Table 1.
Biomarkers, Control Variables, and Outcome Variable Included in Mortality Models (n = 933), Social Environment and Biomarkers of Aging Study, Taiwan, 2000a
| Mean (SD) | % | |
| Death by December 31, 2006 | 17.4 | |
| Sociodemographic variables | ||
| Age in 2000, years (observed range, 54–91) | 66.2 (8.0) | |
| Male sex | 57.9 | |
| Mainlander | 13.2 | |
| Education, years (observed range, 0–17) | 5.2 (4.6) | |
| Urban resident | 43.5 | |
| Baseline health status | ||
| No. of current health conditions (potential range, 0–12)b | 1.3 (1.3) | |
| No. of mobility limitations (potential range, 0–9)c | 1.8 (2.3) | |
| Cognitive function (potential range, 0–24)d | 16.7 (3.5) | |
| CES-D score (potential range, 0–30)e | 5.4 (5.2) | |
| Self-assessed health status (potential range, 1–5; 5 = excellent)f | 3.1 (1.0) | |
| Any smoking in past 6 months | 24.3 | |
| Standard risk factors | ||
| Hypertension | ||
| Normal blood pressure (SBP <120 mm Hg and DBP <80 mm Hg) | 15.5 | |
| Prehypertension (SBP 120–139 or DBP 80–89) | 34.9 | |
| Stage 1 hypertension (SBP 140–159 or DBP 90–99) | 32.2 | |
| Stage 2 hypertension (SBP ≥160 or DBP ≥100) | 17.3 | |
| Use of antihypertensive medication | 22.7 | |
| Total cholesterol, mg/dL | ||
| Desirable (<200) | 50.9 | |
| Borderline-high (200–239) | 33.9 | |
| High (≥240) | 15.2 | |
| High density lipoprotein cholesterol, mg/dL | ||
| Low (<40) | 26.9 | |
| Normal (40–59) | 51.8 | |
| High (≥60) | 21.3 | |
| Body mass indexg | ||
| Underweight (<18.5) | 3.3 | |
| Normal (18.5–23.9) | 45.1 | |
| Overweight (24–26.9) | 30.1 | |
| Obese (≥27) | 21.5 | |
| High waist circumference (females: >80 cm; males: >90 cm) | 49.0 | |
| Glycosylated hemoglobin, %h | 5.8 (1.4) | |
| Use of hypoglycemic agents | 11.7 | |
| Markers of disease progression | ||
| Creatinine clearance, mL/minutei | 62.4 (17.9) | |
| Serum albumin, g/dL | 4.5 (0.3) | |
| White blood cell count, 103 cells/μLh | 6.1 (1.6) | |
| Neutrophils, % | 56.3 (9.4) | |
| Nonclinical markers | ||
| Urinary epinephrine, μg/g creatininehj | 2.5 (2.5) | |
| Urinary norepinephrine, μg/g creatinineh | 21.7 (9.6) | |
| Urinary cortisol, μg/g creatinineh | 26.7 (29.7) | |
| Serum dehydroepiandrosterone sulfate, μg/dLhj | 80.8 (58.1) | |
| Interleukin-6, pg/mLhj | 3.3 (3.5) | |
| Insulin-like growth factor 1, ng/mLh | 107.0 (48.3) |
Abbreviations: CES-D, Center for Epidemiologic Studies Depression Scale; DBP, diastolic blood pressure; SBP, systolic blood pressure; SD, standard deviation.
Descriptive statistics are based on weighted data.
Current illness was measured by counting the following 12 self-reported conditions: high blood pressure, diabetes mellitus, heart disease, cancer or malignant tumor, lower respiratory tract disease, arthritis or rheumatism, gastric ulcer or stomach ailment, liver or gallbladder disease, cataracts, kidney disease, gout, and spinal or vertebral spurs.
The measure of mobility limitations counted how many of the following physical tasks the respondent reported difficulty in performing without aid: standing continuously for 15 minutes and for 2 hours, squatting, raising both hands over one's head, grasping or turning objects with one's fingers, lifting or carrying an object weighing 11–12 kg, running a short distance (20–30 m), walking 200–300 m, and climbing 2 or 3 flights of stairs.
The measure of cognitive function counted the number of cognitive tasks completed incorrectly, including basic orientation questions, a series of 4 subtractions, and immediate memory recall.
Depressive symptoms were measured by means of a 10-item short form of the full Center for Epidemiologic Studies Depression Scale (47), coded according to standard practice based on both the number and severity of symptoms.
Global self-assessed health status was based on the following question: “Regarding your current state of health, do you feel it is excellent, good, average, not so good, or poor?”
Weight (kg)/height (m)2.
Outliers (i.e., values greater than 5 standard deviations above the mean) were recoded to that cutpoint (i.e., trimmed). Values were trimmed for glycosylated hemoglobin (n = 4), white blood cell count (n = 1), epinephrine (n = 1), norepinephrine (n = 1), cortisol (n = 3), dehydroepiandrosterone sulfate (n = 4), interleukin-6 (n = 2), and insulin-like growth factor 1 (n = 1).
Creatinine clearance was estimated on the basis of the Cockcroft-Gault formula (46); outliers (n = 3) for serum creatinine were trimmed before calculation of this measure.
Approximately 11% of values on interleukin-6, 20% of values on epinephrine, and 1% of values on dehydroepiandrosterone sulfate were below assay sensitivity; these cases were assigned a value of 0.