Incidence and progression of diabetic retinopathy in Sub-Saharan Africa: A five year cohort study.

Aims: To describe the incidence and progression of retinopathy in people with diabetes in Southern Malawi over 5 years. To document visual loss in a setting where laser treatment is not available.

Methods: Subjects from a cohort sampled from a hospital-based, primary-care diabetes clinic in 2007 were traced in 2012. Laser treatment was not available. Modified Wisconsin grading of retinopathy was performed using slit lamp biomicroscopy by a single ophthalmologist in 2007 and using four-field mydriatic fundus photographs at an accredited reading centre in 2012. Visual acuity was measured by Snellen chart in 2007 and by 'Early Treatment of Diabetic Retinopathy Study' chart in 2012. HbA1c, blood pressure, HIV status, urine albumin-creatinine ratio, haemoglobin and lipids were measured.

Results: Of 281 subjects recruited in 2007, 135 (48%) were traced and assessed, 15 were confirmed dead. At follow-up (median 5.3 years) ≥2 step retinopathy progression was observed in 48 subjects (36.4%; 95% CI 28.2-44.6). Incidence of sight threatening diabetic retinopathy for those with level 10 (no retinopathy) and level 20 (background) retinopathy at baseline, was 19.4% (11.3-27.4) and 81.3% (62.1-100), respectively. In multivariate analysis 2 step progression was associated with HbA1c (OR 1.2495%CI 1.04-1.48), and haemoglobin level (0.77, 0.62-0.98). 25 subjects (18.8%) lost ≥5 letters, 7 (5.3%) lost ≥15 letters.

Conclusions: Progression to sight threatening diabetic retinopathy from no retinopathy and background retinopathy was approximately 5 and 3 times that reported in recent European studies, respectively. Incidence of visual loss was high in a location where treatment was not available.