India is at early stages of demographic transition to an aging society, but little is known about musculoskeletal health. Mobility and Independent Living among Elders’ Study (MILES), a rural south Indian older adults’ cohort, provides an opportunity to expand our musculoskeletal health understanding. This dissertation goal was to compare peripheral quantitative computed tomography (pQCT) parameters of Indian population with other ethnic groups and, assess its associations with mortality and physical performance.

We observed Indian men compared to US Caucasians had significantly lower trabecular volumetric bone mineral density (vBMD), cortical thickness and higher endosteal circumference, suggesting higher risk of osteoporotic fractures.

Over an average follow up of 64.2 months, among 499 MILES participants, 123 died (73 men;​ 50 women). Among men, trabecular vBMD (radius and tibia), cortical vBMD (radius and tibia), cortical thickness (radius and tibia), polar strength strain index (SSIp) of tibia and muscle density were inversely associated and, endosteal circumference (radius and tibia) were positively associated with mortality. Among women cortical vBMD (radius and tibia), cortical thickness (radius and tibia), SSIp (radius and tibia) were inversely associated, and endosteal circumference (radius and tibia) were positively associated with mortality. Gait speed among men mediated the muscle density and mortality association.

On cross sectional analysis;​ among men, muscle density was associated with grip strength;​ cortical vBMD (radius), trabecular vBMD (tibia), cortical thickness (tibia), endosteal circumference (tibia) and muscle density were associated with short physical performance battery (SPPB);​ cortical thickness (tibia) was associated with 400-meter walk. Among women, trabecular vBMD (radius and tibia), cortical thickness (radius and tibia), SSIp (radius) and muscle density were associated with grip strength;​ cortical vBMD and SSIp of tibia and muscle density were associated with SPPB and;​ trabecular vBMD (tibia) was associated with 400- meter walk.

These dissertation findings have public health importance;​ as it suggests Indian older population have lower bone strength indices. It presents for the first time mortality and physical performance associations with bone and muscle measures. These findings indicate the vulnerability of older population in India, and calls attention of policy makers for musculoskeletal health research and inclusion in national programs.