By Purnima S. Patel, MD
Could periodontal disease be an independent risk factors for AMD? This database analysis published in Retina shows that people with periodontal disease age 60 and younger are nearly twice as likely to have AMD.
Periodontal disease is a common chronic infectious/inflammatory disease that peaks in prevalence in late middle age, and has previously been shown to be an independent risk factor for atherosclerotic vascular disease.
In atherosclerotic disease, periodontal infections can cause molecular mimicry between foreign and self-peptides to produce cross activation of autoreactive B cells and T cells that can lead to tissue pathology.
Similar molecular mimicry mechanisms are also suspected of triggering an inflammatory response that may play a role in the pathogenesis of AMD. Oral pathogens have also been identified in neovascular membranes excised from patients with AMD.
To find out if periodontal disease is independently associated with AMD, investigators analyzed data from the National Health and Nutrition Examination Survey, which included nearly 6,000 adults age 40 and older.
After controlling for sex, race, education, poverty-income ratio, smoking, hypertension, body mass index, coronary vascular disease and C- reactive protein, they found that periodontal disease was independently associated with an increased risk for AMD (odds ratio = 1.96, 95% confidence interval = 1.22–3.14, P = 0.006) for those aged 60 years or younger but not for those older than 60 years (odds ratio = 1.32, confidence interval = 0.93–1.90, P = 0.120).
This was a well-constructed study, with a large sample size and standardized data collection and grading protocol. But it has one important limitation. It lacks participants’ genetic information, specifically the complement factor H gene. Mutations in the CFH gene are known to inhibit regulation of the complement system and independently increase the risk for AMD. Additionally, recall bias could have affected the recording of some variables that relied on self-reporting to measure disease history.
The authors conclude that understanding the influence of oral health on AMD may aid in limiting the disease's visual manifestations, and may lead to a reduced risk for other age-related diseases.