["Geriatrics &Gerontology International, Volume 26, Issue 7, July 2026. ", "\nStrengthening home medical care infrastructure may help reduce regional variation in home oxygen therapy use, particularly in highly aged regions.\n\nABSTRACT\n\nAim\nTo evaluate regional variation in home oxygen therapy (HOT) use in Japan and to examine its association with regional healthcare resources.\n\n\nMethods\nThis ecological cross‐sectional study analyzed aggregated data from the National Database Open Data for Fiscal Year 2023. Patients receiving HOT were identified using reimbursement codes. Age‐standardized claim ratios (SCRs) were calculated for all 47 prefectures by performing indirect standardization based on 5‐year age groups. Multivariable linear regression assessed associations between HOT use and prefecture‐level characteristics reflecting regional contextual factors, including the density of home‐care support clinics, respiratory specialist density, population aging, and respiratory disease‐related mortality.\n\n\nResults\nA total of 324 998 patients had HOT‐related claims nationwide in Fiscal Year 2023. SCRs ranged from 54.4 to 140.4, indicating marked regional variation. A higher density of home‐care support clinics was independently associated with higher SCRs in both the primary model and the model additionally adjusted for population aging and regional disease burden. Population aging was inversely associated with SCRs, indicating lower age‐standardized HOT use in more aged prefectures. Respiratory disease‐related mortality was positively associated with SCRs, whereas no significant association was observed between respiratory specialist density and SCRs.\n\n\nConclusions\nRegional variation in HOT use was associated with the availability of home medical care services, after accounting for regional contextual factors. Lower age‐standardized use in highly aged prefectures may reflect regional characteristics related to HOT provision. These findings suggest an association between regional variation in HOT use and differences in home‐care infrastructure.\n\n"]