title: Hemodynamic instability in chronic fatigue syndrome: indices and diagnostic significance.
abstract: OBJECTIVE
  To evaluate the cardiovascular response to postural challenge in patients with chronic fatigue syndrome (CFS) and to determine whether the degree of instability of the cardiovascular response may aid in diagnosing CFS.
  
  
  METHODS
  Patients with CFS (n = 25) and their age- and gender-matched healthy controls (n = 37), patients with fibromyalgia (n = 30), generalized anxiety disorder (n = 15), and essential hypertension (n = 20) were evaluated with the aid of a standardized tilt test. The blood pressure (BP) and heart rate (HR) were recorded during 10 minutes of recumbence and 30 minutes of head-up tilt. We designated BP changes as the differences between successive BP values and the last recumbent BP. The average and standard deviation (SD) were calculated. Time curves of BP differences were loaded into a computerized image analyzer, and their outline ratios and fractal dimensions were measured. HR changes were determined similarly. The average and SD of the parameters were calculated, and intergroup comparisons were performed.
  
  
  RESULTS
  On multivariate analysis, the independent predictors of CFS patients versus healthy controls were the fractal dimension of absolute values of the systolic BP changes (SYST-FD.abs), the standard deviation of the current values of the systolic BP changes (SYST-SD.cur), and the standard deviation of the current values of the heart rate changes (HR-SD.cur). The following equation was deduced to calculate the hemodynamic instability score (HIS) in the individual patient: HIS = 64.3303 + (SYST-FD.abs x -68.0135) + (SYST-SD.cur x 111.3726) + (HR-SD.cur x 60.4164). The best cutoff differentiating CFS from the healthy controls was -0.98. HIS values >-0.98 were associated with CFS (sensitivity 97%, specificity 97%). The HIS differed significantly between CFS and other groups (P <.0001) except for generalized anxiety disorder. Group averages (SD) of HIS were CFS = +3.72 (5.02), healthy = -4.62 (2.26), fibromyalgia = -3.27 (2.63), hypertension = -5.53 (2.24), and generalized anxiety disorder = +1.08 (5.2).
  
  
  CONCLUSIONS
  The HIS adds objective criteria confirming the diagnosis of CFS.
authors.affiliation: Department of Internal Medicine A, Bnai Zion Medical Center and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: J E
authors.initials: JE
authors.lastname: Naschitz
authors.forename: E
authors.initials: E
authors.lastname: Sabo
authors.forename: S
authors.initials: S
authors.lastname: Naschitz
authors.forename: N
authors.initials: N
authors.lastname: Shaviv
authors.forename: I
authors.initials: I
authors.lastname: Rosner
authors.forename: M
authors.initials: M
authors.lastname: Rozenbaum
authors.forename: L
authors.initials: L
authors.lastname: Gaitini
authors.forename: A
authors.initials: A
authors.lastname: Ahdoot
authors.forename: M
authors.initials: M
authors.lastname: Ahdoot
authors.forename: R M
authors.initials: RM
authors.lastname: Priselac
authors.forename: S
authors.initials: S
authors.lastname: Eldar
authors.forename: E
authors.initials: E
authors.lastname: Zukerman
authors.forename: D
authors.initials: D
authors.lastname: Yeshurun
mesh_terms: D000328:Adult; D001008:Anxiety Disorders / Q000175:diagnosis / Q000503:physiopathology; D001794:Blood Pressure / Q000502:physiology; D003937:Diagnosis, Differential; D015673:Fatigue Syndrome, Chronic / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D005356:Fibromyalgia / Q000175:diagnosis / Q000503:physiopathology; D017709:Fractals; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000503:physiopathology; D007091:Image Processing, Computer-Assisted; D008297:Male; D018667:Tilt-Table Test