Validation of the use of historical events to estimate the age of subjects aged 65 years and over in Cotonou (Benin).

Background: Our aim was to validate the use of historical events as tools for estimating the age of people > or = 65 years in Cotonou (Benin).

Methods: The survey was conducted in Cotonou, the economic capital of Benin. We included people aged > or = 65 years, with at least a primary education level and an administrative document certifying their date of birth. The historical events were the solar eclipse of 1946 covering the national territory and the date of independence (1st August 1960) of Dahomey (Benin). Agreement between estimated and actual age was assessed by the intraclass correlation coefficient and the Bland and Altman graphical representation.

Results: We included 112 subjects. The intraclass correlation coefficient between actual and estimated age by the use of historical landmarks was 0.87 (95% CI = 0.81-0.91), i.e. an excellent concordance. The graph of Bland and Altman did not demonstrate any systematic error of estimation.

Conclusion: The development of similar tools in other parts of Africa and developing countries may improve the quality of information collected in epidemiological studies and thereby enhance the accuracy of the results of studies conducted on age-related disorders such as dementia.