The Burden of Bacterial Antimicrobial Resistance in the WHO Western Pacific Region 1990–2021: A Cross-Country Systematic Analysis With Forecasts to 2050

<p><span><span>Background:</span></span> Antimicrobial resistance (AMR) is recognised as one of the most significant and intricate challenges to global health. Although reports emanating from the WHO Western Pacific Region are increasingly recognising the implications of antibiotic resistance on human health, there is an urgent need for more precise estimates to gain a better understanding of the exact extent of the problem. Here, we present a comprehensive time-trend analysis of regional and country-level AMR burden estimates in the WHO Western Pacific Region (WPR) between 1990 and 2021, with forecasts up to 2050.</p> <p><span><span>Methods:</span></span><b> </b>We estimated deaths and disability-adjusted life-years (DALYs) attributable to and associated with AMR across 11 infectious syndromes, 22 bacterial pathogens, and 84 pathogen–drug combinations for the WHO Western Pacific Region and its constituent countries between 1990 and 2021. Data inputs were drawn from multiple sources, including mortality registration systems, surveillance platforms, hospital records, systematic literature reviews, and other relevant datasets. The modelling framework comprised five key components: estimation of deaths in which infection had a role, the proportion of infectious deaths attributable to specific syndromes, allocation of syndrome-specific deaths to individual pathogens, the percentage of a given pathogen resistant to an antimicrobial drug of interest, and quantification of the excess mortality risk or prolonged infection duration associated with resistance. These elements were combined to estimate disease burden under two counterfactual scenarios: AMR-attributable burden (assuming drug-resistant infections were replaced by drug-susceptible infections) and AMR-associated burden (assuming infections were prevented altogether). Country-level estimates were produced using predictive statistical models, and forecasts of AMR burden were generated through 2050. Uncertainty was quantified by constructing 95% uncertainty intervals (UIs) based on the 2.5th and 97.5th percentiles of 500 draws propagated through the multi-stage computational pipeline, with model performance assessed through out-of-sample cross-validation.</p> <p><span><span>Findings: </span></span>We estimated 1 150 000 deaths (95% UI 1 000 000–1 290 000) associated with bacterial AMR and 213 000 deaths (182 000–245 000) attributable to bacterial AMR across 32 locations in the Western Pacific Region in 2021. Over the past 31 years, AMR mortality trends showed substantial variation across countries of the region and different age groups. Between 1990 and 2021, deaths among children under 5 years dropped by 87.3%, while those among adults aged 70 and older rose by 88.9%. Three pathogens were associated with more than 50% of all deaths (both associated with and attributable to AMR) in 2021: <i>Staphylococcus aureus</i>, <i>Streptococcus pneumoniae,</i> and <i>Escherichia coli</i>. By using age-standardised mortality rates, we showed that the Solomon Islands (121.3 [93.0–150.0]) and Kiribati (121.0 [93.0–150.0]) were the countries with the highest age-standardised mortality rates (ASMR) associated with AMR, while Kiribati also had the highest ASMR attributable to AMR 30.9 (24.1–37.8) per 100 000 population in 2021. Conversely, the country with the lowest burden in WPR in 2021 was New Zealand, whereas Australia had the lowest ASMR in 1990. Our forecasts show that an estimated 1 840 000 deaths (1&nbsp;460&nbsp;000–2&nbsp;230&nbsp;000) associated with AMR and 402 000 deaths (322 000–480 000) attributed to AMR could occur in this region in 2050.<span></span></p> <p><span><span>Interpretation:</span></span><b> </b>We have demonstrated a clear and tangible impact of the WHO Western Pacific Region on the overall estimated global burden of AMR over 30 years, revealing considerable fatal and non-fatal burden of key resistant bacterial pathogens and pathogen–drug combinations. Despite inherent limitations related to data availability, our estimates can serve as a valuable resource for informed decision-making regarding resource allocation and funding—emphasising the need for collaborative, multi-sectoral initiatives among nations to effectively address the complex challenges posed by AMR.<span></span></p> <p><span><span>Funding: </span></span>Wellcome Trust, and the UK Department of Health and Social Care using aid funding managed by the Fleming Fund.</p>