Table 2:
Characteristics of eligible individuals with and without hypernatremia as evidenced by recorded serum sodium levels.
| Total | Not hypernatremic during hospitalization | Hypernatremic during hospitalization | ||
|---|---|---|---|---|
| Variable | Category | N = 1 813 356 | N = 1 680 793 | N = 132 563 |
| Age category | 18–49 years | 233 118 (12.9) | 228 814 (13.6) | 4304 (3.2) |
| 50–64 years | 269 105 (14.8) | 257 549 (15.3) | 11 556 (8.7) | |
| 65–79 years | 657 411 (36.3) | 618 453 (36.8) | 38 958 (29.4) | |
| ≥80 years | 653 722 (36.1) | 575 977 (34.3) | 77 745 (58.6) | |
| Male | 953 378 (52.6) | 888 911 (52.9) | 64 467 (48.6) | |
| Minimum sodium concentration on admission day (mmol/l) | 139 [136–141] | 139 [136–141] | 142 [138–146] | |
| Minimum sodium concentration during hospitalization (mmol/l) | 138 [135–140] | 138 [135–140] | 138 [134–142] | |
| Minimum sodium concentration after admission day (mmol/l) | 138 [135–140] | 138 [135–140] | 138 [135–142] | |
| Maximum sodium concentration on admission day (mmol/l) | 139 [137–141] | 139 [136–141] | 142 [139–146] | |
| Maximum sodium concentration during hospitalization (mmol/l) | 141 [139–143] | 141 [139–142] | 148 [146–152] | |
| Maximum sodium concentration after admission day (mmol/l) | 141 [139–143] | 140 [139–142] | 148 [146–152] | |
| Number of days with sodium measurement per week | 2.0 [1.2–3.0] | 2.0 [1.2–2.9] | 2.2 [1.5–3.2] | |
| Admission-precipitating diagnosis | Infectious disease | 40 562 (2.2) | 36 920 (2.2) | 3642 (2.7) |
| based on ICD-10 code | Malignancy | 335 296 (18.5) | 322 988 (19.2) | 12 308 (9.3) |
| Blood disorders | 15 052 (0.8) | 13 785 (0.8) | 1267 (1.0) | |
| Endocrinological | 65 466 (3.6) | 57 209 (3.4) | 8257 (6.2) | |
| Mental disorders | 7785 (0.4) | 7283 (0.4) | 502 (0.4) | |
| Neurological | 43 666 (2.4) | 40 689 (2.4) | 2977 (2.2) | |
| Ophthalmological | 5791 (0.3) | 5702 (0.3) | 89 (0.1) | |
| Otological | 16 750 (0.9) | 16 492 (1.0) | 258 (0.2) | |
| Cardiovascular | 361 762 (19.9) | 324 412 (19.3) | 37 350 (28.2) | |
| Respiratory | 149 954 (8.3) | 128 679 (7.7) | 21 275 (16.0) | |
| Digestive | 237 913 (13.1) | 227 360 (13.5) | 10 553 (8.0) | |
| Dermatological | 18 510 (1.0) | 17 227 (1.0) | 1283 (1.0) | |
| Musculoskeletal | 90 913 (5.0) | 86 404 (5.1) | 4509 (3.4) | |
| Genitourinary | 121 383 (6.7) | 111 446 (6.6) | 9937 (7.5) | |
| Pregnancy | 39 033 (2.2) | 38 964 (2.3) | 69 (0.1) | |
| Perinatal | 50 (0.0) | 50 (0.0) | 0 (0.0) | |
| Congenital | 2866 (0.2) | 2730 (0.2) | 136 (0.1) | |
| Symptoms/signs | 21 432 (1.2) | 19 340 (1.2) | 2092 (1.6) | |
| Injury/poisoning | 200 981 (11.1) | 188 191 (11.2) | 12 790 (9.6) | |
| New diseases | 36 591 (2.0) | 33 348 (2.0) | 3243 (2.4) | |
| External causes | 4 (0.0) | 3 (0.0) | 1 (0.0) | |
| Examinations | 1596 (0.1) | 1571 (0.1) | 25 (0.0) | |
| BMI (kg/m2) | 22.2 [19.9–24.6] | 22.2 [19.9–24.7] | 21.2 [18.8–23.8] | |
| BMI category | <18.5 kg/m2 | 191 684 (10.6) | 171 131 (10.2) | 20 553 (15.5) |
| 18.5–<25 kg/m2 | 943 232 (52.0) | 883 524 (52.6) | 59 708 (45.0) | |
| ≥25 kg/m2 | 325 582 (18.0) | 309 686 (18.4) | 15 896 (12.0) | |
| Missing | 352 858 (19.5) | 316 452 (18.8) | 36 406 (27.5) | |
| Smoking history | Non-smoker | 1 150 678 (63.5) | 1 063 144 (63.3) | 87 534 (66.0) |
| Current/past smoker | 460 159 (25.4) | 435 492 (25.9) | 24 667 (18.6) | |
| Missing | 202 519 (11.2) | 182 157 (10.8) | 20 362 (15.4) | |
| Consciousness level | Alert | 1 548 278 (85.4) | 1 463 553 (87.1) | 84 725 (63.9) |
| Not clear | 265 078 (14.6) | 217 240 (12.9) | 47 838 (36.1) | |
| Charlson comorbidity index | 0 [0–2] | 0 [0–2] | 0 [0–2] | |
| Activities of daily living | Independent | 971 959 (53.6) | 941 996 (56.0) | 29 963 (22.6) |
| Dependent | 700 965 (38.7) | 612 066 (36.4) | 88 899 (67.1) | |
| Missing | 140 432 (7.7) | 126 731 (7.5) | 13 701 (10.3) | |
| Unscheduled admission | 1 087 416 (60.0) | 979 310 (58.3) | 108 106 (81.6) | |
| Ambulance use | 502 607 (27.7) | 435 602 (25.9) | 67 005 (50.5) | |
| In-hospital death | 112 226 (6.2) | 79 373 (4.7) | 32 853 (24.8) | |
Data are presented N (%) for categorical variables and median [1st–3rd quartile] for continuous variables.
BMI, body mass index; ICD-10, the International Classification of Diseases, Tenth Revision