Long-Term Trend Analysis of Tuberculosis Cases in The Philippines from 2016 To 2023

Samuel John Parreño

doi:10.55489/njcm.170620265425

Authors

Samuel John Parreño Mathematics Division, University of Mindanao, Digos City, Philippines

DOI:

https://doi.org/10.55489/njcm.170620265425

Keywords:

Tuberculosis, Trend analysis, Seasonal decomposition, Philippines, Public health surveillance

Abstract

Background: Tuberculosis (TB) remains a critical public health issue in the Philippines, a high-burden country. Understanding long-term trends is essential for evaluating the effectiveness of public health interventions. This study aims to analyse long-term trends and seasonal patterns of tuberculosis cases in the Philippines from 2016 to 2023. Using time series methods, it seeks to uncover significant trends, identify critical periods for intervention, generate short‑term forecasts, and provide insights to inform and enhance public health strategies.

Methodology: This retrospective time series analysis used monthly TB notification data obtained from the Department of Health’s eFOI (electronic Freedom of Information) portal from 2016 to 2023. We used the STL (Seasonal and Trend decomposition using Loess) technique to isolate the long-term and seasonal patterns in TB notifications. Trend assessment was performed with the Mann-Kendall test. We also fitted a seasonal ARIMA(0,1,2)(0,1,1) model to the Box-Cox‑transformed series for forecasting.

Results: The analysis revealed a significant upward trend in total TB cases, with a mean monthly increase of 0.80%. Seasonal peaks occurred in March, and troughs in December. The Mann-Kendall test confirmed the statistical significance of these trends ( <0.0001). New and relapse TB cases exhibited consistent increases, while retreatment cases showed a slight decline. The seasonal ARIMA forecasts project peaks of approximately 55,213 cases in March 2024 and 58,964 cases in March 2025, followed by mid‑year plateaus and December troughs.

Conclusions: The study identified a persistent increase in TB cases, emphasizing the need for continued and enhanced public health efforts. Forecasted surges in March 2024 and March 2025 highlight the need to intensify active case finding in January-March and to allocate resources adaptively for 2024-2025. Seasonal patterns highlight critical periods for intervention, particularly in the first quarter of the year. These findings can guide more timely resource allocation and targeted TB control measures at both national and local levels.

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