Table 1. Baseline Characteristics of Patients With Varicose Veins vs Patients in the Control Group.
| Varicose Veins Group (n=212 984) | Control Group Matched on Age, Sex, and Calendar Year (n=851 936) | Standardized Difference | Control Group Matched on Propensity Score (n=212 984) | Standardized Difference | |
|---|---|---|---|---|---|
| Women, No. (%) | 147 643 (69.3) | 590 572 (69.3) | 0.0000 | 149 632 (70.3) | 0.0203 |
| Age, mean (SD), y | 54.5 (16.0) | 54.5 (16.0) | 0.0002 | 54.3 (15.6) | 0.0141 |
| Age, No. (%), y | |||||
| 20-34 | 26 797 (12.6) | 107 074 (12.6) | 0.0004 | 26 810 (12.6) | 0.0002 |
| 35-44 | 32 457 (15.2) | 129 983 (15.3) | 0.0005 | 32 235 (15.1) | 0.0029 |
| 45-54 | 47 791 (22.4) | 191 572 (22.5) | 0.0011 | 48 054 (22.6) | 0.003 |
| 55-64 | 43 720 (20.5) | 174 503 (20.5) | 0.0011 | 44 711 (21.0) | 0.0115 |
| 65-74 | 36 714 (17.2) | 146 616 (17.2) | 0.0007 | 37 901 (17.8) | 0.0147 |
| ≥75 | 25 505 (12.0) | 102 188 (12.0) | 0.0006 | 23 273 (10.9) | 0.0329 |
| Comorbidity, No. (%)a | |||||
| Hypertension | 68 969 (32.4) | 248 108 (29.1) | 0.0707 | 68 521 (32.3) | 0.0045 |
| Chronic obstructive pulmonary disease | 54 278 (25.5) | 169 358 (19.9) | 0.1342 | 53 192 (25.0) | 0.0117 |
| Hyperlipidemia | 46 237 (21.7) | 156 921 (18.4) | 0.0822 | 45 520 (21.4) | 0.0082 |
| Ischemic heart disease | 36 975 (17.4) | 117 192 (13.8) | 0.0996 | 35 273 (16.6) | 0.0213 |
| Diabetes | 27 319 (12.8) | 107 062 (12.6) | 0.0078 | 26 328 (12.4) | 0.014 |
| Malignancy | 13 263 (6.2) | 42 909 (5.0) | 0.0517 | 11 729 (5.5) | 0.0307 |
| Chronic renal insufficiency | 11 213 (5.3) | 38 906 (4.6) | 0.0323 | 9332 (4.4) | 0.0412 |
| Atrial fibrillation | 3823 (1.8) | 10 076 (1.2) | 0.0506 | 2768 (1.3) | 0.0401 |
| Heart failure | 3002 (1.4) | 10 595 (1.2) | 0.0145 | 2175 (1.0) | 0.0354 |
| Stroke | 3322 (1.6) | 18 824 (2.2) | 0.0323 | 2753 (1.3) | 0.0412 |
| Utilization of Health Care Serviceb | |||||
| No. of outpatient visits | |||||
| Mean (SD) | 26.1 (21.9) | 18.9 (19.5) | 0.3471 | 24.7 (20.1) | 0.0647 |
| Median (IQR) | 21 (11-35) | 14 (5-27) | 30 (10-34) | ||
| <5 Visits, No. (%) | 18 764 (8.8) | 20 8671 (24.5) | 0.4306 | 18 791 (8.8) | 0.0004 |
| 5 to <14 Visits, No. (%) | 49 453 (23.2) | 210 969 (24.8) | 0.0362 | 49 718 (23.3) | 0.0029 |
| 14 to <27 Visits, No. (%) | 63 597 (29.9) | 214 258 (25.1) | 0.1056 | 64 185 (30.1) | 0.006 |
| ≥27 Visits, No. (%) | 81 170 (38.1) | 218 038 (25.6) | 0.2711 | 80 290 (37.7) | 0.0085 |
| No. of hospital admissions | |||||
| Mean (SD) | 0.19 (0.6) | 0.16 (0.6) | 0.1055 | 0.19 (0.7) | 0.0506 |
| Median (range) | 0 (0-32) | 0 (0-37) | 0 (0-37) | ||
| 0 Admissions, No. (%) | 184 435 (86.6) | 763 706 (89.6) | 0.0943 | 186 397 (87.5) | 0.0274 |
| 1 Admission, No. (%) | 21 666 (10.2) | 63 256 (7.4) | 0.0971 | 19 314 (9.1) | 0.0375 |
| ≥2 Admissions, No. (%) | 6883 (3.2) | 24 974 (3.0) | 0.0174 | 7273 (3.4) | 0.0102 |
| Years of Follow-up, Median (IQR) | |||||
| Deep venous thrombosis | 7.5 (4.0-10.8) | 7.6 (4.2-10.9) | 0.0318 | 7.6 (4.2-10.9) | 0.0263 |
| Pulmonary embolism | 7.8 (4.4-11.1) | 7.7 (4.3-11.0) | 0.0262 | 7.7 (4.2-11.0) | 0.0308 |
| Peripheral artery disease | 7.3 (3.7-10.7) | 7.5 (3.9-10.8) | 0.0304 | 7.4 (3.8-10.7) | 0.0156 |
Abbreviation: IQR, interquartile range.
a
Measured before the index date.
b
Measured during the year before the index date.