Abstract
In the next 15 years, the prevalence of diabetes mellitus is expected to increase by 70% in developing countries and more than 18 million patients with diabetes are predicted in Africa (Shaw et al. 2010). At present, information on diabetic retinopathy [DR] in Africa is available from single countries only and data from West Africa are mainly from Nigeria. However, data are needed to guide the development of ophthalmic services (Burgess et al. 2013). This cross-sectional hospital-based study was performed to determine the magnitude, pattern and associations of DR of patients aged 20 years or older attending an urban diabetic clinic in Cameroon [Central Hospital of Yaoundé (HCY)] between September and mid-October 2010 after approval by the IRB of HCY and written informed consent from patients had been obtained. This research was performed according to the Tenets of the Declaration of Helsinki. The data are intended to provide a basis for improving ophthalmic care in Cameroon. All patients were interviewed using a standardized questionnaire. Visual acuity [VA] testing, slit-lamp biomicroscopy and dilated stereoscopic ophthalmoscopy were performed in all patients. Blood pressure, HbA1c and fasting blood glucose [FBG] levels were measured. DR was graded according to the ETDRS classification based on the findings of dilated stereoscopic ophthalmoscopy and noted for the more affected eye of each patient. For statistics, chi-square tests were used. In total, 371 patients were included [168 males (45.3%) and 203 females (54.7%); mean age 59.2 years (SD 10.9 years)]. Twelve patients had type 1 diabetes (diagnosed < 30 years) and 359 patients had type 2 diabetes (diagnosed at 30 years of age or older). Thirteen patients (3.5%) were on diet only, while 195 (52.6%) had therapy with oral hypoglycaemic agents [OHA], 120 (32.3%) received insulin, and 43 (11.6%) received both insulin and OHA. At the time of examination, mean duration of diabetes was 9.9 years (SD = 7.7), of insulin treatment 7.5 years and of OHA and diet 7 years each. Diabetic retinopathy was identified in 185 of 371 patients (49.9%) and graded as summarized in the Table 1. No relation of the presence of DR with type of diabetes (p = 0.99) or sex of patients (p = 0.13) was seen. However, mean duration of diabetes (13.0 versus 6.9 years, p < 0.001) and HbA1c-levels (9.4% versus 6.8%, p < 0.001) was strongly associated with the presence of DR. While the mean FBS level of patients with retinopathy was higher (10.6 mmol/l) compared to patients without retinopathy (9.4 mmol/l) (p = 0.001), FBS levels did not correlate well with the severity of diabetic retinopathy. In patients with DR, blood pressure was higher (152/85 mmHg) compared to patients without DR (141/82 mmHg) (p < 0.001). Diabetic nephropathy (based on clinical and laboratory findings and diagnosed by a physician) was seen in patients with DR only (21/185, OR 3.3, p = 0.006). Visual acuity was worse in eyes with DR compared to those without any diabetic changes (p < 0.001). In the presence of DR, VA was <6/18 in 107 eyes (29.3%) and even <3/60 in 25 eyes (6.8%). In 54.5% (6/11) of eyes with high-risk proliferative DR [PDR], VA was less than 6/60 and in case of clinically significant macula oedema [CSME] <6/60 in 48/89 eyes (53.9%) and even <3/60 in 9/89 eyes (10.1%). Sight-threatening retinopathy (PDR or CSME), which was subsequently treated by laser photocoagulation, was present in 83 of 371 patients (22.4%), who had relatively high HbA1c levels. In this study, prevalence of diabetic retinopathy in Yaoundé, Cameroon, was 49.9%, which is comparable to recently published data from Douala, Cameroon (40.3%) (Jingi et al. 2014) and Ethiopia (41.4%) (Sharew et al. 2013) but higher than reported from Malawi (32.5%) (Glover et al. 2012). Such data help in the development of strategic plans with the goal of reducing visual impairment and optimizing ophthalmic care of patients with diabetes by appropriate distribution of available resources in a setting with limited ophthalmic infrastructure. To improve care of diabetes patients in Cameroon, a close collaboration between medical diabetic clinics and ophthalmic units should establish an appropriate screening and referral system for early detection and management of DR.
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