Review of some computer software packages for dietary analysis

The increasing use of computers in dietetics has been matched by an increase in the number and types of software packages available. The functions which 'dietetic' software can carry out vary widely, and certain information is essential for the dietitian looking for a package for clinical or research work.
Where dietary analyses are carried out, the number of foods listed in the database and the accuracy with which cooking method, for example, can be specified are vital.
This mini-series of reviews examines several packages on the market. They carry out a variety of tasks, including dietary analyses and menu planning.
Demonstration disks can usually be obtained, allowing interested dietitians to examine the package in greater detail.     

缺失数据插补方法及其在医学领域的应用研究

统计学在医学研究中起着重要的作用,选择合适的统计学方法对于医学研究能否得出可靠和有价值的结论至关重要。本文简要介绍常用的医学数据统计分析方法,包括描述性分析、参数检验、非参数检验、相关分析、回归分析和生存分析。重点讨论多重线性回归、logistic回归、Cox比例风险回归的假设以及针对不同的研究目标和数据类型来选择合适的统计方法来分析和解释医学数据。

     

On the statistical analysis of allelic-loss data

This paper concerns the statistical analysis of certain binary data arising in molecular studies of cancer. In allelic-loss experiments, tumour cell genomes are analysed at informative molecular marker loci to identify deleted chromosomal regions. The resulting binary data are used to infer properties of putative suppressor genes, genes involved in normal cell cycling. Various factors can complicate this inference, including background loss of heterozygosity, spatial (that is, within chromosome) dependence of the binary responses, non-informativeness of markers, covariates such as protein levels or tumour histology, heterogeneity of cells within tumours, and measurement error. We focus on the first three factors, discussing methods for statistical inference that separate background loss from significant loss. We outline the extension to other inferences, such as comparison questions and the relationship to covariates. Using characteristic features of tumourigenesis, we present a framework for the stochastic modelling of allelic-loss data, and build models within this framework; in particular, we propose a simple model that has chromosome breaks at locations of a Poisson process, and preferential selection cells with inactivated suppressor genes. We illustrate these methods on allelic-loss data from induced rat mammary tumours and human bladder cancers. © 1998 John Wiley & Sons, Ltd.     

Appropriate statistical methods are required to assess diagnostic tests for replacement,add-on,and triage

ObjectiveTo explain which measures of accuracy and which statistical methods should be used in studies to assess the value of a new binary test as a replacement test, an add-on test, or a triage test.Study Design and SettingSelection and explanation of statistical methods, illustrated with examples.ResultsStatistical methods for comparative diagnostic accuracy studies are described that take into account the purpose of the new diagnostic test. Methods are described within a framework that defines the major purpose of test comparison: assessing the value of a new test as a replacement test, an add-on test, or a triage test. Methods appropriate for both unpaired and paired study designs for binary test data are given, including regression modeling of diagnostic test accuracy. Implications for efficient study designs are also discussed.ConclusionsAppropriate selection of existing statistical methods is necessary to address research questions about the comparative accuracy of new tests.     

Comparison of software programs for data analysis of complex surveys

OBJECTIVE: To compare specific software programs for data analysis of complex surveys regarding the following characteristics: ease of application, computer efficiency and accuracy of the results. METHODS: Secondary data from the Pesquisa Nacional sobre Demografia e Saúde (National survey on demography and health) (1996) with a target population of women aged 15 to 49 years old were used. This was a probabilistic subsampling drawn in two stages, then stratified, with the probability proportional to size in the first stage. The northern and mid-western regions of the country were selected for the study. The parameters of interest were mean for the age variable, and the proportion for five other qualitative variables. The software programs used were Epi Info, Stata and WesVarPC. RESULTS: The programs have two common options for the files import: the dBASE and text type files. The number of steps previous to the execution of the analyses were twenty- one for Epi Info, eleven for Stata and nine for WesVarPC. Efficiency was high for all them, that is, less that three seconds. The standard errors estimated using Epi Info and Stata were the same, with approximation up to the third decimal; those for WesVarPC were generally higher. CONCLUSIONS: Epi Info is the most limited software program regarding the analyses currently performed; however it is easy to use and free. Stata and WesVarPC are far more complete, however the disadvantage is their cost. The choice of the software program will depend mainly on the user's specific needs.     

From food databases to dietary assessment: A beginning to an end approach for quality nutrition data

Aim: This paper reviews the historical basis of modern assessment of nutrient composition—from food composition tables and the transition to nutrient databases. Method: A narrative review was formed beginning with the first, very crude printed food composition tables, to electronic food databases and continuing to how dietary assessment is currently impacted by state‐of‐the‐art techniques and what that means for food composition. Results: A plethora of studies, especially international studies, have utilised information from food composition via nutrient databases and software designed to extract food composition data into relevant files for dietary assessment. The United States Department of Agriculture's nutrient data bank is widely used, even internationally, and concerns about its appropriateness in other locales needs to be addressed. A number of countries have developed food composition databases unique to the foods of their population. International studies realised a number of problems related to inconsistencies between countries. Essentially, high‐quality food composition data requires up‐to‐date information on food supply, supplement use and potential food contaminants. Food composition tables form the basis for data published on nutrient intakes of individuals via food diaries, food recalls and surveys and, in addition, nutrient claims for some food products; thus, accuracy and reliability are paramount. New tools in dietary assessment, such as food photography, make nutrient assessment more widely available, requiring even more attention paid to the accuracy of food composition databases. Conclusions: The globalisation of food sources and the need for continuity regarding dietary data present challenges needing reconciliation. International concepts for food composition tables have evolved to address these problems.     

Food and dietary supplement databases for What We Eat in America-NHANES

Relative strengths and potential approaches for improvement of food and dietary supplement databases used for tabulating intakes from the dietary component of the What We Eat in America-National Health and Nutrition Examination Survey (NHANES) are discussed. The U.S. Department of Agriculture's Nutrient Data Laboratory develops and maintains the Nutrient Databank System (NDBS) and many nutrient-specific and population-specific databases. NDBS contains data for approximately 8,000 foods and approximately 115 components; tables for compounds of special interest are also available. Nutrient databases need constant revision because of a constantly changing food supply. The completeness of analytical data varies from nutrient to nutrient. The National Center for Health Statistics developed and maintains a database of dietary supplements based on label information. To date, no verification of ingredients has been undertaken. The development of a dietary supplement database containing analytical values would require extensive resources but would be valuable. Databases for vitamin and mineral supplements are compatible with food databases. Databases for botanicals and other supplements include nonnutrient constituents that may not be documented in food composition databases. Gaps in food and dietary supplement composition data exist because of limited resources, changing availability of foods and products and the advent of new compounds of health interest. More data are needed on nutrients and other bioactive constituents in foods and dietary supplements. Analytical methods do not exist for all ingredients or active constituents in foods and dietary supplements. Research needs for further development of meaningful food and dietary supplement databases are similar.     

Discrimination of human semen specimens by NMR data,sperm parameters,and statistical analysis

Abstract

Human seminal fluid is a complex mixture of secretions originated from epididymis and the male accessory sex glands. It contains a variety of both inorganic and organic components, among which proteins are a major part of the high molecular-mass substances. In this study, 83 human seminal plasma samples were analyzed using a combined Nuclear Magnetic Resonance (NMR) Spectroscopy and Principal Component Analysis (PCA) approach to discriminate patients in relation to semen characteristics and/or conditions affecting the fertility status. Results showed a discrimination between patients with leukocytospermia and with the concomitant presence of varicocele/ex varicocele and leukocytospermia. Patients with testicular cancer, necrozoospermia, and azoospermia were separated from the other patient clusters. In addition, a differentiation of semen quality was also possible. This study represents to first use of sperm parameters together with NMR data as variables in the PCA analysis. Furthermore, this methodology allows the identification of the metabolites which play the most important role in identifying differences among human seminal plasma samples.     

Current regulatory status of foods for special dietary uses.

The Food and Drug Administration has redefined foods for "special dietary use". Such foods must now: (1) Supply a special dietary need that exists by reason of a physical or physiological condition, such as convalescence, a pregnancy, lactation, or by reason of a specific disease or disorder; (2) Supply a vitamin, mineral, or other dietary property to supplement diet by increasing total dietary intake; (3) Meet a special nutritional need as the sole item of the diet. The stricter definition of this category of food means that the conventional foods with added nutrients or food for which nutritional claims are made or nutritional information provided will no longer be considered as foods for special dietary uses, although they must conform to standard nutritional labeling requirements. The new regulation establishes a clearly delineated position within which the consumer, industry, and FDA can deal with special dietary foods without the past confusion as to what belonged in this category.     

Sensitivity analysis for healthcare models fitted to data by statistical methods

After fitting complex models to data using statistical methods, a sensitivity analysis can be carried out. This determines which parts of a model are causing the bulk of the uncertainty in the model predictions (model output), and is a decision-support tool for the modeller who contemplates refining a model further or collecting additional data. A simple methodology for carrying out a sensitivity analysis is described. It is envisaged that such a relatively quick insight-generating step would precede the use of a more formal decision-theoretic approach that would address specific questions. Its use is illustrated using a model for breast cancer screening previously published in this journal. A simpler 3-parameter screening model is used in a simulation study of the error of the method as a function of sample size.     

Methods for the statistical analysis of binary data in split-mouth designs with baseline measurements

Many split-mouth trials are characterized by the pairing of site-specific outcome and baseline data within each segment of a subject's mouth. However when the response variable of interest is binary, methods of statistical analysis for this design are not well developed. In this paper we present several analytic approaches that may be taken to the resulting data, showing how the efficiency of statistical inferences can be improved by appropriately incorporating the baseline information. The advantages and disadvantages of the different approaches are discussed in the context of an example from the published literature. The results from a limited simulation study are also presented.     

HIV seroprevalence surveys of childbearing women--objectives, methods, and uses of the data

A seroprevalence survey of human immunodeficiency virus (HIV) among childbearing women is being conducted in 43 States and Territories as one of the family of HIV seroprevalence surveys. This blinded survey, in which serologic test results are not linked to identifiable persons, uses neonatal dried blood specimens on filter paper to test for maternal antibodies to HIV. This survey provides relatively unbiased estimates of prevalence of HIV infection in the population of women delivering live children during given survey periods, by month or quarter of delivery, geographic area, and demographic subgroup. This objective will be met while protecting the integrity and efficient conduct of neonatal screening programs and ensuring patient anonymity. Information from this survey will be used to (a) assess the levels and trends of HIV infection in women and infants, (b) help develop and evaluate prevention programs, and (c) project the number of women and children who will develop HIV infection and the acquired immunodeficiency syndrome (AIDS) and will require health care and social services in the future.     

A review of uses of health care utilization databases for epidemiologic research on therapeutics

OBJECTIVE: Large health care utilization databases are frequently used in variety of settings to study the use and outcomes of therapeutics. Their size allows the study of infrequent events, their representativeness of routine clinical care makes it possible to study real-world effectiveness and utilization patterns, and their availability at relatively low cost without long delays makes them accessible to many researchers. However, concerns about database studies include data validity, lack of detailed clinical information, and a limited ability to control confounding. STUDY DESIGN AND SETTING: We consider the strengths, limitations, and appropriate applications of health care utilization databases in epidemiology and health services research, with particular reference to the study of medications. CONCLUSION: Progress has been made on many methodologic issues related to the use of health care utilization databases in recent years, but important areas persist and merit scrutiny.     

Categorizing variables in the statistical analysis of data: consequences for interpreting the results]

Frequently during the process of data analysis in epidemiological studies, the scale of one or more continuous variables is changed. The objective of this paper was to assess the consequences of categorizing variables during data analysis. We studied three situations with different scenarios for statistical analysis with regression models. The results show that dichotomizing continuous variables can substantially modify the relationships between dependent and independent variables. Thus, for example, in epidemiological studies trying to evaluate the effect of an exposure on a response, the magnitude and/or the direction of this effect can be biased by dichotomizing a variable. We therefore recommend avoiding, as much as possible, the categorization of variables when doing analyses.     

小儿烧伤致伤因素及院前急救统计分析

目的了解小儿烧伤的致伤因素和院前急救现状.方法对十年来两家医院收治的小儿烧伤1403例按年龄、原因、场所以及院前急救进行回顾性分析.结果小儿烧伤以0～3岁居多(占57.09%);热液烫伤比例大(占70.28%);家庭为烧伤主要场所(占78.12%);院前急救失误普遍存在,其中创面处理不当、未建立有效静脉通道和人为原因延误治疗比例较大.结论小儿烧伤有一定规律,院前急救应加以重视.     

A structured vocabulary for indexing dietary supplements in databases in the United States

Food composition databases are critical to assess and plan dietary intakes. Dietary supplement databases are also needed because dietary supplements make significant contributions to total nutrient intakes. However, no uniform system exists for classifying dietary supplement products and indexing their ingredients in such databases. Differing approaches to classifying these products make it difficult to retrieve or link information effectively. A consistent approach to classifying information within food composition databases led to the development of LanguaL?, a structured vocabulary. LanguaL? is being adapted as an interface tool for classifying and retrieving product information in dietary supplement databases. This paper outlines proposed changes to the LanguaL? thesaurus for indexing dietary supplement products and ingredients in databases. The choice of 12 of the original 14 LanguaL? facets pertinent to dietary supplements, modifications to their scopes, and applications are described. The 12 chosen facets are: product type; product source; part of source; physical state, shape or form; ingredients; preservation method; packing medium; container or wrapping; contact surface; label claims/consumer group/dietary use; geographic places and regions; and adjunct characteristics of dietary supplements.