Table 1.

Comparison of demographic variables and paraclinical data of the participants in three groups before the intervention

Variable	Placebo group, N=50	Pethidine 5 mg group, N=50	Pethidine 10 mg group, N=50	P-value
Age; mean ± SD	31.8±4.7	31±5.5	31.5±5.6	0.76
Duration of surgery; mean ± SD	55.2±15.1	57.6±15.9	53.8±13.7	0.44
Preoperative hemoglobin level; mean ± SD	12.5±1.2	12.5±1.1	12.5±1.2	0.85
Preoperative hematocrit level; mean ± SD	38.1±3.7	37.7±3	37.8±3.3	0.71

Note: Analysis of variance test was used to compare the variables among the three groups.

Abbreviation: SD, standard deviation.