Table 1 Baseline characteristics according to the presence of polycythemia
From: Secondary polycythemia in chronic obstructive pulmonary disease: prevalence and risk factors
Characteristic | Polycythemia (N = 128) | No polycythemia (N = 1800) | P value |
|---|---|---|---|
Age (years) | 66.0 (12.4) | 67.9 (12.5) | 0.17 |
Sex, male | 97 (75.8) | 957 (53.2) | < 0.0001 |
Race, non-Hispanic white | 108 (84.4) | 1355 (75.3) | 0.019 |
Body mass index (kg/m2) | 27.7 (6.9) | 27.6 (7.9) | 0.86 |
Pack-years of cigarette smoking | 48.1 (24.0) | 46.4 (30.0) | 0.24 |
Enrollment center, Denver | 43 (33.6) | 268 (14.9) | < 0.0001 |
Hemoglobin (g/dL) | 16.8 (0.9) | 13.9 (1.9) | < 0.0001 |
Hematocrit (%) | 50.3 (2.5) | 42.0 (5.2) | < 0.0001 |
FEV1 percent predicted (%) | 50.9 (27.5) | 53.7 (29.0) | 0.79 |
GOLD airflow limitation severity | Â | Â | 0.0051 |
 2 | 67 (52.3) | 1033 (57.4) |  |
 3 | 53 (41.4) | 532 (29.6) |  |
 4 | 8 (6.2) | 235 (13.1) |  |
DLCO percent predicted (%) & | 61.2 (30.1) | 61.7 (30.7) | 0.86 |
Percent emphysema on CT (%) & | 6.0 (17.2) | 7.3 (16.8) | 0.87 |
Percent air trapping on CT (%) & | 33.6 (31.3) | 35.8 (34.0) | 0.39 |
Pi10 on CT (mm) | 2.63 (0.83) | 2.60 (0.72) | 0.86 |
PA/A ratio, > 1.0 & | 13 (13.1) | 285 (20.6) | 0.090 |
Resting SpO2 | Â | Â | 0.0042 |
 Normal | 50 (39.1) | 946 (52.6) |  |
 Mild hypoxemia | 43 (33.6) | 558 (31.0) |  |
 Moderate hypoxemia | 22 (17.2) | 201 (11.2) |  |
 Severe hypoxemia | 13 (10.2) | 95 (5.3) |  |
Exercise-Induced desaturation & | 36 (29.3) | 400 (23.2) | 0.12 |
LTOT use | Â | Â | 0.012 |
 No use | 101 (78.9) | 1265 (70.3) |  |
 Intermittent | 3 (2.3) | 46 (2.6) |  |
 Nocturnal | 16 (12.5) | 196 (10.9) |  |
 Continuous | 8 (6.2) | 293 (16.3) |  |
Obstructive sleep apnea/CPAP & | 9 (7.0)/7 (5.5) | 213 (11.8)/108 (6.0) | 0.11/0.17 |
Chronic kidney disease | 0 (0) | 65 (3.6) | 0.020 |
Congestive heart failure | 6 (4.7) | 118 (6.6) | 0.57 |
Diabetes mellitus | 17 (13.3) | 333 (18.5) | 0.15 |