Table 3.
Characteristics of the Sample With a Baseline QTVi Within the First QTVi Quartile
|
Variable |
All Subjects (N = 640) | Arousal QTVi Less Than –0.96 (Q1) (n = 417) |
Arousal QTVi Equal to Greater Than –0.96 (Q2-Q4) (n = 233) |
P Value |
|---|---|---|---|---|
| Age, y | 76.2 ± 5.4 | 75.8 ± 5.2 | 76.8 ± 5.6 | .025 |
| White | 579 (90.5) | 372 (89.2) | 207 (92.8) | .179 |
| African-American | 19 (3.0) | 10 (2.4) | 9 (4.0) | .358 |
| Asian | 26 (4.1) | 22 (5.3) | 4 (1.8) | .055 |
| Other | 16 (2.5) | 13 (3.1) | 3 (1.3) | .270 |
| Body weight | ||||
| BMI, kg/m2 | 26.8 ± 3.6 | 26.5 ± 3.5 | 27.2 ± 3.6 | .011 |
| Overweight | 315 (49.2) | 213 (51.1) | 102 (45.7) | .228 |
| Obese | 124 (19.4) | 69 (16.5) | 55 (24.7) | .018 |
| Cardiac assessment | ||||
| Atrial fibrillation | 44 (6.9) | 13 (3.1) | 31 (13.9) | < .001 |
| SBP, mm Hg | 127.0 ± 16.2 | 126.7 ± 15.9 | 127.5 ± 16.6 | .561 |
| DBP, mm Hg | 67.3 ± 9.4 | 67.4 ± 9.1 | 67.1 ± 9.8 | .642 |
| Lifestyle | ||||
| Smoking | ||||
| Never | 237 (37) | 150 (36.0) | 87 (39.0) | .501 |
| Past | 388 (60.6) | 257 (61.6) | 131 (58.7) | .531 |
| Current | 15 (2.3) | 10 (2.4) | 5 (2.2) | .881 |
| Current alcohol consumers | 431 (67.3) | 281 (67.4) | 150 (67.3) | .954 |
| PASE score | 152.5 ± 69.8 | 156.5 ± 70.6 | 144.9 ± 67.6 | .049 |
| Medical history | ||||
| Stroke | 23 (3.6) | 15 (3.6) | 8 (3.6) | .829 |
| CAD/MI | 88 (13.8) | 59 (14.1) | 29 (13.0) | .779 |
| CHF | 23 (3.9) | 13 (3.1) | 12 (5.4) | .232 |
| TIA | 57 (8.9) | 32 (7.7) | 25 (11.2) | .177 |
| Asthma | 60 (9.4) | 35 (8.4) | 25 (11.2) | .306 |
| COPD | 33 (5.2) | 16 (3.8) | 17 (7.6) | .060 |
| HTN | 313 (48.9) | 197 (47.2) | 116 (52.0) | .285 |
| Diabetes | 87 (13.6) | 55 (13.2) | 32 (14.3) | .774 |
| Parkinson disease | 6 (0.9) | 4 (1.0) | 2 (0.9) | .724 |
| Overnight polysomnography | ||||
| AHI, h–1 | 18.7 ± 12.3 | 18.0 ± 12 | 20.0 ± 12.7 | .049 |
| AI, h–1 | 24.0 ± 11.6 | 24.0 ± 11.1 | 24.0 ± 12.5 | .997 |
| AB, % | 6.3 ± 3.1 | 6.2 ± 2.9 | 6.6 ± 3.5 | .077 |
| PLMI, h–1 | 10.8 ± 8.4 | 11.0 ± 8.8 | 10.4 ± 7.7 | .414 |
| MRR, min–1 | 14.7 ± 1.9 | 14.6 ± 1.8 | 14.7 ± 1.9 | .501 |
| T90, min | 12.2 ± 31.5 | 11.0 ± 29.6 | 14.5 ± 34.8 | .186 |
Data are presented as mean ± SD or No. (%). Boldface indicates a P value with statistical significance. AB = arousal burden; AHI = apnea/hypopnoea index; AI = arousal index; CAD = coronary artery disease; CHF = congestive heart failure; DBP = diastolic BP; HTN = hypertension; MI = myocardial infarction; PASE = Physical Activity Scale for Elderly; PLMI = periodic limb movement index; MRR = mean respiratory rate; QTVi = QT variability index; SBP = systolic BP; T90 = time of sleep spent below 90% oxygen saturation; TIA = transient ischemic attack.