The expected LOS does appear to be lower in non-anaemic patients. However, this was not proven to be statistically significantly when compared to patients in whom the anaemia was not corrected (IRR = 0.97, P > 0.05). However, using the same comparison group the expected LOS is 53% higher in participants whose anaemia was corrected (IRR = 1.53, P < 0.001).
Site of surgery showed a statistically significant association with the expected LOS (IRR = 0.9, P = 0.05), which indicates that the expected LOS was 10% lower among participants who underwent knee surgery compared to participants who underwent hip surgery. Age was also a significant predictor of LOS. The expected LOS in patients aged 65 – 75 and > 75 was 13% (P < 0.05) and 45% (P < 0.001) higher compared to patients aged < 65 years, respectively. Gender showed a statistically significant association with LOS (IRR = 0.92, P < 0.05) where the expected LOS was 8% lower in men compared to women. Finally, blood transfusion significantly predicted a 49% increase in the expected LOS (IRR = 1.49, P < 0.001).