Age-related macular degeneration and complement activation-related diseases: a population-based case-control study

Recent evidence suggests an important role for the complement system in the etiology of age-related macular degeneration (AMD). We aimed to investigate whether other diseases known to be associated with complement activation are associated with AMD.

Case-control study.

We reviewed medical records from the United Kingdom General Practice Research Database (GPRD). Cases (n = 18 007) were defined as people aged >/=50 years with a first diagnosis of AMD while registered with a practice included in the GPRD between 1987 and 2002. For each case, 5 controls with no record of AMD (n = 86 169) were matched by gender, practice, and age (within 5 years).

Records were searched for diagnoses of systemic lupus erythematosus (SLE), glomerulonephritis, and diabetic nephropathy occurring before the AMD diagnosis date (or equivalent date for controls).

Diagnosis of AMD.

A diagnosis of SLE was found in 0.07% of controls and 0.13% of AMD cases (confounder-adjusted odds ratio [OR], 1.69; 95% confidence interval [CI], 1.05-2.72). Glomerulonephritis was diagnosed in 0.13% of controls and 0.2% of cases (adjusted OR 1.46; 95% CI, 0.99-2.13). Diabetic nephropathy was strongly associated with AMD with an adjusted OR of 3.00 and a 95% CI of 1.55-5.97, which was independent of the association of diabetes with AMD.

Specific diseases that are associated with complement activation are also associated with AMD. The impact of diabetic nephropathy on AMD may be larger than previously recognized.