A nationwide structure for valid long-term oxygen therapy: 29-year prospective data in Sweden

Abstract

Background: Long-term oxygen therapy (LTOT) improves prognosis in COPD with severe hypoxemia. However, adherence to criteria for eligibility and quality of LTOT is often insufficient and varies between countries. The aim of this study was to evaluate a national structure for prescription and management of LTOT over three decades in Sweden.

Methods: The study was a prospective, population-based study of 23,909 patients on LTOT from 1987 to 2015 in the Swedish National Register of Respiratory Failure (Swedevox). We assessed the prevalence, incidence, and structure of LTOT; completeness of registration in Swedevox; and validity of prescription and management of LTOT in Sweden according to seven published quality indicators.

Results: LTOT was prescribed by 48 respiratory or medicine units and managed mainly by specialized oxygen nurses. Swedevox had a stable completeness of 85% of patients starting LTOT since 1987. The national incidence of LTOT increased from 3.9 to 14.7/100,000 inhabitants over the time period. In 2015, 2,596 patients had ongoing therapeutic LTOT in the registry, a national prevalence of 31.6/100,000. Adherence to prescription recommendations and fulfillment of quality criteria was stable or improved over time. Of patients starting LTOT in 2015, 88% had severe hypoxemia (partial pressure of arterial oxygen [PaO₂] <7.4 kPa) and 97% had any degree of hypoxemia (PaO₂ <8.0 kPa); 98% were prescribed oxygen ≥15 hours/day or more; 76% had both stationary and mobile oxygen equipment; 75% had a mean PaO₂ >8.0 kPa breathing oxygen; and 98% were non-smokers.

Conclusion: We present a structure for prescription, management, and follow-up of LTOT. The national registry effectively monitored adherence to prescription recommendations and most likely contributed to improved quality of care.

Keywords: COPD; LTOT; hypoxemia; oxygen; respiratory failure.

Figure 1

Primary physician-diagnosed cause for starting LTOT. Notes: Reasons for starting LTOT: airways disease, parenchymal disease, pulmonary vascular disease, and other. Airways disease was the main underlying cause for prescribing LTOT (69%). Abbreviation: LTOT, long-term oxygen therapy.

Figure 2

Mean PaO₂ on room air (±2 SD) (A) and mean PaO₂ on oxygen (±2 SD) (B). Notes: The mean PaO₂ breathing ambient air before LTOT start was stable during the study period at 6.5 (SD, 0.9) kPa. The mean PaO₂ on oxygen was stable during the study period at 8.6 (SD, 1.2) kPa. Abbreviations: PaO₂ (air), arterial blood gas tension of oxygen on air; SD, standard deviation; PaO₂ (oxygen), arterial blood gas tension of oxygen on oxygen; LTOT, long-term oxygen therapy.

Figure 3

Percentage fulfilling criteria for LTOT prescription, oxygen delivery mode, and reevaluation of treatment (A) and percentage fulfilling quality criteria for LTOT (B). Notes: The criteria in (A) pertain to the percentage of LTOT patients with prescribed daily LTOT duration above 16 hours/day; portable oxygen at 1-year follow-up, and reevaluation of hypoxemia when LTOT was started in relation to an exacerbation. Oxygen was prescribed for 15 hours/day or more in 98% of patients; prescription of mobile oxygen to ambulatory patients varied during the study period but the aim of >50% was fulfilled; and an increase in reevaluation of oxygen treatment if started in relation to an exacerbation was seen during the study period. The criteria in (B) pertain to the percentage of LTOT patients being non-smokers and the absence of maintenance treatment with oral corticosteroids. The rate of non-smokers was stable at 98% during the study period, in accordance with the quality criteria. Maintenance treatment with oral glucocorticoids was low during the study period. Abbreviation: LTOT, long-term oxygen therapy.