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Rohit C. Khanna, Gudlavalleti V. Murthy, Sannapaneni Krishnaiah, Hira B. Pant, Pyda Giridhar, Clare E. Gilbert, Gullapalli N. Rao; Cataract, Visual Impairment, Blindness And Risk Of Mortality In Rural Population Of The Andhra Pradesh Eye Disease Study, India. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5633.
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To determine if cataract, visual impairment (VI) or blindness increase the risk of mortality in a longitudinal study of adults in rural India.
Between 1996-2000, 10,293 individuals of all ages in three rural and one urban cluster took part in the Andhra Pradesh Eye Diseases Survey (APEDS1). 9-14 years later (June 2009-Jan 2010), these individuals were traced in the three rural areas, the urban site having been redeveloped (APEDS2). During APEDS2, if a participant no longer lived in the cluster, a household member was asked if they had died, and if so the date and cause of death, or migrated and the current location, if known. Blindness was defined as presenting visual acuity (VA) in the better eye of <6/60 and VI as <6/18-6/60. At APEDS1 Lens Opacities Classification System III was used to grade nuclear cataract, and the Wilmer system for cortical and posterior subcapsular cataract. Mortality hazard ratio analysis was performed using Cox proportional hazard regression for those ≥40 years at APEDS2, adjusting for age, sex, diabetes, hypertension, body mass index, age related macular degeneration, smoking and education status.
In APEDS2, 4,270/7,771 rural participants were/would have been ≥40 years. 803 had died (18.8%; 95% CI: 17.6-20%) and 316 had migrated (7.4%; 95% CI: 6.6% - 8.2%). Mortality was higher in males than females (21.7% vs 16.3%; p<0.001). The adjusted mortality hazard ratio (AMHR) was 1.9 (95% CI: 1.4-2.4) for blindness and 1.4 (95% CI: 1.2-1.7) for VI. AMHRs for cataract were: pure nuclear, 1.7 (95% CI: 1.4-2.2); pure cortical, 1.4 (95% CI: 1.0-2.0) and mixed cataract, 1.9 (95% CI: 1.5-2.4). For those having undergone cataract surgery, AHMRs for those with good outcomes (VA 6/6-6/18) was 1.8 (95% CI: 0.99-3.1), for moderate outcomes (VA <6/18-6/60) was 1.8 (95% CI: 1.1- 3.1) and poor outcomes (VA<6/60) was 2.4 (95% CI: 1.3-4.3). The commonest cause of death was ‘natural causes’, being reported more often among blind than non-blind participants (78.1% vs 51.4%, p < 0.001).
All types of cataract, levels of visual loss and aphakia/pseudophakia in APEDS1 had an increased risk of mortality than those unaffected at baseline in this rural setting. The findings support the hypothesis that cataract is a marker for ageing. A limitation is that change in exposure and status was not recorded between the APEDS1 and APEDS2 and the cause of death data may be unreliable.
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