This study developed a smartphone application (app), based on user demand, for the self-care performance of patients with chronic Hepatitis B. The smartphone app was developed in five stages. In the analysis stage, we surveyed the demand for the app among 187 patients with chronic Hepatitis B, analyzed several other apps, and conducted a literature review. In the design stage, the app's purpose was established, and the necessary functions, system interface, database, and screens were designed.

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... n the development stage, the app was developed. In the implementation stage, the master version of the app was used by four specialists and five participants with chronic Hepatitis B. In the evaluation stage, we conducted a heuristic evaluation and a mobile app rating scale evaluation, with these nine subjects. As a result of the evaluations, 19 aspects of the system were modified to further improve the app. This smartphone app is expected to be helpful in performing self-care, serve as a disease-related knowledge source, and promote self-efficacy in chronic Hepatitis B patients. User-interface Screen The developed app was named as "Hepatitis B self-care". Three of the user-interface screens are shown in Figure ( e.g., Figure 2 . Screen on Smartphone App). The main screen is organized into eight areas: self-care, disease-related knowledge, statistics, record liver numbers, my information, notices, role-case, and app information. "Self-care" menu consists of a total of eight items in six areas: regular checkup, medication, diet, drinking, exercise, and body weight. When each item is measured, a preset scoring criterion is applied to it and the results are shown as high, middle, and low. The measured results can be saved and accumulated so that the measured self-care scores can be checked by day, week, and month. "Disease-related knowledge" menu is divided into a total of nine areas. Theoretical explanations (with references) are provided for each area. "Liver lab data record" menu is displayed by touching the test date. The liver lab data are recorded for HBeAg (e antigen)/ eAb (e antibody) and HBV DNA as virus markers, and AST (GOT) and ALT (GPT) as degree of hepatocellular injury. This data can be queried in the "Statistics" area of the main screen. In "Notice" menu, alarms can be set up for a total of three items including medication, self-care, and regular checkup. In the "role-case" menu, the app can be registered and the logged-in users can post or read messages.