Regression Discontinuity and Randomized Controlled Trial Estimates: An Application to The Mycotic Ulcer Treatment Trials

Regression Discontinuity and Randomized Controlled Trial Estimates: An Application to The Mycotic Ulcer Treatment Trials OPHTHALMIC EPIDEMIOLOGY Oldenburg, C. E., Prajna, N., Krishnan, T., Rajaraman, R., Srinivasan, M., Ray, K. J., O'Brien, K. S., Glymour, M., Porco, T. C., Acharya, N. R., Rose-Nussbaumer, J., Lietman, T. M. 2018; 25 (4): 315-322

Abstract

We compare results from regression discontinuity (RD) analysis to primary results of a randomized controlled trial (RCT) utilizing data from two contemporaneous RCTs for treatment of fungal corneal ulcers.Patients were enrolled in the Mycotic Ulcer Treatment Trials I and II (MUTT I & MUTT II) based on baseline visual acuity: patients with acuity = 20/400 (logMAR 1.3) enrolled in MUTT I, and >20/400 in MUTT II. MUTT I investigated the effect of topical natamycin versus voriconazole on best spectacle-corrected visual acuity. MUTT II investigated the effect of topical voriconazole plus placebo versus topical voriconazole plus oral voriconazole. We compared the RD estimate (natamycin arm of MUTT I [N = 162] versus placebo arm of MUTT II [N = 54]) to the RCT estimate from MUTT I (topical natamycin [N = 162] versus topical voriconazole [N = 161]).In the RD, patients receiving natamycin had mean improvement of 4-lines of visual acuity at 3 months (logMAR -0.39, 95% CI: -0.61, -0.17) compared to topical voriconazole plus placebo, and 2-lines in the RCT (logMAR -0.18, 95% CI: -0.30, -0.05) compared to topical voriconazole.The RD and RCT estimates were similar, although the RD design overestimated effects compared to the RCT.

View details for DOI 10.1080/09286586.2018.1469156

View details for Web of Science ID 000433991400006

View details for PubMedID 29718751

View details for PubMedCentralID PMC5980795