Tesis

Performa Kadar Serum Surfactant Protein-D (SP-D) Untuk Diagnosis Penyakit Paru Interstisial Ekstensif Pada Pasien Sklerosis Sistemik = Performance of Serum Surfactant Protein-D (SP-D) in Diagnosing Extensive Interstitial Lung Disease in Systemic Sclerosis Patients.

LatarBelakang : Sklerosis sistemik (SSc) adalh penyakit autoimun heterogen yang memiliki risiko mortalitas yang cukup tinggi. Salah satu manifestasi yang sering ditemukan yaitu penyakit paru interstisial (PPI) yang bertanggung jawab atas 35% kematian pada pasien SSc. Hal ini menjadikan diagnosis PPI terutama yang ekstensif pada pasien SSc sangat penting dalam menentukan tataksana yang optimal. Surfactant protein-D (SP-D) merupakan biomarka serum non-invasif yang mencerminkan kerusakan epitel alveolar dan inflamasi paru yang banyak berperan pada pathogenesis PPI pada SSc. Tujuan : Mengetahui performa kadar serum SP-D untuk diagnosis PPI ektensif pada pasien SSc. Metode : Penelitian ini menggunakan desain potong lintang pada pasien pasien SSc-PPI periode April hingga Juni 2025 yang menjalani pemeriksaan HRCT thoraks dan kadar SP-D serum. Kategori PPI ekstensif ditentukan berdasarkan kriteria Goh (keterlibatan paru > 20%). Analisis meliputi uji korelasi antara SP-D dan luas keterlibatan paru, analisis kurva ROC, menentukan AUC, titik potong optimal berdasarkan indeks youden, sensitivitas, spesifisitas, positive peridictive value (PPV) dan negative predictive value (NPV) berdasarkan titik potong optimal. Hasil : Sebanyak 80 subjek SSc-PPI yang memenuhi kriteria inklusi, didapatkan 20 (25%) subjek dengan PPI ekstensif dan 40 (75%) subjek dengan PPI non-ekstensif. Median kadar SP-D lebih tinggi pada kelompok ekstensif (6,36 ng/ml) dibanding kelompok non-ekstensif (3,56 ng/ml), dengan nilai median secara keseluruhan adalah 4,51 ng/mL. Pola NSIP lebih dominan pada kelompok non-ekstensif (66,7%) sedangkan pola UIP pada kelompok ekstensif (60%). Terdapat korelasi positif lemah antara kadar SP-D dan luas keterlibatan paru (r 0,391; p 0,001). Nilai AUC dengan ketegori moderate (AUC 0,638). Titik potong optimal SP-D sebesar 2,805 ng/mL menghasilkan sensitivitas 90%, spesifisitas 45%, positive predictive value (PPV) 46,1%, dan negative predictive value (NPV) 89,6%. Uji diagnostik kategorik pada titik potong ini menunjukkan signifikansi statistik (p 0,006). Kesimpulan : Kadar serum surfactant protein-D (SP-D) memiliki performa diagnostik moderate untuk diagnosis penyakit paru interstisial ekstensif pada pasien sklerosis sistemik pada titik potong ≥ 2,805 ng/mL dengan sensitivitas 90% dan spesifisitas 45%.
Kata Kunci : Sklerosis sistemik, penyakit paru interstisial, surfaktan protein-D, performa diagnostik, biomarka.


Background: Systemic sclerosis (SSc) is a heterogeneous autoimmune disease associated with significant mortality. One of the most common and severe complications is interstitial lung disease (ILD), which accounts for up to 35% of deaths in patients with SSc. Early diagnosis of extensive ILD in SSc is essential for guiding appropriate management. Surfactant protein-D (SP-D) is a non-invasive serum biomarker that reflects alveolar epithelial injury and pulmonary inflammation, and plays a role in the pathogenesis of SSc-related ILD. Objective: To evaluate the diagnostic performance of serum SP-D levels in diagnosing extensive ILD in systemic sclerosis patients. Methods: This was a cross-sectional study conducted between April and June 2025 involving patients with SSc-ILD who underwent high-resolution computed tomography (HRCT) and serum SP-D measurement. Extensive ILD was defined according to the Goh criteria (lung involvement > 20%). Analyses included correlation between SP-D and the extent of pulmonary involvement, ROC curve analysis, calculation of AUC, optimal cutoff determination using Youden index, and evaluation of diagnostic performance including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: A total of 80 patients met the inclusion criteria, with 20 (25%) classified as having extensive ILD and 60 (75%) as non-extensive. The median serum SP-D level was higher in the extensive ILD group (6.36 ng/mL) than in the non-extensive group (3.56 ng/mL), with an overall median of 4.51 ng/mL. The NSIP pattern was predominant in the non-extensive group (66.7%), while the UIP pattern was more frequent in the extensive group (60%). There was a weak positive correlation between SP-D levels and extent of lung involvement (r 0.391; p < 0.001). The AUC was in the moderate category (AUC 0.638). The optimal cut-off of 2.805 ng/mL yielded a sensitivity of 90%, specificity of 45%, PPV of 46.1%, and NPV of 89.6%. Categorical diagnostic testing at this cut-off demonstrated statistical significance (p 0.006). Conclusion: Serum SP-D levels demonstrate moderate diagnostic performance for identifying extensive interstitial lung disease in systemic sclerosis at a cut-off value of ≥ 2.805 ng/mL, with sensitivity (90%) and specificity (45%).
Keywords: Systemic sclerosis, interstitial lung disease, surfactant protein-D, diagnostic performance, biomarker.