title: A meta-analysis of the mechanism of blood pressure change with aging.
abstract: OBJECTIVE
  We undertook a meta-analysis to determine whether changes in wave reflection substantiate the consensus explanation of why blood pressure (BP) changes with aging.
  
  
  BACKGROUND
  Consensus documents attribute the aging changes in BP to wave reflection moving progressively from diastole into systole. However, the extensive quantitative data on this phenomenon have never been systematically reviewed. Individual studies have been small, and limited to a narrow age range.
  
  
  METHODS
  Using PubMed, Cochrane, and Web of Science databases, we identified 64 studies (including 13,770 subjects, age range 4 to 91 years) reporting the timing of wave reflection, defined as the time from the onset (foot) of the pressure waveform to the shoulder point (anachrotic notch).
  
  
  RESULTS
  In subjects of all ages, reflection times were well within systole. There was a small tendency for younger subjects to have later reflection, but this was only 0.7 ms per year, whereas the weighted mean reflection time was 136 ms (99% confidence interval: 130 to 141 ms) and the mean duration of systole was 328 ms (99% confidence interval: 310 to 347 ms). At this rate of change with age, arrival of wave reflection would only be construed to be in diastole at an extrapolated age of -221 years.
  
  
  CONCLUSIONS
  These findings challenge the current consensus view that a shift in timing of wave reflection significantly contributes to the changes in the BP waveform with aging. We should re-evaluate the mechanisms of BP elevation in aging.
authors.affiliation: International Centre for Circulatory Health, St Mary's Hospital, Imperial College Healthcare NHS Trust and Imperial College London, London, United Kingdom. j.baksi@imperial.ac.uk
authors.forename: Arun J
authors.initials: AJ
authors.lastname: Baksi
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Treibel
authors.forename: Justin E
authors.initials: JE
authors.lastname: Davies
authors.forename: Nearchos
authors.initials: N
authors.lastname: Hadjiloizou
authors.forename: Rodney A
authors.initials: RA
authors.lastname: Foale
authors.forename: Kim H
authors.initials: KH
authors.lastname: Parker
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
authors.forename: Jamil
authors.initials: J
authors.lastname: Mayet
authors.forename: Alun D
authors.initials: AD
authors.lastname: Hughes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001011:Aorta / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003971:Diastole / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008875:Middle Aged; D013599:Systole / Q000502:physiology; D055815:Young Adult