Prevalence and incidence of vertebral deformities

Epidemiology and predictors of fractures associated with osteoporosis

Approximately 40 in 100 women will experience one or more fractures after the age of 50 years. At 50 years for women the lifetime risk is 17.5% for hip fracture, 16% for vertebral fracture, and 16% for Colles' fracture; for men, the respective lifetime risks are 6%, 5%, and 2.5%. The incidence of hip fractures has increased in recent years in most but not all European countries, partly as a result of the aging of the population. However, the age-adjusted incidence has also increased in several countries. The age-adjusted incidence of hip fractures varies greatly between European countries; in women incidence varies from about 50 per 10,000 women in Malta and Poland to 500 per 10,000 in Sweden. In addition, the sex ratio (female:male) varies from 1.6 in Poland to 4.2 in Iceland. A proportion of this large variation may be the result of underreporting of cases, although most European countries now have an adequate hospital registration. The prevalence of vertebral deformities also shows geographic variation. In the multinational European Vertebral Osteoporosis Study, a population-based study, the prevalence of vertebral deformities was similar among men and women at ages 65-69 years (12-13%); at younger ages the prevalence was higher in men than women, whereas the reverse was true at older ages. Incidence data on vertebral fractures are scarce because a large proportion of vertebral fractures are not clinically diagnosed. Prospective epidemiologic studies indicate that bone mineral density (BMD) is the single best predictor of fractures in perimenopausal women. Historic risk factors do not predict bone mass (or fractures) with sufficient precision to be useful in assessment of fracture risk or BMD. However, the presence of one vertebral fracture doubles the risk of future vertebral fracture as assessed by a BMD measurement. At advanced ages, other risk factors may be more important, such as the risk of falling, and combinations of risk factors for falls and low BMD may predict hip fractures. Risk factor assessment is currently of less value for the prediction of other fractures, such as vertebral or Colles' fracture. Determining the causes of the large geographic differences in hip fracture incidence and the large differences in sex ratios for hip fractures in European countries could lead to identification of hitherto unknown risk factors and provide clues for prevention of fractures. Many risk factors cannot be prevented or modified; however, these risk factors (for example, family history, past fracture, and visual loss) can identify risk groups amenable to drug treatment or to preventive measures such as protective hip pads or environmental changes. Assessment of risk factors and definition of risk profiles are important steps toward the prevention of fractures in the elderly.

Quantitative ultrasound techniques for the assessment of osteoporosis: expert agreement on current status. The International Quantitative Ultrasound Consensus Group

Quantitative ultrasound (QUS) methods have been introduced in recent years for the assessment of skeletal status in osteoporosis. The performance of QUS techniques has been evaluated in a large number of studies. Reviewing existing knowledge, an international expert panel formulated the following consensus regarding the current status of this technology. To date, evidence supports the use of QUS techniques for the assessment of fracture risk in elderly women. This has been best established for water-based calcaneal QUS systems. Future studies should include the predictive validity of other QUS systems. Additional clinical applications of QUS, specifically the assessment of rates of change for monitoring disease progression or response to treatment, require further investigation. Its low cost and portability make QUS an attractive technology for assessing risk of fractures in larger populations than may be suitable or feasible for bone densitometry. Additional investigations that assess innovative QUS techniques in well defined research settings are important to determine and utilize the full potential of this technology for the benefit of early detection and monitoring of osteoporosis.

What is the impact of osteoporosis?

A body of evidence points towards a close connection between susceptibility to fractures and osteoporosis. The incidence of osteoporotic fractures, both in absolute figures and in age-specific figures, has increased worldwide throughout this century. Although some reports show that the age-specific incidence is levelling-off, there will be a continuously increasing number of individuals with such fractures that will have implications from an economical point of view not only for the affected individual but for society as a whole. The outcome after such fractures, especially those of the hip, is by no means always favourable, partly due to insufficient results after orthopaedic treatment and partly due to an already high comorbidity. Therefore, trying to prevent osteoporotic fractures by non-pharmacological or pharmacological regimens is of utmost importance.

Vertebral morphometry studies using dual-energy x-ray absorptiometry

Vertebral fractures are one of the most common consequences of osteoporosis. They are usually diagnosed by visual interpretation of lateral radiographs of the lumbar and thoracic spine. Vertebral morphometry, based on measurements of the anterior, middle, and posterior heights of the vertebral bodies from T4 to L4, is a useful adjunct to the visual reading of radiographs. A new generation of dual-energy x-ray absorptiometry (DXA) scanners offers software for acquiring lateral images of the spine and performing vertebral morphometry analysis. Advantages of DXA morphometry include straightforward and reproducible patient positioning, absence of geometrical distortion of the image, low radiation dose, digital acquisition, and simplified, semi-automated scan analysis. The widespread availability of such DXA systems should make the investigation of vertebral fractures more widely accessible.

Vertebral deformities and functional impairment in men and women

The objective of this study was to assess the prevalence and health effects of vertebral deformities in men and women. The study was carried out as part of the cross-sectional baseline phase of The Rotterdam Study, a prospective population-based cohort study of residents aged 55 years or over of a district of Rotterdam, The Netherlands. The prevalence of vertebral deformities according to a modification of the Eastell method and concomitant functional impairment were assessed in a random sample of 750 men and 750 women. The prevalence of moderate (grade I) vertebral deformities was 8 and 7% in men and women, respectively. For severe deformities (grade II), these percentages were 4 and 8%. In men, the prevalence of both moderate and severe deformities increased with age. In women, however, the prevalence of moderate vertebral deformities remained constant, opposite to a marked increase in severe deformities. Moderate vertebral deformity was significantly associated with impaired rising in men only. Severe vertebral deformity was associated with a significantly increased risk of general disability and the use of a walking aid in both men and women, impaired bending in men, and impaired rising in women. It is concluded that (1) vertebral deformities are only slightly less common in men than in women from the general population and (2) severe progression with age occurs in women only and (3) severe vertebral deformity is, particularly in men, related to functional impairment.

Correcting calcium nutritional deficiency prevents spine fractures in elderly women

We tested the spine antifracture and bone sparing efficacy of 1.2 g/day of oral calcium as carbonate in two groups of elderly women, one with prevalent fractures (PF, n = 94) on entry and the other without (NPF, n = 103). It was a prospective randomized, double-blind, placebo-controlled trial in mostly rural communities in women over age 60 who were living independently and were consuming < 1 g/day of calcium. We obtained annual lateral spine radiographs and semiannual forearm bone density over 4.3 +/- 1.1 years and determined vertebral fractures by radiographic morphometry augmented by physician assessment. In the PF group, 15 of 53 subjects on calcium had incident fractures, compared with 21 of 41 on placebo (p = 0.023, chi2). Calcium did not reduce the rate of incident fractures in the NPF group. Those with a prevalent fracture on entry and not treated with calcium were 2.8 times more likely to experience an incident fracture than all others. Change in the forearm bone mass on placebo in the PF group was -1.24 +/- 2.41%/year compared with +0.31 +/- 1.80%/year on calcium (p < 0.001). In the NPF group, the difference was less: -0.39 +/- 2.08%/year versus 0.00 +/- 1.64%/year (p = 0.2). We conclude that in elderly postmenopausal women with spine fractures and selfselected calcium intakes of < 1 g/day, a calcium supplement of 1.2 g/day reduces the incidence of spine fractures and halts measurable bone loss.

Fracture risk following bilateral oophorectomy

To assess fracture risk following bilateral oophorectomy, we conducted a population-based retrospective cohort study among the 463 Rochester, Minnesota women who underwent bilateral oophorectomy for benign ovarian conditions in 1950-1979. During 7220 person-years of observation, there appeared to be a modest increase in the risk of distal forearm fractures (standardized morbidity ratio [SMR] 1.4; 95% CI 1.0-2.0) and vertebral fractures (SMR 1.9; 95% CI 1.3-2.8) but not hip fractures (SMR] 1.1; 95% CI 0.6-1.9). Although our statistical power was quite limited, there was a suggestion that women who became estrogen deficient at a young age were at greater risk of fracture. However, the youngest women were more likely to be on estrogen replacement therapy, and for longer durations, so that the average age at the onset of estrogen deficiency in this population was 47 years.

Normal ranges for vertebral height ratios and prevalence of vertebral fracture in Hong Kong Chinese: a comparison with American Caucasians

We have established the normal ranges for vertebral height ratios and studied the prevalence of vertebral fracture in 481 Chinese women aged 70-79. Our results were compared with those of an American study with a similar methodology. Lateral spine radiographs centered at T8 and L3 were taken, and the anterior, middle, and posterior vertebral heights of each vertebra from T5 to L4 were measured. The means and standard deviations (SDs) of the anterior to posterior, middle to posterior, and posterior to posterior vertebral height ratios were derived after trimming the extreme values from the distribution. The Chinese had smaller vertebral size than the American Caucasians at all levels. Moreover, the anterior to posterior vertebral height ratios were consistently smaller in the Chinese than in the Americans from T10 onward. The means of other vertebral height ratios in the Chinese were similar to the American Caucasians, but the SDs were greater in the Chinese. The prevalence of vertebral fracture was 29% in the Chinese and 25% in the American Caucasians if a cut-off of 3 SD below the mean for vertebral height ratios was used. We conclude that population-specific means and SD should be used for defining vertebral fracture and that the prevalence of vertebral fracture is similar in Hong Kong Chinese and American Caucasians.

The prevalence of vertebral deformity in european men and women: the European Vertebral Osteoporosis Study

Our aim was to determine the prevalence of radiographically defined vertebral deformity, as a marker of vertebral osteoporosis, in different regions and populations within Europe. We used a cross-sectional population-based survey. Population-based sampling frames were obtained from 36 centers in 19 European countries. Stratified random sampling was used to recruit 15,570 males and females aged 50-79 years. Lateral spinal radiographs were taken according to a standardized protocol, and all X-rays were evaluated centrally. Vertebral deformity was morphometrically defined according to the published methods of McCloskey and Eastell. Based on the McCloskey method, the mean center prevalence of all deformities was 12% in females (range 6-21%) and 12% in males (range 8-20%). The prevalence increased with age in both sexes though the gradient was steeper in females. There was substantial geographical variation, with the highest rates in Scandinavian countries. Radiographically defined vertebral deformity is a common disorder and equally frequent in males and females. Using standardized methodology, there is important variation in occurrence across Europe, which might suggest clues to pathogenesis.

Comparison of semiquantitative visual and quantitative morphometric assessment of prevalent and incident vertebral fractures in osteoporosis The Study of Osteoporotic Fractures Research Group

The assessment of radiographs for vertebral fractures is important in the clinical evaluation of patients with suspected osteoporosis, in the epidemiological evaluation of elderly populations, and in clinical trials of osteotrophic drugs. The purpose of this study is to compare visual semiquantitative (SQ) approaches and quantitative morphometric approaches for assessing prevalent and incident vertebral fractures in postmenopausal osteoporosis. We analyzed lateral thoracolumbar spine radiographs (baseline and approximately 3.5 year follow-up) of 503 women (age > or = 65) randomly selected from the Study of Osteoporotic Fractures (SOF) population. SQ assessment by an experienced radiologist graded vertebral fractures from 0 (normal) to 3 (severe). Incident fractures by SQ were defined as an increase of > or = 1 grade on follow-up radiographs. Trained research assistants visually triaged women as normal, uncertain, or probably fractured and visually flagged vertebrae with moderate/severe (grade > or = 2) prevalent fractures or with any (grade > or = 1 change) incident fracture. The radiographs were also digitized by research assistants, and quantitative morphometry (QM) was used to classify vertebral deformities at several cut-offs based on standard deviation (SD) reductions in height ratios from normal means, e.g., QM > or = 3 SD. Incident fractures by QM were defined as a decrease in height of more than 15% (QM15) on follow-up radiographs. Finally, a combination of these methods was used to detect moderate/severe prevalent fractures and any grade of incident fractures. In the overall analysis, the prevalence of fractures varied from 14 to 33% and the incidence from 5 to 10% by woman, depending upon the method and cut-off criteria. In the detailed analysis, considering visually triaged uncertain as abnormal, triage by research assistants detected 97.0% (163/168) of women with SQ grade > or = 1 fractures and 100% (70/70) with SQ grade > or = 2 fractures. Visual flagging by research assistants detected 88.5% (108/122) of SQ > or = 2 prevalent fractures (kappa score, kappa = 0.82) and 85.2% (52/61) of SQ incident fractures (kappa = 0.79). QM > or = 3 SD detected 37.9% (141/372) of SQ > or = 1 prevalent fractures (kappa = 0.51) and 79.5% (97/122) of SQ > or = 2 prevalent fractures (kappa = 0.68), plus 18 vertebrae without SQ fractures. QM 15 detected 59% (36/61) of SQ incident fractures (kappa = 0.70), plus five vertebrae without SQ incident fractures. The combination assessment detected 92% (112/122) of SQ > or = 2 prevalent fractures (kappa = 0.76) and 84% (51/61) of SQ incident fractures (kappa = 0.91). The precision errors of QM vertebral height measurements (baseline versus follow-up) ranged from 2.71 to 2.92%. Nevertheless, excluding the 5719 vertebrae that were clearly normal by morphometry, i.e., within 2 SD of the normal means at both baseline and follow-up, two-thirds (358/556) of the remaining vertebrae changed classification by at least 1 SD category. Visual triage and visual flagging by research assistants appear to be highly effective methods for vertebral fracture assessment in osteoporosis, potentially reducing the number of false-positive and false-negative fractures detected by QM, at least relative to SQ by the radiologists. There is higher concordance among the visual approaches studied than between the visual SQ and quantitative morphometric approaches, with QM having limited ability to detect mild fractures but good ability to detect moderate/severe fractures, as classified by SQ. Use of a combination of sensitive qualitative and quantitative criteria, with adjudication by an experienced radiologist, is feasible and draws upon the relative strengths of each of the methods. Quantitative morphometry should not be performed in isolation, particularly when applying highly sensitive morphometric criteria at low threshold levels, without visual assessment to confirm the detected prevalent or incident vertebral defor

Quantitation of incident spinal fractures: comparison of visual detection with quantitative morphometry

The value of quantitative morphometry in detection of new spinal fractures was assessed in serial radiographs from 83 patients with osteoporosis. From vertebral landmarks on lateral spine radiographs, a computer program allowed calculation of vertebral heights and area. By comparing vertebral dimensions in the two sets of films, incident spinal fractures could be quantitated based either on the minimum criteria of 15% reduction in vertebral height (CM2) or a fall in height and area of 20% and 10% (CM1). The results of quantitative morphometry were compared with those of the consensus and individual readings of visual detection by three experienced investigators in the same paired sets of spinal films. For incident new fractures, the visual consensus method (V-C) showed a very good agreement with individual visual detection (kappa of 0.794 to 0.916) as well as with CM1 (kappa of 0.821). However, there was a poor agreement between the results of consensus reading and of detection by CM2 (kappa of 0.341), due to excessive number of fractures identified by CM2, but not by the visual method. For incident recurrent fractures, there was a poor agreement between V-C and individual visual detection, and between V-C and quantitative morphometry (kappa of 0.306 to 0.496). It was due to severe compression fractures at baseline, which caused further changes in vertebral dimensions difficult to measure accurately by either visual or quantitative morphometry. Thus, if the visual detection of fractures by a consensus of experienced investigators is considered as the "gold standard," quantitative morphometry, based on minimum reduction in vertebral height of 20% accompanied by a minimum decline in area of 10%, provides an objective detection of incident new spinal fractures but not of recurrent fractures.

What is a vertebral fracture?

Vertebral deformities may be caused by a variety of conditions, such as osteoporosis, severe trauma, congenital deformities, Scheuermann's disease, osteoarthritis, and multiple myeloma. For the individual patient, the correct diagnosis of an osteoporotic fracture is a prerequisite for the choice of optimal treatment and will be ensured by careful differential diagnosis based on a spinal radiograph and additional diagnostic procedures. Evaluation of radiographs by experienced radiologists is crucial for the correct diagnosis of vertebral fractures. For clinical trials and epidemiological studies of osteoporosis, qualitative radiological evaluation of radiographs has proven to be insufficient, since results lack reproducibility. Therefore, objective morphometric methods based on vertebral height measurements have been developed for fracture identification and quantification in scientific settings. Satisfactory sensitivity of these methods is usually reached at the expense of specificity, leading to a high number of false positives. With some differences in methodology, most of the morphometric approaches are of comparable validity. However, none of the morphometric methods allows any subclassification of vertebral deformities with respect to etiology. A combined approach based on morphometry as well as standardized radiological evaluation by experts appears to be the most promising solution to the problem. Further efforts are needed to standardize radiological criteria to yield comparable results between individual readers and different studies. It has to be evaluated whether the combined approach (clinical reading and morphometry) is necessary during follow-up evaluation, as morphometry may be sufficient for monitoring once the diagnosis has been established at baseline.

Vertebral fracture epidemiology

Vertebral fractures are the most common but least understood of all osteoporotic fractures. Their study has been hampered by the lack of a common morphometric definition, and the fact that many vertebral fractures are asymptomatic and not clinically evident. Population-based radiographic surveys are therefore required for comparative studies. Risk factors fall into five major categories: (1) age, or age-related, (2) genetic, (3) environmental, (40 endogenous hormones or chronic diseases, and (5) physical characteristics of bone. Bone density is the most clinically useful risk factor, particularly for purposes of prevention. Because vertebral fracture prevalence parallels levels of bone density, bone density is also useful for epidemiological surveys. Based on WHO diagnostic criteria, 54% of postmenopausal white women in the United States have osteopenia, and another 30% have osteoporosis. Existing fractures are also strong, independent predictors of future vertebral fracture risk, but also represent a later, and less treatable, stage of the disease.

Vertebral deformity in the thoracic spine in post-menopausal women: value of lumbar spine bone density

Differential bone loss in the thoracic and lumbar spine is known to occur in some patients with osteoporosis. However, the discriminant value of lumbar spine bone densitometry in the detection of thoracic spine fractures in healthy, population-based women has not been established. The relationship between lumbar spine bone mineral density and thoracic spine vertebral deformities in a prospective study of 79 post-menopausal population-based women aged 45-65 years has been investigated. Lumbar spine bone mineral density was measured using dual energy X-ray absorptiometry, and vertebral morphometry was assessed from lateral thoracic spine radiographs. Seven women (9%) were found to have one or more vertebral deformities in the thoracic spine (reduction in anterior or posterior height > 25%). Only one of these had a lumbar spine bone mineral density T score below -2.5, whilst the T score was between -1 and -2.5 in three and greater than -1 in three. Two of these women also had lumbar spine vertebral deformity but lumbar spine radiographs were normal in the remaining five. There were no significant differences in age, height, weight, hormone replacement therapy use or bone mineral density between women with and without thoracic spine fractures. These results demonstrate that vertebral deformities in the thoracic spine occur in a proportion of healthy post-menopausal women in the absence of densitometric or radiographic evidence of osteoporosis in the lumbar spine. Although often asymptomatic, the significance of these fractures lies in the increased risk of further fractures. In the future, morphometric X-ray absorptiometric techniques may prove valuable in the detection of these fractures and avoid the need for conventional radiography.

Prevalence and severity of vertebral fracture: the Saunders County Bone Quality Study

Vertebral fracture prevalence and severity were analyzed by sex and age in an age-stratified proportionate sample of the enumerated population of women and men 50 years of age and older in Saunders County, Nebraska. The sample consisted of 899 women and 529 men. Of these, all but 10 women and 2 men had readable lateral spine radiographs. For both sexes, fracture prevalence rises with age. Women in their fifties have 10% vertebral fracture prevalence, and women in their eighties, 45% prevalence. Men in their fifties have 29% prevalence, and men in their eighties, 39% prevalence. The rise in prevalence and total spinal deformity with age is much greater for women than for men, but the prevalence of vertebral deformity in the fifties is much greater in men than in women.

Aging changes in vertebral morphometry

We analyzed the vertebral morphometry of healthy premenopausal women and their changes with age and menopause in order to better define the reference population for the clinical and epidemiological evaluation of vertebral fractures. Vertebral morphometry has been performed on lateral thoracic and lumbar spine films from 50 premenopausal and 76 postmenopausal normal women, age range 39-74 years. Vertebral heights and the anterior height/posterior height ratio are significantly lower in postmenopausal compared with premenopausal women. Vertebral anterior height decreases about 1.5 mm/year, whereas middle and posterior height decreases about 1.3 and 1.2/mm year, respectively. A statistically significant reduction of vertebral heights by around 1 mm/vertebra was observed in postmenopausal (n = 16) compared with premenopausal women (n = 20) of the same age (P < 0.05). The results demonstrate that vertebral heights are lower with advancing age and menopause and that the vertebral heights difference in elderly people is not only the consequence of a cohort effect. The results also contribute to better defining the reference population to be chosen for evaluating vertebral deformation.

Effect of oral alendronate on bone mineral density and the incidence of fractures in postmenopausal osteoporosis. The Alendronate Phase III Osteoporosis Treatment Study Group

BACKGROUND

Postmenopausal osteoporosis is a serious health problem, and additional treatments are needed.

METHODS

We studied the effects of oral alendronate, an aminobisphosphonate, on bone mineral density and the incidence of fractures and height loss in 994 women with postmenopausal osteoporosis. The women were treated with placebo or alendronate (5 or 10 mg daily for three years, or 20 mg for two years followed by 5 mg for one year); all the women received 500 mg of calcium daily. Bone mineral density was measured by dual-energy x-ray absorptiometry. The occurrence of new vertebral fractures and the progression of vertebral deformities were determined by an analysis of digitized radiographs, and loss of height was determined by sequential height measurements.

RESULTS

The women receiving alendronate had significant, progressive increases in bone mineral density at all skeletal sites, whereas those receiving placebo had decreases in bone mineral density. At three years, the mean (+/- SE) differences in bone mineral density between the women receiving 10 mg of alendronate daily and those receiving placebo were 8.8 +/- 0.4 percent in the spine, 5.9 +/- 0.5 percent in the femoral neck, 7.8 +/- 0.6 percent in the trochanter, and 2.5 +/- 0.3 percent in the total body (P < 0.001 for all comparisons). The 5-mg dose was less effective than the 10-mg dose, and the regimen of 20 mg followed by 5 mg was similar in efficacy to the 10-mg dose. Overall, treatment with alendronate was associated with a 48 percent reduction in the proportion of women with new vertebral fractures (3.2 percent, vs. 6.2 percent in the placebo group; P = 0.03), a decreased progression of vertebral deformities (33 percent, vs. 41 percent in the placebo group; P = 0.028), and a reduced loss of height (P = 0.005) and was well tolerated.

CONCLUSIONS

Daily treatment with alendronate progressively increases the bone mass in the spine, hip, and total body and reduces the incidence of vertebral fractures, the progression of vertebral deformities, and height loss in postmenopausal women with osteoporosis.

The natural history of kyphosis in postmenopausal women

A cross-sectional study of vertebral morphometry in 449 unscreened postmenopausal women, from the ages of 40 to 80, is reported. The wedge angles of thoracic vertebrae T4-12 were found to increase exponentially as a function of age, up to 70 years. In addition to age, the wedging phenomenon was found to be accentuated by increased bone turnover due to low calcium intake, reduced physical activity, each successive delivery, and breast feeding. Most of these variables were not correlated with isolated vertebral wedge angles, but rather with the sum of them (Sigma, sigma), assumed to assess the impact of those variables on thoracic kyphosis. In a subset of women, sigma was found to be inversely correlated with low spinal mineral density at L2-4. T-11 and T-12 were the vertebrae most frequently deformed (wedge angle exceeding mean +/- 3 SD in a group of 50 young healthy women, 25-45 years old). The distribution of deformed vertebrae was found to be significantly different from those qualified as "fractured" according to Kleerekoper et al.'s (1984) and Melton et al.'s (1989) criteria. The overall information afforded by past and present data indicates that in postmenopausal women, vertebral deformation may occur with the help of mechanical solicitations plus high bone remodeling rates, as well as by structural collapse (fracture). The information obtained does not allow one to quantify the relative contribution of each set of factors to the wedging phenomenon.

Osteoporosis

Two complementary notions need to be considered in the definition of osteoporosis: a reduction in bone mineral density and the occurrence of fracture. Bone mineral density is an established determinant of the risk of future fracture, but current interventions are most usefully targeted before bone density has fallen to the levels at which fractures usually occur. Bone density may now be measured accurately and precisely, and the sensitivity and specificity of this technology for fracture risk prediction are high. It therefore seems reasonable to classify osteoporosis in terms of both a reduction in bone density and the occurrence of fracture. On this basis, a four point scale has recently been proposed by the World Health Organization: 1) normal, 2) low bone mass, 3) osteoporosis and 4) established osteoporosis. While it is likely that this diagnostic classification will change as experience of osteoporosis increases, it is important to have widely adopted guidelines of this type which act as a framework for further research.

Efficacy of treatment of osteoporotic fractures

The efficacy of osteoporosis therapy can be considered at several different levels, ranging from the overall community to the individual patient. Efficacy has different connotations for each group within the community and for the individual, in whom life expectancy--among other parameters--is an important consideration. Some of the questions addressed in this article are the scope of the osteoporosis problem, how many people must be treated for prevention of one further fracture, whether there is a role for targeting likely high risk/high response groups, and what exactly is a successful outcome. Clearly, there are no ideal therapies as yet for osteoporosis, in the context of either prevention or treatment. Moreover, most studies have been performed in selected groups within the community, and the extrapolation to wider clinical subsets is not straightforward. For example, data are almost nonexistent for men or premenopausal women; also it is not clear whether studies on carefully selected healthy elderly women can be simply extrapolated to their less healthy cohorts. Similarly, studies using vertebral deformities as the primary endpoint may be difficult to relate to symptomatic vertebral fractures, and other peripheral fractures including proximal femur. Lastly, the efficacy of some treatments must be related to the risk of further fractures. Thus, many years of therapy may relate to prevention of perhaps only one symptomatic event, with equivocal cost-benefit for the individual. As new therapies are under development, these questions need to be addressed for the efficacy of osteoporosis therapy to be considered.

Variation in vertebral height ratios in population studies. European Vertebral Osteoporosis Study Group

Vertebral height ratios are used to define vertebral deformity in clinical and epidemiologic studies of vertebral osteoporosis. However, few data have been obtained on the variation in these ratios in different populations using standard methods. We examined vertebral morphometric measurements obtained in a population survey from three centers: Malmö (Sweden), Montceau-les-Mines (France), and Graz (Austria), to study the influence of sex and the population center on vertebral height ratios. Radiographs were obtained according to a standardized protocol, and morphometric measurements, anterior height Ha, central height Hc, and posterior height Hp, made in Berlin. The height ratios anterior, Ha/Hp, central, Hc/Hp, posterior I, Hp/Hp', and posterior II, Hp/Hp" (Hp' = posterior height of vertebrae above, Hp" = posterior height of vertebrae below) were calculated for each vertebra from T4 to L4. The mean and standard deviation of these ratios for each sex and each center were derived using a statistical trimming procedure to normalize the distribution. Threshold values for defining grade 1 and grade 2 deformities, wedge, biconcavity, and compression, were calculated using these parameters. Anterior and central vertebral height ratios were smaller in males than females (p < 0.01). There were significant differences between the three centers (p < 0.01) both in the trimmed mean values for anterior and central vertebral height ratios and in the thresholds derived using standard criteria for defining wedge and biconcavity deformity. The data confirm the impression from single-center studies that vertebral height ratios vary between populations and suggest that reference values for vertebral height ratios should be derived separately for males and females within individual populations whenever possible.

Assessment of fracture risk and its application to screening for postmenopausal osteoporosis: synopsis of a WHO report. WHO Study Group

The criteria required for an effective screening strategy for osteoporosis are largely met in Caucasian women. The disease is common and readily diagnosed by the measurement of bone mineral with single- or dual-energy absorptiometry. Such measurements have high specificity but lower sensitivity, so that the value of the technique is greater for those identified as being at higher risk. Against this background there is little evidence that osteoporosis can usefully be tackled by a public health policy to influence risk factors such as smoking, exercise and nutrition. This suggests that it is appropriate to consider targetting of treatment with agents affecting bone metabolism to susceptible individuals. Since the main benefits of the use of hormone replacement therapy (HRT) are probably on cardiovascular morbidity, the major role for selective screening is to direct non-HRT interventions. An appropriate time to consider screening and intervention is at the menopause, but screening at later ages is also worthy of consideration. Since the cost of screening is low and that of bone-active drugs is high, the selective use of screening techniques will improve the cost-benefit ratio of intervention.

Quantification of overload injuries to thoracolumbar vertebrae and discs in persons exposed to heavy physical exertions or vibration at the work-place The shape of vertebrae and intervertebral discs - study of a young, healthy population and a middle-aged control group

The ongoing search for causes (and strategies for prevention) of low back trouble in sub-groups of the population exposed to heavy physical exertions or whole body vibration requires reliable data on the prevalence of lower-spine overload damage. Because published reports on this topic are rare and mostly qualitative, the present study was initiated to assess, objectively and quantitatively, overload damage to vertebrae and intervertebral discs. Part I of the work has involved the establishment of a normative database of shape parameters from measurements of 683 (539 male, 144 female) lateral radiographic views of the thoracolumbar spine of young (17-30 years), healthy subjects. In addition, age-related shape alterations were explored from measurements of 364 male middle-aged (31-57 years), non-exposed controls. Advanced methods for shape analysis and shape parameter construction were required, and duly developed, in order to minimise the influence of confounding factors such as radiographic magnification, image distortion, axial rotation or lateral tilt. The results revealed that the variation in shape parameters varies between 2% and 10% within the group of normals (this being largely biological variability as opposed to measurement error). Within this normal group subtle but statistically significant differences due to gender and geographic origin were observed. Comparison of the normals with the controls revealed only slight, but clearly demonstrable differences. The narrow range of 'normal shape' together with the high accuracy of shape analysis are the foundation for Part II of this study which will involve a comparison of exposed cohorts with the normal standard (adjusted for ageing effects). This will, for the first time, enable objective quantification of the prevalence of overload damage to the spines of persons exposed to heavy physical stresses and whole body vibration, and thus form the basis of a scientific rationale for recommendation of safety guidelines.

The epidemiology of vertebral fractures. European Vertebral Osteoporosis Study Group

Vertebral fractures are recognised as a hallmark of osteoporosis, yet little is known of their epidemiology. This deficiency limits accurate characterisation of the public health importance of osteoporosis. Assessment of the impact of vertebral fractures has been hampered by the absence of formal criteria for identifying fractures on a thoracolumbar radiograph. Initial methods relying upon subjective radiological assessments have given way to morphometric measurements of vertebral heights, with deformities defined according to various algorithms. These methods have been used in a series of studies performed in Rochester, MN, to determine the incidence, outcome, and time trends of vertebral deformities. The results suggest a prevalence rate of vertebral deformity of 25.3 per 100 Rochester women aged 50 years and over (95% CI, 22.3-28.2), with an estimated incidence of 17.8 per 1,000 person-years. The incidence of clinically diagnosed vertebral fractures among women in the same population was 5.3 per 1,000 person-years, suggesting that around 30% of such deformities in women receive clinical attention. Morphometric measurement on the radiographs of women with clinically diagnosed fractures revealed that 80% had grade 2 ( > 4 SD) deformities. Comparable data on the occurrence and health impact of vertebral deformities throughout Europe are urgently required. The European Vertebral Osteoporosis Study (EVOS) is a multicentre epidemiological study that aims to address this issue. It is designed as a radiographic prevalence study in 34 European centres.(ABSTRACT TRUNCATED AT 250 WORDS)