macrophage activation syndrome epidemiology forecast

Key Highlights

• MAS is a rare but life-threatening hyperinflammatory condition that manifests as a secondary form of HLH with high mortality. The total diagnosed pool of MAS is approximately 17,000 in 2024 in the US, and this number is expected to rise over the forecast period due to the rising prevalence/incidence of underlying autoimmune diseases like AOSD, sJIA, SLE and KD that frequently trigger MAS.
• Secondary MAS can affect all age groups and is often triggered by infections, malignancies, or autoimmune flares, whereas primary HLH predominates in children and young adults, reflecting heterogeneity in patient populations and disease burden.
• MAS most commonly emerges as a severe hyperinflammatory complication of rheumatologic diseases, primarily sJIA (13%) and AOSD (9.4%), with Kawasaki Disease contributing a smaller yet clinically important share (1.6%), especially in children. MAS also occurs in other autoimmune conditions, such as SLE, where its prevalence ranges from 1% to 3% and mortality remains high (8–22%) due to delayed recognition and treatment.
• The symptomology of MAS/sHLH is serious and potentially lethal. Mortality has been reported in approximately 20–53% of cases, while sHLH without treatment has a 50–75% mortality rate.
• Growing recognition of MAS’s diagnostic complexity is driving demand for better biomarkers, scoring tools, and diagnostic kits, accelerating growth in the macrophage-focused and MAS diagnostic market segment.
• Secondary findings continue to show wide geographic variability in SLE prevalence, driven by disease heterogeneity, ethnic differences, gender distribution, and age-related patterns.
• sJIA is a rare systemic autoinflammatory disease with significant MAS risk, making accurate estimation essential. Early IL-1/IL-6-targeted therapy improves outcomes, but disease behaviour remains variable.

DelveInsight’s “Macrophage Activation Syndrome (MAS) – Epidemiology Forecast – 2034” report delivers an in-depth understanding of MAS, historical and forecasted epidemiology of MAS in the United States, EU4 (Germany, France, Italy, and Spain), the United Kingdom, and Japan.

Geography Covered

• The United States
• EU4 (Germany, France, Italy, and Spain) and the United Kingdom
• Japan

Study Period: 2020–2034

Macrophage Activation Syndrome (MAS) Disease Understanding

Macrophage Activation Syndrome (MAS) Overview

MAS is a form of secondary Haemophagocytic Lymphohistiocytosis (sHLH) occurring as a life-threatening complication of rheumatic diseases. It is most frequent in sJIA and AOSD. Similar to other forms of HLH, MAS is caused by excessive activation and expansion of T lymphocytes and macrophages, resulting in hyperinflammation. sHLH is mostly triggered by underlying secondary causes, including malignancies, infections, autoimmune diseases, or certain therapies and transplants. However, genetic defects may also contribute to the development of adult HLH cases or secondary HLH cases (MAS is characterized by fever, hepatosplenomegaly, cytopenias, liver dysfunction, coagulation abnormalities, and hyperferritinaemia, and may progress to multiple organ failure.

Macrophage Activation Syndrome (MAS) Diagnosis

The diagnosis of MAS is primarily clinical and relies on recognizing a constellation of symptoms, laboratory abnormalities, and exclusion of other causes of systemic inflammation. Patients typically present with persistent high fever, hepatosplenomegaly, lymphadenopathy, and signs of multiorgan involvement. Laboratory findings include cytopenias affecting at least two blood cell lineages, markedly elevated ferritin levels, hypertriglyceridemia, hypofibrinogenemia, and elevated liver enzymes. A decline in erythrocyte sedimentation rate (ESR) despite ongoing inflammation can also be suggestive. In some cases, bone marrow aspiration may reveal hemophagocytosis, although its absence does not rule out MAS. Diagnosis is further supported by clinical criteria such as the 2016 EULAR/ACR/PRINTO classification criteria for MAS complicating sJIA, which incorporate laboratory thresholds for ferritin, platelet count, AST, triglycerides, and fibrinogen. Early recognition is critical, as MAS can rapidly progress to multiorgan failure if not promptly treated.

Macrophage Activation Syndrome (MAS) Epidemiology

The disease epidemiology covered in the report provides historical as well as forecasted epidemiology segmented by total diagnosed prevalent population of SLE, total diagnosed prevalent population of AOSD, total diagnosed prevalent population of sJIA, total incident population of kawasaki disease, total diagnosed prevalent population of MAS, gender-specific diagnosed prevalent population of MAS, and total treated cases of MAS in the 7MM market covering the United States, EU4 (Germany, France, Italy, and Spain) and the United Kingdom, and Japan from 2020 to 2034.

• The total diagnosed prevalent cases of MAS in the 6MM (US, EU4 and the UK) were about 22,000 in 2024; this number is expected to rise over the forecast period (2025–2034). This growth is driven by an increase in autoimmune, autoinflammatory, and infectious diseases with MAS as a complication.
• In 2024, MAS predominantly affected females in the United States, with ~10,000 cases (58%), while the Male population accounted for ~7,000 cases (the remaining 42%). These cases are expected to increase during the forecast period.
• MAS spans both pediatric and adult populations, occurring most frequently in children with sJIA and KD, while adult cases are more common in AOSD, SLE, and secondary triggers such as infections or malignancies.
• In EU4 and the UK, diagnosed prevalent cases of AOSD were more than 1,000 in 2024.
• Almost all patients diagnosed with MAS receive treatment because the condition progresses rapidly and carries a high risk of mortality.

Scope of the Report

• The report covers a segment of key events, an executive summary, a descriptive overview of MAS, explaining its causes, signs and symptoms, pathogenesis, and diagnostic approaches.
• Comprehensive insight has been provided into the epidemiology segments and forecasts, the future growth potential of the diagnosis rate, and disease progression.
• A detailed review of the MAS epidemiology, detailed assumptions, and rationale behind our approach is included in the report.
• A detailed review of current challenges in establishing the diagnosis.

Macrophage Activation Syndrome (MAS) Report Insights

• Patient Population
• Patient population by gender and age
• Country-wise Epidemiology Distribution

Macrophage Activation Syndrome (MAS) Report Key Strengths

• 10 Years Forecast
• The 7MM Coverage
• MAS Epidemiology Segmentation

Macrophage Activation Syndrome (MAS) Report Assessment

• Epidemiology Segmentation
• Current Diagnostic Practices

FAQs

• What are the disease risks and burdens of MAS epidemiology? What will be the growth opportunities across the 7MM with respect to the patient population about MAS epidemiology?
• What is the historical and forecasted MAS epidemiology patient pool in the United States, EU4 (Germany, France, Italy, and Spain), the United Kingdom, and Japan?
• How often is MAS misdiagnosed or diagnosed late due to overlapping symptoms with flares or infections?
• What are the most common triggers (e.g., infections, flares, medications) preceding MAS episodes?
• What is the incidence and prevalence of MAS across different underlying rheumatic diseases (e.g., sJIA, SLE, KD, AOSD)?
• What are the current gaps in epidemiological reporting, such as under-recognition or lack of standardized diagnostic criteria?

Reasons to Buy

• Insights on patient burden/disease prevalence, evolution in diagnosis, and factors contributing to the change in the epidemiology of the disease during the forecast years.
• To understand Key Opinion Leaders’ perspectives around the accessibility, acceptability, and compliance-related challenges of existing treatment to overcome barriers in the future.
• Detailed insights into various factors hampering disease diagnosis and other existing diagnostic challenges.