Concordance analysis between the glaucoma stages defined from neuroretinal rims and from visual field
2021-07-11
Objective
The purpose of this study is to determine if there exists concordance between the staging system for clasifiying glaucoma from the neuroretinal rims (see http://aprendeconalf.es/glaucoma-staging/clusters.html) and the classic classification with the visual field.
Analysis of visual field
Boxplot of visual field by Glaucoma stages
Conficence intervals for the mean of visual field by neuroretinal rims glaucoma stages
| Stage | n | mean | sd | se | lo.ci | up.ci |
|---|---|---|---|---|---|---|
| I | 34 | -1.196 | 2.388 | 0.4096 | -2.029 | -0.3622 |
| II | 39 | -1.405 | 2.478 | 0.3968 | -2.208 | -0.6018 |
| III | 33 | -7.441 | 7.116 | 1.2388 | -9.964 | -4.9176 |
| IV | 26 | -19.002 | 9.091 | 1.7829 | -22.674 | -15.3304 |
Visual field stages
Definimos a partir del campo visual 4 estadíos al igual que se hizo con los anillos retinianos.
We define from the visual field 4 stages the same as we did for the neuroretinal rims.
| Stage.VF | n | mean | sd | se | lo.ci | up.ci |
|---|---|---|---|---|---|---|
| I | 55 | -0.0875 | 1.199 | 0.1617 | -0.4116 | 0.2367 |
| II | 44 | -4.2889 | 1.557 | 0.2347 | -4.7623 | -3.8154 |
| III | 17 | -12.5394 | 3.077 | 0.7462 | -14.1213 | -10.9575 |
| IV | 16 | -26.7731 | 3.309 | 0.8273 | -28.5364 | -25.0098 |
Concordance analysis
We compute the Kendall’s coefficient of concordance to check the agreement between the Glaucoma stages and the visual field stages.
Kendall's coefficient of concordance Wt
Subjects = 132
Raters = 2
Wt = 0.831
Chisq(131) = 218
p-value = 2.89e-06 We conclude that there is a strong concordance (\(W=0.831\)) and very significant (\(p<0.01\)) between both rankings of glaucoma classification.