Letters

Calcium, vitamin D, and hip fractures Incidence of falls may have decreased

BMJ 1994; 309 doi: https://doi.org/10.1136/bmj.309.6948.193 (Published 16 July 1994) Cite this as: BMJ 1994;309:193
  1. T Mets
  1. Academic Hospital, Free University of Brussels, B-1090 Brussels, Belgium
  2. Health Economics Research Unit, Health Services Research Unit, University of Aberdeen, Medical School, Aberdeen AB9 2ZD.

    EDITOR, - Maric C Chapuy and colleagues report that treatment with cholecalciferol and calcium prevents non-vertebral fractures in elderly women and suggest that this is due to an improvement in bone metabolism.1 As they mentioned in a previous report of this study, however, the resulting increase in bone density is low.2 A more likely explanation for the results might be a decrease in the incidence of falls in the active treatment group. This incidence, however, was not reported.

    A difference in the incidence of falls between the two groups could be explained by the muscular effects of cholecalciferol treatment. Indeed, apart from its action on bone metabolism, a low vitamin D concentration causes muscular weakness, which can be reversed by substitution.3, Chapuy and colleagues mention that the mean serum concentration of 25- hydroxycholecalciferol normalised in the active treatment group but remained low in the controls. In a prospective study that I carried out in 63 elderly women (mean age 82.5 (SD 5.4) years), all living in the community and independent in basic activities of daily living, muscular strength and exercise capacity were related to serum 25- hydroxycholecalciferol concentrations (table).

    Serum 25-hydroxycholecalciferol concentration and mean (SD) grip strength for both hands and distance walked in six minute walking test in 63 elderly women

    View this table:

    Other recent reports on the treatment of osteoporosis in elderly people have also failed to mention the incidence of falls.5 In general, all studies on osteoporotic fractures should mention this incidence as it is essential to the understanding of the dynamics of the intervention.

    References

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    Vitamin D alone may be helpful

    1. D Torgerson,
    2. M Campbell
    1. Academic Hospital, Free University of Brussels, B-1090 Brussels, Belgium
    2. Health Economics Research Unit, Health Services Research Unit, University of Aberdeen, Medical School, Aberdeen AB9 2ZD.

      EDITOR, - Marie C Chapuy and colleagues' recent paper supports their earlier work by showing the beneficial effects of cholecalciferol and calcium supplements in preventing hip fractures.1 In their comment, however, they note that Heikinheimo et al, who gave calciferol injections, showed no significant effect on hip fractures.2 In Heikinheimo et al's study 341 women were given calciferol by annual injection and were compared with 458 controls. Twenty five hip fractures occurred in the calciferol group and 43 in the controls, yielding rate of hip fracture of 7.3% in the intervention group and 9.4% in the controls. This represents a 22% difference between the two groups ((9.4-7.3)/ 9.4x100), which is similar to the difference in rates of hip fracture found by Chapuy and colleagues in their intention to treat analysis.

      The reason that the difference of 22% observed by Heikinheimo et al was not significant was possibly the smaller sample size, which we estimate would have had only an 80% chance of detecting a 58% reduction in hip fractures at the 5% significance level (from 9.4% to 3.9%). Given that this reduction was of a similar magnitude to that observed by Chapuy and colleagues, this suggests that the results of supplementation with cholecalciferol and calcium are primarily due to the vitamin D component rather than calcium.

      Calcium supplementation is expensive,3 but vitamin D is relatively cheap. Thus in economic terms it is important to estimate the independent effects of vitamin D on the incidence of hip fracture.

      References

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      View Abstract

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