Abstract Number: PB0843
Meeting: ISTH 2021 Congress
Background: Thrombotic thrombocytopenic purpura (TTP) is a rare blood disorder, classified as either congenital (cTTP) or immune-mediated (iTTP). A significant proportion of patients with TTP suffer from comorbidities and impaired functioning.
Aims: To describe patient characteristics, comorbidities, and treatments associated with the management of TTP episodes.
Methods: A retrospective database analysis was conducted using insurance claims data collected between Q1 2009 and Q1 2019 from the IBM Watson Health MarketScan® Commercial Claims and Encounters database and the Medicare Supplemental and Coordination of Benefits database. Patients had ≥2 diagnosis claims for thrombotic microangiopathy (ICD-9=446.6; ICD-10=M31.1) and ≥1 TTP-related visit at which treatment with either plasma exchange (PEX) or plasma infusion (PI) was given. Patients were stratified by TTP subtype on the basis of treatment received (iTTP cohort = only PEX; cTTP cohort = only PI; unclassified cohort = PEX and PI). Descriptive statistical analyses were conducted for patient-level demographics, clinical characteristics, and treatments.
Results: Data from 1174 TTP patients were analyzed. Mean (SD) age at baseline was 37.8 (20.2) years for patients with cTTP and 49.1 (17.6) years for iTTP. 67.3% of patients with iTTP and 56.4% with cTTP were female. Mean (SD) baseline Charlson Comorbidity Index (CCI) scores by subtype were iTTP=1.6 (2.3), cTTP=0.9 (1.3), and unclassified=1.0 (1.6). Renal disease, chronic pulmonary disease, and diabetes were the most common comorbidities contributing to baseline CCI score (Table 1). In the iTTP cohort, 88.4% of patients had ≥1 TTP-related inpatient visit versus 28.2% for the cTTP cohort. Comorbid conditions present at TTP-related visits were more prevalent in the inpatient setting. Treatments used during TTP-related visits are shown in Table 2.
|Condition||iTTP (n=805)||cTTP (n=39)||Unclassified (n=330)|
|Any malignancy, including leukemia and lymphoma||95 (11.8)||2 (5.1)||25 (7.6)|
|Cerebrovascular disease||71 (8.8)||7 (17.9)||63 (19.1)|
|Chronic pulmonary disease||105 (13.0)||3 (7.7)||30 (9.1)|
|Mild liver disease||74 (9.2)||4 (10.3)||28 (8.5)|
|Mild to moderate diabetes||101 (12.5)||2 (5.1)||43 (13.0)|
|Renal disease||145 (18.0)||10 (25.6)||63 (19.1)|
|Rheumatologic disease||85 (10.6)||2 (5.1)||26 (7.9)|
|Values are number of patients (%). Because a diagnosis code to distinguish TTP subtypes is not available, an algorithm was developed. The iTTP cohort included patients treated with PEX on the index date and not treated with PI at any point. The cTTP cohort included patients treated with PI on the index date and not treated with PEX at any point. The unclassified cohort included patients treated with both PEX and PI.
The index date was defined as the start date of the first TTP-related visit during the analysis period at which treatment with PEX or PI was given. The baseline period was defined as the 6 months prior to the index date.
Clinical conditions were defined according to ICD-9 and ICD-10 codes.
|Treatment||iTTP (n=805)||cTTP (n=39)||Unclassified (n=330)|
|PEX + corticosteroids||45 (5.6)||0 (0.0)||121 (36.7)|
|PEX + rituximab||19 (2.4)||0 (0.0)||80 (24.2)|
|PEX + other or unclassified biologics||0 (0.0)||0 (0.0)||1 (0.3)|
|PI + rituximab||0 (0.0)||2 (5.1)||76 (23.0)|
|Cryoprecipitate-reduced PI||0 (0.0)||1 (2.6)||62 (18.8)|
|Frozen or fresh-frozen PI||0 (0.0)||38 (97.4)||299 (90.6)|
|Solvent/detergent-treated PI||0 (0.0)||0 (0.0)||4 (1.2)|
|PEX + PI at the same visit||0 (0.0)||0 (0.0)||320 (97.0)|
|Values are number of patients (%).|
Conclusions: This retrospective database analysis is one of the first to classify patients into distinct iTTP and cTTP cohorts, and highlights the considerable clinical burden of disease and the long-term consequences for organ involvement.
To cite this abstract in AMA style:Satija A, Tzivelekis S, Swallow E, Patterson-Lomba O, Briggs A, Yim E, Mellgard B. The Clinical Burden of Congenital and Immune-mediated Thrombotic Thrombocytopenic Purpura: A Retrospective Cohort Analysis [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/the-clinical-burden-of-congenital-and-immune-mediated-thrombotic-thrombocytopenic-purpura-a-retrospective-cohort-analysis/. Accessed December 6, 2023.
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