The risk of burn injury during long-term oxygen therapy: a 17-year longitudinal national study in Sweden

Figures & data

Table 1 Definition of possible burn injury

Data item	ICD-9 codes	ICD-10 codes
Diagnosis	906; 940–949	H16; J68; L55.0–L55.2; L55.8; L55.9; T20–T32; T41.5; T59.8; T59.9; T95.0; Y48.5
Exposure	E890; E899; E837; E868; E919; E869.8; E869.9; E958.1; E929.4; E923.2; E968.0	X00–X09; X14; X47; X49; X69; X76; X77; X88; X97; X98; Y17; Y19; Y25–Y27; W36; ZZA
Procedure	8902; 8903; 8909; 8999; 8930; 8960; 8961	QAB; QAD; QAE; QAC00; QAF10; QAF99; QBB; QBD; QBE; QBC00; QBF10; QBF99; QCB; QCD; QCE; QCC00; QCF10; QCF99; QDB; QDD; QDE; QDC00; QDF10; QDF99; QXB; QXD; QXE; QXC00; QXF10; QXF99

Note: Definition of possible burn injury used for screening of diagnoses, exposures, and procedure codes in the National Patient Register for inpatient and outpatient care and the National Causes of Death Register (diagnoses only).

Abbreviation: ICD, International Classification of Disease.

Table 2 Characteristics of 12,497 patients starting LTOT in Sweden, 1992–2009

Characteristic	N=12,497
Female, %	53
PaO2 on air, kPa (mmHg), mean ± SD, n (%)	6.6±0.9 (49.5±7)
PaCO2 on air, kPa (mmHg), mean ± SD, n (%)	6.2±1.3 (46.5±10)
PaO2 on oxygen, kPa (mmHg), mean ± SD, n (%)	8.9±1.2 (66.8±9)
PaCO2 on oxygen, kPa (mmHg), mean ± SD, n (%)	6.5±1.3 (48.8±10)
FEV1, L, mean ± SD	0.9±0.6
FVC, L, mean ± SD	1.8±0.8
Oxygen dose, L/min, mean ± SD	1.7±1.1
Oxygen duration, h/24 hours, mean ± SD	18±3
Smoking status, %
Never	14
Past	81
Current	2
Missing	3
WHO performance status, %
0–1	46
2–4	47
Missing	7
Burn injuries that occurred before LTOT start	53

Abbreviations: LTOT, long-term oxygen therapy; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; PaCO₂, arterial partial pressure of carbon dioxide; PaO₂, arterial partial pressure of oxygen; WHO, World Health Organization.

Table 3 Burn injuries during LTOT in 12,497 patients

Patient group	Burn injuries, n	Total person-years of LTOT	Rate (95% CI) per 100,000 person-years
Overall	17	27,890	61 (36–98)
Men	4	11,674	34 (9–88)
Women	13	16,215	80 (43–137)
Ever-smokers	14	23,268	60 (33–101)
Never-smokers	3	3,373	89 (18–260)
WHO performance status
0–1	9	15,652	57 (26–109)
2–4	8	10,452	76 (33–151)
Main diagnoses
COPD	14	22,794	61 (34–103)
Others	3	5,096	59 (12–172)
LTOT start year
Before 1998	3	10,060	30 (6–87)
After 1998	14	17,831	79 (43–132)

Note: Rate of burn injury during LTOT per 100,000 person-years in Sweden.

Abbreviations: LTOT, long-term oxygen therapy; CI, confidence interval; WHO, World Health Organization; COPD, chronic obstructive pulmonary disease.