Table 5.

Comparison between umbilicated stones or not

	Males		Females		Total
Morphological type	First stone	Recurrence	First stone	Recurrence	First stone	Recurrence
Umbilicated stones with Randall’s plaque
Type Ia alone	1549	954 (38.1)***,b,xx	501	237 (32.1)x	2050	1191 (36.7)****
Mixed types I+II	869	650 (42.8)**,b, ✝✝	332	171 (34.0)	1201	821 (40.6)✝✝
Mixed types II+I	360	328 (47.7)c, ✝✝✝✝	108	57 (34.6)	468	385 (45.1)✝✝✝✝
Total	2778	1932 (41.0)**,d,xx	941	465 (33.1)xx	3719	2397 (39.2)*,xx
Stones without any umbilication nor Randall’s plaque
Type Ia alone	1551	781 (33.5)b	674	262 (28.0)xx	2225	1043 (31.9)xx
I+II	1332	825 (38.2)a,xx, ✝✝✝	548	282 (34.0)x,✝✝	1880	1107 (37.1)xx,✝✝✝✝
II+I	1433	1105 (43.5)a,✝✝✝✝	493	323 (39.6)✝✝✝✝	1926	1428 (42.6)✝✝✝✝
Total	4316	2711 (38.6)c,xx	1715	867 (33.6)xx	6031	3578 (37.2)xx

^*p=0.02;

^**p < 0.01;

^***p < 0.001;

^****p < 0.0001 vs non-umbilicated stones

^ap < 0.05;

^bp < 0.01;

^cp < 0.001;

^dp < 0.0001 vs females

^xp < 0.01;

^xxp < 0.0001 vs mean occurrence of stone recurrence for a given gender

^✝p < 0.05;

^✝✝p < 0.01;

^✝✝✝p < 0.001;

^✝✝✝✝p < 0.0001 vs type Ia stones for a given gender

Stones of mixed types I+II include stones with various subtypes where COM was the main crystalline phase of calcium oxalate. By contrast, stones of mixed types II+I include stones with various subtypes where COD was the main crystalline phase of calcium oxalate.