Multi-system physiological dysregulation (Physiological Mediator)

An index of physiological dysregulation representing functioning across multiple regulatory systems was constructed for the purposes of this study (see Table ​Table3)3) [14]. The choice of indicators was guided by prior research and data availability [13]. The indicators included were systolic blood pressure (SBP), diastolic blood pressures (DBP), and heart rate (indices of cardiovascular health); hemoglobin A1c, total cholesterol (TC), high-density lipoprotein cholesterol (HDL), BMI (indices of metabolism), and C-reactive protein (an index of immune system). All variables were from 2014 and 2016 HRS half-samples, combined in this study for a complete sample. SBP, DBP, and heart rate were the average of three measurements. BMI was calculated from measured weight and height. All other indicators were assessed with dried blood samples.

Indicators and ‘At Risk’ Values of Physiological Dysregulation Index (Scale 0—8)

Each indicator was dichotomized as ‘not risky’ (0) or ‘risky’ (1) based on its clinical cut-points. The thresholds for the risky categories were: SBP ≥ 140 mmHg, DBP ≥ 90 mmHg, heart rate ≥ 90 beats/min, A1c ≥ 6.5%, TC ≥ 240 mg/dl, HDL < 40 mg/dl, BMI ≥ 25 or < 18.5, and C-reactive protein ≥ 3.0 mg/dl. The physiological dysregulation index was defined as the sum of indicators in the risky category, ranging from 0–8, with higher scores indicating greater physiological dysregulation. On average, study participants had 1.9 physiological indicators with values above clinical cut-points, indicating dysregulation (see Table ​Table44).