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PubMed2004

Estimating equations and tables for adult mid-arm circumference based on measured height and weight: data from the third National Health and Nutrition Examination Survey (NHANES III) and NHANES 1999-2000.

OBJECTIVE: Mid-arm circumference measurement is a prerequisite to selection of proper sized blood pressure (BP) cuffs and accurate BP readings. The purpose of this study was to develop practical prediction equations for estimating mid-arm circumference (AC) in adults using NHANES III & NHANES 1999-2000 data. DESIGN: Both surveys used a complex sample design to obtain nationally representative samples of the USA civilian non-institutionalized population. SUBJECTS: The analytic sample consisted of 5077 men and 5307 women from NHANES III and 2013 men and 2293 women from NHANES 1999-2000. Their height, weight, and mid-arm circumference were measured directly in both surveys. STATISTICAL ANALYSES: Weight, height, and age data from NHANES III were used for model building, and similar data from NHANES 1999-2000 were used for validation. An all-possible regressions procedure by gender was used to derive the prediction equations for AC. RESULTS: The final prediction equations for adult AC were as follows: for measured weight (wt) in kg and height (ht) in cm: Men, AC (cm)=31.76749+0.22626 x (wt) -0.10109 x (ht)+0.05092 x (age)-0.00081813 x (age), R=0.8; Women, AC (cm)=39.29946+0.26410 x (wt) -0.18230 x (ht) +0.01972 x (age)-0.00104 x (age) +0.00045901 x (wt x age) +0.00037509 x (ht x age), R=0.86. Tables of estimated arm circumference by age, weight and gender are presented. CONCLUSION: The prediction equations and tables provide for mid AC estimation using readily available clinical data to select the appropriate BP cuff.

Adult↗
PubMed1999

Complex sampling: implications for data analysis.

Investigators in dental public health often use strategies other than simple random sampling to identify potential subjects; however, their statistical analyses do not always take into account the complex sampling mechanism. Often it is not clear whether a given strategy requires adjustment for stratification and/or cluster sampling of observations. We propose that the need for such adjustment depends on the primary study objective. As a general rule, we recommend that if the study goal is to estimate the magnitude of either a population value of interest (e.g., prevalence), or an established exposure-outcome association, adjustment of variances to reflect complex sampling is essential because obtaining appropriate variance estimates is a priority. However, if the study goal is to establish the presence of an association, especially in a preliminary investigation of novel conditions or understudied populations, obtaining appropriate variance estimates may not be of primary importance; hence, adjustment of variances for complex sampling is not always required, but often is recommended. This paper describes several types of complex sampling designs, methods of adjusting for complex sampling strategies, examples illustrating the effect of adjustment, and alternative approaches for analysis of complex samples.

Analysis of Variance↗
PubMed1997

Tobacco use in Vietnam. Prevalence, predictors, and the role of the transnational tobacco corporations.

OBJECTIVE: To describe tobacco use in Vietnam and the impact of transnational tobacco corporations there. DESIGN: In cities, a multistage cluster design; in communes, a systematic sample design, using face-to-face interviews in all sites. SETTING: Hanoi, Ho Chi Minh City, and 2 rural communes in Vietnam. PARTICIPANTS: Random samples totaling 2004 men and women aged 18 years or older. MAIN OUTCOME MEASURES: Prevalence and correlates of tobacco smoking, amount and duration of smoking, age at initiation, quitting behavior, knowledge of health hazards of and attitudes toward smoking, and cigarette brand smoked, preferred, and recognized as most widely advertised. RESULTS: Smoking prevalence among men (n=970) was 72.8% and 4.3% among women (n=1031). Male smokers had smoked a mean of 15.5 years; the median age at initiation was 19.5 years. Among male smokers, 16% smoked non-Vietnamese cigarettes. More than twice as many (38%), however, said that they would prefer to smoke a non-Vietnamese brand if they could afford the cost. Among those who recalled any cigarette advertising (38%), 71% recalled a non-Vietnamese brand as the most commonly advertised. Male smokers who were significantly more likely to smoke non-Vietnamese brands lived in the south, were engaged in blue collar or business/service occupations, earned higher incomes, and lived in urban areas. CONCLUSIONS: Vietnam has the highest reported male smoking prevalence rate in the world. Unless forceful steps are taken to reduce smoking among men and prevent the uptake of smoking by youth and women, Vietnam will face a tremendous health and economic burden in the near future. Implementation of a comprehensive national tobacco control campaign together with international regulation will be the keys to the eradication of the tobacco epidemic in Vietnam and throughout the developing world.

Adult↗
PubMed2005

Built environment and behavior: spatial sampling using parcel data.

PURPOSE: The quality and economy of inferential research rely heavily on the sampling method. This paper addresses a methodological challenge in environment-behavior research: sampling respondents in relation to their built environmental characteristics. METHODS: A discussion of issues related to traditional neighborhood-based sampling serves to introduce a new spatial sampling strategy. Spatial sampling consists of defining conceptual population of interest, constructing spatial sample frame using parcel-level environmental data in GIS, examining the sample frame, determining the sampling design and size, and drawing the samples. An application of this method is illustrated using a recent study examining environmental correlates of walking and biking. RESULTS: Spatial sampling with parcel-level data ensures sufficient variations in and proper distributions of the environmental variables of interest, while controlling for the conditions of no interest. The use of the individual as unit of analysis offers an economic, generalizable, and easily interpretable approach to environment-behavior research, and discourages the potentially erroneous a priori definition of neighborhoods and aggregation problems. CONCLUSIONS: With its capacity to consider a broad range of detailed environmental variables, spatial sampling contributes to finding new or stronger environment-behavior associations and to the growing number of studies using the social ecologic model.

Bicycling↗
PubMed1997

Preparation of multilayered materials in cross-section for in situ TEM tensile deformation studies.

The success of in situ transmission electron microscopy experimentation is often dictated by proper specimen preparation and sample design procedures. We have developed a novel technique permitting the production of tensile specimens of multilayered films in cross-section for in situ deformation studies. Of primary, importance in the development of this technique is the production of an electron transparent micro-gauge section. This micro-gauge section predetermines the position at which plastic deformation, crack nucleation and growth, and failure are observed. In short, we report in detail, a unique combination of specimen preparation procedural steps and the design of a multilayer foil sample. The ability of these procedures to facilitate the success of in situ TEM tensile studies of layered materials in cross-section is demonstrated using a Cu-Zr multilayer foil.

Copper↗
PubMed2005

Determining ecoregions for environmental and GMO monitoring networks.

A representative environmental monitoring network at the regional scale cannot use raster-based or random sampling designs, but requires a stratified sampling procedure integrating different information layers, and it has to occur in ecologically differing homogeneous regions (ecoregions). These we have determined using a set of spatial strata with ecological variables which we analysed with classification and regression trees (CART). We present a framework for environmental monitoring, that covers different scales, and we transfer the framework to a potential GMO (genetically modified organisms) monitoring network. We use ecoregion and other environmental strata together with existing environmental monitoring networks to determine GMO monitoring sites more precisely.

Agriculture↗
PubMed1993

The animal specimens of terrestrial and limnetic ecosystems in the environmental specimen banking programme of Germany.

In the terrestrial and limnetic sampling areas of the Environmental Specimen Banking Programme of Germany five animal species were collected. The goal of this paper is to show first the concept and criteria of the specimen selection for Environmental Specimen Banking with regard to the function of the specimens in the concept of ESB which refers to the role of the species in the trophic levels of the different ecosystems. Secondly, the substantial parts of the sampling operation procedures like the sampling design and the procedure of sampling are shown for five animal specimens.

Animals↗
PubMed1993

Estimation of the numbers of trichostrongylid larvae on pastures.

Estimates of the density of larvae on herbage are used in epidemiologic studies to determine seasonal or monthly variations in contamination of pastures with third-stage larvae of the trichostrongyles, and to provide an index of the risk of exposure of grazing animals. Estimates of density are affected by many variables, including laboratory techniques, climate, forage types, and farm and animal management methods. Thus, a comparison of results given by different workers is not desirable. In obtaining and interpreting larval density estimates, it is important to standardize the technique over the period of observation. Because techniques for estimation of larvae are cumbersome and time-consuming, statistical design is often compromised. Herbage samples should be taken randomly and with sufficient replication to overcome the variability of the herbage sampling technique. Studies to determine an appropriate sampling design to obtain the best estimate for pastures of all sizes have not as yet been carried out.

Animal Feed↗
PubMed1990

Estimating the infectivity of HIV from partner studies.

The main sources of data for estimating infectivity of the human immunodeficiency virus (HIV) come from studies of the susceptible partners of individuals known to be infected with HIV. Estimation of infectivity from these studies is complicated by limitations imposed by the sampling designs. This paper reviews three sampling schemes that have been used in partner studies and, for each, proposes methods for estimating various theoretic models for infectivity. The methods, as well as procedures for checking goodness-of-fit, are illustrated using data from a study by Peterman and colleagues.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Household survey on drug abuse in Brazil: study involving the 107 major cities of the country--2001.

The prevalence of the use in Brazil of illicit drugs, as well as of alcohol and tobacco, was determined. Further, illicit use of psychotropic medicines, and anabolic steroids were also surveyed. This study was carried out in 107 Brazilian cities with more than 200,000 inhabitants aged 12-65 years. The sampling design adopted was that of sampling per aggregates in three stages: first, the census sectors were selected; second, homes were selected among the sectors; finally, in each home, a respondent was selected in a manner independent of the interviewer. There were 8589 persons interviewed. The questionnaire utilized was that of the SAMHSA (Substance Abuse and Mental Health Services Administration) which was translated and adapted for Brazilian conditions. The lifetime use of alcohol in the 107 major cities of the country was 68.7%, which was close to numbers observed for Chile at 70.8% and the USA at 81.0%. Yet, tobacco lifetime use was 41.1% of the total, which is lower than the prevalence observed in the USA (70.5%). The data on the lifetime use of marijuana in Brazil (6.9%) approximated the findings for Colombia (5.4%), however, being much lower than that observed in the USA (34.2%) and the United Kingdom (25.0%). The prevalence of lifetime use of cocaine was 2.3%, well below the levels for the USA with 11.2% of the total population. The abuse of inhalants was 5.8% of the total, greater than that found in Colombia (1.4%) and about four times less than that in the United Kingdom with 20.0%. Among the medicaments, stimulants had a 1.5% prevalence of lifetime use, and that of benzodiazepines had similar percentages in Brazil (3.3%) and in the USA (5.8%). In this survey, only four individuals reported lifetime use of heroin, which was equivalent to about 0.04% of the sample and much lower than that in the USA with 1.2% and in Colombia reaching 1.5%. These findings will allow the implementation of public policies fitted to the situation with psychotropic drugs in Brazil.

Adolescent↗
PubMed2005

Assessment of sociodemographic factors and socio-economic status affecting the coverage of compulsory and private immunization services in Istanbul, Turkey.

OBJECTIVES: The primary objective of this study was to determine the coverage of the Expanded Programme of Immunization (EPI) of the Ministry of Health and the coverage of private vaccines in the Umraniye Health District in order to establish approaches for improving vaccination services. Other objectives were to define the areas that present higher risks for non-vaccination and to determine the factors that influence vaccination coverage. METHODS: A '30 x 7' cluster sampling design was adopted as the sampling method. Thirty streets were selected at random from each health care region. Sociodemographic and socio-economic characteristics of the population, utilization of vaccination services and vaccination status of children under the age of 5 years were determined by face-to-face interviews. Odds ratios for the sociodemographic and socio-economic characteristics, health centre region and inner country immigration were assessed as possible related factors with the vaccination coverage rates for children under 5 years and under 1 year using the backward elimination method in logistic regression. RESULTS: Vaccination coverage was as follows: hepatitis B third dose, 84.6%; Bacille Calmette-Guérin, 94.8%; diphtheria, tetanus, pertussis (DPT) third dose, 90.1%; oral polio virus (OPV) third dose, 90.0%; measles, 88.7%; DPT booster dose, 79.1%; OPV booster dose, 79.0%; measles, mumps, rubella (MMR), 13.3%; haemophilus influenza type b (Hib), 9.3%; and Varicella vaccine, 3.3%. The full vaccination rates for children under 5 years and under 1 year were 68.3 and 79.5%, respectively. Higher socio-economic status was associated with a higher rate of full vaccination and private vaccination for children under 5 years of age. CONCLUSIONS: Full vaccination rates for children aged less than 1 year and less than 5 years were higher in our district than in Istanbul. However, we did not meet the EPI aims for any of the vaccines, and differences were observed in vaccination coverage rates between different socio-economic groups in the district. Therefore, an intervention programme should be considered to achieve the EPI's goals, particularly in socio-economically disadvantaged groups. Also, the coverage of private vaccination (MMR, Hib, Varicella) is low and more children from higher socio-economic groups receive these vaccines.

Adolescent↗
PubMed1999

Reference values of urinary excretion of cystine and dibasic aminoacids: classification of patients with cystinuria in the Valencian Community, Spain.

OBJECTIVE: Cystinuria is an autosomal-recessive disorder of the kidneys and small intestine affecting a luminal transport mechanism shared by cystine, ornithine, arginine, and lysine. Three different types of cystinuria can be distinguished according to the excretion of these amino acids in urine samples. We propose cutoff values from our population as references and we present a classification of cystinuric patients using quantitative amino acid chromatography in first morning urine samples. DESIGN AND METHODS: A random sample of forty healthy subjects belonging to general population of the Valencian Community were selected as control subjects. Cystine, lysine, arginine, and ornithine were quantified by reverse-phase HPLC. Seventy-two subjects, diagnosed previously as cystinuric by the cyanide-nitroprusside test were classified. Probands excreting more than 113.12 micromol cystine per mmol of creatinine (i.e., 1,000 micromol cystine per gram of creatinine) were classified as homozygotes. Parents of homozygotes in whom excretion of amino acids were normal were classified as heterozygotes type I. Those probands showing the excretion of at least one amino acid and the sum of urinary cystine plus the basic amino acids higher than the corresponding references ranges in our population were classified as heterozygotes type II or type III (heterozygotes non-type 1). RESULTS: We identified 24 homozygotes, 39 non-type I heterozygotes and 3 type I heterozygotes. The remaining 6 probands could not be classified. Means for cystine, lysine, arginine ornithine and their sum in homozygotes and heterozygotes non-type I were significantly (p < 0.001) in excess of the respective reference ranges. Moreover, means values in homozygotes were statistically different (p < 0.001) from heterozygotes non-type I. CONCLUSION: Urinary excretion of cystine per mmol creatinine allow us to distinguish heterozygotes from homozygotes. However, the best discriminator to distinguish non-type I heterozygotes from normal population might be the excretion of lysine per mmol creatinine. Additional studies including characterization of appropriate haplotypes should be carried out for a more precise identification of types of cystinuria.

Adolescent↗
PubMed1991

Utility and predictive value of a rapid measurement of urinary pregnanediol glucuronide by enzyme immunoassay in an infertility practice.

STUDY OBJECTIVE: To assess the clinical utility of measuring urinary pregnanediol glucuronide in random samples in an infertility practice. DESIGN: Samples of urine were collected from patients approximately 3 weeks from their last menstrual period to ascertain if ovulation had occurred. Each sample was tested for specific gravity before analyzing for pregnanediol glucuronide. Simultaneous venipuncture was performed to compare results from the urinary assay to quantitative measures of serum progesterone (P). SETTING: All patients were randomly sampled. PATIENTS: Three hundred ninety women undergoing pituitary down regulation with leuprolide acetate were chosen for study because they routinely initiate medication after documentation of ovulation. OUTCOME MEASURES: The performance of the urinary pregnanediol glucuronide was evaluated as to its sensitivity, specificity, predictive value, and test efficiency compared with a serum measurement of 2.5 ng/mL and 10.0 ng/mL. RESULTS: The performance characteristics of the pregnanediol glucuronide assay were directly related to the hydration status of the patient at the time of sample collection. Regardless of urine specific gravity, if pregnanediol glucuronide was qualitatively detected (greater than 3 micrograms/mL), serum P was greater than 2.5 ng/mL. However, in cases in which pregnanediol glucuronide was undetected (less than 3 micrograms/mL), results were only accurate when the specific gravity was greater than or equal to 1.020. When comparing urinary pregnanediol glucuronide values to serum greater than 10 ng/mL, both specificity and predictive value of a positive test decreased because of increased numbers of false-positive results. CONCLUSIONS: The enzyme immunoassay measurement for pregnanediol glucuronide may replace the use of serum P in documenting the ovulatory status of many patients. However, all specimens must be checked for specific gravity and if less than 1.020, a serum P should be used to ensure accuracy.

Female↗
PubMed2003

Gender inequalities, intimate partner violence and HIV preventive practices: findings of a South African cross-sectional study.

The aim of the paper is to investigate associations between a range of markers of gender inequity, including financial, psychological and physical violence, and two proximal practices in HIV prevention, namely discussion of HIV between partners and the woman suggesting condom use. The paper presents an analysis of data from a cross-sectional study of a representative sample of women from three South African Provinces which was primarily undertaken as an epidemiological study of gender-based violence. A multi-stage sampling design was used with clusters sampled with probability proportional to number of households. Households were randomly selected from within clusters. One randomly selected woman aged 18-49 years was interviewed in each selected home. One thousand three hundred and six women were interviewed (90.3% of eligible women). One thousand one hundred sixty four women had a partner in the previous year and were asked questions related to HIV prevention and gender inequalities in the relationship. The results indicate that discussion of HIV was significantly positively associated with education, living in Mpumalanga Province, the man being a migrant, the woman having multiple partners in the past year and having no confidante. It was significantly negatively associated with living in the Northern Province, the relationship being poor and there being a substantial age difference between partners. The woman suggesting condom use was significantly positively associated with her education, her having multiple partners, domestic violence prior to the past year and financial abuse. It was negatively associated with the relationship being poor. We conclude that this suggests that some indicators of gender inequalities are significantly associated with discussion of HIV and condom use but the direction of association found was both positive and negative. This highlights the need for a more nuanced understanding of gender inequalities and their relationship to HIV risk. Suggestions for key research questions are made.

Adolescent↗
PubMed2000

A limited sampling strategy for determining carboplatin AUC and monitoring drug dosage.

There are several convincing reports showing relationships between the area under the curve of ultrafilterable concentration versus time (AUC) and pharmacodynamics of carboplatin. It is advisable, in treated patients, to check the AUC that is effectively delivered as compared with the prescribed AUC. To this end, limited sampling strategy seems to be an adequate approach since it limits the constraints of repeated blood sampling for both patients and nursing staff. A flexible limited sampling method for assessing ultrafilterable carboplatin AUC was developed. This method was based on a Bayesian estimation of carboplatin clearance using the NON linear Mixed Effect Model (NONMEN) program and a large pharmacokinetic and covariates database (103 patients). The optimal sampling design was a two-sample schedule (1 and 4 h after the end of infusion). During a prospective evaluation, it allowed an adequate estimation of carboplatin clearance with a non-significant bias (-4.5%) and a good precision (9%). In a second stage, this method was clinically applied to monitor carboplatin AUC in a group of 5 patients with metastatic germ cell tumours treated with intensified high dose carboplatin-based chemotherapy for 4 days. Dosage adjustments were performed according to daily controls of their AUC in order to obtain a total AUC of 20 mg/ml x min. By using this strategy all patients effectively received a total AUC very close to this targeted AUC, thus proving the clinical usefulness of this limited sampling method.

Antineoplastic Agents↗
PubMed2005

US demographic trends in mid-arm circumference and recommended blood pressure cuffs: 1988-2002.

Mid-arm circumference (AC) measurement is a prerequisite for the selection of properly sized blood pressure (BP) cuffs and accurate BP readings. This study examined trends in the frequency distribution of mid-AC and corresponding recommended BP cuff sizes using National Health and Nutrition Examination Survey (NHANES) III (1988-1994) and NHANES 1999-2002 data. Both surveys used a complex sample design to obtain nationally representative samples of the civilian noninstitutionalized US population. The sample consisted of 7453 men and 8372 women from NHANES III and 4295 men and 4838 women from NHANES 1999-2002. Mean mid-AC (cm) and associated American Heart Association-defined cuff sizes were assessed. Variables were analysed by gender, age, race/ethnicity, and by hypertension or diabetic co-morbidity. Mid-AC increased significantly between surveys for all age groups; the greatest increase in mid-AC occurred in the 20-39 year age group. Data from NHANES 1992-2002 show that among nonHispanic white and nonHispanic black men aged 20-59 years, the mean mid-AC was >34 cm. Among NHB women aged 40 years and above, the mean mid-AC was greater than or equal to 34 cm. In all, 42% of all men and 26% of all women aged 40-59 years required large BP cuffs. In all, 39% of individuals classified as hypertensive and 47% of self-reported diabetics required a BP cuff greater than the standard adult size. In conclusion, mean mid-AC has increased across many demographic subgroups in the US with implications for the accuracy of BP measurement in clinical practice.

Adult↗
PubMed2004

Strong population structure in the marine sponge Crambe crambe (Poecilosclerida) as revealed by microsatellite markers.

Different categories of molecular markers have been used so far to study the population structure of sponges. However, these markers often did not have the resolution power to address precisely questions on structuring processes, especially at the intrapopulational level. In this study we show that microsatellites fulfil these expectations, allowing a fine description of population structure at different geographical scales in the marine sponge Crambe crambe. Specimens were collected in 11 locations, representing most of the Atlanto-Mediterranean range of the species, and were analysed at six loci. As expected for a sessile invertebrate with lecitotrophic larvae, high levels of between-population structure were found (FST = 0.18) and a significant isolation-by-distance pattern was observed. A strong genetic structure was also found within sampled sites (FIS = 0.21) that may be explained by several factors including inbreeding, selfing and the Wahlund effect. In spite of a sampling design planned to avoid the sampling of clones, genotypically identical individuals for the six loci were found in some locations. The significance of these potential clones is discussed and their effect on the observed pattern of population structure assessed. Patterns of allelic distribution within populations suggest the possibility of a recent colonization of the Atlantic range from the Mediterranean Sea.

Animals↗
PubMed2001

Environmental assessment of a site contaminated by organic compounds.

This paper presents a study on environmental assessment of an abandoned industrial area located in central Italy. Main production was refractory materials and compounds for treatment of industrial wastewater. The present work deals with a methodology for development of a sound sampling design, chemical characterization of soil samples, definition of the degree of site contamination according to law limits and evaluation of the fate and transport of contaminants by EPA simulation model (VLEACH 2.2a). Results indicate that toxic compounds (polycyclic aromatic hydrocarbons and plasticizers) are uniformly distributed in the contaminated site and only in one sampling point their concentrations exceed law limits. Modeling results confirm that contaminants migration to groundwater can be excluded, addressing for a site remediation limited to the surface layer.

Environmental Monitoring↗