Abstract
Purpose: :
To present 9–year incidence data on OAG and evaluate risk factors for definite OAG, based on African–descent participants of the BESs cohort (n=4,314; 40–84 years at baseline; 81–85% participation over 9 years).
Methods: :
Definite OAG was defined by visual field defects plus optic disc damage in at least one eye, after ophthalmologic exclusion of other causes. Persons partly meeting these criteria were classified as suspect OAG. Cumulative 9–year incidence was defined as the development of OAG in at least one eye during follow–up, among persons without OAG in both eyes at baseline. Incidence rates were estimated by the product–limit approach. Relative risk ratios (RR) with 95% confidence intervals (CI) were based on Cox regression models with discrete time.
Results: :
Over 9 years, 125 persons developed definite OAG. Over half (n=66; 53%) of these individuals were unaware of their diagnosis. The incidence of definite OAG was 4.4% (95% CI: 3.7–5.2) and significantly increased with baseline age, from 2.2% at 40–49 years to 7.9% at ages 70+. Men had a slightly higher incidence than women (4.9% vs. 4.1%; RR= 1.3 (0.9,1.8)). The incidence of suspect OAG was 5.6%, for an overall OAG incidence of 8.4%. Baseline factors influencing risk of definite OAG were higher intraocular pressure (RR=1.1 (1.06–1.13) per mmHg higher), OAG family history (RR=2.4 (1.4–4.0)), lower perfusion pressures (e.g., RR for low mean perfusion pressure= 2.6 (1.4–4.6)) and lower systolic blood pressure (RR=0.91 (0.84–1.00) per 10 mmHg increase).
Conclusions: :
This appears to be the first report of long–term OAG risk based on a sizable number of incident cases. A high OAG risk (∼0.5%/year) exists in this population, which has the same ancestry as African–Americans, yet half of the incident cases were undetected. In addition to higher IOP and family history, results suggest a role for vascular factors, since lower perfusion pressure and lower systolic blood pressure at baseline increased long–term OAG risk. These results confirm our earlier findings, which were based on 4–year incidence data.
Keywords: clinical (human) or epidemiologic studies: prevalence/incidence • clinical (human) or epidemiologic studies: risk factor assessment • intraocular pressure