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PubMed2005

End-of-life care in black and white: race matters for medical care of dying patients and their families.

OBJECTIVES: To compare the end-of-life medical care experienced by African-American and white decedents and their families. DESIGN: Cross-sectional, retrospective survey with weighted results based on a two-stage probability sampling design. SETTING: Hospitals, nursing homes, and home-based medical services across the United States. PARTICIPANTS: Surrogates (N=1,447; primarily family members) for decedents from 22 states. MEASUREMENTS: Validated end-of-life care outcomes concerning symptom management, decision-making, informing and supporting families, individualized care, coordination, service utilization, and financial impact. RESULTS: Family members of African-American decedents were less likely than those of white decedents to rate the care received as excellent or very good (odds ratio (OR)=0.4). They were more likely to report absent (OR=2.4) or problematic (OR=1.9) physician communication, concerns with being informed (OR=2.5), and concerns with family support (OR=2.6). Family members of African Americans were less likely than those of whites to report that the decedent had treatment wishes (OR=0.3) or written advance care planning documents (OR=0.4). These differences persist when limiting the sample to respondents whose expectations for life-sustaining treatments matched treatments received. Family members of African-American decedents also were more likely to report financial hardship due to savings depletion (OR=2.1) or difficulty paying for care (OR=2.0) and that family/friends (OR=2.0) or home health workers (OR=1.9) provided home care. CONCLUSION: This national study brings evidence that racial disparities persist into end-of-life care, particularly regarding communication and family needs. Results also suggest different home care patterns and levels of financial impact.

Aged↗
PubMed2002

Optimal designs of two-stage studies for estimation of sensitivity, specificity and positive predictive value.

The cost efficiency of estimation of sensitivity, specificity and positive predictive value from two-stage sampling designs is considered, assuming a relatively cheap test classifies first-stage subjects into several categories and an expensive gold standard is applied at stage two. Simple variance formulae are derived and used to find optimal designs for a given cost ratio. The utility of two-stage designs is measured by the reduction in variances compared with one-stage simple random designs. Separate second-stage design is also compared with proportional allocation (PA). The maximum percentage reductions in variance from two-stage designs for sensitivity, specificity and positive predictive value estimation are P per cent, (1-P) per cent and W, respectively, where P is the population prevalence of disease and W the population percentage of test negatives. The optimum allocation of stage-two resources is not obvious: the optimum proportion of true cases at stage two may even be less than under PA. PA is near optimal for sensitivity estimation in most cases when prevalence is low, but inefficient compared with the optimal scheme for specificity.

Asthma↗
PubMed2006

Prevalence of visual impairment in the United States.

CONTEXT: The prevalence of visual impairment in the US public has not been surveyed nationally in several decades. OBJECTIVE: To estimate the number of US individuals aged 12 years or older who have impaired distance vision due to uncorrected refractive error. DESIGN, SETTING, AND PARTICIPANTS: The National Health and Nutrition Examination Survey (NHANES), using a multistage probability sampling design, included a vision evaluation in a mobile examination center. Visual acuity data were obtained from 13,265 of 14,203 participants (93.4%) who visited the mobile examination center in 1999-2002. Visual impairment was defined as presenting distance visual acuity of 20/50 or worse in the better-seeing eye. Visual impairment due to uncorrected refractive error was defined as (presenting) visual impairment that improved, aided by automated refraction results, to 20/40 or better in the better-seeing eye. MAIN OUTCOME MEASURES: Presenting distance visual acuity (measured with usual corrective lenses, if any) and distance visual acuity after automated refraction. RESULTS: Overall, 1190 study participants had visual impairment (weighted prevalence, 6.4%; 95% confidence interval [CI], 6.0%-6.8%), and of these, 83.3% could achieve good visual acuity with correction (95% CI, 80.9%-85.8%). Extrapolating these findings to the general US population, approximately 14 million individuals aged 12 years or older have visual impairment (defined as distance visual acuity of 20/50 or worse), and of these, more than 11 million individuals could have their vision improved to 20/40 or better with refractive correction. CONCLUSIONS: Visual impairment due to uncorrected refractive error is a common condition in the United States. Providing appropriate refractive correction to those individuals whose vision can be improved is an important public health endeavor with implications for safety and quality of life.

Adolescent↗
PubMedDate not supplied

Analysis of the National Health and Nutrition Examination Survey. Comment on "Prevalence of visual impairment in the United States", by S Vitale, MF Cotch, and RD Sperduto. JAMA 295:2158-63, 2006.

CONTEXT: The prevalence of visual impairment in the U.S. public has not been surveyed nationally in several decades. OBJECTIVE: To estimate the number of U.S. individuals aged 12 years or older who have impaired distance vision due to uncorrected refractive error. DESIGN, SETTING, AND PARTICIPANTS: The National Health and Nutrition Examination Survey (NHANES), using a multistage probability sampling design, included a vision evaluation in a mobile examination center. Visual acuity data were obtained from 13,265 of 14,203 participants (93.4%) who visited the mobile examination center in 1999-2002. Visual impairment was defined as presenting distance visual acuity of 20/50 or worse in the better-seeing eye. Visual impairment due to uncorrected refractive error was defined as (presenting) visual impairment that improved, aided by automated refraction results, to 20/40 or better in the better-seeing eye. MAIN OUTCOME MEASURES: Presenting distance visual acuity (measured with usual corrective lenses, if any) and distance visual acuity after automated refraction. RESULTS: Overall, 1,190 study participants had visual impairment (weighted prevalence, 6.4%; 95% confidence interval [CI], 6.0-6.8%), and of these, 83.3% could achieve good visual acuity with correction (95% CI, 80.9-85.8%). Extrapolating these findings to the general U.S. population, approximately 14 million individuals aged 12 years or older have visual impairment (defined as distance visual acuity of 20/50 or worse), and of these, more than 11 million individuals could have their vision improved to 20/40 or better with refractive correction. CONCLUSIONS: Visual impairment due to uncorrected refractive error is a common condition in the United States. Providing appropriate refractive correction to those individuals whose vision can be improved is an important public health endeavor with implications for safety and quality of life.

Humans↗
PubMed1997

[Research methods in clinical cardiology (VII). Experimental studies in cardiology].

Experimental designs in clinical investigation are discussed in this article. Guideline examples have been used in the area of Cardiology using always the same one only one whenever possible. We have looked for a different perspective from what is generally used in the discussion of the general characteristics of experimental designs, and more specifically of clinical trials and we deal with the aspects of clinical trials which are usually ignored due to their marginal character. We also discuss those characteristics which differentiate clinical trials in respect to other designs and types of questions which are answered by clinical trials. And we finally discuss various aspects such as randomization and its various types (simple, block, stratified, pre-randomized) and variable types of evaluating the answers, masking and the problems in its maintenance, with certain kinds of designs, sample size, etc. There is a brief mention of two particular cases: factorial and cross over designs are both discussed, mentioning their strong and weak points. Likewise, we discuss community trials as another experimental design and examples are provided. Finally, we discuss aspects of criteria: such as, When to stop the trials? or Who are the results applicable to?, and we suggest points to take into consideration when these decisions are made.

Cardiology↗
PubMed2003

The significance of 'anti-HBc only' in the clinical virology laboratory.

BACKGROUND: Isolated detection of hepatitis B core antibody (anti-HBc) in the absence of surface antigen (HBsAg) or antibody (anti-HBs) has been reported, particularly among individuals infected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV). The significance of this phenomenon is unknown and it is unclear whether all individuals with such serological pattern need further molecular investigations. OBJECTIVES: To determine the prevalence of 'anti-HBc only' in samples referred to a clinical virology laboratory and to evaluate its significance and possible mechanisms. STUDY DESIGN: Samples identified as anti-HBc positive (389/4359, 8.9%) during an 11-month period were investigated for HBsAg, anti-HBs, anti-HCV and anti-HIV. 'Anti-HBc only' samples were tested for HBV DNA using a nested qualitative PCR. Viral loads were measured in samples with detectable HBV DNA and the DNA sequences were analysed. RESULTS: Of 379 samples with detectable anti-HBc, 155 (40.9%) were 'anti-HBc only'. HBV DNA was detected in 6/151 (4%), all of which had a viral load <400 copies per ml. Anti-HIV was found in 50/151 (33.1%) and anti-HCV in 14/151 (9.3%). Of these, only one of the HIV infected patients had detectable HBV DNA. Phylogenetic analysis of the HBV surface gene from three patients showed a variety of genotypes (A, E and G). One sequence had a mutation in codon 144, which has previously been reported to give false negative HBsAg results. CONCLUSIONS: 'Anti-HBc only' is a common phenomenon in the clinical virology laboratory but only a small proportion of samples had detectable HBV DNA. The presence of HBsAg mutants with possible false negative HBsAg test result is of concern. Samples with 'anti-HBc only' could be used to monitor the emergence of these mutants.

Adult↗
PubMedDate not supplied

Determination of closed form solution for acceptance sampling using ANN.

Tabled sampling schemes such as MIL-STD-105D offer limited flexibility to quality control engineers in designing sampling plans to meet specific needs. We describe a closed form solution to determine the AQL indexed single sampling plan using an artificial neural network (ANN). To determine the sample size and the acceptance number, feed-forward neural networks with sigmoid neural function are trained by a back propagation algorithm for normal, tightened, and reduced inspections. From these trained ANNs, the relevant weight and bias values are obtained. The closed form solutions to determine the sampling plans are obtained using these values. Numerical examples are provided for using these closed form solutions to determine sampling plans for normal, tightened, and reduced inspections. The proposed method does not involve table look-ups or complex calculations. Sampling plan can be determined by using this method, for any required acceptable quality level and lot size. Suggestions are provided to duplicate this idea for applying to other standard sampling table schemes.

Algorithms↗
PubMed1997

Weapon carrying among black adolescents: a social network perspective.

OBJECTIVES: This report describes the salience of social networks to the phenomena of adolescent weapon carrying. METHODS: A random-walk network sampling design was used to survey 113 adolescents about topics, including weapon carrying. RESULTS: In a probability sample of 12- to 15-year-olds, 20.9% reported ever carrying a weapon. Carriers were eight times as likely as noncarriers to report weapon carrying by an older associate, and 19 times as likely to report weapon carrying by a peer. A significant dose-response effect was present. CONCLUSIONS: This evidence supports the interpretation that modeling of weapon carrying by personal network members is important for its initiation and maintenance in adolescence.

Adolescent↗
PubMed2002

Reduction of spoilage microorganisms in fresh beef using hydrodynamic pressure processing.

Hydrodynamic pressure processing (HDP) was investigated as a technology to reduce spoilage microorganisms found in fresh beef. In two separate studies (studies 1 and 2), retail ground beef and beef roasts were purchased (day 0). The roasts were divided into stew pieces (30 to 40 g). All meat samples, including control samples, were stored at 5 degrees C for 20 h in a plastic film. After storage, designated samples were treated with HDP In study 3, ground beef was treated with HDP (day 0) and stored aerobically (5 degrees C) for 14 days with control samples. Each meat type was vacuum-packaged for HDP (100 g binary explosive, steel shock wave container). The pHs and the aerobic plate counts (log10 CFU/g) were measured on day 0 (studies I and 2) and on days 0, 7, and 14 (study 3) for control samples and for HDP-treated samples. There was no pH difference between control and HDP-treated meat types (studies 1 and 2); HDP reduced bacteria in both meat types in study 1 (2 log) and study 2 (1.5 log) on day 0. In study 3, there was a significant difference (P < 0.05) in pH between control meat (8.2) and HDP-treated meat (5.6) after storage. There was an immediate reduction (1.5 log) of microorganisms following HDP (day 0) and a 4.5-log difference between control samples (9 log) and HDP-treated samples (4.5) after 14 days of storage. With HDP, it is possible to reduce spoilage microorganisms found in or on different meat types (ground beef versus stew pieces), which could extend the shelf life of meat products.

Animals↗
PubMed2004

Smoking behaviour of Czech adolescents: results of the Global Youth Tobacco Survey in the Czech Republic, 2002.

The Czech Republic Global Youth Tobacco Survey (GYTS) is a school-based survey of students in grades 7-9, conducted in 2002. A two-stage cluster sample design was used to produce representative data for all of the Czech Republic. On a large sample of students (N=4,149) from 7-9th grade it reveals that smoking among children has been continually growing. According to the results of this study, over 34% of the respondents smoke. Results of the study help us to understand social and attitudinal factors that affect adolescent smoking habits. Social factors include particularly the convenient availability of cigarettes and the lack of the legal regulation of the retail of cigarettes: over one half of all smokers under 15 years of age regularly purchase cigarettes in regular retail outlets; 72% of them reported never having been restricted in their purchases because of their age. Advertising and media coverage appears to be another important factor that affects smoking in this age group. Over 80% of children under 15 years of age reported that they have been exposed to the tobacco advertising. The study also allows an interesting analysis of the exposure to the environmental tobacco smoke. Compared to non-smokers, this exposure has been significantly higher in the case of smokers--both in their homes and at other locations (58% vs. 25%, and 90% vs. 57% respectively). The analysis of the data also revealed a strong misconception about the health risks related to passive smoking among smokers. The study provides three key findings for health promotion: (1) it is necessary to exert a continuous pressure on the political representation to strictly enforce the regulations of tobacco distribution and availability to minors; (2) school health education as well as community oriented prevention programs need to explicitly communicate non-smoking as a standard; and (3) it is important to increase the attractiveness and availability of smoking cessation programs.

Adolescent↗
PubMed2005

Genetics and environmental risk factors associated with asthma in schoolchildren.

OBJECTIVES: The objective of this study was to investigate the genetic and environmental risk factors associated with asthma among Qatari school children aged 6-12 years. DESIGN: A cross-sectional study was performed. The International study of asthma and allergies in childhood (ISAAC) and some additional questionnaires were used to collect the data of the school children between Feb 2003 and Feb 2004. SETTING: Government primary schools in the State of Qatar. SUBJECTS: A multistage sampling design was used and a representative sample of 3500 children were targeted for this study. Of these, 3204 parents (91.6%) of the children agreed to participate in this study. RESULTS: Of the total study sample 3204 school children living in urban and semi urban areas, 51.9% were boys and 48.1% girls. Their mean age was 8.92 +/- 1.89. The population sample had a high prevalence rate of asthma (19.8%) and allergic rhinitis 30.3%. The frequency of asthma, allergic rhinitis and eczema among parents reflected the same pattern as that seen in the children. Environmental risk factors associated with asthma were pets at home, allergic to certain food or medicine, smoking history among parents or elder siblings (p<0.0001). A stepwise logistic regression analysis results showed that allergic to food and medicine, history of asthma in father, mother, siblings and asthma in second degree relatives and smoking habit of father were significant predictors for asthma after adjusting age and sex and other confounding covariates in the model. CONCLUSION: The present study revealed that the family history of asthma contributed more to childhood asthma than indoor and outdoor environmental factors. Boys were found more asthmatic than girls. The results of this study support the hypothesis that asthma is a multi-factorial disease related to both familial and environmental influences.

Air Pollution↗
PubMed2001

Inverse adaptive cluster sampling.

Consider a population in which the variable of interest tends to be at or near zero for many of the population units but a subgroup exhibits values distinctly different from zero. Such a population can be described as rare in the sense that the proportion of elements having nonzero values is very small. Obtaining an estimate of a population parameter such as the mean or total that is nonzero is difficult under classical fixed sample-size designs since there is a reasonable probability that a fixed sample size will yield all zeroes. We consider inverse sampling designs that use stopping rules based on the number of rare units observed in the sample. We look at two stopping rules in detail and derive unbiased estimators of the population total. The estimators do not rely on knowing what proportion of the population exhibit the rare trait but instead use an estimated value. Hence, the estimators are similar to those developed for poststratification sampling designs. We also incorporate adaptive cluster sampling into the sampling design to allow for the case where the rare elements tend to cluster within the population in some manner. The formulas for the variances of the estimators do not allow direct analytic comparison of the efficiency of the various designs and stopping rules, so we provide the results of a small simulation study to obtain some insight into the differences among the stopping rules and sampling approaches. The results indicate that a modified stopping rule that incorporates an adaptive sampling component and utilizes an initial random sample of fixed size is the best in the sense of having the smallest variance.

Animals↗
PubMed2003

Alzheimer disease in the US population: prevalence estimates using the 2000 census.

CONTEXT: Current and future estimates of Alzheimer disease (AD) are essential for public health planning. OBJECTIVE: To provide prevalence estimates of AD for the US population from 2000 through 2050. DESIGN: Alzheimer disease incidence estimates from a population-based, biracial, urban study, using a stratified random sampling design, were converted to prevalence estimates and applied to US Census Bureau estimates of US population growth. SETTING: A geographically defined community of 3 adjacent neighborhoods in Chicago, Ill, applied to the US population. PARTICIPANTS: Alzheimer disease incidence was measured in 3838 persons free of AD at baseline; 835 persons were evaluated for disease incidence. Main Outcome Measure Current and future estimates of prevalence of clinically diagnosed AD in the US population. RESULTS: In 2000, there were 4.5 million persons with AD in the US population. By 2050, this number will increase by almost 3-fold, to 13.2 million. Owing to the rapid growth of the oldest age groups of the US population, the number who are 85 years and older will more than quadruple to 8.0 million. The number who are 75 to 84 years old will double to 4.8 million, while the number who are 65 to 74 years old will remain fairly constant at 0.3 to 0.5 million. CONCLUSION: The number of persons with AD in the US population will continue to increase unless new discoveries facilitate prevention of the disease.

Aged↗
PubMed2006

Prevalence of and risk factors for lifetime suicide attempts among blacks in the United States.

CONTEXT: Lack of data on the lifetime prevalence and age at onset of suicide ideation, plans, and attempts among blacks in the United States limits the creation and evaluation of interventions to reduce suicide among black Americans. OBJECTIVE: To examine the prevalence and correlates of suicide ideation, planning, and attempts across 2 ethnic classifications of blacks in a nationally representative sample. DESIGN, SETTING, AND PARTICIPANTS: Data are from the National Survey of American Life, a national household probability sample of 5181 black respondents aged 18 years and older, conducted between February 2001 and June 2003, using a slightly modified adaptation of the World Health Organization World Mental Health version of the Composite International Diagnostic Interview. Bivariate and survival analyses were used to delineate patterns and correlates of nonfatal suicidal behavior. MAIN OUTCOME MEASURES: Self-reports of lifetime suicide ideation, planning, and attempts. RESULTS: Survey respondents, categorized as African Americans and Caribbean Americans, reported lifetime prevalence of 11.7% for suicide ideation and 4.1% for attempts. Among the respondents who reported ideation, 34.6% transitioned to making a plan and only 21% made an unplanned attempt. Among 4 ethnic-sex groups, the 7.5% lifetime prevalence for attempts among Caribbean black men was the highest among black Americans. The greatest risk of progressing to suicide planning or attempt among ideators occurred within the first year after ideation onset. Blacks at higher risk for suicide attempts were in younger birth cohorts, less educated, Midwest residents, and had 1 or more Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition disorders. CONCLUSIONS: This study documents the burden of nonfatal suicidality among US blacks, notably Caribbean black men, and individuals making planned attempts. Advancing research on the transition from suicide planning to attempt is vital to the efficacy of health care professionals' ability to screen blacks at risk for suicide.

Adult↗
PubMed2001

Semiparametric analysis of truncated data.

Randomly truncated data are frequently encountered in many studies where truncation arises as a result of the sampling design. In the literature, nonparametric and semiparametric methods have been proposed to estimate parameters in one-sample models. This paper considers a semiparametric model and develops an efficient method for the estimation of unknown parameters. The model assumes that K populations have a common probability distribution but the populations are observed subject to different truncation mechanisms. Semiparametric likelihood estimation is studied and the corresponding inferences are derived for both parametric and nonparametric components in the model. The method can also be applied to two-sample problems to test the difference of lifetime distributions. Simulation results and a real data analysis are presented to illustrate the methods.

Acquired Immunodeficiency Syndrome↗
PubMed2007

Overweight/obesity and attention deficit and hyperactivity disorder tendency among adolescents in China.

OBJECTIVE: This study aims to investigate whether there is any association between attention deficit hyperactivity disorder (ADHD) tendency and overweight/obesity among adolescents. DESIGN: This study was a population-based health survey utilizing a two-stage random cluster sampling design. SUBJECTS: Subjects were recruited from the total population of adolescents who attended high school years 1, 2 and 3 with ages ranging from 13 to 17 years. MEASUREMENTS: Individual body weight and height were measured by medical professionals. Overweight and obesity were determined according to the CDC classification. ADHD tendency was assessed via a structured personal interview using a standardised scale. RESULTS: In all, 1429 students were recruited with 85 (6.3%) classified overweight and 42 (3.1%) obese with a mean BMI score of 19.1 (s.e.=0.15). For ADHD tendency, the average score was 15.48 (s.e.=0.28) with a median score of 16.0. There was a significant association between ADHD tendency and obesity among these adolescent (t=2.18, P=0.040), after adjusting for the potential confounding factors. However, the association between ADHD tendency and overweight did not reach a significant level. CONCLUSION: ADHD tendency is associated with overweight/obesity among adolescents. Clinician should be aware of the increased risk of ADHD among obese adolescents. ADHD should be assessed and proper treatment should be provided in the management of obese.

Adolescent↗
PubMed1989

Somatic mutation and transcriptional deregulation of myc in endemic Burkitt's lymphoma disease: heptamer-nonamer recognition mistakes?

We examined the structure and expression of the myc protooncogene in DNA extracted from a primary (uncultured) endemic Burkitt's lymphoma sample designated eBL3. Dot and Northern (RNA) blot analyses demonstrated extreme levels of myc RNA in the eBL3 sample. Nearly complete sequence data of the altered myc locus isolated from eBL3 DNA demonstrated extensive mutations (duplications, insertions, and deletions) in critical myc regulatory regions. Taken together, the data support the idea that myc transcriptional deregulation in Burkitt's lymphoma disease may be a consequence of the position and number of mutations produced within and around the myc locus. Furthermore, the myc exon-1-intron-1 hypermutable PvuII site is part of a potential heptamer-nonamer recognition sequence, suggesting a mechanism for mutation in endemic Burkitt's lymphoma disease.

Animals↗
PubMed2006

Infertility in a community and clinic-based sample of couples in Moshi, Northern Tanzania.

BACKGROUND: Previous research on the aetiology of infertility in sub-Saharan Africa was generally clinic based and it is not known whether findings from this work are representative of the general population. A better understanding of the medical causes of infertility is crucial for reducing the incidence of infertility and for improving the clinical management. OBJECTIVE: To determine the type and aetiology of infertility in a community and clinic-based sample. DESIGN: Couples identified as infertile in a representative cross-sectional survey from a community-based sample of 2019 women aged 20-44 years and couples seeking care for infertility at a tertiary health facility. SETTING: The community-based sample was drawn from Moshi Urban District and the clinic-based sample from patients seeking care at Kilimanjaro Christian Medical Centre (KCMC) in 2002 and 2003. PARTICIPANTS: Sixty six couples identified as infertile in the community-based sample and 112 couples seeking care for infertility. RESULTS: The percentage of primary infertility was 37.1% and secondary infertility was 62.9%. Female only factor infertility was identified in 65.9% of the couples, male only factor in 6.8%, male and female factors in 15.2% and unexplained infertility in 12.1%. CONCLUSION: The type and aetiology of infertility were the same in the community and clinic-based sample suggesting that the couples seeking infertility health care were representative of the general infertile population. Tubal factor infertility was the commonest cause.

Adult↗