Table 1.

The number of studies and types of UD performed over the last four decades (five studies were overlapping*).

Year	No. of countries (studies*)	No. of patients	Validated scale (urology specific) used, n	Prospective/retrospective, n	IC/CD/NB/unspecified, n	Open/lap or robotic, n
1980–1997	6 (15)	1206	2 (0)	1/14	784/368/54/0	1206/0
1998–2007	11 (24)	2464	20 (6)	4/20	899/428/1105/32	2432/0
2008–2017	18 (41)	4747	37 (23)	14/27	1664/282/2105/696	3939/112
Total	35 (80)	8417	59 (29)	19/61	3347/1078/3264/728	7577/112

lap, laparoscopic.