The Predictive Value Of Pulse Pressure And Ankle Brachial Index For Cognitive Impairment:a Systematic Review

Background:The aging of population has become the trend of human society.The damage of cognitive function seriously affects the quality of life of the elderly,thus impose heavy burdens on patients,their families and the society,which has become an important health problem in today society.It has been proved that cognitive function impairment is an important cause of disability and mortality.It has been proved that pulse pressure and ankle brachial index are independent risk factors for cardiovascular disease.In recent years,more and more studies began to focus on relationship between pulse pressure,ankle brachial index and cognitive function.Due to the limitation of research methods,geographical and other factors,we can't get the exact conclusion,thus in-depth analysis and evaluation are needed.Objective:To explore the predictive value of pulse pressure and ankle brachial index for cognitive impairment,then to provide evidence for early intervention of cognitive impairment.Methods:We use the pulse pressure,ankle brachial index,cognitive impairment as keywords and systematically searched the following electronic databases such as: Cochrane library,Pub Med,EMBASE,Chinese biomedical literature database(CBM),Wanfang database,Chinese CNKI,VIP and Chinese journal full text database(CNKI)from the establishment of the databases to March 2017.Besides,manual search of the relevant articles cited by the reference is applied.We finally draw the conclusion by searching the relevant literature,reading,screening,extracting data,and analyzing.Results:A total of 342 articles were retrieved for the study of the relationship between PP and cognitive function,and finally 5 references were included after screening.A total of 4897 patients of whom 2418 are case group and 2416 control group fit into the inclusion criteria for the pulse pressure and the cognitive study.All of these studies are case control studies,so we used the NOS scale evaluated the literatures quality.These studies are of high quality in general.The results of meta analysis display:Chi2=43.37,df=4,P<0.00001,the results are statistically significant.There was a statistical heterogeneity(I2=91%)among the studies,and the I2 was 91%,indicating that the heterogeneity was significant among the groups.We then performed a subgroup analysis and sensitivity analysis to explore the sources of heterogeneity.We first take into account heterogeneity from the clinical(gender,region and cohort of patients who were hospitalized).Then we carry on Begg's test and Egger's test for publication bias analysis.Begg's test results show that,u=z=-1.47,Pr>|z|=0.221(continuity corrected),z=1.22(continuity corrected),the statistics of Z is <1.96,P>0.05,indicating no statistical significance,so we can think that there is no publication bias of the included studies.In the Egger's test,P=0.181> 0.05,95%CI=-4.04~1.19 contains 0,indicating that the inclusion of the studies don't exist publication bias.The same method was used for the study of relationship between ankle brachial index and cognitive impairment,a total of 398 literatures were retrieved,and ultimately 8 different types of studies were included,including 2 cross-sectional studies,4 cohort studies,1 case-control studies,1 randomized controlled study.The quality of the methodology was evaluated by the corresponding quality assessment tools after reading the text carefully.The results showed that the overall quality of the included 8 studies was high.The data were extracted from each study and qualitative analysis was performed using a descriptive form.Due to the different types of these research,we only made a systematic evaluation,not meta analysis.Conclusion:1.There are relationgships between pulse pressure,ankle brachial index and cognitive dysfunction;2.Pulse pressure may be a predictor of cognitive dysfunction in elderly patients;3.Ankle brachial index may predict the cognitive impairment.Due to the limitation of the number and type of research,we can not get the exact conclusion.We hope that high-quality,large sample of different types of clinical studies to confirm it in the future.