Table 3.
Ambulance call-out IRRs and 95% CIs: IRRs are based on the daily incidence of ambulance call-outs during the 2009 and the 2014 heatwaves compared with the incidence during non-heatwave periods in metropolitan Adelaide in summer (October–March)
| Ambulance call-outs | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| All ages IRR (95% CI) |
0–4 IRR (95% CI) |
5–14 IRR (95% CI) |
15–64 IRR (95% CI) |
65–74 IRR (95% CI) |
75+ IRR (95% CI) |
Observed cases IRR (95% CI) | Excess/reduction (95% CI) | Difference between 2009 and 2014 (95% CI) | |
| Total 2009 | 1.16** (1.09 to 1.24) | 1.08 (0.90 to 1.29) | 0.86 (0.64 to 1.15) | *1.14 (1.04 to 1.24) p=0.004 | *1.11 (1.01 to 1.23) p=0.03 | **1.24 (1.17 to 1.33) | 3760 | 517.5** (308.2 to 726.8) | −297.3# (−644.4 to 49.8) |
| Total 2014 | 1.05 (0.99 to 1.12) | 0.90 (0.75 to 1.08) | 0.83 (0.64 to 1.09) | #1.09 (1.00 to 1.19) | 1.06 (0.97 to 1.15) | 1.04 (0.98 to 1.11) | 4457 | 220.2 (−56.7 to 497.1) | |
| 2014:2009 | 0.91* (0.83 to 0.99) p=0.04 | 0.84 (0.65 to 1.08) | 0.97 (0.66 to 1.44) | 0.96 (0.85 to 1.08) | 0.95 (0.83 to 1.08) | **0.84 (0.77 to 0.92) | |||
| Cardiac 2009 | 1.13 (0.97 to 1.32) | 1.86 (0.65 to 5.30) | #1.16 (0.99 to 1.35) | 1.07 (0.82 to 1.39) | 1.13 (0.96 to 1.34) | 518 | 59.3 (−11.8 to 130.4) | −207.3** (−308.8 to −105.8) | |
| Cardiac 2014 | 0.46** (0.36 to 0.60) | 0.59 (0.08 to 4.39) | **0.33 (0.23 to 0.47) | **0.43 (0.26 to 0.69) | **0.56 (0.44 to 0.71) | 128 | −148.0** (−220.4 to −75.5) | ||
| 2014:2009 | 0.41** (0.30 to 0.56) | 0.32 (0.03 to 3.06) | **0.29 (0.19 to 0.42) | **0.40 (0.23 to 0.69) | **0.50 (0.36 to 0.79) | ||||
Bold typeface indicates significance at p<0.001. The IRRs of 2014 and 2009 were compared to estimate the statistical significance of differences between the two heatwave episodes. Excess or reduction of ambulance call-outs during the 2009 and the 2014 heatwaves and comparison between 2009 and 2014 (expected cases=observed cases divided by the IRR; excess/reduced cases=observed cases−expected cases; comparison between 2009 and 2014=excess/reduced 2014 cases−2009 excess/reduced cases).
Empty cells indicate insufficient data to produce reliable estimates. *p<0.05; **p<0.001; #p<0.1.
IRR, incidence rate ratio.