Primary immune thrombocytopenia (ITP) is the most frequent acute form of thrombocytopenia found in previously healthy children. It is an acquired disease that manifests with a transient or persistent drop in the platelet count (<100 000). Several factors have been found to be associated with primary ITP, such as recent viral infection or administration of certain vaccines. It also exhibits a seasonal pattern with a higher incidence in winter and spring.1

The severity of the disease is determined based on the haemorrhagic manifestations, which do not always correlate to the platelet count. The severity can be categorised applying the criteria used in the United Kingdom2 (asymptomatic, mild symptoms, moderate symptoms or severe symptoms).

There are several treatment options that depend on the chronicity and severity of the ITP. According to the working group on ITP of the Sociedad Española de Hematología y Oncología Pediátricas (Spanish Society of Paediatric Haematology and Oncology, SEHOP),3 the treatment options for newly diagnosed ITP, depending on the severity and risk factors, are: observation, steroid therapy (oral prednisone or intravenous [IV] methylprednisolone) and intravenous immunoglobulin (IVIG). Chronic ITP can be treated with thrombopoietin receptor agonists, such as eltrombopag (via the oral route).

In 2017, the Department of Health detected an increase in the prevalence of ITP in our region, with a tendency to relapse in certain patients. Since there is no specific register of Spanish children with ITP, we thought it would be relevant to review the epidemiological and clinical characteristics of our patients. To that end, we carried out a retrospective descriptive study by selecting cases with diagnostic codes 287 and D69 of the International Classification of Diseases, Ninth Revision (ICD-9) in the Corporate Analysis Platform of the Department of Health of Valencia (ALUMBRA). We then collected data on the variables under study from the health records of the selected patients, entering and encoding the data in an anonymised database.

We included children aged 0 to 15 years with a diagnosis of idiopathic thrombocytopenic purpura or primary immune thrombocytopaenia managed in our department between 2002 and 2017. We excluded patients with a neonatal diagnosis.

The independent variables were: infection or vaccination in the month preceding diagnosis, age at diagnosis, month of onset and sex.

The dependent variables were: incidence, prevalence, platelet count at diagnosis, time elapsed from onset to diagnosis, length of stay, severity,2 number of relapses during follow-up through 2018, and treatment (observation, steroid therapy, gamma globulin, eltrombopag).

The study was approved to be conducted in our hospital by the competent ethics committee and by the Research Committee of the Department of Health.

We performed a descriptive analysis with the statistical software SPSS. We have described variables as mean and standard deviation (SD) if normally distributed, and otherwise as median and range. We assessed the normality of the distribution with the Kolmogorov–Smirnov test.

We found an incidence of 9.23 cases per 100 000 paediatric-aged inhabitants and a prevalence of 24.87 cases per 100 000 paediatric-aged inhabitants in 2017. We found that 39 patients had received a diagnosis of ITP (51% female and 49% male). Table 1 summarises the epidemiological characteristics of the identified cases and the diagnostic tests ordered in the evaluation, along with their results.

Observation was the initial approach in 4, although ITP resolved spontaneously only in 2. Seventy-four percent of patients received IVIG and 56% corticosteroids (overall, 41% of patients required both treatments). Patients treated with IVIG received a median of 2 doses (range, 1–15). Due to progression to chronic ITP, 2 patients were treated with eltrombopag.

Of the 39 patients, 7 progressed to chronic ITP and 2 to persistent ITP, while 1 died as a result of intracranial bleeding, with contradictory findings of the post-mortem examination of the bone marrow and the skullcap as to whether the site of origin was deep or superficial.

Salient findings of our study include a shorter length of stay in the group with moderate symptoms compared to the group with mild symptoms, a result that could be biased due to transfer to a tertiary care hospital. Also, our data corroborated the increase in cases in the winter and spring, and the association with vaccination or infection in the month preceding onset.

As regards the treatment and outcomes of ITP, there are several limitations to our study. On one hand, due to the retrospective design, in the early cases the occurrence of relapses, the response to treatment and the indication for treatment were established based on the judgment of the physician in charge, whereas in later years they were established based in international guidelines.4 Furthermore, the sample was small, so it is difficult to draw conclusions on the subject.

The approach to the treatment of patients with ITP varies between hospitals, so there is a need to standardise its management.