title: Effect of ethnicity and growth on ratio-based transit time surrogate ankle-brachial index marker from a Chinese children's perception.
abstract: OBJECTIVE
  Since its introduction, ankle brachial index (ABI) measurements have been used in numerous clinical studies for its diagnostic and epidemiological values. However, conventional methods to acquire ABI are known to have limitations such as their suitability on uncooperative children when multiple prolonged monitoring is required. A simple and non-occluding technique termed pulse transit time ratio (PTTR) has been recently proposed to be a surrogate ABI marker. This methodological approach is based on the working principle of pulse transit time (PTT). It is known that age and ethnicity have confounding effects on the body proportion but little is known about their effect on the PTTR value.
  
  
  RESULTS
  In this study, 128 healthy subjects (43 Chinese adults, 55 Caucasian and 30 Chinese children) were recruited to assess the effect of the two physiologic parameters. Statistical analyses reveal that age and ethnicity have diverse effects on the acquired transit time-related measurements. Particularly, both the PTT and PTTR parameters were influenced by age (P < 0.05) but not ethnicity (P > 0.05). However, age did not have any effect on either parameter for the adult group (P > 0.05).
  
  
  CONCLUSIONS
  Similar to the ABI concept, the PTTR is the quotient of the transit time acquired from the lower limb and upper limb that indirectly reflects the stiffness of the respective arterial wall. Hence, the findings herein suggest that the PTTR approach shows promise to be a surrogate ABI marker.
authors.affiliation: Division of Research, Singapore General Hospital, Singapore. foo.jong.yong@sgh.com.sg
authors.forename: Jong Yong A
authors.initials: JY
authors.lastname: Foo
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wilson
authors.forename: Gordon R
authors.initials: GR
authors.lastname: Williams
authors.forename: Margaret-Anne
authors.initials: MA
authors.lastname: Harris
authors.forename: David M
authors.initials: DM
authors.lastname: Cooper
mesh_terms: D000328:Adult; D000842:Ankle / Q000098:blood supply*; D044466:Asian People; D001794:Blood Pressure; D001916:Brachial Artery / Q000503:physiopathology*; D002648:Child; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D016491:Peripheral Vascular Diseases / Q000208:ethnology* / Q000503:physiopathology; D017156:Photoplethysmography; D011379:Prognosis; D012846:Singapore / Q000453:epidemiology