Demographic, Mortality, and Economic Outcomes in Hospitalised Patients with Immune Mediated Thrombotic Thrombocytopenic Purpura (iTTP): A Comprehensive Analysis
Authors: Babu Kalaivani , Rajarajan Srinishant , Jayakumar Jayalekshmi , Ramesh Nithya , Ramanan Sruthi P , Chattaraj Asmi , Dhamija Kriti , Khan Eiraj , Kasire Sripada Preetham , Correa Amit , Bhanushali Charmi , Roy Arya Mariam , Helfand Alexander 
Published: December 2024

Background: Immune-mediated Thrombotic Thrombocytopenic Purpura (iTTP) is a rare and life-threatening condition characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ dysfunction. Understanding the demographics, mortality, hospital length of stay, and economic burden associated with iTTP can inform better management strategies and resource allocation. This study aims to provide a detailed analysis of these outcomes using a large dataset.

Methods: We utilized data from a national inpatient sampleset to analyze patients diagnosed with iTTP using ICD-10 code D69.3. The study population included 58,475 hospitalised iTTP patients. We conducted demographic analysis, mortality analysis, and assessed hospital length of stay and charges. Descriptive statistics were computed to summarize demographic characteristics. Logistic regression was employed to assess mortality risk factors, while linear regression models adjusted for various factors were used to analyze hospital length of stay and charges. Standard errors, confidence intervals, and p-values were calculated to determine statistical significance.

Results: Demographics: The mean age of ITTP patients was 61.16 years. The gender distribution was 43.63% male and 56.37% female. The racial breakdown was predominantly White (68.18%), followed by Black (12.69%), Hispanic (12.24%), Asian (3.42%), Native American (0.54%), and other races (2.92%). The Charlson Comorbidity Index (CCI) revealed that 24.27% had no comorbidities, 16.55% had one, 14.21% had two, and 44.97% had three or more comorbidities. Income was evenly distributed across quartiles, and most patients had private insurance (55.39%). The majority were admitted to large (52.95%), teaching hospitals (79.03%) located in urban areas (94.00%). Mortality Analysis: The estimated number of deaths was approximately 3,195, with a mortality rate of 5.46%. Adjusted logistic regression revealed that each additional year of age increased mortality odds by 2.3% (OR = 1.023, p &lt; 0.0001). Female patients had lower mortality odds compared to males (OR = 0.755, p = 0.001). Black patients had higher odds of mortality (OR = 1.364, p = 0.010), while Native American patients showed increased odds, though not statistically significant (OR = 2.307, p = 0.063). Higher income quartiles were associated with decreased mortality (highest quartile OR = 0.780, p = 0.037), and each additional comorbidity increased mortality odds by 15.9% (OR = 1.159, p &lt; 0.0001). Hospital region had no significant effect on mortality. Hospitals with medium (OR=1.43, p=0.007) and large (OR=1.34, p=0.013) bed sizes are associated with higher odds of patient mortality compared to small hospitals. Hospital Length of Stay (LOS): The average LOS was 7.00 days. Older age was associated with a slight increase in LOS (Coefficient = 0.012, p = 0.011). Female patients had a shorter LOS by about 0.71 days (Coefficient = -0.708, p &lt; 0.0001). Black and Asian patients had longer LOS (Coefficients = 0.721, p = 0.016; 1.134, p = 0.045, respectively). Patients in higher income quartiles had shorter stays. Each additional comorbidity increased LOS by 0.568 days (p &lt; 0.0001). Teaching hospitals and larger bed size hospitals were associated with longer stays. Hospital Charges: The average total hospitalization charges were $110,740. Female patients incurred significantly lower charges (Coefficient = -$25,273.09, p &lt; 0.0001). Charges were higher for Black, Hispanic, and Asian patients (Coefficients = $10,960.06, $19,597.10, and $38,009.78, respectively). Higher income quartiles did not significantly affect charges. Each additional comorbidity increased charges by $7,251 (p &lt; 0.0001). Rural hospitals had lower charges, while teaching hospitals and larger hospitals had higher charges.

Conclusion: iTTP predominantly affects older adults and exhibits a higher mortality rate among males, Black patients, and those with higher comorbidities. Hospital length of stay and charges are significantly influenced by patient demographics, comorbidity burden, and hospital characteristics. Findings suggest a need for targeted interventions and resource allocation to address disparities and manage the economic burden of iTTP effectively.