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Dr Opinder Sahota takes a look behind recent headlines that throw doubt on the value of prescribing calcium and vitamin D in elderly patients
Recent months have seen two studies cause much confusion over the issue of whether calcium and vitamin D reduce fractures in the elderly living in care homes.
These studies conflict with existing published data showing that calcium and vitamin D reduce falls in both care home residents and the free-living elderly.
The mechanism through which this happens is thought to be mediated by the direct effects of vitamin D on skeletal muscle.
The BMJ study
The BMJ study1 was a postal study in 3,314 women aged 70 and over with a clinical risk factor for a hip fracture (median follow-up 25 months).
The study end-point was all clinical fractures and although the study concluded that there was no evidence that calcium and vitamin D reduced fractures, compliance was poor, with only about half the participants still taking medication at 24 months.
The other important point of this study is that of 3,314 women who agreed to take part, these were selected from a larger cohort (48,987).
Subjects were invited as identified through GP lists and of the 48,987 invited, 11,022 replied, of which 3,314 agreed to take part.
Clearly there is some selection bias here. It is hard to imagine that these patients were truly representative of the everyday patients we see in general practice.
Furthermore, if we look at the control group, these were sent a leaflet with general advice on falls prevention and how to consume adequate calcium and vitamin D from dietary sources.
Given the selection bias, it is more than likely these women would have acted on this advice and thus limiting the true effect of the control group over the treatment group (some, if not many, subjects in the control group may have decided to significantly improve their vitamin D and calcium intake).
The only real way to refute this would have been to measure vitamin D levels in both groups at the start and end of the study, but this was never done.
The Lancet study
The Lancet (RECORD) study2 was a pragmatic study in 21 centres in the UK which recruited healthy, elderly, community-dwelling men and women (mean age 77) with a low trauma fracture from 'fracture clinics' and randomised them to either vitamin D, calcium, vitamin D and calcium or placebo. Some 15,024 patients met eligibility, of which 5,292 were randomised to the study.
Of those patients who were eligible but didn't take part, their average age was older than the participants in the study and more of them had a history of previous hip fractures than wrist fractures. Perhaps this was a group of patients where calcium and vitamin D would have been effective ?
Of those patients who were not eligible to take part, 43 per cent were defined as having cognitive impairment using the 10 point mini-mental test score. This method of cognitive assessment in an elderly person presenting to hospital acutely, in some cases following an overnight fall, is open to debate.
Compliance was assessed using postal questionnaires. At 24 months compliance was 60 per cent. But if we assume that those patients who did not return the questionnaire were not complying with treatment, this falls to 47 per cent.
So at two years, fewer than half of the patients were still taking tablets, so it is not particularly surprising that the study failed to show a reduction in fractures!
More recently, however, the NICE clinical guidelines for the secondary prevention of osteoporotic fragility fractures in postmenopausal women (published January 2005) has now given us clear guidelines for what to do with elderly patients who present with a low trauma osteoporotic fracture (see below).
Patients presenting with a low trauma osteoporotic fracture (upper limb, wrist, pubic ramus, ankle, hip) aged 75 and over should be prescribed a bisphosphonate and adjunct vitamin D and calcium (for example Adcal D3 or Calcichew D3 Forte), one tablet twice daily. Patients aged under 75 presenting with a low trauma fragility fracture should be started on a bisphosphonate as first-line treatment once osteoporosis is confirmed by bone density scanning.
Where there is a delay for bone density scan, patients should be started on treatment which can then be stopped if the results are normal.
Adequate vitamin D and calcium intake should be ensured and where there is deficiency, over the counter or supplements as described above should be given.
The cost-effective role of antiresorptive agents in the primary prevention of first fractures remains unclear.
However, there is good evidence that blanket prescribing of calcium and vitamin D (for example Adcal D3 or Calcichew D3 Forte) one tablet twice daily to ambulatory care home residents is effective in preventing both falls and fractures and preventing falls in the community-living elderly.
Further guidance from NICE on primary prevention of fractures is expected in June next year.
Opinder Sahota is consultant physician and senior lecturer at QMC, University Hospital Nottingham
1 Porthouse J et al. Randomised controlled trial of calcium supplementation with cholecalciferol (vitamin D3) for prevention of fractures in primary care. BMJ 2005; 330: 1003-1008
2 The RECORD Trial Group. Oral vitamin D3 and calcium for secondary prevention of low-trauma fractures in elderly people (randomised evaluation of calcium or vitamin D, RECORD);
a randomised placebo controlled trial. The Lancet 2005; 365: 1621-1628