OBJECTIVES: Ambulatory oxygen may allow patients with fibrotic lung diseases to lead an active and independent life for longer. This economic analysis compares the health service costs and health-related benefits of ambulatory oxygen with those of usual care from a NHS perspective.

METHODS: Data on costs of ambulatory oxygen and condition-specific health-related quality of life outcomes (measured using the KBILD and SGRQ instruments) were collected alongside a UK prospective, multicentre randomised controlled crossover trial in which participants received ambulatory oxygen or no oxygen for a 2 week period each. The primary outcome measure was change in K-BILD scores. Benefits were also estimated as QALYs derived by translating SGRQ scores to EQ-5D-3L utility weights using a published mapping algorithm.

RESULTS: The incremental costs were £90.16 per person treated with a 3.47 increase in K-BILD score, leading to an incremental cost-effectiveness of £25.96 per unit increase in K-BILD. However, the estimates were highly uncertain. When the QALY was used as an outcome, ambulatory oxygen was dominated by usual care as it was both more costly than usual care and produced fewer QALYs (although the difference in QALYs was not statistically significant). There was a 0.059 probability that ambulatory oxygen would be considered cost-effective at a threshold of £20,000 per QALY.

CONCLUSIONS: The cost-effectiveness of ambulatory oxygen in ILD may depend on the outcome measure used. When evaluated using the K-BILD, its cost-effectiveness will depend on willingness to pay for an improvement in K-BILD score. When evaluated using the QALY (converted from SGRQ), ambulatory oxygen is unlikely to be cost-effective for managing interstitial lung disease. Findings are limited by the short duration of the trial and the lack of data supporting conversion of the trial’s primary outcome (KBILD) to QALYs.