RT Journal
A1 Suissa S, Ernst P
T1 ANtibiotic therapy in patients hospitalized with acute chronic obstructive pulmonary disease
JF JAMA
JO JAMA
YR 2010
FD September 22
VO 304
IS 12
SP 1325
OP 1327
DO 10.1001/jama.2010.1338
UL http://dx.doi.org/10.1001/jama.2010.1338
AB 
To the Editor: Dr Rothberg and colleagues1 reported that antibiotic therapy for the treatment of acute exacerbations of COPD was associated with a lower rate of inpatient mortality (1.04% vs 1.59%). This difference may have been affected by immortal time bias, which can lead to substantial underestimates of the rate ratio by artificially generating a longer survival for treated patients.2- 3