Immune Thrombocytopenia (ITP)


Immune thrombocytopenia (ITP) is an autoimmune condition that may be either acute or chronic and is characterized by a decreased number of circulating platelets. Autoantibodies from a person’s immune system target normal antigens on the surface membranes of platelets, leading to their premature destruction via phagocytosis by macrophages.1 

Incidence of ITP

Most data regarding the incidence and prevalence of ITP come from European studies. The annual incidence of ITP is approximately 5 cases out of every 100,000 children and 2 cases per every 100,000 adults.1,2 

In the United States, the annual incidence of ITP is estimated around 3.3 per 100,000 people.3 In Europe, the annual incidence of ITP among adults is estimated at around 1 to 4 per 100,000 people. In Northern Europe, the annual incidence is approximately 2.68 per 100,000 people.4 In Denmark, the annual incidence of ITP is estimated at 2.25 per 100,000 people.4,5 In France, the annual incidence of ITP is estimated at 2.9 per 100,000 people, depending on age, season, and geographic region.1,6 In the United Kingdom, the annual incidence of ITP is estimated at 1.6 per 100,000 people.4,7

Prevalence of ITP

In the United States, the estimated prevalence of ITP is 9.5 per 100,000 people.3,4 The estimated global prevalence of ITP is over 200,000 people at any one time.4 The prevalence of ITP is higher among adults over the age of 60 years because adults more frequently develop the chronic form of the disease.3

Read more about ITP diagnosis

Age Factors of ITP

The average age of adults at diagnosis is around 50 years, and incidence increases with age.4,8 In children, the incidence of ITP peaks between the ages of 1 and 6 years.1

ITP occurs in people of all ages, with around 40% of cases affecting children under 10 years of age.3 Approximately 80% of children with ITP present with an acute, self-limiting form of the condition, which resolves within 12 months; it often resolves much sooner, sometimes as early as 3 months after onset. The other 10% to 20% of children develop the chronic version of ITP, which lasts more than 12 months after onset.3,9

Adults more commonly develop the chronic form of ITP, resulting in a higher prevalence among those over 60 years of age. An estimated 50% to 70% of adults with ITP have the chronic form.3 

Age also factors into the severity of ITP bleeding complications, including intracranial hemorrhage, which is the most serious, potentially life-threatening complication of ITP. Approximately 0.5% to 1% of children with ITP experience intracranial hemorrhage, and half of those cases lead to fatality.1,2 In contrast, a higher number of adults (approximately 1.5%) with ITP experience intracranial hemorrhage, potentially due to the contribution of comorbid conditions.1,10 

Read more about ITP complications

Sex Factors of ITP

Female predominance occurs between adolescence and the age of 60 years. Male patients are more often affected as children and adults over 60 years of age.1,2 

Seasonal Incidence of ITP

One study analyzing the onset of ITP in 1496 children between June 1997 and May 2000 indicated that the peak incidence of ITP occurred in the spring, while the least number of cases occurred in autumn.11

Researchers found contrasting data regarding obvious seasonal variation among adults with ITP, with some studies finding no seasonal variations and others reporting seasonal variability in ITP incidence. The incidence study in France indicated a seasonal nadir in summer and a peak in winter.1,4,6

Race and Ethnicity Factors of ITP

Race and ethnicity do not seem to impact ITP incidence, as people of all races and ethnicities have been diagnosed with the condition.2,3

Autoimmune Comorbidities Associated With ITP

People diagnosed with other autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis, antiphospholipid syndrome, hemolytic anemia, autoimmune thyroiditis, and primary Sjogren’s syndrome demonstrate an increased prevalence of ITP.12,13

Comorbid autoimmune diseases are common. Between 15% and 20% of patients with SLE develop ITP.13

Read more about ITP prognosis

References

  1. Kessler C. Immune thrombocytopenia (ITP). Medscape. Updated January 7, 2021. Accessed October 10, 2022.
  2. Fogarty PF, Segal JB. The epidemiology of immune thrombocytopenic purpura. Curr Opin Hematol. 2007;14(5):515-519. doi:10.1097/MOH.0b013e3282ab98c7
  3. Immune thrombocytopenia. National Organization for Rare Disorders (NORD). Accessed October 10, 2022.
  4. Michel M. Immune thrombocytopenic purpura: epidemiology and implications for patients. Eur J Haematol Suppl. 2009;82(s71):3-7. doi:10.1111/j.1600-0609.2008.01206.x
  5. Frederiksen H, Schmidt K. The incidence of idiopathic thrombocytopenic purpura in adults increases with age. Blood. 1999;94(3):909-913. doi:10.1182/blood.V94.3.909.415k02_909_913
  6. Moulis G, Palmaro A, Montastruc JL, Godeau B, Lapeyre-Mestre M, Sailler L. Epidemiology of incident immune thrombocytopenia: a nationwide population-based study in France. Blood. 2014;124(22):3308-3315. doi:10.1182/blood-2014-05-578336
  7. Neylon AJ, Saunders PWG, Howard MR, Proctor SJ, Taylor PRA; Northern Region Haematology Group. Clinically significant newly presenting autoimmune thrombocytopenic purpura in adults: a prospective study of a population-based cohort of 245 patients. Br J Haematol. 2003;122(6):966-974. doi:10.1046/j.1365-2141.2003.04547.x
  8. Kohli R, Chaturvedi S. Epidemiology and clinical manifestations of immune thrombocytopenia. Hamostaseologie. 2019;39(3):238-249. doi:10.1055/s-0039-1683416
  9. Bussel JB. Immune thrombocytopenia (ITP) in children: management of chronic disease. UpToDate. Accessed October 10, 2022.
  10. Arnold DM. Bleeding complications in immune thrombocytopenia. Hematology Am Soc Hematol Educ Program. 2015;2015(1):237-242. doi:10.1182/asheducation-2015.1.237
  11. Kühne T, Imbach P, Bolton-Maggs PH, Berchtold W, Blanchette V, Buchanan GR. Intercontinental Childhood ITP Study Group. Newly diagnosed idiopathic thrombocytopenic purpura in childhood: an observational study. Lancet. 2001;358(9299):2122-2125. doi:10.1016/S0140-6736(01)07219-1
  12. Liu Y, Chen S, Sun Y, et al. Clinical characteristics of immune thrombocytopenia associated with autoimmune disease: a retrospective study. Medicine (Baltimore). 2016;95(50):e5565. doi:10.1097/MD.0000000000005565
  13. Demir C, Esen R, Atmaca M, Efe S. Prevalence of autoantibodies related to some autoimmune disorders in patients with chronic idiopathic thrombocytopenic purpura. Clin Appl Thromb Hemost. 2011;17(6):E114-E118. doi:10.1177/1076029610387588

Reviewed by Kyle Habet, MD, on 10/24/2022.

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