Calcium for children and Fosamax discontinuation
Cochrane Database Syst Rev. 2006 Apr 19;(2):CD005119, Winzenberg T and others. PMID: 16625624 This is a review of 19 clinical trials that include 2859 children who received calcium supplementation for at least three months. It includes 1367 participants randomized to get supplements and 1426 who received placebo. All participants received some form of bone mineral testing such as dual-energy X-ray absorptiometry. Findings showed no effect on either the femoral neck or the lumbar spine. There was a minimal positive effect in the upper limb which would appear to have almost no beneficial effect. The authors conclude: “While there is a small effect of calcium supplementation in the upper limb, the increase in BMD which results is unlikely to result in a clinically significant decrease in fracture risk. The results do not support the use of calcium supplementation in healthy children as a public health intervention.” Editor's comments: These results mirror those found in adults. Remember that in clinical trials of new osteoporosis medication, the controls always receive calcium supplements and often also receive vitamin D. Invariably these control individuals lose bone mineral density (BMD) while the test subjects, who are receiving some active medication, gain BMD. So calcium supplementation is not some magic bullet that will either prevent or treat low BMD such as occurs in osteoporosis or osteopenia. Obviously some minimally adequate calcium intake is required or the body will just remove calcium from the bones. But for the normal healthy individual eating a diet that has adequate calcium, supplements are not needed, or at least have no identifiable benefit.
Osteoporosis Int. 2006 Apr 12; [Epub ahead of print], Lo JD, and others. PMID: 16609824. This study looked at the discontinuation rate of women taking bisphosphonates for osteoporosis who were treated in the Kaiser Permanente of Northern California health care delivery system. The authors point out that many studies have found a discontinuation rate for osteoporosis therapy exceeding 50%. In this study of 13,455 women with an average age of about 68, the discontinuation rate after one year was 49.6% when a 60-day refill gap was used to verify discontinuation. An important point is that about 50% of women who had discontinued did restart therapy on another medication within six months. They also point out that the refill gap interval when using a longer time period reduces the discontinuation rate to about 41%. They were unable to identify any clinical factors to predict why women would discontinue therapy. The authors say, “We conclude that apparent discontinuation rates are high within 1 year after initiation, although a subset of women appears to restart bisphosphonate or other osteoporosis therapy.” Editor's comments: This is one study that involved only women where I would have loved to have seen men in the cohort too. I would hope their discontinuation rate would not have been so high. Also, since the women started some other form of therapy within six months, the real discontinuation rate was about 25%, a little more reasonable. There certainly have to be valid reasons in many cases, including death, disability, inability to tolerate the medication or not liking the schedule it is given on, etc. So the glaring headlines on this study are not so glaring with a deeper look. One additional thing I would have liked to have seen would be a subgrouping by whether or not the women had a fracture before starting therapy. I know that my spinal compression fractures before I started Fosamax got my attention. I wouldn't dream of discontinuing therapy because I still remember the pain vividly.