COLING. MILLER ANDDEREKPEARSON 1. 1. Why a Book about Clinical Trials in Osteoporosis? There have been many books published about the design, conduct, and analysis of clinicaltrials. Whyareosteoporosistrialsaspecialcasethatdeserveabookoftheir own? There are three main reasons. First, most diseases have a well-understood definitionandaetiology. Osteoporosisisadiseasethatisunderstoodbythosewo- ing within the subspecialty, but currently there is no definition that is agreeable to both medical and scientific communities and its aetiology is poorly understood. It is within this framework that the pharmaceutical industry is trying to develop new treatmentsfortheso-called“silentepidemic”. In layman’s terms, the disease of osteoporosis is defined as “brittle bones occurring in the elderly that could lead to fractures. ”The classical definition was “a bony fracture caused by minimal trauma owing to a loss in bone mineral. ” A published consensus definition states that osteoporosis is “a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to 1 fractures. ” The National Institutes of Health (NIH) Consensus Conference Statement on Osteoporosis Prevention, Diagnosis, and Therapy states that “osteoporosis is a skeletal disorder characterized by compromised bone strength 2 predisposing to an increased risk of fracture. ” The World Health Organization (WHO) operationally defines osteoporosis as “bone density 2. 5 standard dev- tions (SDs) below the mean for young white adult women at lumbar spine, 3 femoralneck,orforearm”. Itisnowrecommendedthatthediagnosticuseofthis 4 definition is restricted to bone density of the femur.