Introduction A previous survey highlighted a very high degree of physiologically unnecessary home oxygen use in COPD patients (Bhattacharya M, Potter A, Mukherjee R. Assessing for Long Term Oxygen Therapy (LTOT) in an English town. Am J Resp Crit Care Med 2008;177:A665), a common reason for which was noted to be many physicians' belief that issuing oxygen on discharge of breathless COPD patients prevents re-admissions.
Methods A retrospective review of 1942 COPD admissions (including re-admissions) of Birmingham East and North Primary Care Trust patients from April 2007 to November 2010 based on International Classification of Diseases (ICD) coding (J44) of which 295 received home oxygen on discharge; Welch's 2-sample t-test was applied to assess the significance of the difference in the admission rates of the two groups of COPD patients who receive and did not receive LTOT on discharge. A further analysis was performed in a cohort of 186 patients (93 discharged with and 93 without oxygen) with known values of Forced Expiratory Volume in 1 second (FEV1) to examine if oxygen prescription had an effect on the re-admission rate, taking the best FEV1 in the 5 years preceding the first admission. In the known FEV1 group, the logarithm of the number of admissions was taken to account for non-linearity and to count the readmissions only (as log 1=0).
Results In the whole group (COPD diagnosis based on ICD coding: n=1942), the mean annual admission rate in the home oxygen group was 3.18 and 1.67 in the other (p<0.00000000001). In the group with known FEV1 (n=186), the number of re-admissions depended significantly on the FEV1 (p=0.000362); home oxygen prescription on discharge did not have any significant effect on re-admissions (p=0.897).
Conclusion LTOT prescription on discharge is actually associated with a crude increase in hospital admissions of COPD patients. FEV1 remains the strongest predictor of re-admissions. Further prospective studies including detailed pre-discharge physiological assessment prior to issuing home oxygen are necessary.