Table 1.
Baseline Characteristics of the Study Participants by Quartiles of Cystatin C
| Variable | Entire Cohort (n = 1,332) | Cystatin C Quartiles, mg/L | p Value | |||
|---|---|---|---|---|---|---|
| Q1 | Q2 | Q3 | Q4 | |||
| 0.61–0.91 (n = 334) | 0.92–1.01 (n = 311) | 1.02–1.14 (n = 343) | 1.15–2.36 (n = 344) | |||
| Age, years, mean (SD) | 77.73 (3.4) | 76.8 (3.6) | 77.5 (3.4) | 78.1 (3.3) | 78.4 (3.1) | <.001 |
| African American, n (%) | 156 (11.7) | 72 (21.6) | 32 (10.3) | 34 (9.9) | 18 (5.2) | <.001 |
| Education, years, mean (SD) | 12.9 (2.6) | 13.1 (2.6) | 13.0 (2.6) | 12.8 (2.5) | 12.6 (2.5) | .042 |
| Geriatric Depression Scale score, mean (SD) | 1.6 (2.1) | 1.5 (2.0) | 1.5 (1.8) | 1.6 (2.0) | 1.9 (2.3) | .003 |
| Fair or poor self-reported health, n (%) | 179 (13.4) | 28 (8.4) | 45 (14.5) | 48 (13.9) | 58 (16.9) | .011 |
| ≥1 IADL impairment, n (%) | 489 (36.7) | 93 (27.8) | 107 (34.5) | 132 (38.5) | 157 (45.6) | <.001 |
| Current smoker, n (%) | 39 (2.9) | 10 (3) | 7 (2.3) | 7 (2.1) | 15 (4.4) | .27 |
| Alcohol use within previous 30 d, n (%) | 602 (45.2) | 158 (47.5) | 142 (45.7) | 168 (48.9) | 134 (38.9) | .044 |
| History of stroke, n (%) | 39 (2.9) | 14 (4.2) | 9 (2.9) | 9 (2.6) | 7 (2.0) | .399 |
| History of hypertension, n (%) | 478 (35.9) | 101 (30.2) | 100 (32.2) | 120 (34.9) | 157 (45.6) | <.001 |
| History of cardiovascular disease,* n (%) | 134 (10.1) | 32 (9.6) | 26 (8.4) | 32 (9.3) | 44 (12.8) | .249 |
| History of diabetes, n (%) | 66 (4.9) | 17 (5.1) | 14 (4.5) | 20 (5.8) | 15 (4.4) | .813 |
| Body mass index, kg/m2, mean (SD) | 27.6 (4.9) | 26.4 (4.4) | 27.2 (4.6) | 28.2 (5.1) | 28.7 (5.1) | <.001 |
| Creatinine, mg/dL, mean (SD) | 0.77 (0.2) | 0.65 (0.1) | 0.71 (0.1) | 0.77 (0.1) | 0.93 (0.2) | <.001 |
| Estimated GFR,† mL/min/1.73 m2, mean (SD) | 71.1 (14.6) | 88.1 (7.7) | 76.2 (5.7) | 67.9 (5.7) | 53.4 (9.3) | <.001 |
Notes: Age, education, GDS score and creatinine use Kruskal–Wallis tests for skewed distributions. Other continuous variables report p values from ANOVA tests. IADL = Instrumental Activities of Daily Living.
*History of cardiovascular disease includes self-reported history of angina, myocardial infarction, and congestive heart failure.
†Calculated by the CKD-EPI creatinine–cystatin C equation (27).