Stair falls are a major cause of injury and loss of independence for older people and place escalating demands on the National Health Service (NHS). Individual (e.g. psychological and physiological) and environmental (e.g. stair design) factors influence the biomechanics of stair negotiation and thus, affect stair fall risk. In addition, stair-specific risk factors have been identified by comparing predetermined groups for single-parameters that underpin the potential mechanism of a stair fall through biomechanical research in a gait lab. However, it remains unknown if the existing screening tools and single biomechanical parameters have the predictive power to identify older individuals at risk for a stair fall specifically. Therefore, the overall purpose of this thesis was to develop a multivariate approach that has the ability to identify older adults at risk for a stair fall at community level. The first study, which included 25 younger (20-30 years) and 70 older adults (>65 years), established a novel multivariate approach for profiling individual stair-negotiating behaviour. It was found that individual stepping behaviour could be profiled based on multiple biomechanical parameters reflecting risk and safety on stairs and that this approach circumvented the limitations of single-parameter comparisons between predetermined groups. The next study showed that of the 68 included older adults (>65 years) the majority maintained their stair-negotiating behaviour irrespective of step dimensions, which indicated that manipulating the demand of the task would not affect the underpinning mechanism of a potential stair fall. In the final prospective study, the multivariate approach was implemented on 87 older adults (>65 years) over a 12-month follow up period to identify the biomechanical stepping profile linked with the highest stair fall risk. As opposed to the limited predictability of stair fall risk using functional and single-parameter biomechanical approaches and general fall screening tools, the multivariate approach showed potential to predict fall risk, especially during stair ascent. iii Future research should implement the multivariate approach in more people in real life stair negotiation conditions to improve the prediction of the method, so that targeted interventions for improving stair safety in older individuals can be developed
