Letters Section Editor: Robert M. Golub,
MD, Senior Editor.
To the Editor: We were surprised by the results
and conclusions of the study on inpatient rehabilitation and follow-up by
Dr Ottenbacher and colleagues1 and are concerned
that they may be in error due to use of Functional Independence Measure (FIM)
efficiency as an outcome measure. The finding that FIM efficiency (defined
as the change in functional status from admission to discharge divided by
the length of stay [LOS]) increased over time as LOS decreased is not unexpected.
Given that after a certain point the rate of functional status improvement
decreases with length of stay, FIM efficiency must bear an inverse relationship
to LOS, all other factors remaining equal. For this reason, a better measure
is necessary in order to draw conclusions.
Duncan PW, DeJong G, Hoenig H, Vogel B. Length of Stay, Functional Outcome, and Mortality Following Medical Rehabilitation. JAMA. 2005;293(3):294-295. doi:10.1001/jama.293.3.294-d