Thirty-one-year trends in diarrheal mortality and disability-adjusted life years attributable to lack of handwashing facilities

Abstract Background Diarrheal diseases remain a major global public health challenge. Hand hygiene is one of the most cost-effective interventions for preventing the transmission of diarrheal diseases. However, billions of people around the world still lack access to soap and handwashing facilities. Methods Using the Global Burden of Disease (GBD) 2021 database, we quantified the burden of diarrhea attributable to a lack of access to handwashing facilities across 204 countries and territories from 1990 to 2021. We assessed disability-adjusted life years (DALYs), years of life lost (YLLs), and years lived with disability (YLDs), stratified by age, sex, Sociodemographic Index (SDI), and GBD region. Long-term trends were analyzed using age-standardized rates (ASRs) and estimated annual percentage changes (EAPCs). Potential non-linear associations were explored through locally weighted scatterplot smoothing (LOESS) regression. Results Globally, the age-standardized death rate (ASDR) from diarrhea attributable to the lack of handwashing facilities declined from 14.20 (2.10–26.04) to 3.04 (0.42–5.64) per 100,000 between 1990 and 2021, with an average annual decrease of 4.89% (4.64 to 5.14). During the same period, the DALY rate decreased by 76.6%, the YLL rate by 77.9%, and the YLD rate by 32.0%. In 2021, West and East Africa remained high-burden regions, with DALY rates exceeding 600 per 100,000. South Asia recorded the largest absolute number of deaths, with nearly 90,000 fatalities. Countries with low SDI exhibited an ASDR of 17.8 (2.51–33.44) per 100,000, approximately 60 times higher than that of high-SDI countries. Mortality risk was highest among boys under five, and the absolute number of deaths increased among adults aged ≥ 70 years. YLDs were consistently higher in females than in males. Projections suggest continued declines in burden through 2035, although at a slower pace, especially in low-SDI settings. Conclusions Although global diarrhea burdens tied to unavailable handwashing facilities have declined markedly since 1990, stark inequities persist across regions, age groups and development levels. Sustained expansion of WASH infrastructure, targeted hygiene promotion and strengthened surveillance are essential to accelerate progress toward zero preventable diarrheal deaths and universal health coverage.