Baseline characteristics among ITP group and non-ITP group
| Before PSM (1:20 age–sex matching) | 1:2 PSM | |||||
| Non-ITP n=14 460 (%) | ITP n=723 (%) | ASD | Non-ITP n=1336 (%) | ITP n=668 (%) | ASD | |
| Sex | 0.000 | 0.038 | ||||
| Female | 8340 (57.68) | 417 (57.68) | 801 (59.96) | 390 (58.38) | ||
| Male | 6120 (42.32) | 306 (42.32) | 535 (40.04) | 278 (41.62) | ||
| Age | 0.000 | 0.047 | ||||
| <30 | 3720 (25.73) | 186 (25.73) | 333 (24.93) | 173 (25.90) | ||
| 30–45 | 2480 (17.15) | 124 (17.15) | 194 (14.52) | 110 (16.47) | ||
| 45–65 | 3780 (26.14) | 189 (26.14) | 349 (26.12) | 171 (25.60) | ||
| ≥65 | 4480 (30.98) | 224 (30.98) | 460 (34.43) | 214 (32.04) | ||
| Urbanisation | 0.044 | 0.044 | ||||
| Urban | 8427 (58.28) | 406 (56.15) | 727 (54.42) | 376 (56.29) | ||
| Suburban | 4441 (30.71) | 238 (32.92) | 458 (34.28) | 221 (33.08) | ||
| Rural | 1592 (11.01) | 79 (10.93) | 151 (11.30) | 71 (10.63) | ||
| Low income | 72 (0.50) | 6 (0.83) | 0.041 | 6 (0.45) | 4 (0.60) | 0.021 |
| Length of hospital stays* | 1.196 | 0.045 | ||||
| 0 day | 12 897 (89.19) | 286 (39.56) | 556 (41.62) | 286 (42.81) | ||
| 1–6 days | 840 (5.81) | 188 (26.00) | 381 (28.52) | 180 (26.95) | ||
| ≥7 days | 723 (5.00) | 249 (34.44) | 399 (29.87) | 202 (30.24) | ||
| Co-morbidity† | ||||||
| RA | 93 (0.64) | 11 (1.52) | 0.085 | 6 (0.45) | 10 (1.50) | 0.107 |
| Sjogren syndrome | 64 (0.44) | 13 (1.80) | 0.129 | 10 (0.75) | 9 (1.35) | 0.059 |
| Systemic sclerosis | 4 (0.03) | 1 (0.14) | 0.038 | 0 (0.00) | 1 (0.15) | 0.055 |
| Vasculitis | 25 (0.17) | 8 (1.11) | 0.117 | 12 (0.90) | 3 (0.45) | 0.055 |
| Hypertension | 3208 (22.19) | 213 (29.46) | 0.167 | 400 (29.94) | 195 (29.19) | 0.016 |
| Diabetes mellitus | 1409 (9.74) | 109 (15.08) | 0.162 | 211 (15.79) | 103 (15.42) | 0.010 |
| Hyperlipidaemia | 1281 (8.86) | 91 (12.59) | 0.121 | 158 (11.83) | 86 (12.87) | 0.032 |
| Coronary artery disease | 1130 (7.81) | 95 (13.14) | 0.175 | 188 (14.07) | 91 (13.62) | 0.013 |
| Osteoporosis | 525 (3.63) | 51 (7.05) | 0.153 | 88 (6.59) | 45 (6.74) | 0.006 |
| Cerebral vascular accident | 800 (5.53) | 73 (10.10) | 0.171 | 131 (9.81%) | 67 (10.03) | 0.008 |
| Asthma | 619 (4.28) | 35 (4.84) | 0.027 | 79 (5.91) | 35 (5.24) | 0.029 |
| COPD | 1109 (7.67) | 100 (13.83) | 0.200 | 178 (13.32) | 89 (13.32) | 0.000 |
| Chronic kidney disease | 184 (1.27) | 28 (3.87) | 0.165 | 45 (3.37) | 26 (3.89) | 0.028 |
| Chronic liver diseases | 855 (5.91) | 171 (23.65) | 0.516 | 239 (17.89) | 123 (18.41) | 0.014 |
| Hyperthyroidism | 112 (0.77) | 16 (2.21) | 0.119 | 26 (1.95) | 15 (2.25) | 0.021 |
| Thyroiditis | 13 (0.09) | 3 (0.41) | 0.119 | 3 (0.22) | 3 (0.45) | 0.021 |
| Pancreatitis | 21 (0.15) | 9 (1.24) | 0.133 | 10 (0.75) | 7 (1.05) | 0.032 |
| Affective psychosis | 145 (1.00) | 12 (1.66) | 0.057 | 27 (2.02) | 10 (1.50) | 0.040 |
| Ankylosing spondylitis | 20 (0.14) | 4 (0.55) | 0.071 | 3 (0.22) | 2 (0.30) | 0.015 |
| IBD | 153 (1.06) | 11 (1.52) | 0.041 | 17 (1.27) | 11 (1.65) | 0.031 |
| HIV infection | 1 (0.01) | 7 (0.97) | 0.138 | 0 (0.00) | 6 (0.90) | 0.135 |
| APS | 3 (0.02) | 20 (2.77) | 0.236 | 0 (0.00) | 19 (2.84) | 0.242 |
| ITP treatment at baseline‡ | ||||||
| No drug admiration | 199 (27.52) | 189 (28.29) | ||||
| Corticosteroid only | 462 (63.90) | 425 (63.62) | ||||
| HCQ or azathioprine | 62 (8.58) | 54 (8.08) | ||||
*Length of hospital stay was identified within 2 years before index date.
†Comorbidity was identified within 1 year before index date.
‡ITP treatment was identified within 6 months after diagnosis with ITP.
.APS, antiphospholipid antibody syndrome; ASD, absolute standardised difference; HCQ, hydroxychloroquine; IBD, inflammatory bowel disease; ITP, idiopathic thrombocytopenic purpura; PSM, propensity score matching; RA, rheumatoid arthritis.