Definitions and Clinical Cutoff Points of Biomarkers Used to Construct the ALI
| System | Biomarker | Description | Threshold |
|---|---|---|---|
| Cardiovascular system | Systolic blood pressure (mm Hg) | The maximum pressure in arteries during the active phase of the heartbeat | ≥140 |
| Diastolic blood pressure (mm Hg) | The heart refills with blood and the pressure in the arteries is at its lowest | ≥90 | |
| Heart rate (per minute) | The number of times the heart beats in one minute (electrocardiogram) | ≥90 | |
| Metabolic system | Body mass index (BMI)5 | A simple calculation used to assess whether a person has a healthy body weight for their height | ≥30 |
| Waist-to-hip ratio (WHR) | A measurement used to assess body fat distribution | ≥0.90 for males; ≥0.85 for females | |
| Total cholesterol (mmol/L) | The sum of different types of cholesterol in the blood | ≥6.2 | |
| High-density lipoprotein (HDL) cholesterol (mmol/L) | “Good” cholesterol that helps clear other forms of cholesterol | ≤1 | |
| Low-density lipoprotein (LDL) cholesterol (mmol/L) | “Bad” cholesterol that high levels can lead to the buildup of cholesterol in the arteries | ≥4.1 | |
| Glycosylated hemoglobin (HbA1c)(mmol/mol) | A blood test that measures the average level of blood sugar (glucose) over the past 2–3 months | ≥48 | |
| Glucose (mmol/mol) | A simple sugar and a primary energy source for the body’s cells | ≥7 | |
| Triglycerides6 (mmol/L) | A type of fat (lipid) found in blood | ≥1.7 | |
| Kidney function | Creatinine (mmol/L) | Creatinine is a waste product that forms when muscles break down creatine, a substance found in the muscles and consumed through meat and fish | ≥90 |
Notes: For HbA1c, the variable measured in mmol/L contains 23,000 missing values in wave 1a, whereas the variable measured in percentages has only 764 missing values. To address this issue, we use the alternative variable for HbA1c and convert its unit accordingly. Consequently, there is a small transformation error in this variable due to rounding. BMI is calculated as BMI = Weight (kg)/Height (m)2. WHR is calculated as WHR = Waist circumference (cm)/Hip circumference (cm).