Table 3.

Cumulative relative risk of cold spells under different definitions on AECOPD hospitalisations of the total population in Beijing, 2012–2016

Definition	CRR (95% CI)
	Lag0	Lag0–7	Lag0–14	Lag0–21
≤10% and ≥2 days	1.030 (1.002 to 1.058)*	1.200 (1.087 to 1.326)*	1.278 (1.134 to 1.439)*	1.236 (1.055 to 1.448)*
≤10% and ≥3 days	1.027 (1.000 to 1.054)*	1.188 (1.084 to 1.303)*	1.299 (1.166 to 1.448)*	1.353 (1.161 to 1.577)*
≤10% and ≥4 days	1.042 (1.013 to 1.072)*	1.249 (1.136 to 1.374)*	1.343 (1.206 to 1.496)*	1.394 (1.193 to 1.630)*
≤5% and ≥2 days	1.012 (0.980 to 1.045)	1.173 (1.055 to 1.304)*	1.344 (1.188 to 1.519)*	1.354 (1.141 to 1.608)*
≤5% and ≥3 days	1.031 (1.000 to 1.063)*	1.235 (1.114 to 1.369)*	1.381 (1.220 to 1.563)*	1.428 (1.206 to 1.692)*
≤5% and ≥4 days	1.042 (1.006 to 1.079)*	1.268 (1.132 to 1.421)*	1.404 (1.234 to 1.598)*	1.511 (1.262 to 1.809)*
≤3% and ≥2 days	0.982 (0.944 to 1.021)	1.113 (0.960 to 1.290)	1.412 (1.171 to 1.703)*	1.444 (1.113 to 1.873)*
≤3% and ≥3 days	1.009 (0.970 to 1.049)	1.217 (1.051 to 1.411)*	1.525 (1.264 to 1.841)*	1.659 (1.278 to 2.154)*
≤3% and ≥4 days	0.992 (0.951 to 1.035)	1.201 (0.999 to 1.443)	1.644 (1.261 to 2.145)*	1.889 (1.315 to 2.712)*

*P<0.05.

AECOPD, acute exacerbation of chronic obstructive pulmonary disease; CRR, cumulative relative risk.