Table 1

Characteristics of daily data in the training (2005–2013) and testing (2014–2015) datasets

VariableTraining dataset
(n=525 374)
Testing dataset
(n=135 678)
2005–20072008–20102011–20132014–2015
Demographic variables
 Daily incidence of OHCA, cases, median (IQR)133 (109–167)154 (127–187)168 (138–212)173 (146–216)
 Incidence of OHCA, per 100 000 person-years44.551.257.059.7
Patient characteristics
 Age, years, median (IQR)77 (66–85)79 (68–86)80 (69–87)80 (70–87)
 Male sex, n (%)89 872 (59)101 276 (57)110 336 (56)76 892 (57)
Meteorological variables
 Ambient temperature, °C
 Mean value within a day
  Sapporo5.6 (−2.8–14.8)6.5 (−1.8–15)6.5 (−2.8–15.4)7.1 (−1.5–14.6)
  Kobe16.3 (8.8–22.9)16.3 (9.4–22.8)15.7 (7.9–22.6)16.5 (8.7–21.8)
  Naha23.9 (20.4–27.9)23.6 (20.3–28.0)23.7 (19.9–27.6)24.1 (20.2–28.0)
 Differences between maximum and minimum values within a day
  Sapporo7.0 (4.1–10.2)6.6 (4.0–9.7)6.2 (3.9–8.9)6.4 (4.1–9.2)
  Kobe5.0 (3.5–6.4)4.8 (3.5–6.2)5.3 (4.0–6.8)5.4 (4.0–6.9)
  Naha1.0 (0.6–1.8)1.1 (0.6–1.8)1.2 (0.7–1.9)1.2 (0.7–1.9)
 Difference in mean value from the previous day
  Sapporo0.1 (−1.2–1.3)0.1 (−1.2–1.4)0.1 (−1.2–1.3)0.1 (−1.1–1.3)
  Kobe0.1 (−0.9–1.0)0.2 (−0.8–1.0)0.1 (−0.8–1.0)0.2 (−0.8–0.9)
  Naha0.0 (−0.5–0.6)0.1 (−0.4–0.6)0.1 (−0.4–0.6)0.1 (−0.4–0.6)
 Relative humidity, %
  Sapporo91.7 (84.3–96.9)90.6 (83.5–94.6)91.6 (86.2–94.6)89.7 (82.5–94.0)
  Kobe76.9 (715–82.0)76.5 (71.0–82.6)76.7 (71.0–83.2)77.2 (71.5–83.9)
  Naha80.6 (75.3–84.0)80.2 (74.6–84.0)80.3 (74.6–84.2)79.6 (73.3–84.1)
 Precipitation during the previous hour, mm
  Sapporo1.0 (0.0–3.0)1.0 (0.0–3.0)1.0 (0.0–3.0)0.9 (0.0–2.9)
  Kobe0.0 (0.0–0.0)0.0 (0.0–1.0)0.0 (0.0–0.0)0.0 (0.0–0.0)
  Naha0.0 (0.0–2.0)0.0 (0.0–2.0)0.0 (0.0–2.0)0.0 (0.0–2.0)
 Snowfall, mm *
  Sapporo22.0 (9.0–34.0)19.0 (9.0–34.0)28.0 (14.0–42.0)28.0 (9.0–44.0)
  Kobe0.0 (0.0–0.0)0.0 (0.0–0.0)0.0 (0.0–0.0)0.0 (0.0–0.0)
  Naha0.0 (0.0–0.0)0.0 (0.0–0.0)0.0 (0.0–0.0)0.0 (0.0–0.0)
 Cloud coverage, %
  Sapporo91.4 (68.3–98.8)89.9 (64.6–98.7)88.8 (66.3–97.5)84.3 (54.2–96.5)
  Kobe59.9 (33.1–81.7)59.7 (35.2–84.9)64.5 (37.5–86.4)63.5 (36.1–87.1)
  Naha67.8 (32.8–92.0)67.8 (32.0–92.0)75.2 (44.1–93.8)69.6 (36.4–91.4)
 Wind speed, kph
  Sapporo11.0 (7.9–14.6)11.4 (8.1–15.1)11.8 (8.1–16.5)11.8 (8.3–16.6)
  Kobe11.2 (8.5–15.9)11.4 (8.4–16.3)10.2 (7.2–115.2)9.8 (7.2–14.3)
  Naha24.2 (18.1–32.1)24.5 (18.5–31.5)26.1 (19.5–33.2)25.0 (19.0–31.6)
 Atmospheric pressure, hPa
  Sapporo977 (972–981)978 (973–982)977 (972–981)977 (973–982)
  Kobe1010 (1005–1015)1010 (1006–1014)1008 (1003–1012)1008 (1004–1013)
  Naha1014 (1010–1019)1014 (1010–1018)1013 (1009–1018)1014 (1010–1019)
  • Continuous values are presented as medians (IQR).

  • *Snowfall values were calculated for the winter (December–February).

  • †See online supplemental eFigure 1 for more information.

  • OHCA, out-of-hospital cardiac arrest.