Clinical characteristics, treatment patterns and long-term outcomes of warm and mixed autoimmune hemolytic anemia: insights from a real-world study

1 Introduction

Autoimmune hemolytic anemia (AIHA) is a group of anemias characterized by autoantibody-mediated destruction of red blood cells (RBCs). As the most prevalent form of acquired hemolytic anemia, AIHA is marked by its clinical heterogeneity, unpredictable disease progression, high relapse rates and thrombotic risk (1–4). Based on underlying etiology, AIHA is divided into primary and secondary forms (5). Direct antiglobulin test (DAT) and cold agglutinin (CA) level remain the diagnostic cornerstones for AIHA, guiding its major subclassification into: (1) warm AIHA (wAIHA, 37 °C), (2) cold AIHA (cAIHA, ≤4 °C), (3) mixed AIHA (mAIHA), and (4) DAT-negative AIHA, which reflects the optimal temperature at which antibodies bind to RBCs (6, 7). Paroxysmal cold hemoglobinuria, however, is recognized as a distinct entity diagnosed by biphasic Donath-Landsteiner antibody. Among secondary AIHAs, autoimmune disorders (AIDs) and lymphoproliferative diseases (LPDs) constitute the majority of cases, followed by solid tumors, infections, drugs, immunodeficiencies, and hematopoietic stem cell transplantation (1, 2, 8).

As the most prevalent form, wAIHA arises from immune tolerance breakdown characterized by peripheral and splenic T helper 17/regulatory T cell imbalance (9, 10). The immune dysregulation drives autoreactive B-cell expansion and subsequent polyclonal plasma cell differentiation, which generate pathogenic antibodies (primarily IgG, though IgA or warm-reactive IgM may also involve) targeting Rh antigens, band 3, and glycophorin A on RBCs (11, 12). In the spleen, opsonized RBCs bind to Fcγ receptors (FcγR) on resident macrophages, triggering antibody-dependent cellular phagocytosis and cytotoxicity (1, 13). Incomplete phagocytosis of opsonized RBCs leads to spherocytosis in approximately 40% of cases (14). Besides, IgG1/IgG3 activate the classical complement pathway, leading to membrane attack complex formation and complement-dependent cytotoxicity (15).

Glucocorticoids (GCs) remain the standard first-line therapy for wAIHA. For patients presenting with severe manifestations (abrupt onset, hemoglobin [Hb] <6 g/dL, Evans syndrome, IgA-mediated, or DAT-negative status) or for elderly patients with significant comorbidities, the early addition of RTX to GCs is frequently considered (1, 2, 16, 17). While RTX has established its role in relapsed/steroid-refractory wAIHA, the optimal sequencing of other second-line therapies, including azathioprine (AZA), mycophenolate mofetil (MMF), cyclosporine A (CsA), and cyclophosphamide (CTX) remains controversial (17). Splenectomy has been relegated to a later-line option due to risks of life-threatening infections and thrombotic events (18). Recent advances have broadened the treatment landscape for refractory wAIHA (17, 19). Ongoing prospective trials are evaluating promising therapies, including spleen tyrosine kinase (Syk) inhibitors (20, 21), Bruton tyrosine kinase (BTK) inhibitors (19, 22), plasma cell targeting therapies (bortezomib, daratumumab) (23), mammalian target of rapamycin (mTOR) inhibitor sirolimus (SRL) (24), B-cell activating factor (BAFF) inhibitors (25), phosphatidylinositol 3-kinase delta (PI3Kδ) inhibitors (26), and notably, chimeric antigen receptor (CAR)-T cell (27) along with B-cell maturation antigen (BCMA)-targeted T-cell-engager therapy (28). The management of mAIHA lacks consensus due to limited prospective studies (29, 30) and mostly follows the treatment protocol of wAIHA.

Despite existing studies, critical gaps remain in delineating AIHA’s real-world clinical heterogeneity, treatment outcomes, and long-term prognosis, particularly in Asian populations (31, 32) where real-world data from large-scale retrospective studies remain absent. Here, we performed a retrospective analysis of Chinese patients with wAIHA and mAIHA, focusing on comparative clinical, serological, therapeutic, and long-term outcomes, while also systematically examining complication patterns and prognostic factors to provide real-world evidence for individualized management.

2 Materials and methods

2.1 Study population and ethics

In this single-center retrospective study, we screened 629 AIHA patients hospitalized at the Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College from January 2014 to December 2023. The diagnosis required anemia with evidence of hemolysis (elevated lactate dehydrogenase [LDH], indirect bilirubin [IBIL], and free hemoglobin [FHb]; decreased haptoglobin [HAP]; peripheral blood smear findings) and positive DAT (or rigorous differential diagnosis plus response to immunosuppressive therapy for DAT-negative cases). For DAT-positive AIHA, cases were subclassified as wAIHA (CA titer <64; DAT typically positive for IgG or IgG+C3, less commonly isolated C3), cAIHA (CA titer ≥ 64; DAT typically showing isolated C3 positivity), or mAIHA. Given the unavailability of thermal amplitude assessment, mAIHA was operationally defined by the presence of IgG positivity together with CA titers ≥ 64, based on reported clinical criteria (16, 33). CA titers were determined by serial serum dilution from 1:2 to 1:2048. After incubation with washed RBCs at 4°C for 2 hours, the highest dilution showing visible agglutination was recorded as the titer. For all patients, DAT was performed via a microcolumn gel card technique. Briefly, 50 μL of a 1% patient RBC suspension was added to each well of a DC-Screening I card and centrifuged at 1030 r/min for 10 minutes. Complete RBC deposition at the column bottom indicated a negative result; otherwise, it was considered positive. This procedure entailed an initial polyspecific anti-human globulin screening followed by monospecific anti-IgG, -IgM, -IgA, and -C3 testing. IgM and IgA positivity provided additional serological information but was not solely used to determine AIHA subtype classification. Patients with cAIHA (n=32) or DAT-negative AIHA (n=31) were excluded. Finally, 566 patients were enrolled in this study. A standardized unified follow-up was completed for all patients in April 2025. This study received ethical approval from the Ethics Committee of the Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College. All study procedures complied with the Declaration of Helsinki (2024 revision). Written informed consent was acquired from all participants and/or their legally authorized representatives.

2.2 Study definitions

The definition of Evans syndrome (ES) has recently been revised to require immune-mediated cytopenias affecting any two blood cell lineages (34). Given the diagnostic challenges in confirming immune-mediated leukopenia, we adopted classical criteria (concurrent AIHA and immune thrombocytopenia [ITP]). Secondary AIHA was defined by an established underlying disorder considered causally associated with AIHA. Patients with concurrent autoimmune thyroiditis, pernicious anemia, or undifferentiated connective tissue disease (UCTD), defined as persistent ANA ≥1:80 on at least two occasions without fulfilling established classification criteria for a definitive CTD, were not classified as secondary AIHA. Bone marrow response was assessed using the Bone Marrow Responsiveness Index (BMRI = absolute reticulocyte count × [patient Hb/normal Hb]) and Reticulocyte Production Index (RPI = [reticulocyte %/2] × [hematocrit/0.45]) (35).

2.3 Evaluation of treatment and outcome

Therapeutic inclusion required full-dose administration. Post-CR consolidation, cytotoxic chemotherapy, intravenous immunoglobulin [IVIG], erythropoietin [EPO], plasma exchange, immunomodulators, and traditional Chinese medicine were not regarded as standard treatment in this study. RTX was implemented as standard-dose (R-SD; 375 mg/m² weekly ×4 or 1000 mg biweekly ×2) and low-dose (R-LD; 100 mg weekly ×4). Responses were classified as complete (CR: Hb ≥12 g/dL [male] or ≥11 g/dL [female], not attributed to transfusion), partial (PR: either ≥2 g/dL Hb increase from baseline or Hb ≥10 g/dL without transfusion), or no response (NR: neither CR nor PR). No response to GCs specifically required failure to achieve PR after ≥3 weeks of prednisone (≥1 mg/kg/day). Refractory AIHA was defined as NR to ≥3 regimens, including splenectomy and/or ≥1 IST (2). Outcomes included overall survival (OS; time from diagnosis to death), event-free survival (EFS; time from diagnosis to first relapse or death), relapse (Hb decline ≥2 g/dL with evidence of active hemolysis, such as increased LDH, IBIL, or reticulocytosis, independent of blood loss, transfusions, or other causes of anemia), thrombosis, and infections (pulmonary/opportunistic).

2.4 Statistical analysis

All analyses were conducted using SPSS (version 27.0) and R (version 4.5.0). Missing data were handled using complete-case analysis, and no imputation was performed. Continuous variables with normal distribution were presented as mean ± standard deviation (SD) and analyzed using Student’s t-test or one-way ANOVA, while non-normally distributed data were reported as median (interquartile range, IQR) and compared via Mann-Whitney U or Kruskal-Wallis tests. Categorical variables were summarized as frequencies (%) and assessed using Pearson’s chi-square or Fisher’s exact tests. All statistical tests were two-sided, with P < 0.05 considered statistically significant. Time-to-event outcomes were evaluated using Kaplan-Meier analysis with 95% confidence intervals (CIs) calculated. Median follow-up duration was estimated using reverse Kaplan-Meier analysis. Univariable and multivariable Cox regression analyses were performed using the survival package in R, with verification of proportional hazards (PH) assumptions and elimination of collinear variables. Variables with P < 0.2 in univariable analysis were included in the multivariable model. Visualization was implemented with ggplot2 package.

3 Results

3.1 Clinical and laboratory profiles of cohort

The cohort comprised 566 AIHA patients (median onset age 48 years, 70% female), including 449 wAIHA and 117 mAIHA cases. Both groups showed female predominance but with earlier onset in mAIHA cases, exhibiting a distinctive bimodal age distribution (peaks at 20/60 years, trough at 40 years; Supplementary Figure 1A). Notably, 347 patients (61.3%) presented with severe anemia (Hb <6 g/dL) at onset. Secondary forms were more prevalent in mAIHA (39.3% vs 22.5%, Table 1), especially AIDs. Among secondary cases, AIDs and LPDs were the most prevalent etiologies. Systemic lupus erythematosus (SLE) constituted the majority of AIDs, whereas B-cell LPDs, particularly CD5-CD10- small B-cell LPDs, dominated the LPD-associated cases. A comprehensive catalog of all underlying secondary etiologies is detailed in Supplementary Table 1. Serologically, IgG with or without C3 predominated in both wAIHA and mAIHA, with IgA and/or IgM observed in 12% of wAIHA and 16.2% of mAIHA. Notably, mAIHA demonstrated a significantly higher prevalence of IgM-seropositivity compared to wAIHA. Evans syndrome (13.3%, n=75) manifested as concurrent AIHA/ITP (40%), AIHA-first presentation (36%), or ITP-first presentation (24%) (Supplementary Figure 1B). Laboratory analysis showed that mAIHA exhibited distinct cAIHA-like features including decreased RBC/hematocrit, elevated MCV/MCH/MCHC, and higher lymphocyte percentages, despite comparable Hb levels and hemolytic markers with wAIHA. Four patients had UGT1A1-confirmed Gilbert syndrome, which may confound the interpretation of bilirubin levels during hemolysis. Acute aplastic crisis was documented in 13 wAIHA (2.9%) and 5 mAIHA (4.3%) patients, manifesting as pancytopenia (n=4), erythroid/leukocytic reduction (n=3), and isolated erythroid hypoplasia (n=11). Both cohorts exhibited spherocytosis (42.4%, n=240) with comparable acidified glycerol 50% lysis time (75 vs. 80 seconds) and bone marrow compensation impairment (BMRI<121: 35.0%, n=198). Notably, mAIHA showed significantly impaired erythropoiesis compared to wAIHA, as evidenced by lower BMRI and RPI.

Table 1. Baseline demographic and clinical characteristics of cohort.

*Hb at onset was defined as the lowest Hb level measured before the first documented PR/CR.

^†denotes median (interquartile range, IQR); n (%) denotes number (percentage); sd denotes standard deviation; Defined IgM-mediated: IgM (alone or with IgG/C3); IgA-mediated: IgA (alone or with IgG/C3); IgM+IgA-mediated: IgM+IgA (± IgG/C3). Only secondary causes over 5 cases are shown.​

wAIHA/mAIHA, warm/mixed autoimmune hemolytic anemia; Hb, hemoglobin; AIDs, autoimmune and autoinflammatory diseases; LPDs, lymphoproliferative diseases; DAT, direct antiglobulin test; Ig, immunoglobulin; C3: complement component 3; CA, cold agglutinin; RBC, red blood cell; MCV, mean corpuscular volume; MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration; LDH, lactate dehydrogenase; IBIL, indirect bilirubin; FHb, free hemoglobin; HAP, haptoglobin; Ret, reticulocyte; BMRI, bone marrow responsiveness index; RPI, reticulocyte production index; EPO, erythropoietin.

Bold values indicate statistical significance (P < 0.05).

3.2 Treatment landscape and response

GCs remained the first-line therapy in 556 patients (556/566, 98.2%). 92.3% of wAIHA patients and 97.3% of mAIHA patients achieved a hematologic response. The remaining 10 patients were initially treated with RTX (n=4), CTX (n=1) or splenic artery embolization (n=1) due to contraindications to GCs, chemotherapy (n=2) due to primary LPDs, or remained untreated (n=2). Second-line therapy was implemented in 365 cases, predominantly RTX (n=199), which yielded comparable observed ORRs between the SD and LD regimens (86.4% vs. 89.0%). CsA (n=64) was also frequently adopted as second-line treatment, followed by androgens (n=48), CTX (n=17), MMF (n=11), splenectomy (n=9), and BTK inhibitors (n=5). 153 patients (27.0%) received later-line therapy (≥3 lines), including 14 (3.1%) refractory cases with wAIHA and 4 (3.4%) with mAIHA. IVIG (n=213), EPO (n=34), plasma exchange (n=19), and roxadustat (n=8) were used as adjunctive therapies in some patients. One multi-refractory patient who had received up to 13 lines of therapy achieved CR with BCMA-CD3 bispecific antibody therapy (28). The heterogeneous therapeutic landscape in this cohort is delineated in Figure 1A. To eliminate confounding factors from underlying diseases, therapeutic responses were analyzed separately (Table 2). Outcomes in the primary cohort may serve as a more objective reference for regimen efficacy. Responses for regimens with ≥5 evaluable cases are delineated in Figure 1B (primary AIHA) and Figure 1C (secondary AIHA).

Table 2. Therapeutic responses of various regimens in primary and secondary AIHA.

*Four patients who received GCs as initial therapy were unassessable for therapeutic response.

^‡Rituximab standard dose: 375 mg/m² weekly for 4 doses or 1000 mg every 2 weeks for 2 doses; low dose: 100 mg weekly for 4 doses.

^†Androgens are often used in combination with other agents.

AIHA, autoimmune hemolytic anemia; ORR, overall response rate; CR, complete response; BTK, Bruton tyrosine kinase; Syk, spleen tyrosine kinase; CAR-T, chimeric antigen receptor T-cell.

3.3 Relapses and thrombotic/infectious complications

Among patients who experienced a relapse, the median duration from diagnosis to the first relapse was 8.0 months overall, with 8.0 months in wAIHA and 9.5 months in mAIHA. With a median EFS of 17 months, the estimated 1-/3-/5-year EFS rates were 54.5%/37.5%/29.9% respectively (Figure 2A). In patients with >6-month follow-up, relapses occurring ≤6 months post-diagnosis showed significantly inferior OS versus those >6 months (HR 2.04, p=0.021) (Figure 2B). Analysis of 365 relapse events (multiple triggers permitted) identified drug reduction/cessation (71.8%), infections (27.1%, predominantly respiratory), physiological stressors (4.9%: exertion, trauma, surgery, pregnancy, psychological stress), and underlying disease flares (1.9%) as the contributing factors. Thrombosis occurred in 46 (10.2%) wAIHA and 9 (7.7%) mAIHA patients, with one patient experiencing both arterial and venous thrombosis. Arterial events (n=28) predominantly involved stroke (n=19) and the splenic artery (n=8), while venous thrombosis (n=28) primarily manifested as lower extremity deep vein thrombosis (left unilateral n=9, bilateral n=6, right unilateral n=5) and pulmonary embolism (n=5). Notably, 81.8% (45/55) of patients experienced thrombosis during active hemolysis, supporting a prothrombotic state associated with active hemolysis. The early disease phase appeared to represent a high-risk window, with 43.6% (24/55) of patients having thrombosis identified within one month after diagnosis. Concomitant hypercoagulable risk factors were identified in a significant subset of patients (27.3%, 15/55). Notably, some patients exhibited overlapping risk profiles. The identified factors included antiphospholipid antibody positivity (n=8), confirmed antiphospholipid syndrome (n=3), prior splenectomy (n=3), and protein C/S deficiency (n=3). Furthermore, Fine-Gray competing risk modeling quantified the cumulative incidence of relapse and thrombotic events (Figures 2C, D, respectively), with the 1-, 3-, and 5-year cumulative incidences of thrombosis reaching 6.51%, 8.42%, and 9.31%. The immunocompromised state induced by AIHA and its therapeutic interventions predisposed patients to significant infectious risks, particularly pulmonary (33.6% wAIHA [151/449] vs 34.2% mAIHA [40/117]) and opportunistic infections (12.7% [57/449] vs 12.8% [15/117]). Fungal pathogens constituted the predominant opportunistic microorganisms (n=58, 80.6%), with identified species comprising Aspergillus (n=11, 15.3%), Candida (n=11, 15.3%), Pneumocystis jirovecii (n=9, 12.5%), and Cryptococcus (n=4, 5.6%). Bacterial and viral pathogens included Mycobacterium tuberculosis (n=14, 19.4%), varicella-zoster virus (n=7, 9.7%), parvovirus B19 (n=4, 5.6%), and other microorganisms (Nocardia, Pseudomonas aeruginosa, Acinetobacter baumannii). Notably, polymicrobial infection patterns were frequently observed, reflecting profound immunosuppression.

3.4 Survival analysis of overall survival

In the entire cohort (median follow-up 57 months for wAIHA and 59 months for mAIHA), the estimated 1-, 3- and 5-year OS rates were 96%, 92% and 89% (Figure 3A). As of the final unified follow-up, 475 patients (372 wAIHA and 103 mAIHA) were successfully evaluated, among whom the CR rates at the final assessment were 70.4% and 72.8%, with mortality rates of 16.1% (60/372) and 16.5% (17/103), respectively. Analysis of 66 deaths with identifiable causes (51 wAIHA and 15 mAIHA) revealed that 21 (41.2%) and 9 (60.0%) occurred with active AIHA, including 13 (25.5%) and 4 (26.7%) directly attributed to AIHA progression. Infections predominated non-AIHA deaths (31.8%, 21/66; including pulmonary [n=17], fungal [n=9], and sepsis [n=4]). Other causes included cerebro/cardiovascular events, non-LPD malignancies, and multiple organ failure (4 each), plus LPDs and renal failure (2 each). Univariable Cox analysis identified significant OS associations with IgM+IgA-mediated (IgM+IgA [± IgG/C3]; reference: IgG+C3), age ≥60 years, Hb <6 g/dL, BMRI <121, male sex, and RPI <2.3 (ranked by hazard ratio [HR]). No significant correlations were observed with CA titers (wAIHA/mAIHA), etiology (primary/secondary), ES, or spherocytosis (Figures 4A, 3B, C). For detailed visualization, the corresponding Kaplan-Meier curves are presented in Supplementary Figures 2A–H. Given the median CA titer of 64 in mAIHA cohort, we restratified patients by titers (≥1024 vs ≤512) to assess its prognostic impact. While the high-titer group (n=28) showed a trend toward inferior OS, the results were not statistically significant (Figure 3D). Multivariable Cox analysis identified age ≥60 years (HR = 3.40), Hb <6 g/dL (HR = 2.23), BMRI <121 (HR = 2.04), male sex (HR = 1.82), and IgM+IgA-mediated serological pattern (HR = 3.42, versus IgG+C3) as independent risk factors associated with poorer OS (Figure 4B). Additional Cox analyses were performed separately for wAIHA and mAIHA subgroups (Supplementary Figures 3, 4). In wAIHA, IgM-mediated cases were associated with poorer OS in univariable analysis (HR = 3.18), although this association was attenuated after multivariable adjustment (HR = 2.80, P = 0.065). In mAIHA, age ≥60 years was the only factor remaining significant in the multivariable model (HR = 4.64).

4 Discussion

Accounting for the majority of acquired hemolytic anemia, AIHA poses a considerable disease burden, with estimated incidence of 1.8–3 per 100,000 person-years and prevalence of approximately 17 per 100,000 persons (36, 37). While the field of AIHA is evolving rapidly, large-scale retrospective characterizations of Asian cohorts have remained notably absent. Notably, of the 629 hospitalized AIHA patients screened, 32 (5.1%) were classified as cAIHA, lower than previously reported (15–25%), possibly reflecting geographic and climatic variation. Addressing this critical gap as the largest retrospective AIHA study in Asia and the most extensive mAIHA cohort to date, our work provides a panoramic view of the clinical landscape in China, systematically investigating disease profiles, therapeutic responses, and complication patterns in 566 patients over a median 57-month follow-up.

Clinically, attention should be paid to identifying the etiology of AIHA. In our study, we established secondary forms in 22.5% wAIHA and 39.3% mAIHA cases, rather than the equal distribution often cited (1, 16). This discrepancy reflects several real-world complexities. First, no hospitalized patients with a well-established diagnosis of infection- or drug- induced AIHA were identified in this cohort, as establishing definitive causality is challenging and hemolytic episodes can be transient. Notably, pernicious anemia, autoimmune thyroiditis, and UCTD were not considered secondary causes of AIHA, as they likely reflect predisposing genetic or immunologic backgrounds rather than causative relationships (1). Beyond these, difficulties also arose from delayed recognition of underlying disorders when AIHA was the initial presentation, and the masking effect of AIHA therapies on underlying etiologies. Moreover, this suggests that mAIHA, especially, may harbor underlying secondary causes, and particularly AIDs.

Consistent with prior studies of wAIHA, our cohort exhibited female and elderly predominance. In contrast to Western populations, we observed a higher female proportion (71.5% vs. 55%) and younger age (48 vs. 58 years) (3, 37). This disparity likely stems from the distinct landscape of etiologies within our cohort, where AIDs, especially SLE, are slightly more prevalent. This contrasts with Western cohorts, where LPDs, particularly CLL (38), are more commonly implicated (39). Our cohort instead found MZL and LPL/WM as the most common LPDs. Notably, male sex was independently associated with poorer OS, aligning with a large US national AIHA cohort reporting higher in-hospital mortality and several adverse outcomes among male patients (40). While overall secondary AIHA rates were comparable between sexes, their underlying etiologies differed markedly. Secondary cases in males were predominantly LPD-associated (68.4% vs. 32.1% in females), while female cases were AID-associated (63.3% vs. 26.3% in males). This disparity may contribute to survival differences. Nevertheless, potential residual confounding makes male sex an exploratory prognostic factor necessitating further validation. Studies have suggested that IgM-mediated wAIHA typically follows a severe and fulminant clinical course (1, 41), a finding corroborated by our data (HR = 2.80, P = 0.065). Here we made the further observation that wAIHA patients with concurrent IgA involvement (IgM+IgA-mediated) may experience even poorer outcomes (HR = 4.13), though this finding requires cautious interpretation given the limited number of patients with this uncommon serological pattern. Thus, screening for IgM/IgA autoantibodies is essential in DAT-negative patients presenting with severe hemolysis to prevent misdiagnosis.

We also looked into the temporal relationship between AIHA and ITP in ES. Consistent with prior reports (42), concurrent diagnosis remained the most common pattern, yet we further observed a higher frequency of AIHA preceding ITP in sequential cases. Current comprehension of mAIHA remains elusive due to different diagnostic criteria and inadequate research (29). In our study, mAIHA was established using a broader operational definition. Because thermal amplitude was not routinely assessed, this approach may introduce phenotypic heterogeneity (33). Aligning with a prior systematic review, our study confirmed mAIHA’s unique features including predominant AIDs involvement among secondary factors and earlier onset (43 vs. 45 years) (29). Our cohort revealed a distinctive bimodal age distribution, peaking at 20 years (AIDs -related) and 60 years (LPDs -related), which is indicative of its pronounced secondary etiology. Notably, mAIHA demonstrates distinct cold agglutination features compared to wAIHA, with higher prevalence of IgM-mediated cases. IgM pentamers induce RBC aggregation (16), resulting in decreased RBC counts alongside elevated MCV, MCH, and MCHC despite relative reticulocytopenia, reflecting compromised bone marrow compensation. Furthermore, we observed no significant differences in OS, hemolytic parameters, or GCs response among patients with varying CA titers, implying that isolated CA titers might not serve as a dependable indicator of either clinical severity or treatment efficacy (29).

Despite being classified as a “benign” condition, AIHA significantly compromises quality of life through relapse, infections, and thromboembolic events. The 17-month median EFS contrasts with favorable OS. Relapse within ≤6 months significantly worsens prognosis, with drug tapering and infections being primary triggers, underscoring the significance of treatment adherence, proper tapering education, and infection monitoring. Studies suggest that vaccination against respiratory pathogens is recommended to prevent complement activation and subsequent AIHA relapses (1). Thrombotic events were frequently identified early in the disease course, with nearly 50% detected within the first month after diagnosis. Given their strong association with active hemolysis, consideration of prophylactic anticoagulation during active hemolysis may be warranted, especially for patients with identifiable risk factors. Infections, particularly opportunistic infections, significantly compromise AIHA outcomes. Our cohort identified infection as the leading direct cause of non-AIHA related mortality. This aligns with a French study that reported 12.5% 30-day mortality following infection-related hospitalization, highlighting a profound clinical dilemma that requires balancing intensive immunosuppressive therapy with infection risk management (43).

The evolving therapeutic paradigm for LPDs and AIDs has transformed AIHA management. It is important to note that our outcomes should be interpreted cautiously. First, novel agents like Syk inhibitors were preferentially administered in later-line or refractory settings (20), potentially limiting generalizability. Second, the use of concurrent therapies may obscure the independent contributions of individual agents. For instance, the reported 78.1% ORR for androgens (consistent with prior studies (44)) likely reflects combined efficacy with GCs, as androgen is typically employed as an adjunctive therapy. Furthermore, observed responses represent initial achievement rather than sustained remission. Given the shared pathophysiology between AIHA and ITP as immune-mediated cytopenias, therapeutic strategies often provide mutual reference. In ITP, single-dose rituximab (375 mg/m²) has demonstrated comparable efficacy to R-LD in treating GCs-resistant or relapsed cases (45). The observed ORRs were numerically similar between R-LD and R-SD, though the lack of a rigorous design precludes formal non-inferiority conclusions. As the early integration of RTX remains a crucial therapeutic option for severe cases, prospective studies optimizing dosing and frequency are essential to enhance medical economic efficiency. Of particular interest in refractory AIHA is the emerging role of cellular immunotherapy. While limited by a small sample size, autologous CD19 CAR T-cell therapy facilitated complete and treatment-free remission in our multi-refractory cases. Notably, the use of BCMA-CD3 bispecific antibody therapy (T-cell engagers) as a salvage strategy in two relapsed cases demonstrated preliminary efficacy, highlighting a promising approach that merits prospective validation.

These limitations and evolving therapies underscore the need for rigorously designed prospective trials assessing not only response rates but also EFS and quality of life. In summary, this large retrospective study delineates the clinical landscape of AIHA in Chinese patients, with particular focus on the distinct features of mAIHA. Our findings bridge critical knowledge gaps in Asian AIHA management by identifying prognostic indicators and offering evidence-based guidance for clinical decision-making and the development of novel therapies.

Correction note

This article has been corrected with minor changes. These changes do not impact the scientific content of the article.

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Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fimmu.2026.1931581/full#supplementary-material

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Footnotes

Edited by: Ralf J. Ludwig, University of Lübeck, Germany

Reviewed by: Alban Deroux, Centre Hospitalier Universitaire de Grenoble, France

Surbhi Shah, Mayo Clinic Arizona, United States