Elevated serum osmolarity is associated with 28-day all-cause mortality in patients with cardiac arrest

doi:10.5847/wjem.j.1920-8642.2026.009

Abstract

Abstract:

BACKGROUND: Serum osmolality is a prognostic indicator in critically ill patients. This study aimed to evaluate the association between high osmolality and 28-day mortality in patients with cardiac arrest (CA) admitted to the intensive care unit (ICU).

METHODS: Baseline data of adult patients with CA who were admitted to the ICU from 2008 to 2019 were collected from the Medical Information Mart for Intensive Care (MIMIC)-IV. Patients were divided into survivor and non-survivor groups according to the 28-day prognosis. Serum concentrations of sodium, potassium, glucose, and urea nitrogen on the first day of ICU admission were used to determine serum osmolarity. The primary endpoint of this study was 28-day all-cause mortality. Propensity score matching (PSM) analysis was performed to reduce bias between the survivor and non-survivor groups.

RESULTS: Among the 798 included CA patients, the high osmolarity on the first day of ICU admission remained significantly associated with increased 28-day mortality (62.0% vs. 35.5%, P<0.001) and reduced cumulative survival (log-rank P<0.05) after PSM. Cox regression identified the high osmolarity on the first day of ICU admission as an independent predictor. High serum osmolarity on the first day of ICU admission effectively predicted 1-, 3-, 7-, and 28-day all-cause mortality, with the strongest predictive performance for 1-day mortality both before and after PSM (all P<0.05).

CONCLUSION: In this study, elevated serum osmolarity on the first day of ICU admission was independently associated with increased 28-day mortality in CA patients and could serve as a prognostic marker.

Key words: Cardiac arrest, Serum osmolarity, High osmolarity, Mortality

Ping Gong, Hong Zhao, Peijuan Li, Ling Wang, Jin Wang, Rui Yang, Zhangping Sun. Elevated serum osmolarity is associated with 28-day all-cause mortality in patients with cardiac arrest[J]. World Journal of Emergency Medicine, 2026, 17(1): 50-56.

Figures/Tables 5

Figure 1.

Table 1.

Baseline characteristics of the study population between survivor and non-survivor groups

Characteristics	Before PSM				After PSM
Characteristics	Overall n=798¹	Non-survivors n=370¹	Survivors n=428¹	P-value²	Overall n=522¹	Non-survivors n=261¹	Survivors n=261¹	P-value²
Age, years	67.6 (55.8, 80.0)	68.9 (55.7, 80.9)	66.7 (56.1, 79.1)	0.300	67.8 (56.1, 81.0)	67.7 (54.8, 81.3)	67.8 (58.4, 80.8)	0.500
Female	320 (40.1)	162 (43.8)	158 (36.9)	0.048	228 (43.7)	114 (43.7)	114 (43.7)	0.900
Hypertension	334 (41.9)	147 (39.7)	187 (43.7)	0.300	214 (41.0)	108 (41.4)	106 (40.6)	0.900
Diabetes	252 (31.6)	121 (32.7)	131 (30.6)	0.500	169 (32.4)	85 (32.6)	84 (32.2)	0.900
AMI	228 (28.6)	97 (26.2)	131 (30.6)	0.200	153 (29.3)	71 (27.2)	82 (31.4)	0.300
CHF	300 (37.6)	120 (32.4)	180 (42.1)	0.005	196 (37.5)	95 (36.4)	101 (38.7)	0.600
AKI	187 (23.4)	87 (23.5)	100 (23.4)	0.900	125 (23.9)	59 (22.6)	66 (25.3)	0.500
Liver disease	126 (15.8)	72 (19.5)	54 (12.6)	0.008	87 (16.7)	44 (16.9)	43 (16.5)	0.900
Charlson Index	6 (4, 8)	6 (4, 8)	6 (4, 8)	0.018	6 (4, 8)	6 (4, 8)	6 (4, 8)	0.300
Heart rate, beats/min	85 (73, 98)	87 (74, 103)	82 (71, 95)	<0.001	86 (73, 99)	86 (74, 100)	86 (73, 98)	0.600
MAP, mmHg	78 (72, 84)	77 (70, 85)	78 (72, 83)	0.600	78 (72, 84)	78 (70, 85)	78 (72, 83)	0.600
Respiratory rate, breathes/min	20.4 (17.8, 23.9)	21.4 (18.7, 24.9)	19.6 (17.4, 22.8)	<0.001	20.7 (17.8, 24.0)	20.9 (18.0, 24.4)	20.6 (17.7, 23.8)	0.200
Temperature, ℃	36.74 (36.26, 37.16)	36.64 (35.85, 37.09)	36.80 (36.47, 37.20)	<0.001	36.73 (36.25, 37.13)	36.72 (36.20, 37.18)	36.75 (36.32, 37.05)	0.900
SpO₂, %	97.82 (96.11, 99.10)	97.54 (95.88, 98.96)	97.92 (96.38, 99.11)	0.042	97.78 (96.00, 99.06)	97.67 (96.06, 98.96)	97.89 (95.96, 99.13)	0.700
APS III	72 (49, 96)	86 (65, 104)	60 (42, 85)	<0.001	75 (55, 95)	74 (56, 95)	75 (54, 95)	0.900
SAPS II	47 (37, 59)	54 (42, 64)	42 (33, 53)	<0.001	48 (38, 60)	49 (39, 60)	47 (38, 60)	0.600
SOFA	9 (6, 12)	10 (7, 13)	8 (5, 11)	<0.001	9 (6, 13)	10 (6, 13)	9 (6, 12)	0.400
OASIS	43 (36, 49)	45 (39, 50)	39 (33, 47)	<0.001	43 (37, 49)	44 (37, 49)	43 (37, 49)	0.900
GCS	11 (5, 15)	10 (3, 15)	12 (8, 14)	0.011	11 (5, 15)	12 (5, 15)	10 (5, 14)	0.004
Creatinine, μmol/L	65 (55, 77)	69 (59, 82)	62 (54, 71)	<0.001	67 (57, 78)	68 (57, 80)	65 (57, 77)	0.130
WBC, ×10⁹/L	92 (78, 110)	100 (84, 118)	87 (75, 102)	<0.001	95 (80, 111)	96 (81, 114)	93 (80, 109)	0.200
Urine output, mL	1,286 (695, 2,240)	1,068 (416, 1,962)	1,495 (905, 2,365)	<0.001	1,235 (640, 2,161)	1,155 (520, 2,170)	1,280 (700, 2,130)	0.300
Time from collapse to ROSC, min	22 (15, 32)	19 (12, 25)	26 (18, 36)	<0.001	21 (14, 30)	21 (14, 29)	22 (15, 31)	0.342
Defibrillation	28 (3.5)	11 (3.0)	17 (4.0)	0.233	18 (3.4)	7 (2.7)	11 (4.2)	0.338
Use of resuscitation drugs
Adrenaline	223 (27.9)	101 (27.3)	122 (28.5)	0.046	145 (27.8)	62 (23.8)	83 (31.8)	0.026
Dopamine	41 (5.1)	15 (4.1)	26 (6.1)	0.048	29 (5.6)	12 (4.6)	17 (6.5)	0.306
OSM				<0.001				<0.001
Low osmolarity (<290 mmol/L)	44 (5.5)	16 (4.3)	28 (6.5)		29 (5.6)	12 (4.6)	17 (6.5)
Normal osmolarity (290-309 mmol/L)	428 (53.6)	152 (41.1)	276 (64.5)		276 (52.9)	113 (43.3)	163 (62.5)
High osmolarity (>309 mmol/L)	326 (40.9)	202 (54.6)	124 (29.0)		217 (41.6)	136 (52.1)	81 (31.0)

Table 1.

Table 2.

Figure 2.

Figure 3.

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Characteristics	Univariable analysis		Multivariable analysis
Characteristics	HR (95% CI)	P-value	HR (95% CI)	P-value
Gender	0.99 (0.78-1.27)	0.958
Age	1.00 (0.99-1.00)	0.235
Hypertension	0.97 (0.76-1.25)	0.838
Diabetes	0.93 (0.72-1.20)	0.564
AMI	0.94 (0.71-1.23)	0.646
CHF	0.87 (0.68-1.12)	0.293
AKI	0.85 (0.64-1.14)	0.289
Liver disease	0.92 (0.66-1.27)	0.612
Charlson Index	0.95 (0.90-1.00)	0.035	0.92 (0.88-0.97)	<0.001
Heart rate, beats/min	1.00 (1.00-1.01)	0.399
MAP, mmHg	1.00 (0.98-1.01)	0.454
Respiratory rate, breaths/min	1.02 (1.00-1.05)	0.109
Temperature,℃	0.96 (0.86-1.09)	0.544
SpO₂, %	0.98 (0.94-1.03)	0.529
APS III	1.00 (0.99-1.00)	0.353
SAPS II	1.00 (0.99-1.01)	0.551
SOFA	1.01 (0.98-1.04)	0.569
OASIS	1.00 (0.99-1.01)	0.859
GCS	1.05 (1.02-1.08)	<0.001	1.05 (1.02-1.09)	<0.001
Creatinine, μmol/L	1.01 (1.00-1.02)	0.028	1.00 (0.99-1.01)	0.500
WBC, ×10⁹/L	1.01 (1.00-1.01)	0.062
Urine output, mL	1.00 (1.00-1.00)	0.931
Time from collapse to ROSC, min	1.01 (0.99-1.03)	0.342
Adrenaline	1.18 (0.90-1.56)	0.228
Dopamine	1.09 (0.69-1.73)	0.700
Low osmolarity, mmol/L	0.89 (0.49-1.62)	0.703
High osmolarity, mmol/L	1.92 (1.49-2.46)	<0.001	2.02 (1.54-2.64)	<0.001

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