Gastro-esophageal reflux disease (GERD), the most common cause of erosive esophagitis (EE), remains highly prevalent worldwide.

GERD poses substantial burden on both patients and society. EE treatment patterns and unmet needs have been well-studied overseas, but evidence gaps still exist in China.

To fill these evidence gaps, real-world evidence for GERD and EE are needed. To understand GERD market we will analysis :Patient profile,GERD patient journey within hospital (first present, get diagnosed, receive initial and maintenance treatment),medication cost,department differentiation.

To investigate current treatment patterns of GERD / EE in China we will analysis: Current agents used and treatment duration in clinical practice treatment patterns by different reimbursement status treatment pattern by EE/NERD.

To get healing rate of EE we will analysis: Real-world efficacy of the current standard treatment (i.e. PPIs) for patient with two test results of gastroscopy.

The data required for this project are accessible in hospital electronic system; no specific data collection tools or methods are required for this project design. Only algorithms for retrieving and extracting eligible patients' records are required and will be developed by HLT based on the eligibility criteria defined in this protocol.

Inclusion Criteria:

• Medical records of GERD, NERD and/or EE diagnoses （ICD code scope will be confirmed later）from January 1st, 2015 to December 31st, 2017.

oGERD is typically characterized by symptoms of heartburn and acid regurgitation. A diagnosis of EE or NERD can only be confirmed upon endoscopic examination.

• All ages, males or females
• A primary diagnosis of GERD/NERD/EE

For treatment patterns, patients are also required to have received one episode of treatment during the analysis period.

For RW treatment efficacy, the population will be restricted to the EE treatment population who underwent at least two endoscopy examinations.

Exclusion Criteria:

- No exclusion criteria will be applied for investigating diagnosis since all patients diagnosed with GERD, NERD, or EE should be captured regardless of whether they have medical conditions that affect their treatments.

A patient will not be eligible for investigating treatment patterns and RW treatment efficacy if he/she has any of the following exclusion criterion:

• A post-operative diagnosis of gastrointestinal cancers
• A diagnosis of esophageal foreign bodies or neoplasms
• A history of gastric or esophageal surgery
• Zollinger-Ellison syndrome
• Primary esophageal motility disorders (ex: achalasia)
• Esophageal strictures
• Eosinophilic esophagitis
• Identified as pregnant or lactating
• Hospitalized (inpatient) patients (to be confirmed by expert.) due to GERD as primary or secondary diagnosis

The overall analysis population will consist of patients of all ages who were diagnosed with GERD from January 2015 to December 2017.