Identifying risk factors for glaucoma is an important step when managing patients with glaucoma or suspects of having glaucoma. The presence of a first degree relative with glaucoma increases the chances of the subject be diagnosed with glaucoma, along with other risk factors. However, it is important to have an accurate information whether the parents or siblings have glaucoma. The current study identified an accuracy of 76.96% of self-reported family history of glaucoma in our sample. We also found that variables such as education level, family income and health insurance were statistically associated with the accuracy of the self-report.
The importance of identifying first degree relatives with glaucoma has been already demonstrated in previous populational studies. The Los Angeles Latino Eye Study showed that a positive family history of glaucoma in first-degree relatives was an independent risk factor to develop POAG (OR 1.92; 95% CI, 1.25–2.94). [13] The Barbados Eye Study also showed that subjects with family history presented higher risk of having glaucoma (OR 2.43; 95% CI, 1.43–4.15). [14] In the Baltimore Eye Survey, they found that associations of POAG with a history of glaucoma were higher in siblings (OR 3.69) than in parents (OR 2.17). [6] Despite the major significance of these findings, all these studies used the information from self-reported data from the participants. However. our study showed that 23% of subjects who informed to have a first-degree relative with glaucoma did not gave the correct information. Thus, some studies using self-reported data should account for this possible bias.
The increasing use of genetic testing with genome wide association populational studies have identified several genetic markers associated with the risk of developing, allowing the use of polygenic risk scores to identify individuals at high risk of the disease. [15] In contrast to subjective self-reported data collection of positive family history for glaucoma, a gene-based screening for glaucoma represents a more objective approach, less susceptible to information bias. [16] However, the cost of applying genetic testing in every glaucoma suspect may be not feasible for all subjects, especially in poor countries in which access to health still is a challenge. Thus, obtaining reliable information from self-reported positive family history remains as an important part of ophthalmic consultation.
The use of questionnaires and interviews to collect data is a useful approach in medical research, especially in studies in which patient´s perspective is necessary. [17] In these cases, clinicians must rely on their answers. However, in some areas of research, such as vision related-quality of life or glaucoma treatment adherence patterns (patient-reported outcome measures) data can be analyzed using mathematical models to minimize the bias of multidimensionality. [18, 19] Unfortunately when collecting socio-demographic data or clinical data such as co-morbidities or previous ocular surgeries, no mathematical model can be used and self-reported data can suffer from self-reporting bias. [20] In fact, the current study identified an accuracy of 76.96% of glaucoma family history. The current study showed that one way to overcome this bias, would be inviting the allegedly relative with glaucoma to a consultation to confirm the family history or in cases in which consultation is not possible, clinicians could try to evaluate the exams online to see if the information provided is accurate. This approach is not feasible in all cases but could be reserved for those suspects of glaucoma or glaucoma patients in which the information of a positive first-degree family history could improve our management of the case.
In the Glaucoma Inheritance Study in Tasmania, from the 47 POAG patients, 27% were unaware of their family history of POAG. [10] In the current study a similar percentage of subjects (23%) who informed to have a first-degree relative with glaucoma did not gave the correct information and we identified that subjects with college degree, higher family income, and those with health insurance, had more chances of presenting a correct information about the family history for glaucoma. This finding is especially important since Brazil as a developing country with continental geographical area have different socio-economic profiles in different regions with great socio-economical inequalities. In addition to that, in Brazil, most of the population has a free health coverage through a unified health system, created in 1990. [21] Only the minority of the population have access to private health insurances. Therefore, based on the findings from our study, improving the access to better education opportunities, providing higher family income by economical growing could eventually improve the accuracy of self-reported data. It is important to highlight that in the multivariable logistic regression, none of the variables were statistically correlated with the accuracy of glaucoma family history, showing that the accuracy of this data is complex and dependent of several factors and further studies are necessary.
This study has several limitations. First, due to the COVID-19 pandemic situation that occurred during the data collection, some relatives had the diagnosis confirmed or excluded by online consultations. We do not believe this could have jeopardized the results since 2 glaucoma specialists evaluated all the exams. In addition, only subjects that had all the exams necessary for glaucoma diagnosis were included in the study and if the exams were not in adequate quality, the relative was not included in the protocol. Second, by examining only one family member, other cases of glaucoma could have been missed. Third, most of the participants from this study were recruited from the glaucoma clinic in which patients are referred with suspect of glaucoma to investigation or already have the disease. This selection bias could have increased the accuracy reported since glaucoma may not be a complete unknown disease for those participants, since they may have studied about the condition before the initial consultation. Nevertheless, if the same study was conducted in a general clinic, we could have a lower accuracy of positive self-reported glaucoma family history.