1. There was no mortality benefit associated with receiving long-term oxygen supplementation in patients with stable chronic obstructive pulmonary disease (COPD) and resting or exercise-induced moderate desaturation.
2. There were no significant differences between groups in terms of mortality, first hospitalization for any cause, or other measures of subjective quality of life and functional status.
Evidence Rating Level: 1 (Excellent)
Study Rundown: What is the mortality benefit of oxygen supplementation in patients with stable COPD and resting or exercise-induced moderate desaturation? This is the question that researchers from the Long-Term Oxygen Treatment Trial (LOTT) sought to answer. Studies from the 1970s showed that treatment with long-term oxygen therapy in patients with severe COPD was associated with a significant mortality benefit. However, underpowered trials in the 1990s failed to show a mortality benefit of oxygen therapy in patients with mild-to-moderate COPD.
In this unblinded controlled trial, 738 patients with stable COPD with moderate resting desaturation (SpO2 89-93%) or moderate exercise-induced desaturation were randomized to receive long-term supplemental oxygen or no intervention. Across a median follow-up period of 18.4 months, they report null results in terms of the composite primary outcome of overall mortality and time to hospitalization for any cause, these outcomes separately, or COPD exacerbations. Furthermore, there were no significant differences in terms of patient-reported subjective outcomes of quality of life.
This study draws strength from its randomized design and length of follow-up. The consistency of the null results will be important for policymakers deliberating over which patients with COPD qualify for long-term oxygen supplementation. Drawbacks include the lack of blinding, which may have biased self-reported outcomes, and the fact that seriously ill patients may not have enrolled in the trial.
In-Depth [randomized controlled trial]: Originally, LOTT sought to enroll patients who had stable COPD and moderate resting desaturation (SpO2 89 to 93%), but given the lower-than-expected outcome events, the trial was amended to include patients with moderate exercise-induced desaturation (during 6 minute walk test, SpO2 ≥ 80% for ≥5 minutes and <90% for ≥10 seconds). 738 patients meeting these criteria were randomized to receive supplemental oxygen (either nocturnal or continuous depending on the nature of their deficit) or no intervention. The patients were followed for 1 to 6 years with a median follow-up period of 18.4 months. There were no significant differences in the primary outcome, a composite of death or first hospitalization for any reason (HR 0.94, 95%CI 0.79-1.12, p = 0.52), mortality (p = 0.53), or first hospitalization for any cause (p = 0.37). Similarly, there were no consistent differences in groups in terms of measures of quality of life, anxiety, depression, or other measures of functional status (including distance walked in 6 minutes). There were 51 adverse events associated with oxygen therapy, primarily in the form of patients tripping over medical equipment, which occurred in 23 patients.
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