Abstract
Purpose: :
To evaluate the association between smoking and retinopathy in a population-based cohort of 201 long-term surviving Danish type 1 diabetic patients.
Methods: :
A population-based cohort of 201 Danish type 1 diabetic patients was examined in 2007-2008. A Topcon TRC-NW6S camera was used to capture 9 field 45º monoscopic digital color fundus photos of both eyes. Retinopathy was graded according to the modified Airlie House classification scheme as used in the Early Treatment Diabetic Retinopathy Study. The level of retinopathy was determined according to the worse eye. Patients were asked about their current and past smoking habits, and pack-years of smoking were calculated. One pack-year of smoking was defined as 20 daily cigarettes in one year.
Results: :
Median age and duration of diabetes was 58.8 and 43 years, respectively, and 59.7 (120 of 201) were male. The prevalence of current smokers, ex-smokers and never-smokers were 22.9%, 36.8% and 40.3%, respectively. Only 6 patients (3.0%) had no retinopathy. Non-proliferative retinopathy and proliferative retinopathy (PDR) was found in 90 (44.8%) and 105 (52.2%), respectively.The prevalence of PDR was 54.4%, 58.1% and 45.7% in current smokers, ex-smokers and never-smokers, respectively. In a multivariate logistic regression adjusted for age, sex, systolic blood pressure, macrovascular disease and hemoglobin A1c, odds ratio (OR) of PDR was 1.69 for patients with a history of smoking (95% confidence interval [CI] 0.90-3.19, p=0.10) as compared to patients who had never smoked. Correspondingly, OR of PDR was 1.09 (95% CI 0.90-1.34, p=0.34) per pack-year of smoking.
Conclusions: :
A trend of an association between smoking and PDR was found in long-term surviving type 1 diabetic patients. Even though not statistically significant, patients with a history of smoking were 69% more likely to have PDR. The lack of statistical significance might be explained by selective mortality and a limited sample size due to a high mortality in this long-term surviving cohort.
Keywords: diabetic retinopathy • clinical (human) or epidemiologic studies: risk factor assessment • proliferation