Perea-Bartolome et al. BMC Public Health 2011, 11:504 http://www.biomedcentral.com/1471-2458/11/504 telephoned to remind them of the appointment. Evalua- tion will be carried out in the Faculty of Psychology of the University of Salamanca, in Room 19 (specifically used for neuropsychological tests). The sessions will be individualized, and the procedure will be the same for all participants, using the aforemen- tioned measurement instruments. The estimated duration of the evaluation is 120 min- utes, with two resting intervals of about 15 minutes each. The clinical and laboratory test data can be collected on occasion of a second interview to be arranged with the participants and/or relatives. Statistical analysis A descriptive analysis of the data will be made, estab- lishing comparisons with the baseline evaluation of the previous study. Posteriorly, an analysis will be made of the qualitative variables using the chi-squared test, and the qualitative and quantitative variables will be analyzed using the Student t-test and analysis of variance (ANOVA), depending on whether two or more cate- gories are involved. An analysis will be made of the cor- relations of the quantitative variables, together with multiple regression analysis to identify the variables associated with cognitive impairment diagnosed by the neuropsychological tests. Likewise, an evaluation will be made of the sensitivity, specificity and predictive values of the tests employed in screening for cognitive impairment, using the neuropsy- chological evaluation made as gold standard. Lastly, we will analyze the evolution of the different parameters between the two evaluations made, attempt- ing to identify those variables with greater predictive capacity in reference to the evolution of cognitive impairment. The information will be analyzed according to the place of residency, age and sex of the patient, the family situation and patient cognitive impairment, risk factors and comorbidity index. Data input will be made using the Teleform system, with a questionnaire previously designed for the project, and exporting the data to the SPSS statistical package for posterior analysis. Ethical and legal issues In order to guarantee data confidentiality, all the electro- nic and paper copies of the protocol, signed informed consent documents and results of the tests made in each of the patients will be kept locked in a safe place, and only the study investigators will have access to the data on the subjects who agree to participate in the study. The protocol was approved (August 10, 2010) by the Clinical Research Ethics Committee of Salamanca Page 6 of 8 University Hospital (Spain), and complies with Spanish data protection law 15/1999 and its recently developed specifications (Royal Decree (RD) 1720/2007). Knowl- edge and agreement to cooperate has been established with the implicated services, signed by the legal repre- sentative of the center. Methodological limitations The main limitation is sample loss inherent to studies of this kind, since the voluntary nature of participation and the population characteristics referred to age, etc., implies a certain loss of subjects versus the initially esti- mated sample size. The main causes underlying such losses are death and increased physical or mental impairment of the participants. Discussion There are studies in which a link has been established between cardiovascular risk factors and the develop- ment of dementia. However, few studies have related mild cognitive impairment to cardiovascular risk. We hope that this study will afford objective information on the representative prevalence of mild cognitive impairment in the population over 65 years of age in Salamanca. We will conduct an analysis of the cardiovascular risk factors in the selected sample, allowing us to establish the possible correlation between certain cardiovascular risk markers and mild cognitive impairment. If found, such a correlation would be very useful for future stu- dies designed to allow a certain prevention of such impairment, based on control of the cardiovascular risk factors. The results obtained moreover will allow us to assess the predictive capacity in detecting cognitive impairment from the applied screening tests (MMSE and 7 Minute Screen), since their results will be contrasted with those of the detailed neuropsychological explorations. The importance of the early detection of cognitive impair- ment should be stressed, since it will allow the start of adequate treatment and thus can contribute to improve patient quality of life. Lastly, we wish to point out that since a randomized population-based sample from the city of Salamanca is involved, the information obtained may be of increased representativeness - particularly considering that many studies suffer bias due to the lack of purely randomized criteria in selecting the participants. Acknowledgements This project was supported by the Regional Health Management of the Castilla-León Health Service (BIO39/SA04/10), Carlos III Institute of Health of the Ministry of Health of Spain (RETICS RD06/0018, RedIAPP) and Infosalud Fundation. The project will be developed by the Primary Care Research Unit of La Alamedilla health centre, Salamanca. Spain.