The Epidemiology Of Immune Thrombocytopenia and Clinical Features Of Patients At a Single Center In Northwestern Turkey
Authors: Pamuk Gulsum Emel , , Internist Ahmet Koylu , Uyanik Mehmet Sevki , Fellow Hematology , Demir Muzaffer , Pamuk Omer Nuri 
Published: October 2019

Introduction
There is only a few data about the epidemiology of immune thrombocytopenia (ITP). Until now, no data about the frequency of ITP in Turkey has been reported. It is quite difficult to perform an epidemiologic study because there are multiple pathogenic mechanisms in ITP and no laboratory or clinical data is characteristic for the diagnosis. We determined the epidemiology of ITP in northwestern region of Turkey and we evaluated the clinical features in our ITP patients.

Methods
Twohundred-and-sixteen patients diagnosed with ITP between 2000-2012 at our center were retrospectively evaluated. Our hospital has been the only tertiary referral center for hematological diseases (benign and malignant) for a mixed rural and urban population of 616000 people (316000 males, 300000 females) for longer than 16 years. The incidence rates and prevalence per 100000 poulation aged ≥16 years were calculated.

Results
Of 216 ITP patients, 159 (73.6%) were females and 57 (26.4%) were males (female/male: 2.8). The mean annual incidence of ITP was 2.92/100000 (95%CI: 1.57-4.27) and the overall prevalence was 35.1/100000 (95%CI: 30.3-39.8). The prevalence in women (53/100000, 95%CI: 44.8-61.2) was higher than the prevalence in men (18/100000, 95%CI: 15.4-20.6). The mean age at the time of diagnosis was 42.3 years (median age: 40, range:8-87). Of 162 ITP patients who were given first-line therapy, there was complete response (CR) in 124 (76.5%) and partial response (PR) in 22 (13.6%) (Table 1). Seventythree (50%) of the 146 patients who obtained response (CR+PR) with first-line therapy relapsed at a median of 6 months (range: 2-98 months). The median follow-up in patients who did not relapse was 11 months (range: 2-108 months). The frequency of relapse-free remission in patients responsive to first-line therapy was 61% at one year and 52% at 5 years. Thirtynine patients (48.1%) who were responsive to second-line therapy (CR+PR) relapsed at a median of 5.5 months (range: 2-83 months). Twentyfive patients (53.2%) who were steroid-responders relapsed at a median of 6 months (range: 2-83 months). Ten patients (34.5%) who were responsive to splenectomy relapsed at a median of 6.5 months (range: 2-54 months). Splenectomy was performed in 49 ITP patients. In 30 patients, it was the second-line treatment modality; in 13 patients, it was third-line; and in 6, it was fourth-line. Splenectomized patients were followed up for a median of 35.5 months (range: 2-187 months). The median duration from diagnosis until splenectomy was 7 months (range: 2-102). Of 49 patients who underwent splenectomy, 43 (87.8%) had CR and one (2%) had PR. Nine of the 44 patients (20.5%) relapsed at a median of 24 months (range: 5.5-141). The median duration of remission in 35 patients (79.5%) who did not relapse was 30.5 months (range: 2-84 months). When splenectomy and steroids were compared as second-line treatment options, CR rate was higher with splenectomy (p=0.002) and total response (CR+PR) tended to be better (96.7% vs. 82.5%, p=0.09). Patients responsive to steroids as second-line therapy tended to relapse more than patients treated with splenectomy (53.2% vs. 33.3%, p=0.088). When relapse-free remission durations with splenectomy and steroids were compared, it was seen that it was longer with splenectomy (p<0.001). The relapse-free remission rates after splenectomy were 90% at 1 year and 62% at 5 years. These rates were lower with steroid therapy (45% at 1 year, 36% at 5 years).

Conclusions
The annual incidence and prevalence of ITP in northwestern Turkey was similar to data from western countries –at the lower limit for some countries. Effective treatment strategies seem to be steroids as first-line therapy and splenectomy in refractory cases.

Disclosures:
No relevant conflicts of interest to declare.