What test can be used to compare the two treatment groups on the primary endpoint? Ophthalmology The

Question:

What test can be used to compare the two treatment groups on the primary endpoint?

Ophthalmology

The Sorbinil Retinopathy Trial was conducted among 497 type I (insulin-dependent) diabetic patients who had little or no evidence of retinopathy at baseline [31]. Retinopathies are abnormalities of the retina that sometimes occur among diabetic patients and can result in substantial losses of vision in advanced stages. Patients were randomized to either Sorbinil, an aldose-reductase inhibitor, or placebo and were seen at 1 year and then every 9 months up to 48 months after randomization. In addition, all subjects had a final visit at the end of the trial (max = 56 months). Sixteen of the patients provided no follow-up. The primary endpoint of the trial was based on change in retinopathy severity level from baseline to maximum follow-up (i.e., severity level at maximum follow-up ˆ’ severity level at baseline). An ordinal grading scale was used to evaluate change: 2+ levels better, 1 level better, no change, 1 level worse, €¦, 5+ levels worse. The outcome data by treatment group are given in Table 10.49.

Table 10.49: Outcome data for the Sorbinil Retinopathy Trial (n = 481) change in retinopathy level

Better Worse No change 1 Level 2 Levels 3 Levels 4 Levels 5+ Levels Total 2+ Levels Group 1 Level Placebo Sorbinil 17 84