[Adherence to ambulatory oxygen therapy. Assessment and determinants in patients receiving long-term oxygen therapy]

The provision of ambulatory oxygen in addition to a stationary oxygen supply has been suggested to increase adherence to long-term oxygen therapy (LTOT) and promote ambulation. The degree of adherence to ambulatory oxygen therapy and the determinants of adherence remain largely unknown.

These were assessed in patients treated with LTOT (oxygen concentrator plus small oxygen cylinders with a demand oxygen delivery system [DODS]) in a tertiary care hospital supplied according to the Belgian criteria for LTOT refunding. Adherence to ambulatory oxygen was defined as mean use of ambulatory oxygen greater than 30 min/day. Patients' files were reviewed and a questionnaire was sent for assessing patients' view on the use of ambulatory oxygen.

Forty-six patients were included. Mean use of ambulatory oxygen was 40±36min/day. Twenty-three patients were adherent to ambulatory oxygen according to our definition. There was no difference between adherent and non-adherent patients regarding lung function or blood gases, nor was there any correlation between mean daily ambulatory oxygen use and any parameter. However, patients with MMRC 4 dyspnoea scale had a significantly lower use of ambulatory oxygen than patients with less severe dyspnoea (mean 33±24 vs 42±39min/day ; P=0.03) despite self reporting better adherence to LTOT.

Adherence to ambulatory oxygen in this series of patients is quite low but at the higher end of data reported previously. Patients with MMRC 4 dyspnoea scale had a lower use of ambulatory oxygen despite reporting better adherence to LTOT. We could not identify any other predictive factors of adherence to ambulatory oxygen.