Epidemiology of osteoporosis in women in southern Italy.

Studies on the distribution of bone mineral density (BMD) values in different age groups and in different populations are valuable for understanding the causes of the appreciable geographical variability in fracture incidence. We studied a population of southern Italy in an area where the incidence of hip fracture had been previously estimated. With a completion rate of 85%, we recruited a group of 264 women between 45 and 79 years of age, representative of non-institutionalized and active women in the population, and measured bone density both at the lumbar spine (L1-L4) and at the right femoral neck using a dual X-ray absorptiometry (DEXA) system. We report the age group distribution of BMD in this population. The elderly showed higher mineralization, as compared to an international pooled sample. The prevalence of osteoporosis among women of 50-79 years of age was 40%; the rate changed according to the measurement site. Our results show that a large proportion of women would not have been diagnosed as having osteoporosis if we had relied on a single measurement site. A very low percentage of cases (as low as 4% in the 50-59 years age group) was diagnosed at both sites. The lack of concordance in BMD estimate between measurement sites is significant at younger ages, with an almost dichotomous distribution of cases diagnosed either at the lumbar or femoral site, suggesting the hypothesis that distinct patterns of bone involvement and bone mass lowering exist and all eventually lead to systemic involvement. Longitudinal follow-up of this population should help address some of the questions raised by these results.

Determinants of bone mineral density in immobilization: a study on hemiplegic patients.

Osteoporosis that develops during immobilization is a severe condition that confers increased risk of fractures with their burden of mortality and disability. The aim of this study was to investigate the determinants of immobilization osteoporosis. As a model of this condition we studied hemiplegic subjects, measuring bone mineral density in the paralyzed lower limb as compared with the non-paralyzed one. In spite of the limits related to the loss of nervous stimulation, this model offers the advantage of a proper control for the complex genetic and environmental cofactors involved. We examined 48 hemiplegic subjects (31 men, 17 women in menopause) admitted consecutively over a 9-month period. Mean length immobilization was 10.9 months for men (range 1-48 months) and 7.8 months for women (range 1-40 months). The average time since menopause was 14.9 years (range 1.7-23.9 years). For each subject the following were performed: questionnaire, medical examination, anthropometric measurements, evaluation of the scores for spasticity and for lower limb motor capacity in order to account for the different degrees of disability among patients. Bone mineral density was measured using dual-energy X-ray absorptiometry (DXA) at both femoral necks. For each patient we defined a percentage difference in bone loss between the paralyzed and non-paralyzed limb. Regression coefficient were calculated by multiple logistic regression. There was significant bone loss in the paralyzed limb in both sexes, accounting for up to 6.3% in women. Multiple regression analysis showed that the degree of bone loss depends significantly and directly on the length of immobilization, even when controlling for age and sex in the regression model (R = 0.193, p = 0.034). However, when time since menopause was included in the regression model, with length of immobility as a covariate, it was the only significant determinant of bone loss (R = 0.312, p = 0.039). No additional factors were observed among men. No differences were shown with regard to anthropometric measurements or functional scores. Length of immobilization accounts only for a small fraction of bone loss, which does not exceed 5% of the total variance. Our data show that postmenopausal women should be considered at highest risk for osteoporosis in cases of immobility and that different factors, other than length of immobility, might come into play in determining bone loss in this condition.

[The extremely low incidence of proximal femoral fractures due to osteoporosis in the population on the island of Ischia]. / Rilievo di un'incidenza estremamente bassa di fratture del femore prossimale da osteoporosi nella popolazione dell'isola di Ischia.

We present the raw data from a study done on the incidence of osteoporotic hip fractures on Ischia, an island facing the Bay of Naples. Its 43,975 inhabitants form a well-defined, stable and homogeneous population. Since no air transportation to the mainland is available for residents, acute health care is provided by the sole local hospital. We carried out a discharge data survey by reviewing the hospital medical records from 1980-1989. During that decade, 148 residents (111 women, 37 men) had new hip fractures. The age-sex adjusted incidence for the population aged 50 years or more was 170.3 cases/100,000/year [95% confidence interval (CI) = 144.8-195.9] (women = 241.4 with 95% CI = 211.0-271.9; men = 79.4 with 95% CI = 62.0-96.9). Age-specific rates increased with age and were higher among women only over 60 years old. On the basis of the 1981 census and comparison of age-adjusted rates, we determined that incidence rates of these fractures for men and women on Ischia are among the lowest in the world: Ischian men have a hip fracture incidence second only to that of South African Bantu males. The female/male ratio on the island, one of the highest reported, is 3.05:1. Our data suggest that further studies on Ischia may provide important clues regarding risk and/or protective factors for hip fracture.

[The determinants of bone mineral density in hemiplegic patients. Preliminary data]. / Determinanti della densità minerale ossea in pazienti emiplegici. Dati preliminari.

We studied a group of hemiplegic patients to determine the amount of bone loss of the paretic versus the normal limb and to evaluate the importance of several variables in determining this difference. Thirty consecutive subjects with hemiplegia caused by a cerebral vascular accident were studied: 15 postmenopausal women (average age 65.1 years) and 15 men (average age 58.3 years) (average age of entire group, 63.2 years; age range of entire group, 27-84 years). The mean duration of immobilization was 7.7 months for women (range 1-40 months) and 10.5 months for men (range 1-48 months). All subjects had a complete physical examination, underwent bilateral femoral neck DEXA, and filled out a questionnaire. The percent difference (delta) between the paretic and normal limb was 6.1% in the women and 3.8% in the men. Logistic regression analysis, after control for age and sex, indicated that the degree of demineralization depended significantly and directly on the duration of immobilization and depended inversely on the time elapsed since menopause. Our data evidence the importance of immobilization osteoporosis and point to the role of hormonal factors in its pathogenesis.