Case-control Study Of The Risk Factors For Age Related Macular Degeneration

Objective:Age related macular degeneration (AMD) is a degenerative disease of the macular and the leading cause of blindness and visual impairment among people aged 50 years or over in the United States and other developed countries throughout the world. The incidence is increasing with the tendency of outstanding population aging in Chinese social. The pathogeny and pathogenesis of AMD are unknown, and there is no effective treatment. Given that AMD induced visual impairment is essentially an old age affliction, most investigators have therefore concentrated on the identification of risk factors associated with the development and progression of AMD to find modifiable factors, so that patients can be advised on how to prevent the development of AMD. In view of the undesirable effects of AMD on the patient,s working ability and mental health, identification and modification of these risk factors may be effective in decreasing the incidence and controlling the progression of AMD. In this article, we explore the possible risk factors of AMD.Methods: A group comparing case-control study was carried out. Eighty-five AMD were diagnosed in three hospitals from January 2005 to January 2007. The controls were one hundred subjects without AMD. All the participants underwent stardard questionnaire survey and detail eye examination. Stereoscopic color fundus photographs and fundus fluorescein angiography were used to the cases. Uniform questionnaires were administered to obtain demographic information and exposure information of related factors, such as age, gender, occupation, education, body mass index (BMI), history of sunlight exposure, history of smoking and drinking, history of antioxidant use, hypertension, hyperlipemia, angiosclerosisand,diabetes, refraction error, history of cataract and previous cataract operation. Using SPSS 11.5 for Windows software package established databank. Statistical analysis ofχ2 test and multi-factors non-conditional Logistic regression were performed to screen the risk factors.Results: One hundred controls were compared with eighty-five patients with AMD. Mean age was 71.28 years (50-85years) for AMD cases and 70.85 years (50-86years) for controls. Thirty-six (constituent ratio 42.4%) of the subjects in AMD group and forty seven (47.0%) of those in the control group were male respectively. Fifty-five (64.7%)of patients with AMD were atrophic AMD and others were exudative AMD (35.3%). The data of AMD cases and controls have comparability by balanced test with regard to age and gender. Statistical analysis of Logistic regression displayed that ultimate factors, such as smoking, taking antioxidant and hypertension entered the model, in which AMD was dependent variable and risk factors were independent variables. The established regression equation was㏑ [P/(1-P)] = -0.485 + 0.778 X1 - 0.897 X2 + 0.694 X3. The multi-factors Logistic regression show that smoking OR (odds ratio)=2.177,95% CI (confidence interval)=1.167～4.062, and hypertension(OR=2.001,95% CI =1.063～3.766)are risk factors for AMD, while taking antioxidant regularly (OR=0.408,95% CI =0.200～0.832)is a protective factor for AMD. The dose-response were observed between smoking and odds ratio of AMD by trend test. The risk of smoking increased notablely with the amount smoked per day.Conclusion: The result of this case-control study hints some factors such as smoking and hypertension can increase the risk of AMD, taking antioxidant regularly can reduce the risk of AMD. The advoidance of smoking and the prevention of hypertension may reduce the risk of developing AMD. The relations of other factors and AMD need further investigation. In short, AMD is caused by many kinds of factors, the prevention measures must be taken synthetically. The risk factors being avoided, and the protective factors being paid attention to can reduce the prevalance and prevent AMD in the future.