Table 1.

Summary of results

	Averagea	Spreada	Number	Test and test statistic	P-value
Age
Group A	72	65–79	109	Mann-Whitney U-test = 5771	0.716
Group B	70	64–77	109
Length of postoperative stay (days)
Group A	7	7–9	109	Mann-Whitney U-test = 3351	< 0.001
Group B	9	8–11	109
Pre-operative haemoglobin level (g/dl)
Group A	13.8	12.8–14.4	109	–	–
Group B	13.5	12.7–14.6	109
Postoperative haemoglobin level (g/dl)
Group A	10.8	10.0–11.9	108c	–	–
Group B	10.2	9.3–11.6	103d
Peri-operative haemoglobin dropb (g/dl)
Group A	2.79	1.13	108	Unpaired t-test t209 = 3.521	0.001
Group B	3.35	1.18	103

^aThe average and spread represent the median and inter-quartile range unless stated otherwise.

^bThe average and spread shown are the mean and the SD.

^cOne patient in Group A received allogenic transfusion in the recovery room prior to postoperative haemoglobin check – this patient's measurement was not included in postoperative haemoglobin calculation.

^dSix patients in Group B received allogenic transfusion in the recovery room prior to postoperative haemoglobin check – these patients' measurements were not included in postoperative haemoglobin calculation.