Fragility, fear of falling, physical activity and falls among older persons: some theoretical considerations to interpret mediation.
BACKGROUND
In their letters to the editor, Lacherez et al. [Lacherez, P.F., Wood, J.M., Kerr, G.K., 2007. Does activity level mediate or suppress the association between fear of falling and falls? Prev. Med. 31; (Electronic publication ahead of print)] and Hafeman and Schwartz [Hafeman, D., Schwartz, S., 2007. Assessing mediation: The necessity of theoretical considerations. Prev. Med. 26; (Electronic publication ahead of print)] questioned the correctness of using the term 'mediation' in our paper [Wijlhuizen, G.J., Jong, R. de, Hopman-Rock, M., 2007. Older persons afraid of falling reduce physical activity to prevent outdoor falls. Prev. Med. 44, 260-264.]. In this paper, we concluded that (outdoor) Physical activity mediates the relationship between Fear of falling and outdoor Falls. We investigated whether the term 'inconsistent mediation' might be a more appropriate term to use in this context.


METHODS
Based on literature, we describe the relationship between fear of falling, physical activity, and falls within a causal model.


RESULTS
Two causal pathways between Fear and Falls exist, with the causal pathway going from Fear of falling via Physical activity to Falls counteracting (is inconsistent with) the causal pathway going from Fear of falling via Hesitancy to Falls.


CONCLUSIONS
The term 'inconsistent mediation' might be more appropriate to describe the causal relationships between Fear of falling, Falls, and Physical activity.
Wijlhuizen
Gert Jan
GJ
Department Physical Activity and Health, TNO Quality of Life, Leiden, The Netherlands. GertJan.Wijlhuizen@tno.nl
Chorus
Astrid M J
AM
Hopman-Rock
Marijke
M
D000058:Accidental Falls; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015984:Causality; D015444:Exercise / Q000502:physiology*; D005239:Fear / Q000523:psychology*; D016330:Frail Elderly / Q000523:psychology*; D006801:Humans; D008962:Models, Theoretical; D009043:Motor Activity