Table 4.

Duration of interval that elapses when the Spigelman staging system increases by one stage or by two stages

	Median years	Range years
Overall one stage higher (36 episodes)	4	1–18
Change from stage 0 to I (6 episodes)	3.5	3–18
Change from stage I to II (6 episodes)	5	1–10
Change from stage II to III (15 episodes)	4	1–15
Change from stage III to IV (9 episodes)	4	1–8
Overall two stages higher (13 episodes) without intercurrent endoscopy	7	1–28
Change from 0 to II (8 episodes)	6.5	1–28
Change from I to III (1 episode)	11
Change from II to IV (4 episodes)	4	1–13