Survival in adult patients with chronic primary and secondary immune thrombocytopenia: A population‐based study

BACKGROUND: Few studies have investigated long‐term survival in patients with primary immune thrombocytopenia (pITP). Further, changes in prognosis over the past decades and prognosis of secondary immune thrombocytopenia (sITP) are largely unstudied. Our objectives were to study comorbidity‐adjusted prognostic changes and causes of death in chronic pITP and sITP patients. STUDY DESIGN/METHODS: Using nationwide Danish health registries 1980–2016, we identified 1762 patients with chronic pITP (median age 58 (IQR, 37–73) years) and 128 with chronic sITP (median age 59 (IQR, 40–73) years). Patients were age‐sex‐matched to 74,781 general population comparators. Comorbidity was assessed using Charlson Comorbidity Index (CCI). RESULTS: Overall median survival was reduced by 5.1 years (95% CI, 0.7–9.4) (p < .001) for pITP and 11.1 years (95% CI, 5.8–16.4) (p < .001) for sITP. 5‐year survival increased from 69% (95% CI, 59–78) in 1980–89 to 80% (95% CI, 75–83) in 2010–16 for pITP, and decreased from 100% (95% CI, 89–98) to 64% (95% CI, 87–91) for sITP. However, numbers were small for sITP. 5‐year survival for pITP with high CCI was 41% (95% CI, 32–49), and 85% (95% CI, 83–87) for low CCI. Bleeding, infection and hematological cancer were relatively frequent causes of death with adjusted subhazard ratios of 3.25 (95% CI, 2.33–4.52), 1.53 (95% CI, 1.08–2.16) and 2.16 (95% CI, 1.12–4.16) in pITP respectively, and 10.52 (95% CI, 1.43–77.36) for hematological cancer in sITP. CONCLUSIONS: Long‐term survival is reduced in chronic ITP but seems to be improving. Comorbidity and sITP are associated with a poor prognosis.