Temperature Variability and Hospital Admissions for Chronic Obstructive Pulmonary Disease: Analysis of Attributable Disease Burden and Vulnerable Subpopulation

Figures & data

Table 1 Descriptive Statistics for Daily COPD Hospitalization During 2013–2015 in Guangzhou, China

	Total Number (%)	Daily COPD Hospitalization
		Mean (SD)	Min–Max
Overall	71,070 (100.0)	64.9 (24.1)	14–155
Emergency admission	22,682 (31.9)	20.7 (7.3)	5–55
Nonemergency admission	47,719 (67.1)	43.6 (19.3)	4–110
Sex
Male	54,969 (77.3)	50.2 (19.1)	9–120
Female	16,100 (22.7)	14.7 (6.5)	1–41
Age (years)
0–64	11,369 (16.0)	10.4 (5.2)	1–29
65+	59,701 (84.0)	54.5 (20.4)	12–128
Occupation
White collar	1950 (2.7)	1.8 (1.7)	0–10
Blue collar	8135 (11.4)	7.4 (3.7)	0–21
Unemployed	37,875 (53.3)	34.6 (13.8)	7–84
Marital status
Unmarried	1380 (1.9)	1.3 (1.2)	0–6
Married	67,277 (94.7)	61.4 (23.2)	14–153
Divorced/widowed	1563 (2.2)	1.4 (1.3)	0–8
Season
Spring	20,265 (28.5)	73.4 (23.1)	26–139
Summer	17,359 (24.4)	62.9 (27.0)	18–155
Autumn	15,851 (22.3)	58.1 (19.8)	14–110
Winter	17,595 (24.8)	65.2 (23.7)	18–143

Abbreviations: COPD, chronic obstructive pulmonary disease; max, maximum value; min, minimum value.

Table 2 The Average (SD) of Daily Temperature Variability, Weather Conditions During 2013–2015 in Guangzhou, China

	Full Year	Spring	Summer	Autumn	Winter
Daily mean temperature (^°C)	23.3 (6.3)	22.8 (4.4)	29.5 (1.9)	25.4 (3.9)	15.3 (3.6)
Relative humidity (%)	73.5 (14.0)	81.6 (10.3)	78.1 (9.0)	68 (13.3)	66 (16)
Hourly TV (^°C)
Lag 0–1 days	2.5 (0.8)	2.3 (0.9)	2.4 (0.6)	2.6 (0.7)	2.8 (1.0)
Lag 0–3 days	2.8 (0.8)	2.6 (0.9)	2.6 (0.5)	2.8 (0.6)	3.2 (0.9)
Lag 0–6 days	3.0 (0.7)	2.9 (0.9)	2.8 (0.4)	3.0 (0.6)	3.5 (0.8)
Lag 0–7 days	3.1 (0.7)	3.0 (0.9)	2.8 (0.3)	3.0 (0.5)	3.6 (0.8)
Daily TV (^°C)
Lag 0–1 days	4.2 (1.3)	3.7 (1.5)	4.2 (0.9)	4.3 (1.1)	4.7 (1.6)
Lag 0–3 days	4.2 (1.1)	3.8 (1.2)	4.0 (0.6)	4.2 (0.8)	4.7 (1.3)
Lag 0–6 days	4.3 (0.9)	3.9 (1.1)	4.0 (0.4)	4.2 (0.7)	4.9 (1.0)
Lag 0–7 days	4.3 (0.9)	4.0 (1.1)	4.0 (0.4)	4.2 (0.6)	4.9 (0.9)

Abbreviation: TV, temperature variability.

Figure 1 Percentage changes of COPD hospitalization with 1°C increase in temperature variability (TV) along various exposure days. The dots are estimated effects, and the error bars are the 95% confidence intervals. COPD is the chronic obstructive pulmonary disease. TV is temperature variability. TV01 is temperature variability at lag 0–1 day, and so on.

Table 3 The Percentage Change (%) of Daily COPD Hospitalization Associated with 1°C Increase in TV Over Lag 0–6 Days for Subgroups

	Hourly TV			Daily TV
	PC (95%CI)	Z-Test	P-value	PC (95%CI)	Z-Test	P-value
Overall	4.3 (2.2–6.4)	–	–	4.0 (2.3–5.8)	–	–
Emergency admission	5.4 (2.7–8.1)	Ref	Ref	5.6 (3.3–7.8)	Ref	Ref
Nonemergency admission	3.6 (1.1–6.2)	−0.919	0.358	3.2 (1.1–5.3)	−1.103	0.270
Sex
Male	4.6 (2.5–6.8)	Ref	Ref	4.4 (2.6–6.2)	Ref	Ref
Female	3.0 (−0.3–6.4)	−0.792	0.429	2.7 (0.0–5.6)	−0.953	0.341
Age (years)
0–64	6.0 (2.2–9.9)	Ref	Ref	5.3 (2.2–8.5)	Ref	Ref
65+	4.0 (1.8–6.1)	−0.909	0.363	3.8 (2.0–5.6)	−0.832	0.406
Occupation
White collar	−0.1 (−7.7–8.1)	Ref	Ref	2.2 (−4.3–9.2)	Ref	Ref
Blue collar	7.7 (3.3–12.2)	1.642	0.100	6.5 (2.8–10.3)	1.075	0.282
Unemployed	4.2 (1.9–6.7)	1.013	0.311	3.7 (1.7–5.8)	0.418	0.676
Marital status
Unmarried	−2.0 (−11.1–8.1)	Ref	Ref	−2.3 (−10.0–6.0)	Ref	Ref
Married	4.4 (2.3–6.5)	1.244	0.214	4.2 (2.4–6.0)	1.510	0.131
Divorced/widowed	8.8 (−0.2–18.7)	1.567	0.117	9.8 (2.0–18.2)	2.077	0.038
Season
Spring	2.6 (−1.1–6.5)	Ref	Ref	3.7 (0.4–7.1)	Ref	Ref
Summer	4.1 (−3.9–12.8)	0.317	0.751	7.6 (0.1–15.5)	0.911	0.362
Autumn	1.7 (−4.1–7.8)	−0.260	0.795	3.3 (−1.5–8.2)	−0.155	0.877
Winter	4.2 (−0.3–9.0)	0.520	0.603	3.4 (−0.5–7.4)	−0.125	0.900

Abbreviations: PC, percentage change; Ref, reference groups; TV, temperature variability.

Table 4 COPD Burden Due to Temperature Variability During 2013–2015 in Guangzhou, China

	Hourly TV		Daily TV
	AN (*1000)	AF (%)	AN (*1000)	AF (%)
Overall	8.5 (4.6–12.1)	12.0 (6.5–17.1)	10.9 (6.5–15)	15.4 (9.2–21.1)
Emergency admission	3.3 (1.8–4.7)	14.6 (7.8–20.9)	4.7 (3.0–6.2)	20.5 (13.0–27.4)
Nonemergency admission	4.9 (1.6–7.9)	10.3 (3.4–16.6)	5.9 (2.1–9.4)	12.4 (4.5–19.6)
Sex
Male	7.1 (4.0–10.0)	12.9 (7.2–18.1)	9.1 (5.6–12.4)	16.6 (10.2–22.5)
Female	1.4 (−0.1–2.8)	8.7 (−0.8–17.2)	1.7 (0.0–3.3)	10.9 (−0.1–20.6)
Age (years)
0–64	1.8 (0.7–2.8)	16.1 (6.4–24.7)	2.2 (1.0–3.3)	19.6 (8.6–29.2)
65+	6.6 (3.2–9.8)	11.1 (5.4–16.4)	8.7 (4.8–12.2)	14.5 (8.0–20.5)
Occupation
White collar	0.0 (−0.5–0.4)	−0.3 (−27.4–20.8)	0.2 (−0.4–0.6)	8.8 (−20.7–30.9)
Blue collar	1.6 (0.8–2.4)	20.1 (9.4–29.4)	1.9 (0.9–2.8)	23.5 (11.2–34.0)
Unemployed	4.5 (2.1–6.7)	11.9 (5.5–17.8)	5.5 (2.7–8.0)	14.4 (7.1–21.2)
Marital status
Unmarried	−0.1 (−0.6–0.3)	−6.2 (−42.6–20.6)	−0.1 (−0.8–0.3)	−10.3 (−56.1–21.6)
Married	8.3 (4.5–11.8)	12.3 (6.8–17.5)	10.7 (6.5–14.6)	15.9 (9.7–21.8)
Divorced/widowed	0.4 (0.0–0.6)	22.5 (−0.7–40.2)	0.5 (0.1–0.8)	32.6 (8.0–50.5)
Season
Spring	1.5 (−0.7–3.4)	7.4 (−3.3–16.9)	2.7 (0.4–4.8)	13.5 (1.8–23.8)
Summer	1.8 (−2.0–4.9)	10.5 (−11.6–28.2)	4.4 (0.1.0–7.6)	25.3 (0.6–43.8)
Autumn	0.8 (−2.1–3.2)	4.9 (−13.2–20.1)	2.0 (−1.0–4.5)	12.7 (−6.5–28.4)
Winter	2.4 (−0.2–4.5)	13.4 (−1.1–25.7)	2.6 (−0.4–5.1)	14.8 (−2.5–29.1)

Note: AF and AN were the TV-attributable fraction and number of COPD hospitalizations, which were calculated based on the TV over lag zero to six days.

Abbreviations: AF, attributable fraction; AN, attributable number; COPD, chronic obstructive pulmonary disease; TV, temperature variability.