Burn injury during long-term oxygen therapy in Denmark and Sweden: the potential role of smoking

Figures & data

Table 1 Characteristics of 31,495 patients starting long-term oxygen therapy in Sweden and Denmark 2000–2009

Characteristic	Denmark, N=23,741	Sweden, N=7,754
Men	10,147 (43)	3,592 (46)
Mean age at start (range), years	73 (18–104)	74 (25–98)*
Main diagnosis
COPD	14,775 (62)	5,767 (74)
Pulmonary fibrosis	973 (4)	1,277 (17)
Others	7,993 (34)	710 (9)
Median follow-up (IQR), years	0.54 (1.5)	1.2 (2.1)*
Deaths during follow-up	19,717 (83)	5,882 (76)

Notes: Data presented as n (%) unless otherwise specified.

* P<0.001.

Table 2 Burn injuries while on LTOT in 31,495 patients starting therapy in Sweden and Denmark 2000–2009

Patient group	Denmark		Sweden
	n/person-years	Rate (95% CI)	n/person-years	Rate (95% CI)
Overall	49/28,798	170 (126–225)	12/14,146	85 (44–148)
Men	26/11,599	224 (146–328)	2/5,789	35 (4–125)
Women	23/17,199	134 (85–200)	10/8,357	120 (57–220)
Age at start
>70 years	21/15,982	131 (81–200)	5/8,244	61 (20–142)
≤70 years	28/12,815	218 (145–316)	7/5,901	119 (48–244)
Main diagnoses
COPD	36/20,716	174 (122–241)	9/11,036	82 (37–155)
Others	13/8,082	161 (86–275)	3/3,110	96 (20–282)
Ever-smokers	No data	No data	10/12,066	83 (40–152)
Never-smokers	No data	No data	2/1,528	131 (16–472)

Notes: n, number of burn injuries; person-years, total person-years of LTOT; Rate (95% CI), rate per 100,000 person-years (95% confidence interval).

Abbreviations: LTOT, long-term oxygen therapy; CI, confidence interval.

Table 3 Univariate and multivariate Cox regression of the risk of burn injury while on LTOT

Factor	Univariate model, hazard ratio (95% CI)	Multivariate model, hazard ratio (95% CI)
Denmark vs Sweden	1.9 (1.0–3.7)	1.8 (1.0–3.5)
Men vs women	1.2 (0.7–2.0)	1.2 (0.7–2.0)
Age at start	0.97 (0.95–0.99)	0.97 (0.95–0.99)
COPD vs other diagnosis	1.02 (0.6–1.8)	1.2 (0.7–2.3)

Abbreviations: LTOT, long-term oxygen therapy; CI, confidence interval.