Functional dyspepsia (FD) is a common functional gastrointestinal disease. Several patient-reported outcome questionnaires have been established to evaluate the severity of FD, including Dyspepsia Symptom Severity Index (DSSI), Nepean Dyspepsia Index (NDI), and Short-Form Nepean Dyspepsia Index (SF-NDI). Functional Dyspepsia Symptom Diary (FDSD) is a newly symptom-focused patients-reported outcome measure raised by the Patient-Reported Outcome Consortium's Functional Dyspepsia Working Group. The association of the novel FDSD and other scores-related to FD has not been fully investigated. Furthermore, the severity of FD is varied among different patients. It remains unclear how the moderate and severe FD can be defined by the FDSD.

Inclusion Criteria:

• 1. 18-70 years old
• 2. Patients who met the Rome IV diagnostic criteria of FD
• 3. Normal upper endoscopy and abdominal ultrasonography within one year.

Exclusion Criteria:

• 1, Patients with local or systemic diseases which may cause dyspeptic symptoms:

  1. Known active peptic ulcer, cholecystitis, gallstone, gastrointestinal obstruction, gastroparesis, and etc.
  2. Known acute or chronic diseases of liver or kidney
  3. Obvious hematological abnormality, or endocrine and metabolic diseases
  4. suspected incomplete or complete bowel obstruction
  5. Known malignancy
  6. Other conditions which may be associated with dyspeptic symptoms (such as NSAIDs associated dyspepsia)

• 2, Pregnancy

• 3, Inability to give informed consent

Patients 18-70 years old who met the Rome IV diagnostic criteria of FD with normal upper endoscopy and abdominal ultrasonography within one year were eligible for our study. Patients with local or systemic diseases which may cause dyspeptic symptoms were excluded. Patients who were pregnant or unable to give informed consent were also excluded.