. Author manuscript; available in PMC: 2023 Jan 1.

Published in final edited form as: Am J Ophthalmol. 2021 Jul 21;233:189–215. doi: 10.1016/j.ajo.2021.07.016

Table 7.

ROP Zone and Stage Severity Over Time

Year	1990–1999				2000–2009				2010–2019				TOTAL
	N	%	BW	GA	N	%	BW	GA	N	%	BW	GA	N	%	BW	GA

Zone 1	11	1%	711.7	25.1	64	7%	616.4	24.4	70	15%	611.2	24.3	145	6.6%	619.3	24.4
Zone 2	713	86%	834.6	26.5	774	87%	815.6	26.3	396	84%	808.1	26.1	1883	86%	820.6	26.3
Zone 3	101	12%	1008.9	28.0	54	6%	1065.8	28.9	7	1%	932.1	27.1	162	7.4%	1023.9	28.2

Total	825		858.5	26.7	892		815.5	26.3	473		780.7	25.8	2190
									p < 0.001^ǂ						p < 0.001^#	p < 0.001^#
Stage 1	275	33%	982.1	27.8	310	35%	927.2	27.4	217	46%	877.1	26.6	802	37%	931.6	27.3
Stage 2	423	51%	815.2	26.3	329	37%	800.4	26.2	220	47%	711.2	25.4	972	44%	784.9	26.0
Stage 3	122	15%	708.1	25.2	247	28%	700.3	25.1	36	8%	624.7	24.5	405	18%	694.7	25.1
Stage 4	6	1%	843.3	26.7	4	0%	570.0	24.3	0	0%			10	0.5%	734.0	25.7
Stage 5	1	0%	610.0	24.0	3	0%	595.0	24.3	0	0%			4	0.2%	600.0	24.3

Total	827		858.5	26.7	893		815.5	26.3	473		780.7	25.8	2193		823.2	26.3
									p < 0.001^ǂ						p < 0.001^#	p < 0.001^#

ANOVA analysis comparing changes in birthweight and gestational age across zone and stage severity

^ǂ

Chi-square analysis comparing change in incidence of severity groups across all 3 decades

Abbreviations: BW - birthweight, g - grams, GA - gestational age, n - number