Table 2.
Cohort studies reporting prevalence and incidence of diabetic retinopathy in Africa
| Study | Methods | Subjects and subgroups | n | Outcome |
||
|---|---|---|---|---|---|---|
| Any diabetic retinopathy, % (95% CI) | Proliferative diabetic retinopathy, % | Percentage of subjects progressing | ||||
| 1. Mauritius 1992–1998 | ||||||
| Initial population-based study, 1992 [7] | Population-based study of prevalence of diabetes and diabetic retinopathy: methodology outlined in Table 1 | All subjects with diabetes | 746 | 30.2 (26.9–33.5) | 1.3 | |
| Known diabetes | 388 | 44.3 (39.4–49.2) | 2.3 | |||
| Newly diagnosed diabetes | 358 | 14.8 (11.1–18.5) | 0.3 | |||
| Second survey, 1998 [10] | Of those assessed for complications in 1992, 528 attended the follow-up survey. Grading of retinopathy as in first assessment | Subjects with diabetes | 302 | 33.8 | 3.0 | 25.2 |
| Diabetes with no diabetic retinopathy at baseline | 227 | 23.8* | 0.4† | 23.8 | ||
| Diabetes, mild non-proliferative diabetic retinopathy at baseline | 58 | 5.2† | 27.7 | |||
| Diabetes, moderate non-proliferative diabetic retinopathy at baseline | 17 | 29.4† | 35.3 | |||
| 2. South Africa 1982–2002 | ||||||
| Baseline assessment, 1982 [11] | 88 black South Africans with diabetes requiring insulin therapy diagnosed < 30 years attending the diabetes clinic at Baragwanath Hospital, Soweto were screened for diabetic complications. 66 were examined for retinopathy by a physician using direct ophthalmoscope | Subjects with diabetes requiring insulin therapy diagnosed < 30 years | 66 | 12.1 | 0 | |
| Subgroup subsequently seen at 10 years | 33 | 6 | 0 | |||
| Subgroup subsequently seen at 20 years | 17 | 12 | ||||
| 10-year follow-up, 1992 [12] | Of the original cohort, 24 were lost to follow-up, 10 had died. Of 54 still attending clinic, 36 were examined. In three patients cataracts prevented fundal view | Subjects with diabetes requiring insulin therapy diagnosed < 30 years | 33 | 52 | 3 | |
| 20-year follow-up, 2002 [13] | Of the original cohort, 21 died, 39 were lost to follow-up, 28 were still attending clinic, of which 17 were assessed for complications | Subjects with diabetes requiring insulin therapy diagnosed < 30 years | 17 | 59 | ||
*
Incidence of diabetic retinopathy at 6 years.
†
Incidence of proliferative diabetic retinopathy at 6 years.