Establishment of normative biometric data for body composition based on computed tomography in a North American cohort

BACKGROUND & AIMS

Accurate and reproducible biomarkers are required to allow a more personalized approach to patient care. Body composition is one such biomarker affecting outcomes in a range of surgical and oncological conditions. The aim of this study is to determine the age and sex specific distribution of body composition data, based on information gathered from computed tomography (CT).

METHODS

This prospective study used healthy subjects from the medical records linkage of the Rochester Epidemiology Project, based in Minnesota, USA. Each patient had a CT scan without intravenous contrast performed between 1999 and 2001. Quantification was performed using previously validated semi-automated in-house developed software for body composition analysis. Subcutaneous adipose tissue area, visceral adipose tissue area, intermuscular adipose tissue area and skeletal muscle area were measured and indexed to subject height. Generalized Additive Models for Location, Scale and Shape were used to assess the location, scale, and shape of each variable across age, stratified by sex. Z-scores specific to sex were assessed for each of the parameters analyzed. Age-specific z-scores were calculated using the formula: Z = (Index Variable - μ)/σ or Z = (√ (Index Variable) - μ)/σ.

RESULTS

There were 692 subjects enrolled in the study. The fitted model equation was offered for each variable with values presented for μ and σ. Modelling with penalized splines was performed for VAT index, IMAT index and total adipose tissue index. Scatterplots of each variable were produced with lines of Z-scores as a visual representation.

CONCLUSION

This study offers comparative data to allow comparison amongst multiple populations. This will form an important reference for future research and clinical practice.

Hip load capacity and yield load in men and women of all ages

Quantitative computed tomography (QCT) based finite element (FE) models can compute subject-specific proximal femoral strengths, or fracture loads, that are associated with hip fracture risk. These fracture loads are more strongly associated with measured fracture loads than are DXA and QCT measures and are predictive of hip fracture independently of DXA bone mineral density (BMD). However, interpreting FE-computed fracture loads of younger subjects for the purpose of evaluating hip fracture risk in old age is challenging due to limited reference data. The goal of this study was to address this issue by providing reference data for male and female adult subjects of all ages. QCT-based FE models of the left proximal femur of 216 women and 181 men, age 27 to 90 years, from a cohort of Rochester, MN residents were used to compute proximal femoral load capacities, i.e. the maximum loads that can be supported, in single-limb stance and posterolateral fall loading (Stance_LC and Fall_LC, respectively) [US Patent No. 9,245,069] and yield load under fall loading (Fall_yield). To relate these measures to information about hip fracture, the CT scanner and calibration phantom were cross-calibrated with those from our previous prospective study of hip fracture in older fracture and control subjects, the Age Gene/Environment Susceptibility (AGES) Reykjavik cohort. We then plotted Stance_LC_, Fall_LC and Fall_yield versus age for the two cohorts on the same graphs. Thus, proximal femoral strengths in individuals above 70 years of age can be assessed through direct comparison with the FE data from the AGES cohort which were analyzed using identical methods. To evaluate younger individuals, reductions in Stance_LC, Fall_LC and Fall_yield from the time of evaluation to age 70 years can be cautiously estimated from the average yearly cross-sectional decreases found in this study (108 N, 19.4 N and 14.4 N, respectively, in men and 120 N, 19.4 N and 21.6 N, respectively, in women), and the projected fracture loads can be compared with data from the AGES cohort. Although we did not set specific thresholds for identifying individuals at risk of hip fracture, these data provide some guidance and may be used to help establish diagnostic criteria in future. Additionally, given that these data were nearly entirely from Caucasian subjects, future research involving subjects of other races/ethnicities is necessary.

Quantifying Rome symptoms for diagnosis of the irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, diagnosed on symptom-based criteria. Many have reported discrepancies between formal Rome criteria and diagnoses made in clinical practice. The aim of the study was to explore whether a quantitative version of the Rome criteria would better represent a clinical diagnosis of IBS than the current dichotomous criteria for symptom measure.

METHODS

As part of a large, case-control study, participants completed a validated bowel disease questionnaire. Rome criteria were analyzed based on 15 individual symptoms. Penalized logistic regression model with stepwise selection was used to identify significant symptoms of IBS which were independently associated with case-control status.

KEY RESULTS

In cases with a clinical diagnosis of IBS, 347 (70%) met Rome criteria for IBS. Increasing number of Rome symptoms were found related to the odds of being diagnosed with IBS. Nearly half of the Rome-negative case group experienced infrequent symptoms suggesting milder disease. Five of 15 Rome symptoms were associated with predicting case-control status in the final model, with 96% correctly classified among Rome-positive cases, 76% for Rome-negative cases, and 91% for controls.

CONCLUSIONS AND INFERENCES

Irritable bowel syndrome appears to be a spectrum disorder. Quantifying individual symptoms of Rome criteria has greater utility than the current application in representing the degree of IBS affectedness and appears to better reflect a clinical diagnosis of IBS applied by physicians. The use of a quantitative diagnostic Rome "score" may be helpful in clinical practice and research studies to better reflect the degree an individual is affected with IBS.

A comprehensive assessment of environmental exposures among 1000 North American patients with primary sclerosing cholangitis, with and without inflammatory bowel disease

BACKGROUND

The relationships between primary sclerosing cholangitis (PSC) and the environment are largely unknown.

AIM

To validate associations reported in previous studies and to identify novel environmental exposures among PSC patients.

METHODS

We performed a multicenter, case-control analysis utilising self-administered questionnaires. Responses between cases (n = 1000) and controls (n = 663) were compared using multivariable logistic regression adjusted for age and gender. The model was further stratified based on inflammatory bowel disease (IBD) status (with IBD n = 741 without IBD n = 259).

RESULTS

Smoking was associated with PSC only when IBD was present (OR, 0.5; 95% CI 0.4-0.7) but not among those PSC patients without IBD (OR, 0.9; 95% CI 0.7-1.2). Compared to controls, women with PSC (irrespective of the presence of IBD) were less likely to have received hormone replacement therapy (HRT; OR, 0.5; 95% CI 0.4-0.7) and were more likely to have recurrent urinary tract infections (OR, 1.6; 95% CI 1.2-2.3). PSC patients regardless of gender or IBD status were less likely to eat fish (OR, 0.4; 95% CI 0.3-0.6) and grilled/barbecued meat (OR, 0.8; 95% CI 0.7-0.9). In contrast, PSC patients with and without IBD were more likely to consume steak/burgers that were more well done (OR, 1.3; 95% CI 1.2-1.5).

CONCLUSIONS

IBD (rather than PSC) is associated with smoking. Women with PSC are more likely to have recurrent urinary tract infections and less likely to receive HRT. Dietary intake and methods of food preparation differ in PSC patients when compared to controls.

Isolation and characterization of human osteoblasts from needle biopsies without in vitro culture

SUMMARY

We isolate and characterize osteoblasts from humans without in vitro culture. These techniques should be broadly applicable to studying the pathogenesis of osteoporosis and other bone disorders.

INTRODUCTION

There is currently no data regarding the expression of specific genes or pathways in human osteoblasts that have not been subjected to extensive in vitro culture. Thus, we developed methods to rapidly isolate progressively enriched osteoblast populations from humans and characterized these cells.

METHODS

Needle bone biopsies of the posterior iliac crest were subjected to sequential collagenase digests. The cells from the second digest were stained with an alkaline phosphatase (AP) antibody, and the AP+ cells were isolated using magnetic cell sorting.

RESULTS

Relative to AP- cells, the AP+ cells contained virtually all of the mineralizing cells and were enriched for key osteoblast marker genes. The AP+ cells were further purified by depletion of cells expressing CD45, CD34, or CD31 (AP+/CD45/34/31- cells), which represented a highly enriched human osteoblast population devoid of hematopoietic/endothelial cells. These cells expressed osteoblast marker genes but very low to undetectable levels of SOST. We next used high-throughput RNA sequencing to compare the transcriptome of the AP+/CD45/34/31- cells to human fibroblasts and identified genes and pathways expressed only in human osteoblasts in vivo, but not in fibroblasts, including 448 genes unique to human osteoblasts.

CONCLUSIONS

We provide a detailed characterization of highly enriched human osteoblast populations without in vitro culture. These techniques should be broadly applicable to studying the pathogenesis of osteoporosis and other bone disorders.

Fracture risk following bariatric surgery: a population-based study

The effects of bariatric surgery on skeletal health are poorly understood. We found that bariatric surgery patients are more prone to fracture when compared to the general population. While further studies of fracture risk in this population are needed, bone health should be discussed in bariatric surgery clinics.

INTRODUCTION

Bariatric surgery is an increasingly common treatment for medically complicated obesity. Adverse skeletal changes after bariatric surgery have been reported, but their clinical importance remains unknown. We hypothesized that bariatric surgery patients are at increased risk of fracture.

METHODS

We conducted a historical cohort study of fracture incidence among 258 Olmsted County, Minnesota, residents who underwent a first bariatric surgery in 1985-2004. Relative fracture risk was expressed as standardized incidence ratios (SIRs), while potential risk factors were evaluated by hazard ratios (HR) obtained from a time-to-fracture regression model.

RESULTS

The mean (±SD) body mass index at bariatric surgery was 49.0 ± 8.4 kg/m(2), with an average age of 44 ± 10 years and 82% (212) females. Gastric bypass surgery was performed in 94% of cases. Median follow-up was 7.7 years (range, 6 days to 25 years), during which 79 subjects experienced 132 fractures. Relative risk for any fracture was increased 2.3-fold (95% confidence interval (CI), 1.8-2.8) and was elevated for a first fracture at the hip, spine, wrist, or humerus (SIR, 1.9; 95% CI, 1.1-2.9), as well as for a first fracture at any other site (SIR, 2.5; 95% CI, 2.0-3.2). Better preoperative activity status was associated with a lower age-adjusted risk (HR, 0.4; 95% CI, 0.2-0.8) while prior fracture history was not associated with postoperative fracture risk.

CONCLUSIONS

Bariatric surgery, which is accompanied by substantial biochemical, hormonal, and mechanical changes, is associated with an increased risk of fracture.

Long-term mortality following fractures at different skeletal sites: a population-based cohort study

Adjusting for age, sex, and precipitating cause, the relative risk of death was increased following fractures at most skeletal sites.

INTRODUCTION

This study aims to determine long-term survival following fractures due to any cause at each skeletal site.

METHODS

In a historical cohort study, 2,901 Olmsted County, MN, USA, residents ≥35 years old who experienced any fracture in 1989-1991 were followed passively for up to 22 years for death from any cause. Standardized mortality ratios (SMRs) compared observed to expected deaths.

RESULTS

During 38,818 person-years of follow-up, 1,420 deaths were observed when 1,191 were expected (SMR, 1.2; 95 % CI, 1.1-1.3). The overall SMR was greatest soon after fracture, especially among the men, but remained elevated for over a decade thereafter. Adjusting for age and sex, relative death rates were greater for pathological fractures and less for severe trauma fractures compared to the fractures due to no more than moderate trauma. In the latter group, long-term mortality was increased following fractures at many skeletal sites. After further adjustment for precipitating cause, overall SMRs were elevated not only following fractures at the traditional major osteoporotic sites (i.e., distal forearm, proximal humerus, thoracic/lumbar vertebrae, and proximal femur) combined (SMR, 1.2; 95 % CI, 1.1-1.3) but also following all other fracture types combined (SMR 1.2; 95 % CI, 1.1-1.4), excluding the hand and foot fractures not associated with any increased mortality.

CONCLUSIONS

The persistence of increased mortality long after the occurrence of a fracture has generally been attributed to underlying comorbidity, but this needs to be defined in much greater detail if specific opportunities are to be identified for reducing the excess deaths observed.

A comparison of DXA and CT based methods for estimating the strength of the femoral neck in post-menopausal women

The study goal was to compare simple two-dimensional (2D) analyses of bone strength using dual energy x-ray absorptiometry (DXA) data to more sophisticated three-dimensional (3D) finite element analyses using quantitative computed tomography (QCT) data. DXA- and QCT-derived femoral neck geometry, simple strength indices, and strength estimates were well correlated.

INTRODUCTION

Simple 2D analyses of bone strength can be done with DXA data and applied to large data sets. We compared 2D analyses to 3D finite element analyses (FEA) based on QCT data.

METHODS

Two hundred thirteen women participating in the Study of Women's Health Across the Nation (SWAN) received hip DXA and QCT scans. DXA BMD and femoral neck diameter and axis length were used to estimate geometry for composite bending (BSI) and compressive strength (CSI) indices. These and comparable indices computed by Hip Structure Analysis (HSA) on the same DXA data were compared to indices using QCT geometry. Simple 2D engineering simulations of a fall impacting on the greater trochanter were generated using HSA and QCT femoral neck geometry; these estimates were benchmarked to a 3D FEA of fall impact.

RESULTS

DXA-derived CSI and BSI computed from BMD and by HSA correlated well with each other (R=0.92 and 0.70) and with QCT-derived indices (R=0.83-0.85 and 0.65-0.72). The 2D strength estimate using HSA geometry correlated well with that from QCT (R=0.76) and with the 3D FEA estimate (R=0.56).

CONCLUSIONS

Femoral neck geometry computed by HSA from DXA data corresponds well enough to that from QCT for an analysis of load stress in the larger SWAN data set. Geometry derived from BMD data performed nearly as well. Proximal femur breaking strength estimated from 2D DXA data is not as well correlated with that derived by a 3D FEA using QCT data.

Trends in subtrochanteric, diaphyseal, and distal femur fractures, 1984-2007

The incidence of non-hip femur fractures increased between 1984 and 2007, with an increase in the rates for women after 1996.

INTRODUCTION

Recent reports have suggested that non-hip femur fractures may be decreasing over time, similar to proximal femur fractures.

METHODS

Incidence rates for non-hip femur fractures among Olmsted County, Minnesota, residents were assessed before and after 1995 when the oral bisphosphonate, alendronate, was approved in the USA.

RESULTS

From 1984 to 2007, 727 non-hip femur fractures were observed in 690 Olmsted County residents (51% female [median age, 71.6 years] and 49% male [21.4 years]). Altogether, 20% of the fractures were subtrochanteric, 51% were diaphyseal, and 29% involved the distal femur. Causes included severe trauma in 51%, minimal to moderate trauma in 34%, and pathologic causes in 15%. The overall age- and sex-adjusted annual incidence of first non-hip femur fracture was 26.7 per 100,000 (25.0 per 100,000 for women and 26.6 per 100,000 for men). Incidence rates increased with age and were greater in women than men. Between 1984-1995 and 1996-2007, age-adjusted rates increased significantly for women (20.4 vs. 28.7 per 100,000; p = 0.002) but not for men (22.4 vs. 29.5 per 100,000; p = 0.202).

CONCLUSION

The incidence of first non-hip femur fractures rose between 1984 and 2007, with an increase in the rates for women after 1995.

Sclerostin levels during growth in children

Serum sclerostin levels are associated with cortical porosity, suggesting that changes in sclerostin production during growth may play a role in defining cortical structure.

INTRODUCTION

Sclerostin, produced by osteocytes, is a potent inhibitor of Wnt signaling and bone formation. While sclerostin levels increase with age in adults and are higher in men compared to women, there is currently no information on changes in circulating sclerostin levels during growth in humans.

METHODS

We measured serum sclerostin levels in 6- to 21-year-old girls (n = 62) and boys (n = 56) and related these to trabecular and cortical bone microarchitectural parameters using high-resolution peripheral quantitative computed tomography and to markers of bone turnover.

RESULTS

Serum sclerostin levels were higher in boys as compared to girls and declined in both sexes following the onset of puberty. There was no consistent relationship between sclerostin levels and trabecular bone parameters in either sex. However, serum sclerostin levels were inversely associated with cortical volumetric bone mineral density and cortical thickness in girls and positively associated with the cortical porosity index in both girls and boys. Bone turnover markers were positively correlated with serum sclerostin levels in both sexes.

CONCLUSION

The gender difference in serum sclerostin levels appears to be established during puberty, and sclerostin levels tend to decline in late puberty in both girls and boys. Serum sclerostin levels are associated with cortical porosity, suggesting that changes in sclerostin production during growth may play a role in defining cortical structure.

Determinants of forearm strength in postmenopausal women

Bone strength at the ultradistal radius, quantified by micro-finite element modeling, can be predicted by variables obtained from high-resolution peripheral quantitative computed tomography scans. The specific formula for this bone strength surrogate (-555.2 + 8.1 × [trabecular vBMD] + 19.6 × [cortical area] + 4.2 × [total cross-sectional area]) should be validated and tested in fracture risk assessment.

INTRODUCTION

The purpose of this study was to identify key determinants of ultradistal radius (UDR) strength and evaluate their relationships with age, sex steroid levels, and measures of habitual skeletal loading.

METHODS

UDR failure load (~strength) was assessed by micro-finite element (μFE) modeling in 105 postmenopausal controls from an earlier forearm fracture case-control study. Predictors of bone strength obtained by high-resolution peripheral quantitative computed tomography (HRpQCT) in this group were then evaluated in a population-based cohort of 214 postmenopausal women. Sex steroids were measured by mass spectrometry.

RESULTS

A surrogate variable (-555.2 + 8.1 × [trabecular vBMD] + 19.6 × [cortical area] + 4.2 × [total cross-sectional area]) predicted UDR strength modeled by μFE (R(2) = 0.81), and all parameters except total cross-sectional area declined with age. Evaluated cross-sectionally, the 21% fall in predicted bone strength between ages 40-49 years and 80+ years more resembled the change in trabecular volumetric bone mineral density (vBMD) (-15%) than that in cortical area (-41%). In multivariable analyses, measures of body composition and physical activity were stronger predictors of UDR trabecular vBMD, cortical area, total cross-sectional area, and predicted bone strength than were sex steroid levels, but bio-available estradiol and testosterone were correlated with body mass.

CONCLUSIONS

Bone strength at the UDR, as quantified by μFE, can be predicted from variables obtained by HRpQCT. Predicted bone strength declines with age with changes in UDR trabecular vBMD and cortical area, related in turn to reduced skeletal loading and sex steroid levels. The predicted bone strength formula should be validated and tested in fracture risk assessment.

Mortality in the vertebroplasty population

BACKGROUND AND PURPOSE

Vertebroplasty is an effective treatment for painful compression fractures refractory to conservative management. Because there are limited data regarding the survival characteristics of this patient population, we compared the survival of a treated with an untreated vertebral fracture cohort to determine whether vertebroplasty affects mortality rates.

MATERIALS AND METHODS

The survival of a treated cohort, comprising 524 vertebroplasty recipients with refractory osteoporotic vertebral compression fractures, was compared with a separate historical cohort of 589 subjects with fractures not treated by vertebroplasty who were identified from the Rochester Epidemiology Project. Mortality was compared between cohorts by using Cox proportional hazards models adjusting for age, sex, and Charlson indices of comorbidity. Mortality was also correlated with pre-, peri-, and postprocedural clinical metrics (eg, cement volume use, RDQ score, analog pain scales, frequency of narcotic use, and improvement in mobility) within the treated cohort.

RESULTS

Vertebroplasty recipients demonstrated 77% of the survival expected for individuals of similar age, ethnicity, and sex within the US population. Compared with individuals with both symptomatic and asymptomatic untreated vertebral fractures, vertebroplasty recipients retained a 17% greater mortality risk. However, compared with symptomatic untreated vertebral fractures, vertebroplasty recipients had no increased mortality following adjustment for differences in age, sex, and comorbidity (HR, 1.02; 95% CI, 0.82-1.25). In addition, no clinical metrics used to assess the efficacy of vertebroplasty were predictive of survival.

CONCLUSIONS

Vertebroplasty recipients have mortality rates similar to those of individuals with untreated symptomatic fractures but have worse mortality compared with those with asymptomatic vertebral fractures.

Genetic analysis of aquaporin-4 in neuromyelitis optica

OBJECTIVE

Autoantibodies to aquaporin-4 (AQP4) are specific and pathogenic for neuromyelitis optica (NMO). Therefore, we evaluated whether AQP4 single-nucleotide polymorphisms (SNPs) are associated with susceptibility to NMO or whether mutations that potentially alter AQP4 structure or expression are present in some patients.

METHODS

We genotyped 8 AQP4 SNPs chosen based on their minor allele frequency, location, and novelty in 177 NMO sporadic cases, 14 NMO familial cases, and 1,363 matched controls by TaqMan-based assay. We performed bidirectional sequencing of the promoter (1 kb), exons 0-4, and flanking splice consensus sequences, and the 5' and 3' untranslated regions of 177 sporadic and 14 familial NMO cases.

RESULTS

One of 8 SNPs (minor allele frequency = 0.01) was associated with NMO (NC 18.8; chrom pos. 22695167: T>A): odds ratio (95% confidence interval) = 13.1 (1.4-126.7); p = 0.026. In 3 patients with NMO (2 related), we detected 2 different missense allelic mutations at Arg19 (R19I and R19T). None of the 1,363 control subjects had Arg19 mutations (p = 0.001).

CONCLUSIONS

Except for one uncommon SNP, no tested SNP was associated with NMO, nor were 3 SNP haplotypes, providing no support for the hypothesis that genetic variation in AQP4 accounts for overall susceptibility to NMO. Two different allelic Arg19 missense mutations are specific to NMO and segregated with the disease in one pedigree. Although the pathobiology underlying this is not yet established, their effects on the structure of the M1 isoform N terminus or the regulatory sequence of the M23 isoform by virtue of their location support a role of AQP4 orthogonal array formation on molecular susceptibility to NMO.

Assessing forearm fracture risk in postmenopausal women

A diverse array of bone density, structure, and strength parameters were significantly associated with distal forearm fractures in postmenopausal women, but most of them were also correlated with femoral neck areal bone mineral density (aBMD), which provides an adequate measure of bone fragility at the wrist for routine clinical purposes.

INTRODUCTION

This study seeks to test the clinical utility of approaches for assessing forearm fracture risk.

METHODS

Among 100 postmenopausal women with a distal forearm fracture (cases) and 105 with no osteoporotic fracture (controls), we measured aBMD and assessed radius volumetric bone mineral density, geometry, and microstructure; ultradistal radius failure load was evaluated in microfinite element (microFE) models.

RESULTS

Fracture cases had inferior bone density, geometry, microstructure, and strength. The most significant determinant of fracture in five categories were bone density (femoral neck aBMD; odds ratio (OR) per standard deviation (SD), 2.0; 95% confidence interval (CI), 1.4-2.8), geometry (cortical thickness; OR, 1.5; 95% CI, 1.1-2.1), microstructure (structure model index (SMI); OR, 0.5; 95% CI, 0.4-0.7), and strength (microFE failure load; OR, 1.8; 95% CI, 1.3-2.5); the factor-of-risk (applied load in a forward fall / microFE failure load) was 15% worse in cases (OR, 1.9; 95% CI, 1.4-2.6). Areas under receiver operating characteristic curves (AUC) ranged from 0.62 to 0.68. The predictors of forearm fracture risk that entered a multivariable model were femoral neck aBMD and SMI (combined AUC, 0.71).

CONCLUSIONS

Detailed bone structure and strength measurements provide insight into forearm fracture pathogenesis, but femoral neck aBMD performs adequately for routine clinical risk assessment.

Secular trends in hip fracture incidence and recurrence

The decline in hip fracture incidence is now accompanied by a further reduction in the likelihood of a recurrent hip fracture among survivors of the first fracture.

INTRODUCTION

Hip fracture incidence is declining in North America, but trends in hip fracture recurrence have not been described.

METHODS

All hip fracture events among Olmsted County, Minnesota residents in 1980-2006 were identified. Secular trends were assessed using Poisson regression, and predictors of recurrence were evaluated with Andersen-Gill time-to-fracture regression models.

RESULTS

Altogether, 2,752 hip fractures (median age, 83 years; 76% female) were observed, including 311 recurrences. Between 1980 and 2006, the incidence of a first-ever hip fracture declined by 1.37%/year for women (p < 0.001) and 0.06%/year for men (p = 0.917). Among 2,434 residents with a first-ever hip fracture, the cumulative incidence of a second hip fracture after 10 years was 11% in women and 6% in men with death treated as a competing risk. Age and calendar year of fracture were independently associated with hip fracture recurrence. Accounting for the reduction in first-ever hip fracture rates over time, hip fracture recurrence appeared to decline after 1997.

CONCLUSION

A recent reduction in hip fracture recurrence is somewhat greater than expected from the declining incidence of hip fractures generally. Additional research is needed to determine the extent to which this can be attributed to improved patient management.

Comparison of sex steroid measurements in men by immunoassay versus mass spectroscopy and relationships with cortical and trabecular volumetric bone mineral density

In men, measurement of serum testosterone and estradiol levels with immunoassays correlated with mass spectroscopic measurements, and correlations of sex steroids with volumetric bone mineral density were similar.

INTRODUCTION

While immunoassays have been used extensively for measurement of serum testosterone (T) and estradiol (E(2)) levels, there is concern about their specificity, particularly at low E(2) levels as present in men.

METHODS

We compared T and E(2) measured by mass spectroscopy to levels measured by immunoassay in men (n = 313, age 22 to 91 years) and related these to volumetric bone mineral density (vBMD) at various skeletal sites.

RESULTS

Serum T and non-SHBG bound (or bioavailable) T levels by immunoassay correlated well with the corresponding mass spectroscopy measurements (R = 0.90 and 0.95, respectively, P < 0.001); the correlations for serum E(2) measured using the two techniques were less robust (R = 0.63 for total E(2) and 0.84 for bioavailable E(2), P < 0.001). Overall relationships between serum bioavailable T and E(2) levels with vBMD at various skeletal sites were similar for the immunoassay and mass spectroscopic measures.

CONCLUSIONS

Although E(2) levels with immunoassay correlate less well with the mass spectroscopic measurements than do the T measurements in men, our findings indicate that the fundamental relationships observed previously between vBMD and the sex steroids by immunoassay are also present with the mass spectroscopic measurements.

Men transmit MS more often to their children vs women: The Carter effect

OBJECTIVE

Multiple sclerosis (MS) is approximately twice as common among women as men. If men have greater physiologic resistance to MS, they might theoretically require stronger genetic predisposition than women to overcome this resistance. In this circumstance, men would be expected to transmit the disease more often to their children, a phenomenon known as the Carter effect. The authors evaluated whether the Carter effect is present in MS.

METHODS

The authors studied 441 children (45 with definite MS) of an affected father or mother (197 families of interest) from 3598 individuals in 206 multiplex pedigrees. The authors compared transmission of MS from affected men with transmission from affected women.

RESULTS

Fathers with MS transmitted the disease to their children more often (transmitted: 18, not transmitted: 99) than mothers with MS (transmitted: 27, not transmitted: 296) (p = 0.032; OR: 1.99, 95% CI: 1.05, 3.77). Adjusting for both the sex of the affected child and multiple transmissions from a single affected parent, the sex of the affected parent remained as an independent risk factor for transmission of MS to children, fathers transmitting more often than mothers (p = 0.036; OR: 2.21, 95% CI: 1.05, 4.63).

CONCLUSIONS

The authors have demonstrated the Carter effect in multiple sclerosis (MS). These observations may be explained by greater genetic loading in men that leads to relative excess paternal vs maternal transmission. Linkage analysis in genetic studies of MS may be more informative if patrilineal transmission were given additional weighting.

Influence of baseline deformity definition on subsequent vertebral fracture risk in postmenopausal women

INTRODUCTION

Approaches for recognizing vertebral fractures remain controversial.

METHODS

An age-stratified population sample of 512 postmenopausal women was followed with serial radiographs for up to 12 years (4455 person-years).

RESULTS

112 women experienced a new vertebral fracture (20% reduction in any vertebral height from baseline) within this study period, for an annual age-adjusted (to US white women > or =50 years of age in 2000) incidence of 23 per 1000. Depending on the morphometric definition used, the prevalence of vertebral deformities at baseline ranged from 3 to 90%. A recent method to standardize vertebral heights produced the best agreement with a qualitative clinical reading of the films [kappa (kappa), 0.53]. Almost all of the different baseline definitions predicted future vertebral fractures, but most of the predictive power was attributable to the severe (e.g., 4 SD) deformities included within more generous (e.g., 3 SD) classifications. Whereas the generous definitions were more sensitive, and the restrictive ones more specific, their overall abilities to predict a new vertebral fracture were roughly comparable as evaluated by the c-index (analogous to the area under an ROC curve).

CONCLUSION

This result suggests that the choice of a morphometry definition depends on the particular application and, in particular, on whether it is more important to maximize sensitivity or specificity.

IFNG polymorphisms are associated with gender differences in susceptibility to multiple sclerosis

Interferon-gamma (IFNgamma) treatment is deleterious in multiple sclerosis (MS). MS occurs twice as frequently in women as in men. IFNgamma expression varies by gender. We studied a population-based sample of US MS patients and ethnicity-matched controls and independent Northern Irish and Belgian hospital-based patients and controls for association with MS, stratified by gender, of an intron 1 microsatellite [I1(761)*CAn], a single nucleotide polymorphism 3' of IFNG [3'(325)*G --> A] and three flanking microsatellite markers spanning a 118 kb region around IFNG. Men carriers of the 3'(325)*A allele have increased susceptibility to MS compared to noncarriers in the USA (P=0.044; OR: 2.58, 95% CI: 0.97-8.08) and Northern Ireland (P=0.019; OR: 2.37, 95% CI: 1.10-5.13). There is a nonsignificant trend in the same direction in Belgian men (P=0.299; OR: 1.50, 95% CI: 0.71-3.26). Men carriers of I1(761)*CA13, which is in strong linkage disequilibrium with the 3'(325)*A, have increased susceptibility (P=0.050; OR: 2.22, 95% CI: 0.98-5.40), while men carriers of I1(761)*CA12 have decreased susceptibility (P=0.022; OR: 0.46, 95% CI: 0.23-0.90) to MS in the USA. Similar associations were reported in Sardinia between the I1(761)*CA12 allele and reduced risk of MS in men. Flanking markers were not associated with MS susceptibility. Polymorphisms of IFNG may contribute to differences in susceptibility to MS between men and women.

Association of APOE polymorphisms with disease severity in MS is limited to women

The authors studied the association of an exon 4 (E4*epsilon2/3/4) and three promoter polymorphisms of APOE with disease course and severity stratified by gender in 221 patients with multiple sclerosis from two overlapping population-based prevalence cohorts. Women carriers of the E4*epsilon2 allele took longer to attain an Expanded Disability Status Scale score of 6 (p = 0.015) and had more favorable ranked severity scores than noncarriers (p = 0.009). There was no association in men. Alleles epsilon3 or epsilon4 and promoter polymorphisms were not associated with disease course or severity.

Progression of familial and non-familial dilated cardiomyopathy: long term follow up

BACKGROUND

It is unknown whether progression of familial idiopathic dilated cardiomyopathy differs from progression in the non-familial form. It has been suggested that familial disease indicates a worse prognosis, and that this should be considered when planning the timing of heart transplantation.

OBJECTIVE

To compare five year survival or time to heart transplantation in an unselected series of patients with dilated cardiomyopathy who had been evaluated for familial v non-familial disease through the echocardiographic investigation of first degree relatives.

DESIGN

Medical records were reviewed and questionnaires were mailed to all patients who had previously participated in a family based study of dilated cardiomyopathy. Information was gathered about survival, heart transplantation, and left ventricular ejection fraction (LVEF) measurements. Survival data were censored at the time of cardiac transplantation.

RESULTS

Follow up data were obtained for 99 of 101 patients (69 with non-familial and 30 with familial disease). Five year survival was 55% for non-familial and 51% for familial patients (NS). The main predictor of mortality was an LVEF of < 30%. Familial status did not predict mortality. There was no significant difference in follow up LVEF values between the groups.

CONCLUSIONS

Five year survival is not significantly different in the familial and non-familial forms of dilated cardiomyopathy.

The gene for HMSN2C maps to 12q23-24: a region of neuromuscular disorders

BACKGROUND

Hereditary motor and sensory neuropathy type 2C (HMSN2C, Charcot-Marie-Tooth 2C [CMT2C]) is an autosomal dominant motor and sensory neuropathy involving limb, diaphragm, vocal cord, and intercostal muscles.

OBJECTIVE

To identify the chromosome localization for this disorder in one large American family of English and Scottish ethnicity.

METHODS

Variable clinical severity led the authors to combine several approaches to accurately identify affected patients. Genome-wide two-point linkage analysis, high-definition mapping, and multipoint and recombinant haplotype analyses were performed. Mutation analysis of the triplet repeat region of ataxin-2 was also carried out.

RESULTS

The initial genome-wide scan identified a region at 12q24, and fine mapping provided a maximal lod score of 4.73 (D12S1645 and D12S1583 at theta = 0.01 and 0, respectively). With multipoint analysis, a higher lod score of 5.17 was obtained and localized to the same region at 119.0 cM. Haplotype analysis narrowed the region to approximately 5.0 cM between D12S1646,D12S1330 and D12S105,D12S1339 (12q23.3-24.21). Ataxin-2, the gene responsible for spinocerebellar ataxia type 2 (SCA2), localizes to this region, but no triplet repeat expansion or point mutations within the repeat were found.

CONCLUSIONS

The gene for HMSN2C maps to 12q23-24. This region is associated with SCA2, scapuloperoneal spinal muscular atrophy, and congenital distal spinal muscular atrophy. Further studies are needed to demonstrate the specific gene alteration and its relationship with nearby genes.

Correlates of osteoprotegerin levels in women and men

Osteoprotegerin (OPG) is a potent antiresorptive molecule that binds the final effector for osteoclastogenesis, receptor activator of NF-kappaB ligand (RANK-L). OPG production is regulated by a number of cytokines and hormones, including sex steroids, but there are few data on age and gender effects on circulating serum OPG levels, as well as possible relationships between OPG levels and bone turnover markers or bone mineral density (BMD). Thus, we measured serum OPG levels in an age-stratified, random sample of men (n = 346 age range, 23-90 years) and women (n = 304; age range 21-93 years) and related them to sex steroid levels, bone turnover markers and BMD. Serum OPG levels increased with age in both men (R = 0.39, p < 0.001) and women (R = 0.18, p < 0.01). Premenopausal women had higher OPG levels than men under age 50 years (171 +/- 6 pg/ml vs 134 +/- 6 pg/ml, respectively, p < 0.001), whereas serum OPG levels were no different in postmenopausal women compared with men = 50 years (195 +/- 7 pg/ml vs 188 +/- 7 pg/ml, respectively, p = 0.179). OPG levels correlated inversely with serum bioavailable testosterone levels in men = 50 years (R = -0.27, p < 0.001), but no associations were present with either estrogen or testosterone levels in the women. In the men, there was a trend for OPG levels to be associated positively with bone resorption markers and inversely with BMD. Collectively, the gender difference in OPG levels suggests that sex steroids may regulate OPG production in vivo, as has been found in vitro. Moreover, OPG production may also rise with increases in bone turnover, probably as a homeostatic mechanism to limit bone loss. Further studies directly testing these hypotheses should provide additional insights into the potential role of OPG in bone loss related to aging and sex steroid deficiency.

A comparison of software packages that assess linkage using a variance components approach

We report single-point and multipoint results from three statistical genetics software packages using a variance components approach for quantitative traits. When possible, we have shown the effects of covariates. Results from GENEHUNTER, SOLAR, and ACT software packages are compared for the quantitative trait immunoglobulin E (IgE) using chromosome 5 asthma familial data from Oxfordshire (England), Perth (Australia), and Freiburg (Germany), and using the genome-wide German data. Although few differences among variance components results for GENEHUNTER, SOLAR, and ACT were detected on a limited region of chromosome 5, these packages showed larger disagreement in the German data for chromosomes 1, 9, and 14.

Feasibility of an affected sibling pair study in ischemic stroke: results of a 2-center family history registry

BACKGROUND AND PURPOSE

We sought to determine pedigree availability for a concordant sibling pair study of genetic risk factors in ischemic stroke.

METHODS

Probands with confirmed ischemic stroke were prospectively enrolled. Family histories were obtained by systematic interview. A study neurologist prospectively assigned stroke subtype.

RESULTS

Of 310 probands (median age, 75 years; range, 26 to 97 years; 48% women), 75% had at least 1 living sibling; 10%, at least 1 concordant living sibling; 2%, at least 1 concordant sibling living in the same city; and 7%, at least 1 concordant living and 1 discordant living sibling. Likelihood of having a concordant sibling increased significantly with proband age, even after adjustment for sibship size (P=0.002). Positive family history of stroke was not related to either proband stroke subtype or risk factor profile.

CONCLUSIONS

Approximately 10 probands were screened to find 1 potentially concordant living sibling. A concordant sibling pair study should be multicentered and enable enrollment of siblings from diverse geographic areas.

Effects of raloxifene, a selective estrogen receptor modulator, on bone turnover markers and serum sex steroid and lipid levels in elderly men

Several lines of evidence implicate estrogen deficiency as a cause of bone loss in elderly men. Thus, in 50 elderly men (mean age +/- SD, 69.1 +/- 6.0 years), we performed a randomized blinded study to assess the effect of 6 months of treatment with 60 mg/day of raloxifene (a selective estrogen receptor modulator [SERM] that has an agonist effect on bone but is not feminizing) versus placebo on bone turnover markers. The mean changes in bone turnover markers, serum sex steroid, or lipid levels with treatment did not differ between groups. However, changes in urinary cross-linked N-telopeptide of type I collagen (NTX) excretion were related directly to the baseline serum estradiol level in the raloxifene (r = 0.57; p = 0.004) but not in the placebo-treated (r = 0.15; p = 0.485) men (p = 0.015 for the difference between groups). Moreover, the men in whom NTX excretion decreased after raloxifene treatment had significantly lower baseline estradiol levels (mean +/- SEM, 22 +/- 2 pg/ml) than the men in whom urinary NTX excretion didn't change or increased after raloxifene therapy (30 +/- 3 pg/ml; p = 0.03), and no such difference was found in the placebo group. Thus, raloxifene has no significant effect on bone turnover markers or lipid levels in elderly men. However, the association noted between baseline estradiol levels and the change in urine NTX excretion in the raloxifene-treated men suggests that a subset of men with low estradiol levels may respond to raloxifene or other SERMs, and further studies are needed to directly test this possibility.

Relationship of serum sex steroid levels to longitudinal changes in bone density in young versus elderly men

Estrogen appears to play an important role in determining bone mineral density in men, but it remains unclear whether estrogen primarily determines peak bone mass or also affects bone loss in elderly men. Thus, we assessed longitudinal rates of change in bone mineral density in young (22-39 yr; n = 88) vs. elderly (60-90 yr; n = 130) men and related these to circulating total and bioavailable estrogen and testosterone levels. In young men bone mineral density increased significantly over 4 yr at the mid-radius and ulna and at the total hip (by 0.32-0.43%/yr), whereas it decreased in the elderly men at the forearm sites (by 0.49-0.66%/yr), but did not change at the total hip. The rate of increase in bone mineral density at the forearm sites in the young men was significantly correlated to serum total and bioavailable estradiol and estrone levels (r = 0.22-0.35), but not with total or bioavailable testosterone levels. In the elderly men the rates of bone loss at the forearm sites were most closely associated with serum bioavailable estradiol levels (r = 0.29-0.33) rather than bioavailable testosterone levels. Moreover, elderly men with bioavailable estradiol levels below the median [40 pmol/liter (11 pg/ml)] had significantly higher rates of bone loss and levels of bone resorption markers than men with bioavailable estradiol levels above 40 pmol/liter. These data thus indicate that estrogen plays a key role both in the acquisition of peak bone mass in young men and in bone loss in elderly men. Moreover, our findings suggest that age-related decreases in bioavailable estradiol levels to below 40 pmol/liter may well be the major cause of bone loss in elderly men. This subset of men is perhaps most likely to benefit from preventive therapy.

Role of serum leptin, insulin, and estrogen levels as potential mediators of the relationship between fat mass and bone mineral density in men versus women

Although fat mass is related to bone mineral density (BMD), the potential mechanism(s) of this effect remain to be defined. Thus, we assessed the role of the candidate hormones, leptin, insulin, and estrogen in mediating fat mass effects on the skeleton. Specifically, we related these hormones and fat mass to BMD at the total hip, mid-lateral spine, and mid-distal radius in a sample of 137 premenopausal women (age range 21-54 years), 165 postmenopausal women (34-93 years), and 343 men (23-90 years) recruited from the general population. Fat mass and BMD were significantly related in pre- and postmenopausal women at multiple sites, whereas this relationship was only weakly present in men at the total hip. Serum leptin levels were also significantly related to BMD in the women, but not in the men. Insulin was associated with hip BMD in the women, and bioavailable estradiol (E2) was correlated with BMD at all sites in men and in postmenopausal women. In the women, adjusting for leptin reduced the strength of the association between fat mass and BMD, with further adjustments for insulin or bioavailable E2 having no additional effects. Adjusting for leptin in the men had no consistent effect on the relationship between fat mass and BMD. Collectively, these data suggest that there is a sexual dimorphism in the relationship of fat mass and leptin to BMD, with both being positively associated with BMD in women but not in men. In women, leptin may also mediate at least part of the protective effect of fat mass on the skeleton.

Role of axillary node dissection in patients with T1a and T1b breast cancer: Mayo Clinic experience

HYPOTHESIS

The incidence of nodal positivity in patients with early breast cancer is low, and axillary lymph node dissection may not be justified in all such patients.

DESIGN

Retrospective case series.

SETTING

Tertiary institution.

PATIENTS

All patients with T1a and T1b breast cancer who had both primary breast surgery and axillary lymph node dissection at Mayo Clinic in Jacksonville, Fla, from January 1, 1992, through February 28, 1998.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Tumor size and biological grade, estrogen and progesterone receptor status, number of nodes harvested, and number of nodes positive for disease.

RESULTS

Of 163 patients studied, 39 had T1a and 124 had T1b tumors. Node positivity was 0% for T1a and 11.3% for T1b tumors (P =.03). Lymph node involvement and estrogen receptor status were not related (P =.29). However, the risk of lymph node positivity for progesterone receptor-negative (P =.01) and estrogen receptor-negative/progesterone receptor-negative tumors was significantly higher than for progesterone and estrogen/progesterone receptor-positive tumors (P =.04). Furthermore, the risk of lymph node positivity was significantly higher as tumor size increased (P =.002). Finally, higher tumor grade conferred a higher risk of lymph node involvement (P =.02).

CONCLUSIONS

T1a tumors have minimal risk of nodal positivity and may not require subsequent axillary lymph node dissection in the future. T1b tumors should be managed with routine analysis of axillary lymph node status. Whether sentinel node mapping can change this standard awaits further study.

Lymph node-positive prostate cancer: evaluation of the results of the combination of androgen deprivation therapy and radiation therapy

OBJECTIVE

To evaluate the outcome of patients with pathologic stage IV prostate cancer treated with androgen ablation plus external-beam radiation therapy.

PATIENTS AND METHODS

Sixty consecutive patients treated between August 1986 and February 1995 with androgen ablation plus radiation therapy for stage IV (T1-4 N1 M0) adenocarcinoma of the prostate were selected for outcome analysis in this retrospective study. Bilateral pelvic lymphadenectomy was performed in 56 patients (93%). The 4 remaining patients had pelvic adenopathy on computed tomography, which was confirmed histologically in all patients. The median pretreatment prostate-specific antigen (PSA) level was 28.8 ng/mL (mean, 55 ng/ mL; range, 0.1-428 ng/mL). All patients received radiation therapy to the prostate, and 29 (48%) had pelvic node radiation. Biochemical failure was defined according to the American Society for Therapeutic Radiology and Oncology criteria of 3 successive increases in the PSA level.

RESULTS

The median follow-up duration for surviving patients was 101.1 months (range, 20-134 months). Biochemical failure with (in 2 patients) or without (in 10 patients) clinically evident disease relapse was noted in 12 patients (20%). Four additional patients (7%) had clinical relapse without biochemical failure. Local recurrences were observed in 6 patients (10%), and this clinical impression was confirmed by biopsy in 4 patients. Thirteen patients (22%) died of causes related to prostate cancer. The biochemical relapse-free, clinical disease-free, overall, and cause-specific survival rates at 5 years were 82%, 84%, 76%, and 80%, respectively.

CONCLUSIONS

This observational case series of patients treated with the combination of external-beam radiation therapy and permanent androgen ablation for pathologic stage IV prostate cancer suggests that the addition of androgen deprivation therapy to radiation therapy may improve disease outcome. In the absence of randomized trial results, these observations may be beneficial in clinical decision making.

Long-term fracture risk among infertile women: a population-based cohort study

Nulliparity has been linked to bone loss and fractures, but the contribution of infertility is unclear. The purpose of this study was to assess the long-term risk of fractures among infertile women. In a population-based retrospective cohort study, all 658 Olmsted County, Minnesota, women with infertility (failure to conceive after 1 year despite intercourse without contraception) first diagnosed at Mayo Clinic in 1935-1964 were followed for fractures. Risk was assessed by comparing new fractures of each type to the number expected from sex-specific and age-specific fracture rates in the general population (standardized incidence ratios [SIR]). During 18,130 person-years of follow-up, 184 women experienced at least one fracture when 291 would have been expected on the basis of fracture incidence rates in the general population (SIR 0.6, 95% CI 0.5-0.7). There was no increase in proximal femur fractures (SIR 1.0, 95% CI 0.6-1.6) and a statistically significant decrease in the risk of distal forearm fractures (SIR 0.7, 95% CI 0.5-0.97), two of the three sites traditionally associated with osteoporosis. By contrast, there was a significant increase in subsequent vertebral fractures (SIR 1.9, 95% CI 1.4-2.4) that was consistent across divergent causes of infertility and reported menstrual patterns. Although an apparent increase in the risk of vertebral fractures requires further investigation, we saw no indication of an increase in limb fractures, suggesting that infertility does not have long-term adverse skeletal effects like those reported for athletes and dieters with irregular menses.

Patient outcomes following defibrillation with a low energy biphasic truncated exponential waveform in out-of-hospital cardiac arrest

PRIMARY OBJECTIVE

To determine the outcome of patients with out-of-hospital cardiac arrest and ventricular fibrillation as the presenting rhythm while using automated external defibrillators (AEDs) that delivered non-escalating, impedance-compensated low-energy (150 J) shocks.

MATERIALS AND METHODS

AEDs delivering low-energy biphasic truncated exponential (BTE) shocks were employed in an emergency medical services (EMS) system in which first-arriving personnel - police, firefighters or paramedics - delivered the initial shocks. Patients were classified according to their response to shocks: restoration of sustained spontaneous circulation (ROSC) without need for epinephrine and other advanced life support (ALS) interventions; and ALS, those requiring epinephrine in all instances. The primary end-point was neurologically-intact discharge survival. Secondary end-points were ROSC with shocks only and the call-to-shock time interval.

RESULTS

Of 42 patients with VF arrest treated with BTE shocks, 35 were bystander-witnessed. Of these 35, 14 (38%) regained a sustained ROSC on-scene with shocks only, needing no epinephrine for ROSC. All 14 survived to discharge home. Of the remaining 21 patients needing ALS intervention, only two (9.5%) survived to discharge. Overall, 16/35 patients (46%) survived to discharge home, an outcome comparable to our experience with patients treated with escalating high-energy monophasic waveform shocks.

CONCLUSIONS

Low-energy (150 J) non-escalating biphasic truncated exponential waveform shocks terminate VF in out-of-hospital cardiac arrest with high efficacy; patient outcome is comparable with that observed with escalating high-energy monophasic shocks. Low-energy shocks, in addition to high efficacy, may confer the advantage of less shock-induced myocardial dysfunction, though this will be difficult to define in the clinical circumstance of long-duration VF provoked by a pre-existing diseased myocardial substrate.

Relative contributions of testosterone and estrogen in regulating bone resorption and formation in normal elderly men

Young adult males who cannot produce or respond to estrogen (E) are osteopenic, suggesting that E may regulate bone turnover in men, as well as in women. Both bioavailable E and testosterone (T) decrease substantially in aging men, but it is unclear which deficiency is the more important factor contributing to the increased bone resorption and impaired bone formation that leads to their bone loss. Thus, we addressed this issue directly by eliminating endogenous T and E production in 59 elderly men (mean age 68 years), studying them first under conditions of physiologic T and E replacement and then assessing the impact on bone turnover of withdrawing both T and E, withdrawing only T, or only E, or continuing both. Bone resorption markers increased significantly in the absence of both hormones and were unchanged in men receiving both hormones. By two-factor ANOVA, E played the major role in preventing the increase in the bone resorption markers, whereas T had no significant effect. By contrast, serum osteocalcin, a bone formation marker, decreased in the absence of both hormones, and both E and T maintained osteocalcin levels. We conclude that in aging men, E is the dominant sex steroid regulating bone resorption, whereas both E and T are important in maintaining bone formation.

Fracture risk among patients with Paget's disease: a population-based cohort study

Localized disruption of bone architecture leads to an increased risk of pathological fractures in patients with Paget's disease, but the impact of the disease on overall fracture risk is unknown. We addressed this issue among 236 Olmsted County, Minnesota residents (107 women and 129 men) first diagnosed with Paget's disease from 1950 through 1994. These subjects (mean +/- SD age at diagnosis, 69.6+/-12.2 years) were followed subsequently for 2798 person-years. During this period of observation, 33 pathological fractures were attributed to Paget's disease (1 skull, 11 vertebra, 1 shaft/distal humerus, 1 pelvis, 6 proximal femur, 2 shaft/distal femur, and 11 tibia/fibula). Excluding the fractures through pagetic bone, there was no increase in overall fracture risk in this cohort (standardized incidence ratio [SIR], 1.2; 95% CI, 0.9-1.4). However, there was a statistically significant increase in the risk of subsequent vertebra (SIR, 3.0; 95% CI, 2.2-4.1) and rib fractures (SIR, 1.7; 95% CI, 1.1-2.4) but not fractures of the proximal femur (SIR, 0.6; 95% CI, 0.3-1.1) or distal forearm (SIR, 1.4; 95% CI, 0.7-2.5). Thus, unselected patients with Paget's disease in the community, who mostly have mild disease, have a significantly increased risk of vertebral fractures, although this may relate partly to increased surveillance. Additional work is needed to clarify the relationship between Paget's disease and vertebral fractures and to identify individuals at increased risk for more aggressive therapy.

Clinical utility of routine screening for abdominal aortic aneurysm during echocardiography

BACKGROUND

The aim of this study was to determine the clinical utility of transthoracic echocardiography (TTE) as a screening method for the detection of abdominal aortic aneurysms (AAA).

PATIENTS AND METHODS

Each patient who was referred to the echocardiography laboratory TTE was included into the study. After complete cardiac assessment the abdominal aorta was evaluated. Patients with a known, a clinically suspected, or a previously operated AAA were excluded.

RESULTS

During the study period, 14,876 patients underwent TTE. 13,166 (88.5%) of the patients were 50 years and older. Of these 6953 (52.8%) were men and 6213 (47.2%) were women. A total of 108 (0.82%; 95% confidence interval (CI) 0.67-0.99) clinically unsuspected AAA of at least 3 cm in diameter (range 3 cm-6.8 cm) were detected. There were 93 (86.1%) men and 15 (13.9%) women with a mean age of 73.8 years (range 59-90). In 7 patients an AAA was suspected by TTE but not verified on subsequent abdominal ultrasound, as the diameter of the abdominal aorta was less than 3 cm. The prevalence of an AAA in patients 50 years and older was 1.34% (95% CI 1.08-1.64) for men and 0.24% (95% CI 0.14-0.40) for women. In patients less than 50 years old no aneurysm was detected. Seventeen patients who were found to have an AAA with a mean diameter of 4.4 cm (range 3-6 cm) underwent successful elective conventional AAA repair after a mean interval of 13.9 months (range 0.2-49 months) following the initial diagnosis.

CONCLUSIONS

TTE performed in a highly selected cardiac patient group in a tertiary referral center is not a useful tool to screen for clinically unsuspected abdominal aortic aneurysms due to the low prevalence. The detection of an aneurysm should be confirmed by conventional abdominal ultrasound.

Relationship of serum leptin levels with body composition and sex steroid and insulin levels in men and women

Whether the higher serum leptin levels in women are due to gender differences in fat mass or to other factors such as sex steroids remains unclear. In addition to sex steroids, serum insulin levels also appear to be related to leptin levels, although whether this effect is independent of the effects of body composition is unclear. The purpose of this study was to identify the major determinants of circulating serum leptin levels. We studied a large, population-based cohort of 345 men (23 to 90 years), 137 premenopausal women (21 to 54 years), and 212 postmenopausal women (34 to 94 years), including 47 women on hormone replacement therapy (HRT). Serum leptin levels were related to body composition as assessed by dual-energy x-ray absorptiometry (DEXA) and to circulating sex steroid and insulin levels. Serum leptin levels remained significantly higher in women versus men even after adjustment for fat mass, and leptin levels were significantly correlated with fat mass independently of age. By univariate analyses, logarithmically transformed serum leptin levels correlated positively with bioavailable estrogen ([E] estradiol plus estrone) in postmenopausal women not on HRT, and negatively with total and bioavailable testosterone (T) levels in men. Serum insulin levels were directly related to leptin levels regardless of gender and age. By multivariate analyses, fat mass, lean mass, and insulin levels were the strongest predictors of leptin levels in all groups. In addition, bioavailable E entered the model in the postmenopausal women not on HRT. These studies indicate that the fat mass, lean mass, and insulin level are the major determinants of the serum leptin level in adults. Moreover, after adjusting for these variables, bioavailable E also explains a significant proportion of the variance in leptin levels among postmenopausal women not on HRT.

Association of two variants in IL-1beta and IL-1 receptor antagonist genes with multiple sclerosis

We studied the putative association of a C-->T polymorphism in exon-5 of IL-1beta and an 85 bp tandem repeat in intron-4 of IL-1 receptor antagonist (IL-1ra) genes with susceptibility to or outcome of MS. DNA from 122 cases from a population-based cohort in Olmsted County, MN who were previously categorized for disease severity and temporal course and 244 ethnically-matched controls were analyzed. There was no association between either polymorphism and disease susceptibility. Allele-2 of IL-1beta and allele-3 of the IL-1ra polymorphisms were associated with a favorable outcome (P=0.023 and P=0.030).

Unilateral pallidotomy for Parkinson's disease: speech, motor, and neuropsychological outcome measurements

We studied the effects of unilateral medial pallidotomy in the first 57 consecutive Parkinson's disease (PD) patients undergoing this MRI/electrophysiologically guided procedure at our institution, obtaining qualitative and quantitative measures of speech, motor function, activities of daily living, and neuropsychological functioning at 3 and 12months post-operatively. Speech intelligibility was typically preserved, declining mildly in one-third of patients post-operatively. Pallidotomy significantly improved motor function similarly in patients >/=65 or <65years (n=20). Cognitive abilities generally remained stable following surgery; however, performance on measures of letter fluency and semantic fluency declined in patients with left pallidotomies. We conclude that in our series mild deterioration in speech may occur with unilateral pallidotomy in patients otherwise responsive to this treatment.

Association of a myeloperoxidase promoter polymorphism with multiple sclerosis

Myeloperoxidase (MPO) generates hypochlorous acid and other reactive oxygen intermediates leading to tissue damage. MPO is expressed in macrophages-microglia in multiple sclerosis (MS) lesions. A G-->A substitution that abolishes an SP1 transcription factor consensus sequence in the promoter reduces gene expression. We studied the association of the genetic variant with MS. We did not find an association with gender, age at onset, susceptibility to, or the course and severity of MS in a population-based sample of 122 patients from Olmsted County.

Genetic variation in the B7-1 gene in patients with multiple sclerosis

Co-stimulation of T cells by B7-1, a protein that is expressed on antigen presenting cells, favors a T helper type1 (Th1) cellular response. Th1/Th2 bias may influence disease susceptibility or course of MS. We screened the entire coding sequence as well as the 5'- and 3'-untranslated regions of the B7-1 gene using a mutation scanning technique, dideoxyfingerprinting, in DNA from 111 patients with MS from Olmsted County, Minnesota. We identified five genetic variants. None alter protein structure nor have apparent functional significance. Selected variants of sufficient frequency were tested for an association with course and severity of MS and one was tested for an association with susceptibility; none of the association tests were positive.

Verifying the stroke-free phenotype by structured telephone interview

BACKGROUND AND PURPOSE

Case-control, cohort, and twin studies support a genetic contribution to ischemic stroke risk. Sibling pair linkage methods require identification of concordant or discordant siblings or both. We designed and tested a structured telephone interview to verify the stroke-free phenotype.

METHODS

A coordinator unaware of medical record data used an 8-item questionnaire to conduct a structured telephone interview of 70 outpatients aged >60 years. The questionnaire inquired about the sudden onset of deficits in strength, sensation, vision, and language. A subject was defined as stroke free by interview if responses to all items on the questionnaire were negative. Results of the telephone interview were compared with data obtained from a systematic medical record review (benchmark).

RESULTS

Interview time was 5 minutes or less for all subjects. All subjects who began the interview completed it. Records were reviewed in all subjects. Medical record review detected ischemic stroke or transient ischemic attack (TIA), or both, in 5 patients (7%). There were no significant differences in sex distribution or risk factor rates in patients who were designated stroke free or not stroke free by interview. Having 1 or more positive items on the questionnaire was significantly associated with finding stroke (P<0.001), TIA (P<0.001), or either stroke or TIA (P<0.001), on medical record review. The telephone interview had a sensitivity of 1.0 (95% CI 0.48 to 1.0), specificity of 0.86 (95% CI 0.75 to 0.93), positive predictive value of 0.36 (95% CI 0.13 to 0.65), and negative predictive value of 1.0 (95% CI 0.94 to 1.0).

CONCLUSIONS

Our instrument can identify the stroke-free individual with a high degree of confidence in a very efficient manner. It may be particularly suited for centralized verification of stroke discordancy in multicentered sib-pair genetic studies.

The epidemiology of ovarian cancer: a population-based study in Olmsted County, Minnesota, 1935-1991

PURPOSE

To determine trends in incidence and survival between 1935 and 1991 and to evaluate risk factors for ovarian cancer among Olmsted County, Minnesota women.

METHODS

All newly diagnosed cases of ovarian cancer among Olmsted County women in 1975-1991 were identified using the medical records linkage system of the Rochester Epidemiology Project. In order to assess trends, incidence rates in the subset of Rochester women were compared with Rochester rates for 1935-1974. Survival was evaluated by the Kaplan-Meier product-limit method. A case-control analysis of risk factors compared Olmsted County women with invasive epithelial ovarian cancer and an age-matched group of women from the community by logistic regression.

RESULTS

Altogether, 129 Olmsted County women were newly diagnosed with ovarian cancer in 1975-1991. The age-adjusted (to 1970 United States whites) incidence rate was 22.5 per 100,000 person-years. Median survival from initial diagnosis was 3.7 years. Compared to an equal number of controls, the 103 women with invasive epithelial disease were more likely to be nulliparous (odds ratio [OR] 1.9; 95% CI 0.95-3.9) but less likely to have a history of thyroid disease (OR 0.4; 95% CI 0.2-0.8), hypertension (OR 0.4; 95% CI 0.1-0.9) or nonsteroidal estrogen use (OR 0.5; 95% CI 0.2-0.9). Prior hysterectomy (OR 0.5; 95% CI 0.2-0.9) and unilateral oophorectomy (OR 0.2; 95% CI 0.04-0.7) were also associated with reduced risk.

CONCLUSION

The incidence of ovarian cancer in this community in 1975-1991 was little changed from rates 20 years earlier. There has been some improvement in survival from ovarian cancer in this population compared to 1935-1974, but still less than 50% survive for 5 years. Prior hysterectomy and unilateral oophorectomy appear protective for ovarian cancer.

Determinants of bone loss from the femoral neck in women of different ages

An age-stratified sample of 304 women from Rochester, Minnesota, aged 30-94 years (median 60 years) at baseline underwent measurement of femoral neck bone mineral density (BMD) over a follow-up period extending to 16 years. The average rate of change in femoral neck BMD was -1.0% per year (range -10.0% to +13.4%) and did not vary significantly with age. Because there was no marked increase in the rate of loss around the time of menopause, nor convincing evidence of there being a subset of fast losers, there was fairly good tracking of individual values over time; the correlation of baseline with femoral neck BMD values 16 years later was 0.83. Although a large number of potential determinants was assessed, the only consistent predictor of femoral neck bone loss in women of different ages was baseline femoral neck BMD (r = -0.15; p = 0.023). Otherwise, different sets of risk factors were identified for premenopausal women, women within 20 years of menopause, and women 20 years or more postmenopausal, but the predictive power of these different multivariate models was modest. Nonetheless, these data indicate that femoral neck BMD is quite predictable for extended periods of time. This is reassuring with respect to the use of statistical models that incorporate such data to estimate future fracture risk.

Cross-sectional versus longitudinal evaluation of bone loss in men and women

We evaluated age- and sex-specific differences in bone density at a variety of skeletal sites in a population-based sample of 348 men (age 22-90 years) and 351 women (age 21-93 years) by dual-energy X-ray absorptiometry. Several patterns of age-related bone loss were observed, but adjustments for height (or, where possible, calculation of bone mineral apparent density) dampened the apparent rate of bone loss from most skeletal sites as judged from cross-sectional measurements at baseline. Cross-sectional data also overestimated the rate of bone loss observed longitudinally over 4 years at many sites, particularly the hip and spine; conversely, in some forearm regions, cross-sectional rates of loss underestimated the bone loss seen prospectively. Longitudinal rates of bone loss were generally greater among individuals age 70 years or older compared with younger men and women, but some of the latter effect was due to a greater proportion of younger women on hormone replacement therapy, whose rate of bone loss was generally less. These observations highlight the limitations of cross-sectional data for defining the patterns of bone loss over life at different skeletal sites.

Comparison of techniques to estimate total body skeletal muscle mass in people of different age groups

An estimate of total body muscle mass with dual-energy X-ray absorptiometry (DXA; appendicular muscle mass divided by 0.75) was compared with 24-h urinary creatinine excretion in 59 healthy men and women [20-30 yr (younger), 45-59 yr (middle age), and 60-79 yr (older)] who stayed in a clinical research center for 5 days. Total body water ((2)H(2)O dilution), fat (underwater weighing), bone mineral (DXA), and total body protein mass (based on a 4-compartment model) were also measured. Muscle mass estimates by DXA and creatinine were highly correlated (r = 0.80). However, stepwise multiple regression indicated that a significant amount of additional between-subject variability in DXA-based muscle mass estimates could be explained by total body water. Creatinine excretion, knee extensor strength, and total body protein mass all decreased with age, suggesting a decline in muscle cell mass with aging. However, DXA-based muscle mass and measures of nonfat body mass (i.e., lean body mass by (2)H(2)O and fat-free body mass by underwater weighing) did not change with age. These results indicate that DXA and urinary creatinine excretion give different results regarding the decline in total body muscle mass with aging. The factor(s) responsible for the apparent underestimate of age-related sarcopenia by DXA remain to be fully defined, but changes in body water may be an important contributor.

Use of intraoperative duplex ultrasonography and routine patch angioplasty in patients undergoing carotid endarterectomy

OBJECTIVE

To determine the value of routine patch angioplasty and intraoperative duplex ultrasonography (US) during carotid endarterectomy (CEA) for high-grade internal carotid artery stenosis.

PATIENTS AND METHODS

The charts of 102 consecutive patients who underwent CEA with routine patching and intraoperative duplex US for treatment of high-grade carotid stenosis between June 1991 and January 1997 were reviewed retrospectively. Recurrent stenosis was defined as a narrowing in the common or internal carotid artery of more than 40%.

RESULTS

Of 102 patients, 65 (63.7%) were men, and 37 (36.3%) were women (mean age, 72.4 years). Thirteen patients (12.7%) had bilateral CEAs. Intraoperative duplex US revealed abnormalities during 29 (25.2%) of 115 CEAs; 14 abnormalities (12.2%) were major and underwent immediate revision. No perioperative neurologic events or deaths occurred. Mean length of follow-up was 21.3 months (range, 1.3-72.6 months). Late neurologic events occurred in 2 patients, and 5 patients died during follow-up. All neurologic events and deaths were unrelated to the patients' carotid surgery. Twelve patients (11.8%) developed moderate restenosis (40%-69%). In 4 of these patients restenosis resolved during further follow-up. No patient developed severe recurrent carotid stenosis.

CONCLUSION

Morbidity and mortality following CEA with routine patch angioplasty and intraoperative duplex US appear to be low. Routine intraoperative duplex US detects correctable technical problems that subsequently lead to a low incidence of symptomatic stenosis. The low incidence of recurrent stenosis suggests that routine postoperative follow-up may not be necessary or cost-effective unless the patient has symptoms or a contralateral stenosis.

Long-term use of oral anticoagulants and the risk of fracture

BACKGROUND

Vitamin K participates in bone metabolism and, since oral anticoagulants antagonize vitamin K, their use may increase the risk of osteoporosis.

OBJECTIVE

To evaluate fracture risk at all skeletal sites following exposure to oral anticoagulants.

METHODS

In a population-based retrospective cohort study, 572 Olmsted County, Minnesota, women 35 years or older at their first lifetime venous thromboembolism event between 1966 and 1990 were followed up for fractures. Risk was assessed by comparing new fractures with the number expected from sex- and age-specific fracture incidence rates for the general population (standardized incidence ratio [SIR]).

RESULTS

Altogether, 480 fractures occurred during 6314 person-years of follow-up. Increasing exposure to oral anticoagulation was associated with an increased SIR for vertebral fractures: at less than 3 months of exposure, 2.4 (95% confidence interval [CI], 1.6-3.4); 3 to less than 12 months, 3.6 (95% CI, 2.5-4.9); and 12 months or more, 5.3 (95% CI, 3.4-8.0); and for rib fractures: at less than 3 months, 1.6 (95% CI, 0.9-2.7); 3 to less than 12 months, 1.6 (95% CI, 0.9-2.6); and 12 months or more, 3.4 (95% CI, 1.8-5.7). The data revealed no increased risk for other types of fractures. Oral anticoagulation for 12 months or more was an independent predictor of vertebral fractures (P = .009) and rib fractures (P = .02), but not other fractures.

CONCLUSIONS

Long-term exposure to oral anticoagulation is associated with an increased risk of vertebral and rib fractures. The mechanism by which this occurs is still unclear and needs further investigation.

Assessment of dysequilibrium after acoustic neuroma removal

OBJECTIVE

Published data evaluating the rate of dysequilibrium after acoustic neuroma removal are inconsistent. The purpose of this investigation was to determine the incidence and severity of dysequilibrium and quality of life in a group of patients after acoustic neuroma surgery.

STUDY DESIGN

The study design was a retrospective chart review and survey that included demographic and medical history questions, the Dizziness Handicap Inventory (DHI), the UCLA Dizziness Questionnaire (UCLA-DQ), and the Health Status Questionnaire (HSQ).

SETTING

The study was conducted in a multispecialty tertiary care clinic.

PATIENTS

Two hundred thirty-seven subjects who underwent initial surgical removal of an acoustic neuroma between January 1990 and June 1997 were studied.

MAIN OUTCOME MEASURES

Correlation of dysequilibrium with age, gender, and tumor size was measured. Survey analysis including DHI, UCLA-DQ, and HSQ scores.

RESULTS

Sixty-five percent of patients reported persistent dysequilibrium after surgery. A majority of those with dysequilibrium had DHI, UCLA-DQ, and HSQ scores that suggested minimal impact on the quality of life. The HSQ scores were statistically significantly poorer for the patients with dysequilibrium than for those without dysequilibrium.

CONCLUSIONS

Sixty-five percent of patients reported dysequilibrium after acoustic neuroma removal. The quality-of-life impact was mild.

Hip fractures among infertile women

A retrospective cohort study was conducted in a population-based inception cohort of 1,157 Olmsted County, Minnesota, women with infertility (failure to conceive after 1 year despite intercourse without contraception) that was first diagnosed at the Mayo Clinic (Rochester, Minnesota) between 1935 and 1964. In this relatively young cohort, 31 hip fractures were observed during 35,849 person-years of follow-up; 36.5 had been expected (standardized incidence ratio = 0.85, 95% confidence interval 0.58-1.20). Standardized incidence ratios did not differ by type or cause of infertility. The data suggested that women with consistently irregular menses may have a greater risk of hip fracture. This finding should be confirmed by additional studies with longer follow-up periods and with assessment of other fracture outcomes.