Long Delays Seen in Essential Thrombocythemia Diagnosis After Platelet Rise

Patients with essential thrombocythemia faced an average delay of 26.5 months between their first high platelet count and diagnosis.

Patients experienced a significant delay in receiving an essential thrombocythemia (ET) diagnosis, with the average time from the first observed elevated platelet count to diagnosis spanning over two years (26.5 months), suggesting that the burden of ET may be underestimated and highlights the need for greater awareness among healthcare providers, according to a poster presented the European Hematology Association 2025 Congress.

The study found distinct trends among patients with elevated platelet counts. On average, platelet levels were 678 x 10⁹/L near the index date. At that time, 50.5% of patients had counts of 600 x 10⁹/L or higher, and 10.5% had levels of 1,000 x 10⁹/L or higher. At the first sign of elevated platelets, the average count was 603.9 x 10⁹/L, with 31.1% of patients reaching 600 x 10⁹/L or more and 4.6% reaching 1,000 x 10⁹/L or more.

Overall, 4.4% of patients had a history of splenomegaly. Nearly half (49.3% of patients) had another medical condition, most commonly high blood pressure (49.3%), high cholesterol (36.5%) or diabetes (15.6%). Coronary artery disease was seen in 9.3% of patients, and peripheral artery disease in 3%. In addition, 19.4% had a history of blood clots, most often deep vein thrombosis (7.2%), pulmonary embolism (4.5%), heart attack (3.9%) or stroke (3.8%).

Among the 1,350 patients studied, the median age at the index date was 64 years. Most patients (69.5%) were female, and 83.3% identified as White.

Study Design

This study reviewed medical records from adults diagnosed with ET between January 1, 2012, and September 5, 2024, across eight hospitals within the Massachusetts General Brigham health system. To be included in the analysis, patients needed to have an official diagnosis of ET recorded during a medical visit, a second visit confirming the diagnosis by a specialist, and a high platelet count — 450×10⁹/L or higher — within the three months before their diagnosis.

Researchers focused on each patient’s health care activity during the period leading up to their diagnosis. This included information such as age, other health conditions, history of blood clots, lab results and the amount of time between the first high platelet count and the official diagnosis. The study also tracked how often patients used health care services like outpatient visits, hospital stays and emergency room visits during this pre-diagnosis period.

To better understand patterns of care, researchers compared health care use before and after the first sign of elevated platelets. This approach may help identify ways to improve how and when patients with ET are diagnosed and managed, according to the poster.

Because this study used data from academic hospitals in one health system, results may not reflect the experiences of patients treated at community centers. Some early medical history, including the first signs of elevated platelets, may have occurred outside the system and were not captured. Diagnoses and lab values were based on medical record codes, which could be incomplete or misclassified. The reasons behind patients' health care visits before diagnosis were not included in this analysis but may be explored in future studies.

ET is a rare, chronic blood cancer marked by persistently high platelet counts, increased risk of blood clots, and the potential to progress into more serious conditions like myelofibrosis or acute leukemia, the investigators noted.

Although blood clots may occur before diagnosis, elevated platelet levels are often missed, especially in patients without symptoms. These challenges, along with low disease awareness, can delay diagnosis. There is limited real-world research on how long it takes to diagnose ET and the possible complications linked to those delays.

Reference

1. “Real-world Characterization of Diagnosis Journey in Patients With Essential Thrombocythemia: A Retrospective Analysis of Electronic Health Records Data,” by Dr. Evan C. Chen et al., EHA 2025 Congress.

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