Kesahihan dan Keandalan Inflammatory Bowel Disease Questionnaire-9 (IBDQ-9) versi Bahasa Indonesia untuk Menilai Kualitas Hidup Pasien dengan Penyakit Radang Usus = Validity and Reliabilty of the Inflammatory Bowel Disease Questionnaire-9 (IBDQ-9) Indonesian Version to Measure the Quality of Life in Patients with Inflammatory Bowel Disease