Role of variation coefficient of stone density in determining success of shock wave lithotripsy in urinary calculi

Table 2 Characteristics of patients and stones in stone free and failure groups

Parameter	Unsuccessful group	Successful group	P value
Age (years)1	38.82 ± 13.84	38.94 ± 15.13	0.93
Gender, n (%)			0.78
Male	118	176
Female	47	66
Stone volume2	240 (80-439)	200 (36-400)	< 0.0001
SSD (cm)1	9.63 ± 2.32	9.45 ± 2.56	0.47
Stone density (HUs)2	1217.30 (318-2000)	720.00 (110-1800)	0.0001
SHI (HUs)2	172.95 (22.7-571.4)	190.15 (17.7-583.9)	< 0.0001
VCSD2	15 (2-92)	28 (4-83)	< 0.0001
Stone laterality, n (%))			0.19
Left sided	80	133
Right sided	85	109
Stone location			0.69
Upper pole	12	17
Mid pole	29	38
Lower pole	46	79
Pelvis	39	55
Ureter	39	53

¹Continuous variables shown in mean (standard deviation).

²Continuous variables shown in median (quartile).

SHI: Stone heterogeneity index; HUs: Hounsfield units; VCSD: Variation coefficient of stone density; SSD: Skin-stone distance.