Purpose
To determine the frequency that pattern dystrophy of the retinal pigment epithelium was misdiagnosed as age-related macular degeneration (AMD).
Methods
Patients with ICD-9 codes for AMD or retinal dystrophies (362.51, 362.52, 362.70, 362.74, and 362.76) of two retina specialists (SBB, NMB) at a university-based practice from January 1, 2005 through December 31, 2012 were retrospectively reviewed to identify those with a pattern dystrophy of the RPE as confirmed by fundus photographs and, when available, fluorescein angiograms, evaluated by two retina specialists (VC, NMB). Medical records and referral letters of those patients with a confirmed diagnosis of pattern dystrophy subsequently were reviewed to determine if the previous diagnosis was AMD.
Results
1092 patient records were reviewed, among which 86 had a diagnosis of pattern dystrophy of the RPE. Subsequent review confirmed 64 with pattern dystrophy and no large drusen (pattern dystrophy and no AMD); 17 additional cases had pattern dystrophy with ≥1 large druse in either eye (pattern dystrophy and AMD); 2 others had poor image quality; 3 others had co-existing vitreomacular interface abnormalities. Of the 64 cases of pattern dystrophy and no AMD, 36 (56%, 95% confidence interval [CI]: 43% to 69%) initially were referred as AMD. Among these 36 misdiagnosed patients, the median age was 69 years (interquartile range, 58 years to 82 years), 67% were women, 97% were Caucasian and 75% had pattern dystrophy in both eyes. Also among these 36 patients (61 eyes), the median presenting visual acuity was 20/40 (interquartile range, 20/25 to 20/63); 7 eyes (11%, 95%CI: 5% to 22%) had geographic atrophy involving the fovea; 4 eyes (7%, 95%CI: 2% to 16%) had geographic atrophy not involving the fovea; 4 eyes (6%, 95%CI: 2% to 15%) had choroidal neovascularization, all 4 received anti-VEGF therapy. None of the other 32 misdiagnosed patients received anti-VEGF therapy. Eleven (31%, 95%CI: 16% to 48%) of the 36 misdiagnosed patients were taking dietary supplements for AMD; all 11 were advised to consider discontinuing the supplements.
Conclusions
In this university-based clinic, while pattern dystrophy of the RPE is far less common than AMD, a majority of pattern dystrophy cases appear to be misdiagnosed as AMD which could impact physician-patient discussions regarding diagnosis, prognosis and management.
Keywords: 412 age-related macular degeneration •
696 retinal degenerations: hereditary