First Prospective Cohort Study of Diabetic Retinopathy from Sub-Saharan Africa

Abstract

PurposeTo describe the prevalence, incidence, and progression of retinopathy and to report associations with demographic, clinical, and biochemical variables in people with diabetes in Southern Malawi.DesignProspective cohort study.ParticipantsSubjects were systematically sampled from 2 primary care diabetes clinics.MethodsWe performed the first prospective cohort study of diabetic retinopathy from Sub-Saharan Africa over 24 months. Visual acuity, glycemic control, blood pressure, human immunodeficiency virus (HIV) status, urine albumin-to-creatinine ratio, hemoglobin, and lipids were assessed. Retinopathy was graded at an accredited reading center using modified Wisconsin grading of 4-field mydriatic photographs.Main Outcome MeasuresIncidence of sight-threatening retinopathy and progression of retinopathy by 2 steps on the Liverpool Diabetic Eye Study Scale.ResultsA total of 357 subjects were recruited to the 24-month cohort study. At baseline, 13.4% of subjects were HIV positive and 15.1% were anemic. The 2-year incidence of sight-threatening diabetic retinopathy (STDR) for subjects with level 10 (no retinopathy), level 20 (background), and level 30 (preproliferative) retinopathy at baseline was 2.7% (95% confidence interval [CI], 0.1–5.3), 27.3% (95% CI, 16.4–38.2), and 25.0% (95% CI, 0–67.4), respectively. In a multivariate logistic analysis, 2-step progression of diabetic retinopathy was associated with glycosylated hemoglobin (odds ratio [OR], 1.27; 95% CI, 1.12–1.45), baseline grade of retinopathy (OR, 1.39; 95% CI, 1.02–1.91), and HIV infection (OR, 0.16; 95% CI, 0.03–0.78). At 2 years, 17 subjects (5.8%) lost ≥15 letters.ConclusionsIncidence of STDR was approximately 3 times that reported in recent European studies. The negative association of HIV infection with retinopathy progression is a new finding.

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

“…DR progression at 5 years was associated with lower haemoglobin level. In our group’s prospective, 24 month cohort study lower haemoglobin was associated with presence of STDR at baseline (reported elsewhere [ 14 ]) but not with progression of DR [ 15 ]. An association between anaemia and presence of DR has been reported in Indian [ 27 – 29 ] and Chinese [ 30 ] cross-sectional studies.…”

“…Of 34 subjects without STDR at baseline (2007) and seen at 7 years 12 (35.3%; 19.2–51.4) had developed the condition at 7 years. Fig 2 and S3 Fig combine data from our 24 month cohort study performed between 2012 and 2014 and published elsewhere [ 14 , 15 ], 5 year progression data detailed in this manuscript and 6 and 7 year data from the 41 subjects described above to give a composite graph of DR progression over 7 years.…”

“… Figures for 0, 1 and 2 years taken from our group’s 24 month cohort study performed between 2012 and 2014 and published elsewhere [ 14 , 15 ] (light blue symbols; n = 177); 5 years from subjects in the 2007 cohort traced and assessed in 2012 (mid blue symbols; n = 93); 6 and 7 years from subjects in the 2007 cohort who were recruited (systematic random sampling) into the 24 month cohort study in 2012 and therefore followed for a further 2 years (dark blue symbols; n = 27). Error bars indicate 95% CI.…”

“…High quality cohort studies of DR from Africa or Asia are scarce. In our group’s separate prospective cohort study performed in Malawi between 2012 and 2014, 2 year incidence of STDR for subjects with level 10 and level 20 retinopathy at baseline was 2.7% (95% CI 0.1–5.3) and 27.3% (16.4–38.2), respectively [ 15 ]. A subset of this cohort are taking part in further follow-up to investigate the efficacy of laser treatment for DR in this population.…”

“…Additionally, we undertook a prospective, 2 year cohort study of patients attending two hospital-based diabetes clinics. Data from this study has been published elsewhere [ 14 , 15 ].…”