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Introduction Acute chest syndrome (ACS) is a clinical presentation of fever, chest pain, pulmonary symptoms, and new infiltrates on lung imaging. It affects nearly 50% of patients with sickle cell disease during their lifetime and often leads to hospitalization. The mortality rate is variable ranging from 3 to 9 %. and depends on several factors. We aimed to identify the clinical and epidemiological characteristics of patients admitted with ACS on a national scale and factors affecting clinical outcomes in inpatient setting. Methods: We utilized the National Inpatient Sample (NIS) database 2019 for the purpose of this study. Using this database, we identified patients with a principle diagnosis of ACS using International Classification of Diseases (ICD-10) codes. Data on demographic characteristics such as age, sex, race, insurance type were collected. Additionally, we selected clinically significant medical comorbidities such as asthma, chronic obstructive pulmonary disease (COPD), coronary artery disease (CAD), chronic kidney disease (CKD), heart failure, hypertension, diabetes mellitus (DM), sepsis, obesity, and others. The primary endpoint of this study was to identify factors influencing all-cause mortality, while the secondary endpoint was to identify factors influencing mechanical intubation, in-patient blood transfusion, and length of stay. We used multivariate logistic regression analysis to adjust for confounders. A p value of ≤0.05 considered statistically significant. Results: Baseline Characteristics Our analysis consisted of 22,459 patients who were admitted with principal diagnosis of ACS. 49.5% were female and 50.5% were male. Mean age was 30.5 years. African American race was predominant (92%) with sickle cell Hb-SS disease (87%). Major insurance payer was Medicaid (47%) followed by Medicare (27%) and then private insurance (21%). Asthma was the most common comorbidities (24%) and majority of patient had Charlson Comorbidity Index (CCI) score of zero (55%). The details of clinical and epidemiological characteristics are shown in Table 1. Clinical outcomes and factors influencing mortality Only 0.89% patient died of ACS. Average length of stay was 6.86 days. 34% of the patient required packed red blood cell (pRBC) transfusion. 3.2% needed mechanical ventilation. In multivariate analysis, factors associated with mortality included age of patient, CCI and sepsis. Younger patient had higher odds of mortality however this was not statistically significant. There was no difference in mortality with sex, race and insurance status of the patients. Factors affecting inpatient transfusion, mechanical ventilation and length of stay Female, higher CCI score and sepsis on admission were associated with higher needs of inpatient pRBC transfusion. Within race, White (OR 3.16, CI 1.44-6.93, P <0.01) and Hispanics (OR 2.68, CI 1.59-4.51, P<0.01) had higher odds of receiving transfusion compared to African Americans (OR 1.84, CI: 1.17-2.89, P <0.01). Similarly patient with sepsis, supraventricular tachycardia had more odds of needing mechanical ventilation. Patient's insurance status was also related to increased odds of intubation. Comorbidities such as asthma and CAD were not associated with need of mechanical ventilation and in fact our study shows they had less odd of needing mechanical ventilation. Length of stay was influenced by several of epidemiological and clinical comorbidities. Females had less odds of longer length of stay compared to male (OR: 0.65, P <0.01). Comorbidities such as asthma, heart failure, CAD, DM2 and hypertension did not increase the length of stay while patients with sepsis and high CCI score had higher odds of hospitalization for extended period of time. The details are in Table 2. Conclusion We found mortality was 0.89% in patients admitted with ACS compared to 3 to 9% previously reported. Sepsis and CCI were one of the predictors for odds of having higher mortality, need of blood transfusion, mechanical ventilation and increased length of stay in patient with ACS. Female, White and Hispanic had higher odds of needing transfusion then African Americans. Comorbidities such as asthma, heart failure, CAD, DM 2 and hypertension did not increase the odds of prolonged hospital stay.

Introduction: Vitamin B12 deficiency is a common nutritional issue associated with mild anemia and neurological deficits. While rare, hemolytic anemia and low platelet count can be complications of this deficiency, often misdiagnosed as thrombotic microangiopathy (TMA), specifically thrombotic thrombocytopenic purpura (TTP). Pseudo TMA features can occur with B12 deficiency and can be effectively treated with vitamin B12 supplementation. In contrast, true TMA requires plasmapheresis. This systematic review aims to differentiate between pseudo TMA and TMA cases through an analysis of published case reports, providing valuable insights to avoid unnecessary treatments. Methods: We performed systematic review from Pubmed, Web of Science, and Scopus database. Twin independent reviewers (SY and BL) performed the screening using Covidence. Search keywords included “((hemolytic anemia) AND (vitamin B12 deficiency)) OR ((cobalamin deficiency) AND (hemolytic anemia)) Filters: English” for Pubmed, “(((ALL=(Cobalamin deficiency)) OR ALL=(vitamin B12 Deficiency))) AND ALL=(hemolytic anemia) Filter: English” for Web of Science and “( vitamin AND b12 AND deficiency OR cobalamin AND deficiency ) AND hemolytic AND anemia AND ( LIMIT-TO ( LANGUAGE , ”English“ ))” from Scopus. Only case reports in English with full-text availability and adult subjects were selected. Cases without final clinical outcome after treatment were excluded. After a comprehensive review, we identified 43 case reports and series with a total 53 patients that fulfilled our criteria. The details of selection process is illustrated in the prisma diagram (Figure 1). Results: The majority of cases involved males with low hemoglobin and platelet counts upon admission. Evidence of hemolysis was observed, indicated by increased lactate dehydrogenase (LDH), undetectable haptoglobin, and elevated or normal total and direct bilirubin levels. Peripheral blood films confirmed the presence of hemolytic anemia. Due to the co-occurrence of thrombocytopenia and hemolytic anemia, some cases were initially diagnosed as TTP, leading to the initiation of plasmapheresis. In 16 out of 53 reported case reports/series, patient received plasmapheresis. However, low reticulocyte index and normal ADAMTS 13 suggested an alternative diagnosis. Once ADAMTS 13 levels were normal, plasmapheresis was discontinued as TTP was ruled out. Diagnosis of B12 deficiency was confirmed by low B12 levels and elevated methylmalonic acid (MMA) levels. Leading cause for B12 deficiency were pernicious anemia in 28/53 cases, followed by dietary deficiency, and malabsorption due to surgery. Some patients also exhibiting concurrent iron deficiency anemia and folate deficiency. Treatment with subcutaneous B12 injections showed improvement in hemolysis as early as one week. Conclusion: Many cases of Vitamin B12 deficiency presenting with hemolytic anemia and thrombocytopenia are mistakenly diagnosed as TTP, leading to unnecessary and expensive plasmapheresis. Routine B12 level checks should be performed in all patients with hemolytic anemia, as B12 deficiency can be rapidly diagnosed and effectively treated, avoiding misdiagnoses and unnecessary interventions associated with TTP. The short turnover time for B12 levels (hours) compared to ADAMTS 13 activity (1-2 days) further supports the importance of routine B12 assessment in these patients.