Clinical characteristics
The clinical characteristics of patients treated with HCQ and those
without are listed in Table 1. In the HCQ group, the mean age of HCQ
initiation was 12.0 years old, and the mean interval from ITP onset to
HCQ initiation was 26.4 months. The mean platelet counts at the time of
HCQ initiation was 85 × 109/L, higher than the level
that usually required medication, which may be explained by the
combination therapy initiated before HCQ such as corticosteroids and
TRO-RAs. In the HCQ group, 50% of patients had positive ANA at
baseline, 47.6% of patients suffered from symptoms associated with
autoimmune diseases, and 64.7% of patients had other positive markers
associated with autoimmune diseases except for ANA, such as
antiphospholipid antibodies and low C3/C4. Treatments before HCQ
included corticosteroids, IVIG, rituximab, TPO-RAs, and splenectomy,
which previously failed in maintaining long-term effective. The median
follow-up for patients treated with HCQ and those without were 56 and 34
months, respectively. Of note, at the last follow-up, 69.0% of patients
in the HCQ group achieved CR/R, with a higher frequency than in the
non-HCQ group (69.0% vs. 48.3%; odds ratio, 2.39; 95% CI, 1.15 to
4.95).