean±standard deviation.

ECP, eosinophil cation protein; CRP, c-reactive protein; BNP, B-type natriuretic peptide; EF, ejection fraction; TG, triglyceride; CK, creatinine kinase; CK-MB, creatinine kinase-MB fraction; LD, lactate dehydrogenase.

^*P<0.05.

Table 6

Multivariate logistic regression analysis for survival

Variable	OR	95% CI	P-value
Age	1.008	0.964-1.054	0.736
Sex	0.981	0.251-3.831	0.978
Diabetes mellitus	0.515	0.158-1.681	0.272
Never smoker	-	-	0.156
Ex-smoker	3.575	0.793-16.118	0.097
Current smoker	0.850	0.159-4.557	0.850
Mechanical ventilation applied	5.327	1.430-19.846	0.013^†
pH	1.303	0.021-81.406	0.900
PCO₂	0.905	0.829-0.987	0.024^*
PaO₂	1.029	0.989-1.071	0.157
HCO₃	1.106	0.945-1.293	0.209
O₂ saturation	0.915	0.843-0.994	0.036^*
CK	0.998	0.994-1.001	0.199
TG	1.009	0.999-1.019	0.082

OR, odds ratio; CI, confidence interval; CK, creatinine kinase; TG, triglyceride.

^*P<0.05.

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ORCID iDs: Young-Joo Cho
https://orcid.org/http://orcid.org/0000-0002-9414-5934
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