Evaluation of the Digital Surveillance System for Acute Hepatitis B in Thasala Hospital, Nakhon Si Thammarat Province, Thailand, 2025

Abstract

Background: Hepatitis B virus infection poses a significant public health challenge both globally and in Thailand. The morbidity rate of acute hepatitis B in the country has been rising steadily. Over the period 2021–2025, Nakhon Si Thammarat Province followed the same upward trend, with Thasala District recording the highest morbidity rate in the province. The Division of Epidemiology has since replaced the former reporting system with the Digital Disease Surveillance (DDS) platform. This study aims to describe the structure of workflow and to evaluate system attributes of the DDS for acute hepatitis B at Thasala Hospital, Nakhon Si Thammarat Province.

Methods: A mixed-methods cross-sectional descriptive study was conducted at Thasala Hospital. Medical records of all patients diagnosed with acute hepatitis B and related ICD-10TM codes Version 2016, including primary codes (B16.0–B16.2, B16.9) and related secondary codes, between January 1 and December 31, 2025 were reviewed. In-depth interviews were also carried out with relevant stakeholders to explore the reporting process and their perspectives on the surveillance system.

Results: Of the 527 medical records reviewed, 210 patients met the case definition. Only 43 of those were reported to the DDS, yielding a system sensitivity of 20.48%. The main reason for under-reporting was inconsistent ICD-10TM coding: physicians did not assign the relevant code in 64.07% of missed cases, most commonly in the inpatient department (33.60%) and the hemodialysis unit (31.80%), compounded by inconsistency between the epidemiological case definition and clinical practice in distinguishing acute from chronic infection. The positive predictive value stood at 47.25%, calculated from 91 reports in the system, largely because chronic hepatitis B patients had been reported alongside acute cases. The distribution of patients by sex, age, nationality, and area of residence was consistent between medical records and the DDS, indicating good representativeness. Timeliness was excellent, with a median reporting interval of one day (interquartile range of three days) and 96.70% of reports submitted within seven days. Data completeness was 100% across all key variables. Accuracy ranged from 96.70% to 100%. Interviews revealed that the system was easy to use and operationally stable, although it lacked flexibility and its data were underutilized at the facility level.

Discussion and Recommendation: The acute hepatitis B surveillance system at Thasala Hospital demonstrated clear strengths in timeliness and data quality, yet its sensitivity remained low. This reflects limitations in diagnostic coding practices and staff understanding of disease reporting requirements. The epidemiological case definition should be reviewed and revised to better align with actual clinical practice. In addition, laboratory results should be integrated with diagnostic codes within the DDS trigger mechanism and workforce capacity in disease reporting should be strengthened.