Area-level socioeconomic inequalities in pancreatic cancer mortality in Japan: a multilevel analysis

The number of deaths from pancreatic cancer has increased worldwide, including in Japan, and prognosis remains poor. Socioeconomic inequalities in pancreatic cancer mortality have been reported in Japan; however, whether they persist in recent years remains unclear. We aimed to investigate these inequalities across Japan using a multilevel framework. We conducted a nationwide ecological study using the Vital Statistics (2015–2022) of Japan and the 2015 and 2020 Population Censuses of Japan, with municipality-level deprivation derived from the Area Deprivation Index. We estimated the mortality rate ratio of pancreatic cancer deaths by employing multilevel Poisson models with a random intercept, accounting for municipalities nested within secondary medical areas, incorporating the estimated municipality-level smoking rate, the Rurality Index for Japan, and the absence of Designated Cancer Care Hospitals. We found a positive association between deprivation and pancreatic cancer mortality, after incorporating covariates, particularly among men aged under 75 years (mortality rate ratio 1.12; 95% confidence interval, 1.08–1.16), while a weaker positive association was observed among women aged under 75 years. These findings update Japanese evidence, showing that socioeconomic inequality remained evident among men in 2015–2022 after accounting for regional characteristics within a multilevel framework.