Systematic screening for diabetic retinopathy has been identified as a cost-effective use of health service resources, with national screening programs based on digital photography being implemented across Europe.10
The previous system included the referral of all diabetes patients to the hospital, retinography by a technician, and the study of all images and subsequent reporting by an ophthalmologist.13
The inclusion of general practitioners in the screening program might help us to avoid excessive referrals of patients to hospital. In a previous study, we demonstrated that, after correct training and direct support by an ophthalmologist in close collaboration with the general practitioner, the screening of diabetic retinopathy could be undertaken by primary health care centers.6
This study describes a system that has given general practitioners the responsibility for referring any pathologic retinal images to a retina specialist via the virtual private network common to any primary care unit and hospital ophthalmology service. This new development may help us to approach diabetes control by fundus camera through primary care health professionals and may involve general practitioners.
In this study, we have used the EURODIAB protocol which recommends two photographs in two 45° fields, the first centered on the temporal to the macula and the second on the nasal to the papilla, which has proven effective in diabetic retinopathy screening in other studies.7
The demographic characteristics of the two groups were similar, and are consistent with the literature on diabetes mellitus.18
This similarity has allowed us to compare the groups and study them statistically.
We can see in that 4551 patients (63.80% of all registered diabetics) in Group 1 were screened versus just 884 (17.63%) in Group 2. This is surprising, if we consider that the financial incentives and the waiting list for screening are similar in both groups. We do not believe that the urban or rural origin of the patients influenced the results, because both groups had a similar demographic distribution. We can suppose that the greater involvement of general practitioners in the Group 1 cohort has made an observable difference.
also presents data that is similar for both groups, but with differences in the number of patients requiring pupil dilatation, number of retinographies per eye, and number of patients referred to the ophthalmology service. However, these differences are not statistically significant.
The prevalence of diabetic retinopathy is similar in both groups and not statistically significant. Taking into account the percentage of patients with diabetic retinopathy, we observed that the prevalence was 8.37% in Group 1 and 9.16% in Group 2. These levels are inferior to those in other published cross-sectional studies,18
but we should point out that the screening was carried out in diabetic patients who had not been diagnosed previously, because the latter were being monitored by the ophthalmology department. Furthermore, in studies with similar methods, such as that published by Soulié-Strougar in France,20
the prevalence of diabetic retinopathy was found to be 8.57%.
In the present study, there were some differences in the severity of diabetic retinopathy between the groups. Group 1 had fewer patients with severe and proliferative diabetic retinopathy, which was significant in statistical analysis (P = 0.04 for severe diabetic retinopathy and P < 0.001 for proliferative diabetic retinopathy). There was also a significant difference (P = 0.04) in the number of patients who had laser treatment (0.94% in Group 1 versus 0.79% in Group 2). Finally, diabetic macular edema was more prevalent in Group 2 (2.03% versus 1.32% in Group 1), and the differences are also significant in statistical analysis. Although we could detect the influence of general practitioners in Group 1, due to the small number of patients screened in Group 2 (17.63%), we cannot rule out that any change in a single patient to a more severe form of diabetic retinopathy may have altered the outcome.
It is important that severe and proliferative forms of diabetic retinopathy are correctly diagnosed by general practitioners and that the patients with these deleterious forms of the disease, which may cause marked deterioration in visual acuity, are treated promptly in an ophthalmology department. Important in this study was the diagnosis of supposed diabetic macular edema. It is noteworthy that, of all cases detected with the nonmydriatic fundus camera, the diagnosis of clinically significant macular edema was confirmed by biomicroscopy, and that focal laser photocoagulation was carried out in those patients. The diagnosis of diabetic macular edema is important because it is the leading cause of blindness in patients with Type 2 diabetes mellitus. Despite some studies describing the spontaneous disappearance of diabetic macular edema in up to 30% of cases,21
we think it is important to detect and treat these types of diabetic macular lesions. Furthermore, it is important that patients with severe macular lesions, such as age-related macular degeneration, macular drusen, and myopia in the macular area, are correctly diagnosed by general practitioners.
Finally, we should bear in mind that if we extrapolate the results and consider that 63.80% of patients with diabetes mellitus were screened in Group 1, we may surmise that in Group 2 as many as 203 patients with diabetic retinopathy were not detected (78 of them with severe or proliferative diabetic retinopathy), and 42 patients with diabetic edema macular went undetected, which may have caused the loss of visual acuity in about 120 patients in Group 2.
In diseases for which diagnosis is based mainly on imaging, as in diabetic retinopathy, the contribution of new imaging technology is essential. The possibility of using nonmydriatic cameras allows interaction between the different health care professionals who examine patients with diabetes. The differences between the two methods of screening do seem to be important, and the inclusion of general practitioners in the diagnosis of diabetic retinopathy appears to be advantageous. It is important to note that, in the present study, the 73 participating general practitioners from 135 in our area were chosen at random and were not selected according to any specific criteria, although they were given special training in order to be able to evaluate the images. The results are more significant in view of the fact that the general practitioners included in Group 1 showed a varying degree of interest in taking part in the program. Some showed a lot of interest from the start and others not so much, but, despite that, there was a good response from all of them a few months into the program.
The weakness of this study is the small number of patients in Group 2, which could have influenced the results, considering that the health care centers for Group 2 had a high number of patients with severe diabetic retinopathy, and a low number of patients successfully treated by laser, but this can be due only to the limited number of patients referred to the nonmydriatic fundus camera unit.