Hip protectors to prevent femoral fracture
Authors: Sophia E de Rooikj
Journal: BMJ (2006)

The ageing of Western populations increases the incidence of people with hip fractures, with corresponding expectations of decline in function or mortality. By 2050 the worldwide annual incidence of hip fractures among elderly people will be 4.5 million,1 and prevention will be more important than ever.

There are three main pathways to preventing hip fracture. Firstly, Close and colleagues found in a randomised trial among community dwelling elderly people with recurrent falls that an interdisciplinary approach significantly reduced the risk of further falls.2 Patients assigned to the intervention group underwent a detailed medical and occupational-therapy assessment with referral to relevant services. Secondly, most hip fractures are due to osteoporosis, which is treatable. Frail elderly people may prefer, however, to avoid the possible adverse effects of osteoporosis drugs and to use non-pharmacological strategies to decrease the risk of hip fracture. As most hip fractures affect the greater trochanter of the femur, the third preventive strategy is to wear a hip protector. Hip protectors, devices comprising external padding for the hip, date from almost 50 years ago, when the first design was patented by M L Raymond in 1959.

It subsequently took 34 years to study the efficacy of hip protectors systematically in a large randomised trial.3 This trial, among elderly people living in a nursing home, showed a relative risk of hip fractures of 0.44 (95% confidence interval 0.21 to 0.94) in the intervention group. Subsequent trials yielded similar results. In 1999 Parker and colleagues reviewed these studies and concluded that hip protectors seemed to reduce the risk of hip fractures among institutionalised elderly people.4 A subsequent large scale cluster randomised trial reached similar conclusions.5

But a big problem remained, as emphasised in an editorial in the BMJ in 2002—the low rate of usage of hip protectors owing to practical issues. Although the cost effectiveness of using protectors was unclear, because of the high morbidity and costs associated with hip fractures,6 protectors became widely used.

Now the debate on the benefits of hip protectors has been brought to life again. In their Cochrane review in 2005 Parker and colleagues concluded that “there is no evidence of effectiveness of hip protectors from studies in which randomisation was by individual patient within an institution, or for those living in their own homes. However, data from cluster randomised studies indicated that in institutionalised [people] hip protectors appeared to reduce the incidence of hip fractures.”7 These findings prompted several questions, such as how an intervention could be effective in one way when randomised by cluster, and not in another when randomised to individuals within the same type of institutional setting.8 This could be explained by the introduction of statistical bias through cluster randomisation instead of direct randomisation.

In this issue (p 571) Parker and colleagues present an update of their previous analysis.9 Pooled data from studies among institutionalised elderly people showed a significant reduction in hip fracture rates associated with use of hip protectors (relative risk 0.77; 0.62 to 0.97). But this result is sensitive to inclusion or removal of two large and heterogeneous cluster studies. When only the individual, directly randomised studies were analysed the incidence of hip fracture was not reduced (0.77; 0.54 to 1.34) in this subgroup, without any heterogeneity. The overall pooled data also lost its significant evidence of effectiveness when one cluster study with methodological flaws was removed,5 as was recently found in another systematic review.8 This other review found a positive effect of hip protectors on hip fracture among nursing home residents, but it did not include a negative study in the meta-analysis.10

Are we back to where we were before hip protectors were invented? Yes, probably—although the accumulated evidence indicates that hip protectors may be effective in specific subgroups of elderly people. Such groups might include highly motivated elderly people living in the community and people at high risk of hip fracture living in nursing homes, with high rates of use encouraged by nursing staff. Until clinical trials among such groups confirm the effectiveness of hip protectors, the continued use of these devices should not be widely advocated. It may also be wise to study how to increase concordance with the use of protectors (which varies between 20% and 92%11) because this has important effects on the efficacy of this intervention.