A comparative study of quality of life, functional and bone outcomes in osteogenesis imperfecta with bisphosphonate therapy initiated in childhood or adulthood.

Bisphosphonates have been used for treatment of bone fragility disorders for over 25 years to increase bone mineral density (BMD). Anecdotally, bisphosphonate-treated Osteogenesis Imperfecta (OI) has a different trajectory to the natural history of untreated OI in terms of fracture incidence, quality of life and physical function, with minimal published evidence to support this clinical observation. This study describes functional outcomes of a cohort of adults with OI, stratified according to severity and treated with intravenous bisphosphonates as children. Reported outcomes included fracture incidence before and after puberty, mobility and BMD outcomes of this cohort. The cohort was compared to adults with OI who were never treated as children. All participants completed four questionnaires: a study specific questionnaire addressing fracture and treatment history, WHOQOL-BREF (quality of life), SF-36 (musculoskeletal function) and IPAQ (physical activity), and medical records were reviewed. Fifty-two adults with OI (80% response rate) completed the questionnaires; 33 of whom were treated with bisphosphonates in childhood. The childhood treated cohort had higher lumbar spine BMD than the adult treated cohort (z-score - 0.4 at mean age 21.3 years versus -2.1 at mean age 40.9 years; p = 0.003). Pre-pubertal fracture incidence was reduced for all severities of OI in the childhood treated cohort (less severe OI, p = 0.01; more severe OI, p < 0.001), but post-pubertal fracture incidence was higher for less severe OI (p < 0.001). In less severe OI, childhood treated individuals had higher levels of physical activity (p = 0.004) and physical functioning (p = 0.01) than adult treated individuals. Incidence of scoliosis was not different between cohorts. There were no differences in quality of life scores between the two cohorts. Improvements in BMD do not appear to influence the prevalence of scoliosis. Results suggest that treatment with bisphosphonates at an earlier age improves physical activity, particularly in less severe forms of OI but may not alter quality of life.