Patient characteristics
| Variable | Overall |
| (n=452) | |
| Age (years) | 81 (74–85) |
| Male sex, n (%) | 240 (53) |
| Body mass index (kg/m2) | 21.9±4.0 |
| Systolic blood pressure (mm Hg) | 113 (102–126) |
| Heart rate (per min) | 66 (60–76) |
| Admissions in past year, n (%) | 115 (25) |
| First admission due to heart failure | 296 (66) |
| Diabetes, n (%) | 124 (27) |
| Haemoglobin (g/L) | 11.7 (10.2–13.0) |
| B-type natriuretic peptide at admission (pg/mL) | 570 (308–1121) |
| B-type natriuretic peptide at discharge (pg/mL) | 220 (112–423) |
| Creatinine (mg/dL) | 1.0 (0.8–1.4) |
| Creatinine ≥2.5, n (%) | 26 (6) |
| Left ventricular ejection fraction (%) | 51 (41–62) |
| Krumholz score | 1 (0–2) |
| Socioeconomic variables | |
| Living alone, n (%) | 80 (18) |
| Low income*, n (%) | 42 (9) |
| Number of housemates | 1 (1–3) |
| Geographic and climate variables | |
| Altitude of patients’ residence (m) | 64 (15–188) |
| Altitude ≥200 m of patients’ residence, n (%) | 100 (22) |
| Distance from patients’ residence to hospital† (km) | 16 (7–24) |
| Population‡ (persons) | 647 (284–1863) |
| Proportion of the population ≥65 years‡(%) | 35 (28–42) |
| Proportion of the population ≥75 years‡ (%) | 20 (16–25) |
| Number of hospital or clinics‡ (%) | 0 (0–2) |
| Mean temperature in a day§ (°C) | 15.7±0.3 |
| Maximum daily temperature§ (°C) | 21.0±0.9 |
| Minimum daily temperature§ (°C) | 11.5±0.8 |
| Difference of daily temperature§ (°C) | 9.5±1.5 |
Data are expressed as mean±SD, median (IQR) or number (percentage).
*Patients who were certified as a resident tax exemption.
†Kitaishikai Hospital.
‡In the minor administrative district (Cho-Aza district) located at patients’ residence.
§Average temperature in a day from July 2006 to June 2014 in the major administrative district (Gun-City district) located at patients’ residence.