Healthcare resource burden associated with hyponatremia among patients hospitalized for heart failure in the US

Figures & data

Table 1.  Baseline demographics and characteristics for matched cohorts of hyponatremic and non-hyponatremic patients.

	Hyponatremic discharges, n (%)	Non-hyponatremic discharges, n (%)
Sample discharges	25,855 (100.00%)	25,855 (100.00%)
Age
Mean	75.36	75.36
SD	13.78	13.78
Median	78.00	78.00
Gender
Female	14,436 (55.83%)	14,436 (55.83%)
Male	11,419 (44.17%)	11,419 (44.17%)
Race
American Indian	138 (0.53%)	150 (0.58%)
Black	2944 (11.39%)	4823 (18.65%)
Hispanic	1102 (4.26%)	1059 (4.10%)
White	17,655 (68.32%)	16,166 (62.53%)
Other/unknown	4006 (15.49%)	3657 (14.14%)
Primary payer
Medicare	21,113 (81.66%)	21,019 (81.30%)
Medicaid	1381 (5.34%)	1366 (5.28%)
Commercial	2434 (9.41%)	2587 (10.01%)
Other	927 (3.59%)	883 (3.42%)
Admission type
Emergency	20,755 (80.27%)	19,615 (75.87%)
Urgent	3363 (13.01%)	3836 (14.84%)
Elective	1732 (6.70%)	2365 (9.15%)
Other/unknown	5 (0.02%)	39 (0.15%)
3M® APR-DRG severity of illness
1-Minor	2 (0.01%)	206 (0.80%)
2-Moderate	7189 (27.81%)	9487 (36.69%)
3-Major	14,246 (55.10%)	13,597 (52.59%)
4-Extreme	4418 (17.09%)	2565 (9.92%)
3M® APR-DRG risk of mortality
1-Minor	293 (1.13%)	1208 (4.67%)
2-Moderate	9585 (37.07%)	10,413 (40.27%)
3-Major	10,849 (41.96%)	11,010 (42.58%)
4-Extreme	5128 (19.83%)	3224 (12.47%)
Comorbidities
Cancer/neoplasm/ malignancy	1932 (7.47%)	1976 (7.64%)
Cirrhosis/hepatic disease	1385 (5.36%)	822 (3.18%)
HIV/AIDS	71 (0.27%)	65 (0.25%)
Pulmonary	10,199 (39.45%)	10,603 (41.01%)
Deyo-Charlson comorbidity index
Mean	4.7	4.8
SD	2.7	2.6
Median	4.0	4.0

3M® APR-DRG = All Patient Refined Diagnosis Related Groups.

Table 2.  Hospital characteristics of matched cohorts of hyponatremic and non-hyponatremic patients.

	Hyponatremic discharges, n (%)	Non-hyponatremic discharges, n (%)
Sample discharges	25,855 (100.00%)	25,855 (100.00%)
Number of hospitals	446
Provider region
East North Central	3434 (13.28%)	3434 (13.28%)
East South Central	1684 (6.51%)	1684 (6.51%)
Middle Atlantic	3472 (13.43%)	3472 (13.43%)
Mountain	945 (3.65%)	945 (3.65%)
New England	563 (2.18%)	563 (2.18%)
Pacific	2970 (11.49%)	2970 (11.49%)
South Atlantic	8329 (32.21%)	8329 (32.21%)
West North Central	1653 (6.39%)	1653 (6.39%)
West South Central	2805 (10.85%)	2805 (10.85%)
Population served
Urban	22,403 (86.65%)	22,842 (88.35%)
Rural	3452 (13.35%)	3013 (11.65%)
Teaching status
Teaching	9846 (38.08%)	10,006 (38.70%)
Non-teaching	16,009 (61.92%)	15,849 (61.30%)
Hospital bed size
006–099	1029 (3.98%)	1053 (4.07%)
100–199	2700 (10.44%)	2541 (9.83%)
200–299	4167 (16.12%)	4068 (15.73%)
300–499	9808 (37.93%)	9896 (38.27%
500+	8151 (31.53%)	8297 (32.09%)

Figure 1.  Hospital and Intensive Care Unit (ICU) length of stay (LOS) (a) and costs (b) for hyponatremic and non-hyponatremic patient cohorts after matching.

Figure 2.  Intensive Care Unit (ICU) admission and 30-day hospital readmission, for any cause and hyponatremia-related for hyponatremic and non-hyponatremic patient cohorts after matching.

Table 3.  Relative increase in healthcare utilization and costs and odds for Intensive Care Unit (ICU) admission and 30-day readmission for hyponatremic patients vs non-hyponatremic patients based on multivariate analysis.

Utilization/cost	Relative increase	Odds ratio	CI Lower	CI Upper	p-value
Length of stay	21.5%		20.1%	23.0%	<0.001
Hospitalization cost	25.6%		23.8%	27.3%	<0.001
ICU length of stay	13.7%		10.0%	17.6%	<0.001
ICU cost	24.6%		22.2%	29.5%	<0.001
Event
ICU admission		1.58	1.37	1.84	<0.001
30-day readmission (all cause)		1.19	1.14	1.24	<0.001
30-day readmission (hyponatremia-related)		5.10	4.77	5.46	<0.001

p-values were calculated using generalized linear model.

CI, 95% Confidence Interval; Lower, Lower Bound; Upper, Upper Bound.