Cox proportional hazard regressions for estimation of adjusted HRs on SLE
| Variable | HR (95% CI) | |||
| 1:20 age-matched and sex-matched population | 1:2 PSM population | |||
| Model 1: ITP exposure alone | Model 2: ITP exposure +demographic variables | Model 3: model 2+medical utilisation and comorbidities at baseline | Model 4: conditional cox model with ITP exposure alone | |
| ITP (ref: non-ITP) | 28.7 (17.3 to 47.6) | 28.5 (17.2 to 47.3) | 25.1 (13.7 to 46.0) | 17.4 (5.28 to 57.4) |
| Sex (ref: male) | ||||
| Female | 20.7 (5.01 to 84.8) | 20.5 (4.94 to 84.9) | ||
| Age (ref: 30–45) | ||||
| <30 | 1.19 (0.63 to 2.24) | 1.20 (0.62 to 2.32) | ||
| 45–65 | 0.58 (0.28 to 1.21) | 0.56 (0.25 to 1.25) | ||
| ≥65 | 0.44 (0.18 to 1.07) | 0.42 (0.15 to 1.21) | ||
| Urbanisation (ref: Urban) | ||||
| Suburban | 1.09 (0.63 to 1.88) | 1.13 (0.65 to 1.97) | ||
| Rural | 0.68 (0.24 to 1.91) | 0.71 (0.25 to 2.01) | ||
| Low income | Cannot estimate | Cannot estimate | ||
| Length of hospital stays* (ref: 0 day) | ||||
| 1–6 days | 1.35 (0.69 to 2.65) | |||
| ≥7 days | 0.91 (0.35 to 2.35) | |||
| Comorbidity† | ||||
| Rheumatoid arthritis | 2.02 (0.39 to 10.40) | |||
| Sjogren syndrome | 6.02 (1.33 to 27.34) | |||
| Systemic sclerosis | Cannot estimate | |||
| Vasculitis | 4.24 (0.84 to 21.5) | |||
| Hypertension | 1.36 (0.56 to 3.33) | |||
| Diabetes mellitus | 0.75 (0.24 to 2.38) | |||
| Hyperlipidaemia | 0.41 (0.09 to 1.79) | |||
| Coronary artery disease | 0.23 (0.03 to 1.79) | |||
| Osteoporosis | 1.20 (0.34 to 4.21) | |||
| Cerebral vascular accident | 1.93 (0.51 to 7.26) | |||
| Asthma | 1.41 (0.43 to 4.68) | |||
| Chronic obstructive pulmonary disease | 1.06 (0.40 to 2.77) | |||
| Chronic kidney disease | Cannot estimate | |||
| Chronic liver diseases | 1.55 (0.71 to 3.39) | |||
| Hyperthyroidism | 1.93 (0.58 to 6.40) | |||
| Thyroiditis | Cannot estimate | |||
| Pancreatitis | Cannot estimate | |||
| Affective psychosis | Cannot estimate | |||
| Ankylosing spondylitis | Cannot estimate | |||
| IBD | 0.70 (0.09 to 5.24) | |||
| HIV | Cannot estimate | |||
| APS | Cannot estimate | |||
*Length of hospital stay was identified within 2 years before index date.
†Comorbidity was identified within 1 year before index date.
APS, antiphospholipid antibody syndrome; IBD, inflammatory bowel disease; ITP, idiopathic thrombocytopenic purpura; PSM, propensity score matching; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus.