Newly diagnosed immune thrombocytopenia in children and adults: a comparative prospective observational registry of the Intercontinental Cooperative Immune Thrombocytopenia Study Group

Abstract

Background: Primary immune thrombocytopenia is a bleeding diathesis with an unknown etiology in predisposed individuals with immune disturbances. Although it is claimed that children and adults differ in clinical and laboratory aspects, few data exist to corroborate this observation. Our objective was to assess comparative data from children and adults with newly diagnosed immune thrombocytopenia.

Design and methods: Clinical and laboratory data of 1,784 children and 340 adults were extracted from the Pediatric and Adult Registry on Chronic Immune Thrombocytopenia. The registry represents a prospective cohort of children and adults with newly diagnosed immune thrombocytopenia. Participating investigators registered their patients immediately after the diagnosis using a web based data transfer. Children aged under 16 years were compared with adults aged 16 years and over with descriptive statistical analyses.

Results: The presenting mean platelet count of children and adults was 18.1 and 25.4 × 10(9)/L. Signs of bleeding were reported in 24% of children and in 23% of adults, and intracranial hemorrhage in 10 of 1,784 children and in 6 of 340 adults. Co-morbidity was observed in 3.9% of children and in 30% of adults. Bone marrow aspiration and laboratory tests (antinuclear antibodies, human immunodeficiency and hepatitis C virus) were performed more frequently in adults. Children and adults were followed with a 'watch and wait' strategy in 20% and in 29%, respectively. Immunoglobulins were used more frequently in children and corticosteroids in adults.

Conclusions: Comparative data of children and adults with newly diagnosed immune thrombocytopenia revealed similarities in presenting platelet counts and in bleeding, whereas differences occurred in co-morbidity, diagnostic procedures and therapy.

Figure 1.

Black bars (from left, 0%, to the right, 100%) indicate patients with a presenting platelet count of <20x10⁹/L, and white bars (from right, 0%, to the left, 100%) patients with a presenting platelet count of ≥20x10⁹/L. c: children, a: adults.

Figure 2.

(A) Platelet count of children and adults at the time of ITP diagnosis. The vertical line indicates a platelet count of 20x10⁹/L. (B) Platelet counts of children and adults at the time of the diagnosis of ITP are plotted as quantile-quantile plot to compare the distribution of platelet counts of children and adults. A logarithmic scale was chosen in order to highlight platelets <50x10⁹/L. With equal size of the number of observations (N) for children and adults, each data set is ranked from the smallest to the highest value. This gives N pairs (x,y) from (x_min/y_min) to (x_max/y_max) and each pair is a point in the quantile-quantile plot. If the two distributions are similar, the points occur approximately on the diagonal of the plot. For unequal size of the two data sets interpolation to the same quantile is used.

Figure 3.

Black bars (from left, 0%, to the right, 100%) indicate the percentage of patients in whom a given laboratory test was performed and white bars (from right, 0%, to the left, 100%) indicate the percentage of patients in whom that given test was not performed. Test results are presented in Table 3. c: children, a: adults.

Figure 4.

Percentage of children (white bars) and adults (black bars) is shown according to their initial management: observation without active treatment, intravenous immunoglobulins (IVIG), corticosteroids (CS), anti-D antibodies (anti-D).