Table 3.
Bivariate and multivariable analysis of the association between natremia levels and hospital costs or diagnosis-related group (DRG) categories: Lausanne University Hospital, 2012–2018.
| Hospital costs (CHF) | Diagnosis-related group categories | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Bivariate | Multivariable | Bivariate | Multivariable | ||||||
| Median [IQR] | p value | Mean ± SE | p value§ | Inlier | Highlier | p value | OR (95% CI) | p value§ | |
| Natremia levels | <0.001 | <0.001 | <0.001 | ||||||
| Normal | 10,299 [7,029–16,025] | 14,962 ± 341 | 3,851 (69.6) | 565 (56.3) | 1 (reference) | ||||
| Decreased | 13,142 [8,644–22,586] | 19,025 ± 485 | 1,684 (30.4) | 439 (43.7) | 1.66 (1.41–1.95) | <0.001 | |||
| Natremia levels | <0.001 | <0.001 | <0.001 | ||||||
| Normal | 10,299 [7,029–16,025] | 14,920 ± 340 | 3,851 (69.6) | 565 (56.3) | 1 (reference) | ||||
| Mild (130–135 mEq/L) | 12,610 [8,470–21,318] | 17,516 ± 567 | 1,194 (21.6) | 273 (27.2) | 1.49 (1.24–1.78) | <0.001 | |||
| Moderate (125–129 mEq/L) | 14,577 [9,789–26,675] | 22,210 ± 1,030 | 317 (5.7) | 111 (11.1) | 2.19 (1.66–2.88) | <0.001 | |||
| Severe (<125 mEq/L) | 14,628 [9,232–27,542] | 23,395 ± 1,422 | 173 (3.1) | 55 (5.5) | 1.95 (1.34–2.82) | <0.001 | |||
| p value for trend | <0.001 | <0.001 | |||||||
| Persistent hyponatremia | <0.001 | 0.001 | <0.001 | ||||||
| Normal | 10,299 [7,029–16,025] | 14,966 ± 341 | 3,851 (69.6) | 565 (56.3) | 1 (reference) | ||||
| Non-persistent | 13,725 [9,073–24,295] | 20,188 ± 582 | 1,084 (19.6) | 323 (32.2) | 1.90 (1.58–2.27) | <0.001 | |||
| Persistent | 12,305 [7,932–18,851] | 16,695 ± 807 | 600 (10.8) | 116 (11.6) | 1.23 (0.96–1.57) | 0.109 | |||
| p value for trend‡ | 0.001 | 0.109 | |||||||
CHF, Swiss Francs; CI, confidence interval; IQR, interquartile range; OR, odds ratio; SE, standard error; Inlier, length of stay is similar to nationwide average for a given DRG; highlier, length of stay is longer than nationwide average.
Multivariable model.
Based on log-transformed data.
Results are expressed as median [interquartile range] or multivariable-adjusted mean ± standard error for continuous variables and as number of hospitalizations (percentage) or multivariable-adjusted odds ratio (95% confidence interval) for categorical variables. Between-group bivariate analysis performed using Kruskal–Wallis test for continuous variables and chi-square for categorical variables. Multivariable analysis conducted using multilevel mixed-effects linear regression for continuous variables and multilevel mixed-effects logistic regression for categorical variables. Multivariable analyses were performed adjusting for age (four categories), gender, main cause for hospitalization (eight categories), and number of associated comorbidities.