Purpose
To investigate the associations between inflammatory markers and incidence of early and late age-related macular degeneration (AMD) in a cataract surgical cohort.
Methods
We followed cataract surgical patients from Westmead Hospital, Sydney, aged 64+ years for 5 post-operative years in the Australian Cataract Surgery and Age Related Macular Degeneration (CSAMD) Study. We performed annual examinations with retinal photography to assess incident AMD using a side-by-side grading method. Preoperative and one-month postoperative images provided baseline information. Incident early AMD was defined as the new appearance of either indistinct soft/reticular drusen or co-existing retinal pigmentary abnormality and distinct soft drusen, in persons without early AMD in either eye at baseline. Incident late AMD was defined as the new appearance of neovascular AMD or geographic atrophy in persons without previous late AMD in either eye. White cell count (WCC), high sensitive C-reactive protein (hs-CRP) and fibrinogen were assessed from blood taken 3-5 years after surgery.
Results
Of 1930 patients recruited, 1597 (82.7%) were followed up for 1 to 5 years postoperatively; 1277 (80.0% of 1579) had gradable retinal images at baseline and follow-up visits and were at risk of late AMD. Of the 1277, 791 (61.9%) had blood samples taken. Median (interquartile range) values were: WCC, 6.90 (5.80-8.20) x10-9/L; hs-CRP, 2.31 (1.08-4.65) mg/L; fibrinogen, 3.60 (3.10-4.10) g/L. Of 1277 at risk, 45 developed late AMD. Of 921 at risk, 143 developed early AMD. After adjusting for age, sex and current smoking, WCC above the median was associated with increased risk of late AMD (odds ratio, OR, 2.21, 95% confidence interval, CI, 1.04-4.73); hs-CRP above the median was associated with increased risk of early AMD (OR 1.64, 95% CI 1.08-2.48); additional adjustment for hs-CRP in the model for late AMD, or WCC in the model for early AMD, did not alter these associations. Further adjustment for baseline large drusen and retinal pigment abnormalities weakened the association of WCC with late AMD (OR 1.84, 95% CI 0.84-1.05). Fibrinogen was not associated with early or late AMD incidence.
Conclusions
The specific associations of WCC with late AMD and hs-CRP with early AMD suggest different inflammatory processes leading to late and early AMD in patients after cataract surgery.
Keywords: 412 age-related macular degeneration •
557 inflammation •
464 clinical (human) or epidemiologic studies: risk factor assessment