A list of device-specific thresholds for the clinical interpretation of peripheral x-ray absorptiometry examinations

The UK National Osteoporosis Society (NOS) has recently issued new guidelines on the use of peripheral x-ray absorptiometry (pDXA) devices in managing osteoporosis. The NOS guidelines recommend a triage approach in which patients bone mineral density (BMD) measurements are interpreted using upper and lower thresholds specific to each type of pDXA device. The thresholds are defined so that patients with osteoporosis at the hip or spine are identified with 90% sensitivity and 90% specificity. Patients with a pDXA result below the lower threshold are likely to have osteoporosis at the hip or spine, patients with a result above the upper threshold are unlikely to have osteoporosis, while those between the two thresholds require a hip and spine BMD examination for a definitive diagnosis. This report presents data from a multicenter study to establish the triage thresholds for a range of pDXA devices in use in the UK. The subjects were white female patients aged 55–70 years who met the normal referral criteria for a BMD examination. For each device, at least 70 women with osteoporosis at the hip or spine and 70 women without osteoporosis were enrolled. All women had hip and spine BMD measurements using axial DXA systems that were interpreted using the National Health and Nutrition Examination Survey (NHANES) reference range for the hip and the manufacturers reference ranges for the spine. Data are presented for five different devices: the Osteometer DTX-200 (forearm BMD), the Schick AccuDEXA (hand BMD), the GE Lunar PIXI (heel BMD), the Alara MetriScan (hand BMD), and the Demetech Calscan (heel BMD). The clinical measurements were supplemented by theoretical modeling to estimate the age dependence of the triage thresholds and the effect of the correlation coefficient between pDXA and axial BMD on the percentage of women referred for an axial BMD examination. In summary, this study provides thresholds for implementing the new NOS guidelines for managing osteoporosis using pDXA devices. The figures reported apply to postmenopausal white women aged 55–70 years who meet the conventional criteria for a BMD examination. The results confirm that the thresholds are specific to each type of pDXA device and that the NOS triage algorithm requires 40% of women to have an axial DXA examination.On behalf of the National Osteoporosis Society Bone Densitometry Forum.     

An emancipatory study of contemporary nursing practice

Changes in health care facilities have created the necessity for individual nurses to change, eg, change jobs, pursue additional education, become independent entrepreneurs. There is a shortage of nurses that places stress on those who remain to care for an increasing number of persons with too few resources. The purposes of this study were to explore nurses' perceptions of the circumstances of their work lives and to describe the processes by which they can create change in these circumstances. The methodology was an emancipatory design combining tenets of critical inquiry and feminist research. The method used was a dialectical process of reflection and action (praxis). Three diverse groups of nurses met weekly over 6-10 weeks. Using the group process method, each group reflected on, discussed, and analyzed the phenomenon of practicing nursing today. The outcome of an emancipatory study is reflected in the power of the process. The group interaction increased awareness, promoted reflection on the status quo, and energized the groups to derive possible solutions to changing that status quo. It is not the solutions themselves that are as relevant as is the obvious cogency of the process to achieve individual and group emancipation. Six codifications reflected the themes that emerged and 5 processes for exploring untested feasibilities for change were identified. The participants perceived themselves more as subjects in their history than objects to be manipulated, capable of transforming a rather dismal situation of nursing practice into one that was critical, creative, and freer from constraints. The implication of this study is that nurses are encouraged to adopt and adapt this process of group interaction because of its demonstrated credibility to empower and validate the role that nurses have to derive and implement solutions to change their unsatisfactory status quo.     

The ageing phenome: caloric restriction and hormones promote neural cell survival, growth, and de-differentiation

The phenome represents the observable properties of an organism that have developed under the continued influences of both genome and environmental factors. Phenotypic properties are expressed through the functions of cells, organs and body systems that operate optimally, close to equilibrium. In complex organisms, maintenance of the equilibrium is achieved by the interplay of several regulatory mechanisms. In the elderly, dynamic instability may lead to progressive loss of normal function, failure of adaptation and increased pathology. Extensive research (reported elsewhere in this journal) has demonstrated that genetic manipulations of endocrine signaling in flies, worms and mice increase longevity. Another effective strategy for prolonging the lifespan is caloric restriction: in data presented here, the persistence of estrogen-sensitive cells in the hypothalamus of caloric restricted 22-month-old female mice, may explain the persistence of reproductive function at an age, when reproductive function has long ceased in ad libitum fed controls. Still another strategy utilizes the effects of epidermal growth factor (EGF) to promote in vitro proliferation of neuroglia, astrocytes and oligodendrocytes. Their subsequent de-differentiation generates immature precursor cells potentially capable of differentiating into neuroblasts and neurons. These and other examples suggest that, in terms of functional outcomes, "the genome proposes but the phenome disposes".     

Patterns of intra-cluster correlation from primary care research to inform study design and analysis

OBJECTIVE: To provide information concerning the magnitude of the intraclass correlation coefficient (ICC) for cluster-based studies set in primary care. STUDY DESIGN AND SETTING: Reanalysis of data from 31 cluster-based studies in primary care to estimate intraclass correlation coefficients from random effects models using maximum likelihood estimation. RESULTS: ICCs were estimated for 1,039 variables. The median ICC was 0.010 (interquartile range [IQR] 0 to 0.032, range 0 to 0.840). After adjusting for individual- and cluster-level characteristics, the median ICC was 0.005 (IQR 0 to 0.021). A given measure showed widely varying ICC estimates in different datasets. In six datasets, the ICCs for SF-36 physical functioning scale ranged from 0.001 to 0.055 and for SF-36 general health from 0 to 0.072. In four datasets, the ICC for systolic blood pressure ranged from 0 to 0.052 and for diastolic blood pressure from 0 to 0.108. CONCLUSION: The precise magnitude of between-cluster variation for a given measure can rarely be estimated in advance. Studies should be designed with reference to the overall distribution of ICCs and with attention to features that increase efficiency.     

Social inequalities and children's height in Trinidad and Tobago

OBJECTIVE: The aim of the study was to report the association of socio-economic factors with child's height. DESIGN: Cross-sectional study based on a representative national sample of government schools. SETTING: Trinidad and Tobago in 1999. SUBJECTS: A total of 2608 boys and girls mean age 5.8 y, range 4.38-6.99 y and 3080 mean age 8.6 y, range 7.00-10.44 y olds. OUTCOME: Measurement of height and a questionnaire completed by parents. In the analysis height was expressed as standard deviation scores (s.d.s.) based on the British height curves (1990) or height below -1.5 s.d.s. RESULTS: Ethnicity, parental heights, birthweight, maternal age at child's birth and number of children in the family were the main factors associated with children's height. Lack of piped water supply in the home was the only socio-economic factor consistently associated with height (mean difference in s.d.s. adjusted only for age group, gender and ethnicity -0.192, 95% CI -0.257 to -0.127 and in addition adjusted for the variables listed above -0.080, 95% CI -0.141 to -0.019). Parental education, household overcrowding and employment status were weakly associated with height in the partially adjusted model only. Analysis of severe growth failure gave similar results. CONCLUSION: The impact of socio-economic factors on height is marginal in Trinidad and Tobago. As socio-economic factors may have an impact on a broad range of health indicators, height and rates of undernutrition should not be used as sole criteria for assessing progress in decreasing health differentials caused by social inequalities.