Analysis of the burden of disease for male infertility globally and in China from 1990 to 2021.

Background: Infertility affects one in six couples globally, with male infertility contributing to 50% of cases. Despite its high prevalence, male infertility is underexplored in some regions due to cultural and societal factors. Epidemiological data remain sparse and inconsistent. This study uses Global Burden of Disease (GBD) 2021 data to assess the global and Chinese burden of male infertility and project future trends. Methods: Using the GBD 2021 dataset, we analyze global male infertility trends from 1990 to 2021 across different subgroups (age, region, and country), focusing on prevalence, disability-adjusted life years (DALYs), and their corresponding age-standardized rates (ASRs), and compare these trends with China. We examine the correlation between the Socio-Demographic Index (SDI) and the burden of male infertility at national and regional levels. Spearman's rank correlation assesses the relationship between ASRs and SDI. Decomposition analysis identifies drivers of the growing male infertility burden globally, in China, and across SDI regions. The slope index of inequality (SII) and the concentration index (CII) quantify global health inequalities, and the Bayesian-Aperiodic-People-Cohort (BAPC) model predicts future trends in male infertility prevalence and DALYs globally and in China. Results: In 2021, the global prevalence of male infertility surpassed 55 million cases, with over 300,000 DALYs. China accounted for approximately 20% of the global burden, with ASRs significantly exceeding the global average. Globally, male infertility prevalence and DALYs increased steadily from 1990 to 2021, particularly in low and low-middle SDI regions, such as South Asia, Southeast Asia, and Latin America. In contrast, China exhibited a stable trend with a gradual decline after 2008. Population growth was identified as the primary driver of global prevalence increases, while age-related factors played a more significant role in China. South and East Asia reported the highest absolute numbers of prevalence cases and DALYs, contributing to half of the global burden. However, the highest ASRs for prevalence and DALYs were recorded in Eastern Europe and Western Sub-Saharan Africa, reaching 1.5 times the global average. Conclusions: This study underscores the increasing global burden of male infertility, accompanied by pronounced disparities across regions and socioeconomic groups. While the burden in China shows signs of decline, low and low-middle SDI regions continue to face rising prevalence and DALYs. Official attention, along with a comprehensive approach to managing environmental factors, lifestyle changes, and sexually transmitted diseases (STDs), is essential to address these disparities and mitigate the growing global burden of male infertility.