Validitas Diagnostik New Formula untuk Membedakan Talasemia Alfa dan Defisiensi Besi
Devina Amanta Setiawan, Dr. dr.Tri Ratnaningsih, M.Kes, Sp.PK. Subsp.B.D.K.T.(K), Subsp.H.K.(K),; dr. Riat El Khair, MSc., Sp.PK, Subsp.P.I.(K),QHIA, M.A.R.S
2025 | Tesis | S2 Kedokteran Klinik
Latar belakang: Talasemia alfa dan defisiensi besi (DB) merupakan penyebab anemia
mikrositik hipokromik yang umum dijumpai. Keduanya menunjukkan gambaran
penurunan Hemoglobin A2 (HbA2), sehingga alur skrining talasemia yang ada saat
ini sulit membedakan keduanya dan berisiko menyebabkan kesalahan diagnosis
serta tatalaksana yang membahayakan pasien. New Formula (NF), indeks
yang mengombinasikan HbA2 dengan parameter sel darah merah dapat menjadi metode
skrining yang lebih akurat, praktis, dan ekonomis untuk membedakan kedua
penyakit di atas. Penelitian terkait validitas diagnostik NF masih terbatas,
terutama penentuan cut-off optimal dan penilaian Area Under the Curve
(AUC) yang belum pernah dilakukan pada populasi di Indonesia.
Tujuan: Menilai validitas diagnostik NF untuk membedakan antara talasemia alfa
dan DB.
Metode: Penelitian potong lintang ini dilakukan di Departemen Patologi Klinik
dan Kedokteran Laboratorium FK-KMK UGM. Sampel diambil secara consecutive
sampling dari peserta skrining talasemia dengan eritrosit mikrositik atau
hipokromik. Diagnosis ditegakkan berdasarkan kadar feritin serum (untuk DB),
serta tes cepat imunokromatografi (ICT) Anti Hb Bart dan/atau analisis genetik
(untuk talasemia alfa). Analisis receiver operating curve (ROC)
dilakukan untuk menilai validitas diagnostik NF.
Hasil: Dari 82 subjek penelitian, 45 (55%) dikelompokkan sebagai DB dan 37
(45%) sebagai talasemia alfa. Ditemukan perbedaan signifikan pada rerata HbA2
(2,63±0,39 vs 2,83±0,39; p=0,041) dan NF (10,20±1,50 vs 9,19±1,25; p=0,002) antara kelompok DB dan talasemia alfa. Cut-off
optimal NF adalah <9>cut-off HbA2 ?2,25, yang memiliki AUC 0,605, akurasi 59,76%, sensitivitas 100%, dan
spesifisitas 26,67%.
Kesimpulan: New Formula menunjukkan validitas diagnostik yang baik dalam membedakan talasemia alfa dan DB serta dapat digunakan sebagai alat skrining
Background: Alpha-thalassemia and iron deficiency (ID) are common causes of microcytic
hypochromic anemia. Both conditions show decreased levels of Hemoglobin A2
(HbA2), which makes it difficult for current thalassemia screening algorithms
to differentiate between them, leading to a risk of misdiagnosis and harmful
patient management. The New Formula (NF), an index that combines HbA2 with red
blood cell parameters, could be a more accurate, practical, and economical
screening method to differentiate the two conditions. Research on the
diagnostic validity of NF is still limited, especially the determination of an
optimal cut-off and Area
Under the Curve (AUC) assessment, which has not been conducted in the
Indonesian population.
Objective: To assess the diagnostic validity of NF for differentiating between
alpha-thalassemia and ID.
Methods: This cross-sectional study was conducted at the Department of Clinical
Pathology and Laboratory Medicine, FK-KMK UGM. Samples were taken by
consecutive sampling from thalassemia screening participants with microcytic or
hypochromic erythrocytes. Diagnosis was established based on serum ferritin
levels (for ID), and the immunochromatographic rapid test (ICT) for Anti-Hb
Bart and/or genetic analysis (for alpha-thalassemia). A receiver operating
curve (ROC) analysis was performed to assess the diagnostic validity of NF.
Results: Of the 82 study subjects, 45(55%) were classified as ID and 37(45%) as alpha-thalassemia. Significant differences were found in the mean of HbA2 (2.63±0.39 vs 2.83±0.39;p=0.041) and NF (10.20±1.50 vs 9.19±1.25;p=0.002) between the ID and alpha-thalassemia groups. The optimal cut-off for NF was <9>
Conclusion: The New Formula shows good diagnostic validity in differentiating alpha-thalassemia from ID and can be used as an initial screening tool.
Kata Kunci : talasemia alfa, defisiensi besi, mikrositik hipokromik, HbA2, New Formula
