Association of the second derivative of photoplethysmogram with age, hemodynamic, autonomic, adiposity, and emotional factors

The second derivative of photoplethysmogram (SDPTG) is used as an arterial stiffness marker. This study aimed to examine the associations between SDPTG indices and age, in addition to hemodynamic, autonomic, adiposity, and emotional factors.This study had a cross-sectional chart review design, and electronic medical records of 262 women outpatients (mean ± SD,|38.57| ± |11.64 years) were reviewed. Among SDPTG measurements, b/a, c/a, d/a, and (b-c-d)/a were considered. Hemodynamic measurements included systolic and diastolic blood pressure (SBP and DBP) and cardiac output. Autonomic measurements included low and high frequency (LF and HF) values of the heart rate variability. Adiposity measurements included body mass index (BMI) and waist-hip ratio (WHR). Tension, anger, depression, fatigue, confusion, and vigor scores using the Profile of the Mood States were included as emotional markers. All data were normalized through the Box-Cox transformation, and 4 hierarchical regression models were constructed.Age was independently predictive of SDPTG, hemodynamic, autonomic, and adiposity factors (β; 0.143-0.648).After the adjustment for age, SBP and DBP showed negative correlations with d/a (r = -0.201, -0.262), whereas BMI, WHR, LF, and HF showed positive correlations with c/a (r = 0.126, 0.131, 0.151, 0.234). In the hierarchical regression modeling, age and hemodynamic factors were directly predictive of SDPTG indices (β; 0.103-0.626). Age had moderating effects between diastolic blood pressure, heart rate, depression scores, and SDPTG indices (β; 0.104-0.176).In conclusion, age, hemodynamic, adiposity, and autonomic factors may be independently associated with SDPTG indices for women. As age has moderating effects between hemodynamic, emotional factors, and SDPTG indices, its moderating effects should be considered when assessing arterial stiffness using SDPTG indices.