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Abstract
Aim: To explore the association of use versus no use and the influence of pack-year use of smokeless tobacco with that of early and late age-related macular degeneration (AMD) in rural and urban south Indian population. We hypothesized that the use and pack-years of use would be significantly associated with both early and late AMD. We therefore sought to examine subjects who gave a history of using smokeless tobacco and we quantified the usage as pack-years, to examine the association with that of early and late AMD.
Materials and methods: This was part of Sankara Nethralaya: Rural–Urban Age-related Macular degeneration study (SN-RAM study), which was conducted between 2007 and 2010. Subjects aged 60 years or older or those turning 60 in the present calendar year, with a history of using smokeless tobacco were noted along with duration and number of packs used per day. Smokeless tobacco was defined as chewed-tobacco (loose leaves) and/or snuff (finely chopped tobacco). Subjects underwent detailed ophthalmic evaluation including cataract grading using the Lens Opacities Classification System (LOCS III), 45° 4-field stereoscopic fundus photography and AMD evaluation. Pack-years of smokeless tobacco use was stratified as <15, 15–34 and ≥35 years; the association of tobacco use and pack-years of use with that of early and late AMD was examined. A p value of < 0.05 was considered statistically significant.
Results: The number of smokeless tobacco users was significantly higher in rural (n = 767) than in urban groups (n = 281), p < 0.001. Of the 1048 users, 238 subjects (23%) provided details regarding quantification of use. There were no significant differences in the pack-years between rural and urban areas, p = 0.756 or that between AMD and no AMD, p = 0.562. Use of smokeless tobacco compared with no use was significantly associated with late AMD, OR= 3.178, 95%CI: 1.095, 9.227, p = 0.033, when adjusted for age, gender, rural-urban differences, presence of diabetes, socioeconomic status, systolic and diastolic blood pressure, total cholesterol, low-density and high-density lipoprotein levels. The association was not significant for early AMD, p = 0.582. The pack-years of use did not show a statistically significant association with early or late AMD. Furthermore, out of the 1048 subjects, 547 reported as using areca nut. Of which, 415 (75.8%) subjects had no AMD, 119 (21.7%) showed evidence of early AMD and 13 (2.4%) had late AMD. There was no significant association between the use of areca nut and early AMD, (X2 (1, N = 930) = 2.345, p = 0.126) or with that of late AMD (X2 (1, N = 761) = 0.075, p = 0.785).
Conclusions: Smokeless tobacco use compared with no use, is associated with late AMD, regardless of the pack-years of use. Tobacco use is a modifiable risk factor. Efforts to reduce or stop the use of smokeless tobacco is indicated in an effort to prevent vision loss with respect to late AMD.
Declaration of interest
The authors declare no conflicts of interest. This work was funded by Jamshetji Tata trust, Mumbai, India.