Table 3.
Incidence density ratios (95% confidence intervals) of number of days of hospitalization by categories of current serum sodium (mmol/L) in participants with heart failure with ejection fraction (n=50,162*)
| All-cause hospitalization | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 115.00–133.99 | 134.00–137.00 | 137.01–140.99 | 141.00–142.99 | 143.00–175.00 | p trend | |||||
| Person Observations | 52,594 | 180,231 | 273,793 | 138,483 | 86,329 | |||||
| Number of days hospitalized | 123,738 | 337,860 | 443,990 | 219,419 | 150,607 | |||||
| Person-Observation-years | 8,860.70 | 39,648.51 | 70,754.61 | 38,424.21 | 23,513.82 | |||||
| Mean number of days hospitalized/100 POY | 1,396.5 | 852.1 | 627.5 | 571.0 | 640.5 | |||||
| Crude IDR | 2.20 (2.06–2.34) | 1.42 (1.35–1.49) | 1.00 (ref) | 0.91 (0.86–0.96) | 1.01 (0.95–1.07) | <.0001 | ||||
| Age adjusted IDR | 2.22 (2.09–2.37) | 1.42 (1.35–1.50) | 1.00 (ref) | 0.90 (0.85–0.95) | 1.00 (0.94–1.06) | <.0001 | ||||
| Multivariable modelǂ | 2.03 (1.90–2.18) | 1.37 (1.30–1.44) | 1.00 (ref) | 0.91 (0.86–0.96) | 1.00 (0.94–1.06) | <.0001 | ||||
| Heart failure hospitalization | ||||||||||
| Person Observations | 52,594 | 180,231 | 273,793 | 138,483 | 86,329 | |||||
| Number of days hospitalized | 8,945 | 24,974 | 36,847 | 18,865 | 14,375 | |||||
| Person-Observation-years | 8,860.70 | 39,648.51 | 70,754.61 | 38,424.21 | 23,513.82 | |||||
| Mean number of days hospitalized/100 POY | 100.95 | 62.99 | 52.08 | 49.10 | 61.13 | |||||
| Crude IDR | 1.85 (1.50–2.29) | 1.37 (1.16–1.61) | 1.00 (ref) | 0.93 (0.80–1.09) | 1.38 (1.18–1.63) | <.0001 | ||||
| Age adjusted IDR | 1.88 (1.55–2.28) | 1.42 (1.20–1.68) | 1.00 (ref) | 0.90 (0.78–1.04) | 1.32 (1.12–1.57) | <.0001 | ||||
| Multivariable modelǂ | 1.73 (1.39–2.16) | 1.33 (1.09–1.61) | 1.00 (ref) | 0.83 (0.70–0.98) | 1.09 (0.92–1.29) | <.0001 | ||||
The 138–140.99 mmol/L is the reference serum sodium category. Missing values are as follows: eGFR = 773, serum potassium=40, race=2,861. POY= person-observation years. IDR = incidence density ratio. There were 731,430 serum sodium measurements during the follow-up period (728,776 used in the model because 2,654 were excluded because they died or were censored on the same day as their sodium measurement).
Sample size is 50,162 because 770 people with any length of stay > 180 days were excluded.
Adjusted for age, sex, race, body mass index, estimated glomerular filtration rate, serum potassium, hypertension, hyperlipidemia, coronary artery disease, atrial fibrillation, diabetes mellitus type II, chronic obstructive pulmonary disease, anemia, angiotensin converting enzyme inhibitor/angiotensin receptor blocker prescription, beta blocker prescription, and calcium channel blocker prescription.