Improvement in Spine Bone Density and Reduction in Risk of Vertebral Fractures During Treatment with Antiresorptive Drugs
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There is an inverse and linear relationship between bone mineral density (BMD) and fracture risk in women. Investigators have queried whether BMD fully explains the fracture reduction benefits seen with osteoporosis therapies, since it appears that fracture reduction benefits are substantial with small incremental improvements in BMD. It is unclear whether other factors, such as improved bone integrity or architecture, might also be responsible for reduced fracture risk. By meta-analysis of 12 osteoporosis treatment trials that used antiresorptive therapies, Cummings and colleagues measured the relationship between incremental change in BMD and incident vertebral fractures. This relationship was compared with data from the placebo arm of the Fracture Intervention trial, which demonstrated a 1.5-fold increase in vertebral fracture risk for each 0.10 decline in BMD, which establishes a baseline for the relationship between "natural" changes in BMD and subsequent fracture.
Based on this analysis, Cummings et al calculate that increases in BMD by antiresorptive treatments explain only a small portion of the reduced fracture risk. For instance, the 4% improvement in BMD seen in 1 3-year trial of alendronate would only explain 16% of the reduction in fractures. Although the improvements in BMD induced by antiresorptive treatment are important, other mechanisms not apparent on BMD must play a role in fracture reduction.
Cummings SR, et al. Am J Med. 2002; 112:281-289.
The Relationship Between Insomnia and Health-Related QOL in Patients with Chronic Illness
In persons who suffer compelling chronic health conditions such as congestive heart failure, diabetes mellitus, and depression, it is easy for complaints like insomnia to be misperceived as modest in affecting overall quality of life (QOL). Indeed, comorbidities may complicate sleep quality, and worsen primary sleep disturbances. In this study, Katz and McHorney sought to discern whether, in patients suffering other chronic conditions, insomnia is independently detrimental to health-related QOL, and to quantify the effect of insomnia upon QOL in comparison with the effect of other chronic conditions.
The study population was comprised of patients from outpatient settings who were administered a depression scale, and the SF-36 QOL assessment tool. Inclusion criteria required the patient to also have either hypertension, diabetes, congestive heart failure, recent MI, or depression.
Sixteen percent of study subjects had severe insomnia, and 34% had mild. As severity of insomnia increased, so did decrements in QOL. Insomnia was independently associated with impaired QOL, even after adjustment for competing conditions (including depression). Although insomnia had diverse effect across the SF-36 parameters, certain select categories showed prominent impact. For instance, in persons with severe insomnia, the decline in physical function score was of comparable magnitude to the effect of congestive heart failure. Addressing insomnia as an independent morbidity, even in persons with major competing chronic medical conditions, may have a valuable effect on QOL.
Katz DA, McHorney CA. J Fam Pract. 2002;51:229-235.
Effects of Calcium Supplementation on Serum Lipids in Normal Older Women
Calcium supplementation (CAS) is generally recommended for adult women based on the fact that osteoporosis (OSPS) may be prevented or ameliorated by enhanced dietary calcium. Previously, some data have shown that oral CAS tends to bind intestinal fatty acids and bile acids, resulting in reduced fat absorption, and subsequent favorable effect on HDL and LDL, but other studies have failed to confirm this phenomenon. Reid and colleagues report on the first randomized controlled trial to study the issue in normal postmenopausal women.
Women (n = 223) had to be free of OSPS at entry, postmenopausal for > 5 years, older than age 55, and not long-term users of HRT or other treatments for OSPS. Women were randomly assigned to placebo or 400 mg CAS QAM and 600 mg QPM (before meals) for 1 year. Calcium was administered as calcium citrate. Outcomes measured were changes in fasting HDL, triglycerides, and LDL (calculated), measured at baseline, 2, 6, and 12 months.
At 1 year, the most substantial effect of CAS upon lipids was a 7% increase in HDL compared with baseline. There was a trend toward reduced LDL, and a statistically significant improvement in HDL/LDL ratio. It remains to be explored whether men might enjoy similar benefits from CAS.
Reid IR, et al. Am J Med. 2002;112: 343-347.
Dr. Kuritzky, Clinical Assistant Professor, University of Florida, Gainesville, is Associate Editor of Internal Medicine Alert.