Age and Ageing Advance Access originally published online on March 22, 2008
Age and Ageing 2008 37(3):353; doi:10.1093/ageing/afn059
Reply
SIR—We thank our colleagues for their comments on our paper [1] and agree that the interactions between fall prevention interventions may depend on the nature of the interventions and the population involved.In our VIP study [2] of fall prevention there was a significant negative interaction (P = 0.016) between the two interventions, home-based exercise and home safety. In our Age & Ageing paper [1], in which we describe the lack of difference in the number of falls prevented by single interventions compared with multifactorial interventions, we have offered some possible explanations for this, such as confusion with advice from different health professionals. This may have been more likely to occur in the VIP trial where both the exercise programme and the home safety programme were delivered at home [2]. In the study by Day et al. [3] there was a group exercise programme away from home and home hazard management at home. In this study most participants rated their health as ‘good to excellent’ whereas participants in the VIP trial were older and had severe visual impairment.
Although single interventions may be more cost effective and reach the greatest numbers in population-based fall prevention programmes, clinicians seeing individual patients will advise intervention in a number of areas. We suggest that with individual patients the interventions are introduced only as rapidly as acceptance and adherence allow.
The study of Day et al. [3] was not included in our meta-analysis because they used ‘time to first fall’ rather than the total number of falls in their analysis. We would be very interested in the interaction effect in their study using all falls during the trial as the outcome measure.
Despite negative interactions in some situations, multifactorial interventions do have benefit. This may not be evident if suboptimal statistical approaches are used. We do not feel there is any justification for researchers now to report ‘time to first fall’ or number of ‘fallers’ rather than the total number of falls as the primary outcome measure in fall prevention trials. Analysis of efficacy using the total number of falls uses information on all fall events, increases the power of the study and has clinical relevance [4].
The loss of power using ‘fallers’ as the outcome measure can be seen by comparing the significant results of our meta-analysis of multifactorial interventions in the community setting [1] with one published concurrently using number of ‘fallers’ as the outcome measure and showing no significant benefit [5]. Such meta-analyses showing no benefit due to lack of statistical power do not help the promotion of falls prevention. This is disappointing when there is clear evidence of significant benefit when comprehensive, clinically important outcome measures are used.
Department of Medical and Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
* To whom correspondence should be addressed Email: john.campbell{at}stonebow.otago.ac.nz
References
- Campbell AJ, Robertson MC. Rethinking individual and community fall prevention strategies: a meta-regression comparing single and multifactorial interventions. Age Ageing (2007) 36:656–62.
[Abstract/Free Full Text] - Campbell AJ, Robertson MC, La Grow SJ, et al. Randomised controlled trial of prevention of falls in people aged
75 with severe visual impairment: the VIP trial. BMJ (2005) 331:817–20.[Abstract/Free Full Text] - Day L, Fildes B, Gordon I, et al. Randomised factorial trial of falls prevention among older people living in their own homes. BMJ (2002) 325:128.
[Abstract/Free Full Text] - Robertson MC, Campbell AJ, Herbison P. Statistical analysis of efficacy in falls prevention trials. J Gerontol Med Sci (2005) 60:530–4.
[Abstract/Free Full Text] - Gates S, Lamb SE, Fisher JD, et al. Multifactorial assessment and targeted intervention for preventing falls and injuries among older people in community and emergency care settings: systematic review and meta-analysis. BMJ (2008) 336:130–3.
[Abstract/Free Full Text]
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