Purpose: Osteoporosis is a major health concern among the elderly, underscoring the importance of investigating its prevalence across different geographical regions. There is a current research gap regarding the incidence of osteoporosis and its variation by altitude within Sichuan, China. This study aimed to assess the prevalence of osteoporosis among populations residing at different altitudes in western Sichuan Province.

Basic procedures: This study utilized data from a population-based cohort in Sichuan, China. Representative locations were selected, and cluster random sampling was employed to conduct cohort studies across multiple sites in southwestern China. T Baseline data were collected from populations in Mianzhu, Kangting, and Sertar between July 2020 and August 2021. To assess differences in osteoporosis incidence among populations at different altitudes and with varying characteristics, we applied Chi-square and rank-sum tests.

Main findings: The study involved 4074 participants, including 1404 males (34.46%) and 791 individuals diagnosed with osteoporosis (19.42%). The prevalence of osteopenia in mid-altitude and high-altitude regions was 20.05% and 16.28%, respectively, while the prevalence of osteoporosis was significantly different, at 25.85% in mid-altitude areas compared to 13.00% in high-altitude areas (P < 0.001). Further analysis identified statistically significant differences in the prevalence of osteopenia and osteoporosis among females (P<0.001), middle-aged (P=0.015) and elderly populations (P=0.038), as well as among individuals who were underweight (P=0.011), normal weight (P<0.001), overweight (P<0.001), and obese (P=0.038). As altitude increased, the prevalence of osteoporosis decreased in all groups except the elderly, while the prevalence of osteopenia decreased among women and across various BMI categories, but increased among middle-aged and elderly individuals. Additionally, in high-altitude regions, Kangting recorded an 18.10% prevalence of osteopenia and a 14.26% prevalence of osteoporosis, compared to Sertar, which exhibited a 6.54% prevalence of osteopenia and a 6.23% prevalence of osteoporosis, indicating significant differences (P<0.001).

Conclusion: This study demonstrates that higher altitudes are associated with a decreased prevalence of osteopenia and osteoporosis, particularly among females and middle-aged individuals. These results emphasize the importance of developing region-specific osteoporosis prevention strategies.