Professor Tator et al.! seek to show that admitting patients to an acute spinal injury service between 1974 and 1981 had a better outcome than patients treated between 1947 and 1973. They seek to show that mortality, length of stay and neurological recovery were better in the group admitted to a spinal unit. They point out that: ' ... The most robust clinical study designs involve prospective random allocation of similar groups of patients to either treatment or control groups so that significant differences between the two groups can be attributed with confidence to the treatment. In the present study it would not have been feasible to randomly allocate the patients to either the ASCIU or another hospital . . .' However, the major flaw that they failed to evaluate is that treatment has changed between 1947/73 and 1974/81. Even on a spinal unit, treatment outcomes depend on the treatment available at the time.