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PubMed2003

A discussion of chain referral as a method of sampling hard-to-reach populations.

Nursing research often requires inquiry into sensitive topics that involve hidden or hard- to reach populations. However, identifying and sampling these populations for research purposes is often fraught with difficulties. Barriers include society's lack of tolerance of diverse groups, social stigma, concern for issues of confidentiality, and fear of exposure because of possible threats to security. Chain referral sampling techniques are proposed to minimize bias while maintaining privacy and confidentiality. Techniques of chain referral sampling are detailed for use in researching sensitive topics and hidden populations. When carefully planned and executed, this sampling design offers transcultural nurse researchers a reasonable method for accessing and studying special populations that are particularly hard-to-reach.

Humans↗
PubMed2005

Measuring alcohol consumption: a comparison of graduated frequency, quantity frequency, and weekly recall diary methods in a general population survey.

OBJECTIVE: The objective of this study is to compare self-reports of alcohol consumption obtained by graduated frequency (GF), quantity frequency (QF), and prospective weekly diary methods in a Swiss general population survey using a within-subject design. Another objective is to examine the consumption means, ranking order, and drinking classifications and to relate differences in consumption means and classification inconsistencies to social and drinking characteristics. METHOD: The data came from the first wave of a longitudinal study on changes in alcohol consumption. A subsample of 767 respondents who completed the three measures was examined. The sample design was accounted for. RESULTS: Weekly drinking diary (WDD) yielded over 50% more alcohol consumption than the QF and GF measures did. Measures on quantity and graduated frequencies did not differ significantly. There were more light drinkers found on QF and more harmful drinkers on the WDD. Classification inconsistencies between GF and the weekly drinking diary were significantly related to gender and problematic drinking.

Adolescent↗
PubMed2004

Effect of hyaluronan supplementation on boar sperm motility and membrane lipid architecture status after cryopreservation.

We investigated the effect of supplementing extended boar semen with different amounts of hyaluronan (HA) prior to freezing on post-thaw sperm characteristics. Using a split sample design, the effect of HA at a final concentration of 500 or 1000 microg/ml semen on post-thaw motility parameters, and membrane lipid architecture status assessed by merocyanine-540/YOPRO-1 and flow cytometry were evaluated. HA-supplementation improved motility parameters (P < 0.05 to P < 0.001) and decreased the percentage of hyperactivated spermatozoa (P < 0.05). HA-supplemented samples had more spermatozoa showing high lipid membrane stability as assessed with merocyanine-540. In conclusion, HA appeared to preserve post-thaw spermatozoa viability in vitro and maintained membrane stability after cryopreservation.

Animals↗
PubMed1991

Occupational mortality of women aged 15-59 years at death in England and Wales.

STUDY OBJECTIVE: The aim was to analyse occupational mortality differences among women using follow up data from a large nationally representative sample. DESIGN: Occupational information was obtained from the 1971 census records of women in the Longitudinal Study carried out by the Office of Population Censuses and Surveys (OPCS) and related to their subsequent mortality in the period between the 1971 and 1981 censuses. SETTING: In the Longitudinal Study, census, vital statistics, and other OPCS records are linked for a 1% sample of the population of England and Wales. The women studied in this paper were drawn from the 513,071 persons in the 1971 census who were included in the Longitudinal Study and whose entries were traced at the National Health Service Central Register by 1977. PARTICIPANTS: The analysis was based on 77,081 women aged 15-59 years in the Longitudinal Study for whom occupational information was collected in the 1971 census (99% of whom were in paid employment in the week before the census). There were 1553 deaths among these women in the follow up period analysed here. MEASUREMENTS AND MAIN RESULTS: Numbers of deaths in each occupational group at census were compared to those expected on the basis of age specific death rates among all women in the study. "Professional, technical workers, and artists" had significantly low mortality while "Engineering and allied trades workers nec" had significantly high mortality. Among the latter, cancer mortality of electrical production process workers was extremely high. A number of other cause specific associations (which appear to confirm proportionate Decennial Supplement analyses) were suggested by the data; examples include high levels of mortality from ischaemic heart disease among cooks, lung cancer and respiratory disease among charwomen and cleaners, and accidents, poisonings, and violence among several groups of professional and technical workers. CONCLUSIONS: By using prospective follow up from the census, occupational differences in mortality can be identified among women in paid employment. As follow up of this study continues, numbers of deaths available for analysis will increase, allowing increasingly comprehensive analyses to be undertaken.

Adolescent↗
PubMed2003

[Bioequivalence and therapeutic exchange of pharmaceutical specialties: application to cyclosporin in renal transplantation].

The aim of this study was to perform a quantitative meta-analysis of the average bioequivalence criteria between Sandimmun and Sandimmun Neoral in kidney transplant patients, and to review the new bioequivalence criteria and their application to generic formulation of cyclosporin. In Medline, we searched for clinical trials evaluating the bioequivalence between Sandimmun and Sandimmun Neoral in kidney transplant patients and we collected the information regarding the bioequivalence, study design, sample size, and time post-transplant. The effect was measured by the Wolf method; publication bias was evaluated by the Galbraith method and the Rosenthal formula was used to calculate the number of additional studies with no statistical differences needed to get a statistically non-significant overall estimation. We selected 6 clinical trials with a latin square design and 4 clinical trials with sequential design. The average bioequivalence criteria between Sandimmun Neoral and Sandimmun were 1.327 (90% CI: 1,311 a 1,344), 1,663 (90% CI: 1,635 a 1,692) and 0.559 hours (90% CI: 0.544 a 0.574 hours) for logharitmic transformation of area under the curve and maximum concentration, and time to maximum concentration, respectively. For these three outcomes, we found statistical differences between different study designs and for area under the curve and maximum concentration, the average bioequivalence criteria significantly fall with the post-transplant time. We conclude Sandimmun Neoral and Sandimmun are not bioequivalents and the experience reached with these two drugs is not applicable to the evaluation of generic formulations of cyclosporin.

Clinical Trials as Topic↗
PubMed2003

Association between number of physician visits and influenza vaccination coverage among diabetic adults with access to care.

OBJECTIVE: The proportion of diabetic adults that receives the influenza vaccine is less than ideal. This study determined the relationship between the number of physician visits in the previous 12 months and the likelihood of influenza vaccination among diabetic adults with access to care. RESEARCH DESIGN AND METHODS: Data on 1807 diabetic adults with access to care in the 1999 National Health Interview Survey (NHIS) were analyzed. Prevalence of influenza vaccination was determined by number of physician visits. Logistic regression was used to determine the independent association between number of physician visits and influenza vaccination coverage, controlling for age, sex, race/ethnicity, education, income, employment census region, and comorbidity. STATA was used for analyses to account for the complex sampling design of NHIS. RESULTS: Overall, 56% of subjects received the influenza vaccine. Proportions vaccinated by number of physician visits were as follows: 35% (no visit), 47% (1-3 visits), 58% (4-9 visits), and 61% (>or=10 visits). Compared with people with no physician visit, people with 4-9 visits (odds ratio [OR] 2.61) and >or=10 visits (2.96) were significantly more likely to be vaccinated. However, after controlling for covariates, only people with >or=10 visits (2.34) were significantly more likely to be vaccinated. CONCLUSIONS: In this nationally representative sample, repeated physician visits by diabetic adults with access to care were associated with only modest increases in influenza vaccination coverage. In adjusted analysis, odds of influenza vaccination were not significantly associated with number of physician visits, except in people with >or=10 visits.

Adult↗
PubMed2005

A review of methods for futility stopping based on conditional power.

Conditional power (CP) is the probability that the final study result will be statistically significant, given the data observed thus far and a specific assumption about the pattern of the data to be observed in the remainder of the study, such as assuming the original design effect, or the effect estimated from the current data, or under the null hypothesis. In many clinical trials, a CP computation at a pre-specified point in the study, such as mid-way, is used as the basis for early termination for futility when there is little evidence of a beneficial effect. Brownian motion can be used to describe the distribution of the interim Z-test value, the corresponding B-value, and the CP values under a specific assumption about the future data. A stopping boundary on the CP value specifies an equivalent boundary on the B-value from which the probability of stopping for futility can then be computed based on the planned study design (sample size and duration) and the assumed true effect size. This yields expressions for the total type I and II error probabilities. As the probability of stopping increases, the probability of a type I error alpha decreases from the nominal desired level (e.g. 0.05) while the probability of a type II error beta increases from the level specified in the study design. Thus a stopping boundary on the B-value can be determined such that the inflation in type II error probability is controlled at a desired level. An iterative procedure is also described that determines a stopping boundary on the B-value and a final test critical Z-value with specified type I and II error probabilities. The implementation in conjunction with a group sequential analysis for effectiveness is also described.

Biometry↗
PubMed1995

[Cataract-related blindness in Morocco. The Moroccan Group of Epidemiologic Evaluation of Blindness].

The lack of sound and recent epidemiological data on the prevalence and causes of blindness has hampered the development and evaluation of the Moroccan Programme for the Prevention of Blindness. For this reason a population-based survey using a stratified (urban/rural) sampling design for random selection of clusters was carried out in the Kingdom of Morocco from May 15 until June 30, 1992. The procedures used for this survey were those proposed by the WHO Programme for the Prevention of Blindness. A total of 10,198 people were recruited and 8878 examined for a participation rate of 87%. The size and representativity of the sample satisfactorily guaranteed the order of magnitude and accuracy of eye health indicators used by health planners. The crude point prevalence of blindness was 0.8%, that of bilateral poor vision was 2.3%, and that of unilateral poor vision was estimated to be 2.8%. Based on these findings 195,000 people would be blind and 1,300,000 would be at risk of becoming so, for a total of approximately 1,500,000 people with serious visual impairment. Age-related cataract was the most important cause of blindness (45.5%) and bilateral poor vision (43.1%). The prevalence of cataract-related visual impairment--operable or inoperable--was estimated to be 2.1% of the survey sample. Applying a realistic algorithm to the survey data, it was estimated that the backlog for cataract surgery in Morocco in 1992 was in the order of 502,000 eyes in approximately 287,000 people. The percentage of patients who had undergone cataract surgery in hospital was 0.8%. Posterior lens dislocation according to the traditional "couching" method was noted in 0.1% of people studied. It was estimated that 25% of the demand for cataract surgery was covered by available facilities and that 40% of people with aphakia could not obtain eye care.

Adolescent↗
PubMed1994

Control of airborne latex by use of powder-free latex gloves.

OBJECTIVE: Our objective was to assess airborne latex allergen exposure in the workplace of a hospital laboratory technician with occupational latex sensitization and repeated anaphylactic episodes from this. Her allergic manifestations had cleared only when coworkers changed to powder-free latex gloves. Therefore a laboratory still using powdered latex gloves was selected for comparative airborne latex sampling. DESIGN: The design was a survey. SETTING: We used a hospital hematology laboratory, and a biochemistry laboratory was used for comparison. PARTICIPANTS: The index case with latex allergy is described. An average of 10 employees worked on the day shift in the same laboratory, and 10 employees worked in the biochemistry laboratory studied. MAIN OUTCOME MEASURE: Airborne latex allergen levels obtained by high airflow area sampling were compared in the laboratory using powder-free latex gloves and in the laboratory using powdered latex gloves. RESULTS: Levels were below the level of detection (< 0.02 ng/m3 of latex allergen) in the laboratory using powder-free latex gloves but ranged from 39 to 311 ng/m3 in the laboratory using powdered gloves. CONCLUSIONS: Airborne latex allergen is produced with use of powdered latex gloves. Such usage by coworkers may provoke respiratory and anaphylactic response to latex in sensitized subjects. Use of powder-free gloves by coworkers may enable such patients to continue work in their trained profession and may prevent measurable airborne latex exposure. Affected patients, however, still need to avoid direct latex contact.

Adult↗
PubMed2000

[Prevention of cervix cancer. Comparison of the sample quality obtained using cotton swab or cervical brush].

OBJECTIVE: To determine the pap smear adequacy, and to compare the quality using cervical cytobrush with that obtain by using cotton swab in the endocervical sample. DESIGN: Transversal study. Carried out in two periods both pre and post intervention. SETTING: Primary care centre in the south of Madrid. INTERVENTION: We have analysed all the pap smear performed during two periods. In the first period we obtained 1130 smears using cotton swab and 884 smears using cervical cytobrush in the second period. We used the Ayre Spatula to obtain the exocervical samples. RESULTS: 2014 pap smears were analysed. Of the 1130 smears examined in the primary study using the cotton swab, 25.9% were inadequate because of the absence of the transformation zone cells. In the second group, 884 pap smears obtained by using the cytobrush, only 13.9% were reported as inadequate smears, p < 0.00001 (chi square). 18 smears were positive for malignancy (6 suspicious, 9 CIN I, 3 CIN III, all under the age of 49. 14.6% were positive for infections. There were no significant differences in the smear adequacy in regards to the professional who obtained the sample. CONCLUSIONS: We have improved the smear adequacy 12% by using the cytobrush. We recommend the cytobrush for endocervical smears to avoid having to repeat the sample. We consider it necessary to indicate the smear adequacy in all pathology reports.

Adolescent↗
PubMed1995

The Community Epidemiology Laboratory: studying alcohol problems in community and agency-based populations.

This paper describes the Community Epidemiology Laboratory (CEL) of the Alcohol Research Group, a project focusing on the epidemiology of alcohol problems and community responses to those problems. Since 1980, a series of probability surveys have been conducted in the general population and in a wide range of health and social service agencies in a northern California county. The agency-based samples have included all agencies or representative samples of each system (alcohol treatment, drug treatment, mental health treatment, emergency rooms, primary health care, criminal justice and welfare) with probability samples of clients interviewed at intake. These studies have addressed questions regarding (1) the burden and epidemiologic description of alcohol problems in a community; (2) the relationship of alcohol to other health and social problems; (3) the influence of social policy on the constitution of services and care of individuals; and (4) health services issues of access and pathways to treatment. The project is designed for comparable analysis of studies with special focus on women and ethnic minorities. This paper provides an overview of the CEL, including its major research questions, overall design, sampling principles, methodological issues and measures. It highlights the main findings and discusses the limitations and advantages of such methodologies for further understanding alcohol problems in a community.

Adolescent↗
PubMed2002

Using Dietary Reference Intake-based methods to estimate the prevalence of inadequate nutrient intake among school-aged children.

OBJECTIVE: To estimate the prevalence of inadequate usual intakes of nutrients by school-aged children. DESIGN: A descriptive study using data from the US Department of Agriculture 1994 to 1996 Continuing Survey of Food Intake by Individuals. Each subject provided two 24-hour recalls. We adjusted for day-to-day variation in nutrient intake and estimated the percentage of children with intakes below the Estimated Average Requirement (EAR) using the Software for Intake Distribution Estimation Program. SUBJECTS: A national sample of noninstitutionalized children aged 6 to 18 years (N=2,692). STATISTICAL ANALYSES: Chi2 tests showed that background characteristics or percentages with intakes below the EAR were the same across the 6 gender-age and racial/ethnic groups. The SUDAAN statistical package was used to account for the complex sample design. RESULTS: Usual intakes were more favorable for 5 B vitamins and iron than for the other nutrients examined. High percentages of children had intakes below the EAR for vitamin E. Many children aged 9 years and older had intakes below the EAR for folate and magnesium. Females aged 9 years and older had low calcium intakes relative to the Adequate Intake value. Females aged 14 to 18 years were at highest risk of usual intakes that did not meet the EARs. Few males in this age group met the EAR for vitamin E or magnesium. APPLICATIONS: Females aged 14 to 18, in particular, should be targeted for efforts to improve nutrient intakes. Studies should monitor children's usual nutrient intakes after adjusting for day-to-day variation.

Adolescent↗
PubMed2002

Compulsory substance abuse treatment: an overview of recent findings and issues.

An overview of research trends and issues in the area of compulsory substance abuse treatment is presented, using a sample of 170 English-language articles obtained from a search of 4 databases (Medline, PubMed, Embase, PsychINFO, supplemented by a manual search). About half (51%) of these articles were non-empirical (i.e. literature reviews, policy proposals, legal and ethical commentaries on compulsory treatment). A subsample of empirical studies published since 1988 (n = 71) was coded to summarize research trends in relation to 3 key issues: (1) how compulsory treatment was studied (country of origin; type of compulsory treatment; treatment population), (2) the evidence base for judging effectiveness of compulsory treatment (research design; sampling; type, timing and results of outcome measures), and (3) the relationship between compulsory treatment and coercion (measurement strategies). Directions for future research are discussed.

Coercion↗
PubMed1999

Determination of acrylic acid in air by using diffusion denuder tubes combined with HPLC technique.

A procedure for the determination of atmospheric acrylic acid in air at the microgram m-3 to mg m-3 level is described. Diffusion-based sampling, designed to discriminate gaseous analytes from their particulate counterparts, has been used. Acrylic acid is collected with an efficiency of > 98% in tubular denuders coated with sodium hydroxide-barium hydroxide-hydroquinone monomethyl ether, and analyzed by high performance liquid chromatography with UV absorbance detection. The detection limit is 2.9 micrograms m-3 at a flow rate of 0.5 L min-1 and 30 min sampling time. A precision (p = 0.95, n = 10) of 7.5% of the overall procedure was achieved at the 100 micrograms m-3 level. Results of laboratory studies concerning the effect of the coating reagent and the relative humidity on the sampling efficiency as well as possible interferences, in particular by ozone, and the elimination of these interferences are discussed. This method was developed to monitor workplace atmospheres as well as ambient air in industrial environments.

Acrylates↗
PubMed1984

Sampling and data collection methods in the National Evaluation of School Nutrition Programs.

A nested sampling design is described in which school districts are selected, schools within those districts that cover grades one through 12 are selected, and finally students within each of the grades are selected. The article describes how nutritional status information is collected from each student, economic and food expenditure data are collected from the students' parents, and information on food services is collected from district and school administrators. Sample weighting and adjustments for nonresponse bias are discussed in the appendix.

Adolescent↗
PubMed2000

The influence of hearing and age on speech recognition scores in noise in audiological patients and in the general population.

OBJECTIVE: To describe the influence of pure-tone audiometry and age on the speech recognition score in noise, both in audiological patients and also in a random population sample. DESIGN: In a cross-sectional study, speech recognition scores (SRS) using monosyllabic words presented in a fixed background noise were evaluated on 1895 audiological patients of both genders with normal hearing or sensorineural hearing losses. The background noise was speech weighted and presented with a signal to noise ratio of +4 dB. In 291 participants, SRS in quiet was estimated as well. A female random population sample also was tested (N = 513). RESULTS: The major predictor for the SRS-noise was high-frequency hearing thresholds. If hearing was normal, age had no effect on speech recognition. Young persons with hearing loss had higher SRS-noise than older persons with the same degree of hearing loss. The difference between young and old persons became larger the greater the hearing loss. Predictive SRS-noise with consideration taken to hearing function and age are presented. SRS-noise correlated stronger with pure-tone audiometry and age than SRS-quiet. Controls performed better (by 10 to 20%) than their same-aged peers with similar hearing loss. CONCLUSION: It is recommended that speech recognition tests be performed in background noise. SRS-noise is a valuable tool for audiologists and audiological physicians to identify patients in need of pedagogic rehabilitation programs or further diagnostic investigations.

Adult↗
PubMed2005

Sense of coherence as a moderator of the effects of stressful life events on health.

STUDY OBJECTIVE: To test the hypothesis that Antonovsky's concept of sense of coherence (SOC) moderates (that is, buffers) the health impacts of stressful life events in a population based sample. DESIGN: Multiple linear and Poisson regression analyses of longitudinal data from a national survey of population health were used to examine the relations among SOC, the experience of recent stressful life events (for example, family breakdown, financial crisis, physical abuse), and two outcomes, self reported health status (SRH) and self reported number of physician visits during the previous year. SETTING: General population of Canada. PARTICIPANTS: Nationally representative sample of household residents aged 30 years of age or greater surveyed in 1998 and 2000 (n = 6505). MAIN RESULTS: After controlling for age, sex, and previous health status, a significant moderating effect (t = 2.24, p = 0.025) in the expected direction was found on respondents' SRH. The mean difference in SRH between those who did and did not experience a recent stressful life event was 0.24 (95% CI: 0.16, 0.32) in people with a below average SOC and 0.04 (95% CI: -0.04, 0.11) in people with a higher than average SOC score. The postulated moderating effect of SOC was not significant (t = 1.1, p > 0.05) in predicting the number of visits to a physician. CONCLUSIONS: SOC seems to buffer the impact of recent stressful life events on SRH.

Adaptation, Psychological↗
PubMed2004

Total number and mean size of alveoli in mammalian lung estimated using fractionator sampling and unbiased estimates of the Euler characteristic of alveolar openings.

Estimation of alveolar number in the lung has traditionally been done by assuming a geometric shape and counting alveolar profiles in single, independent sections. In this study, we used the unbiased disector principle to estimate the Euler characteristic (and thereby the number) of alveolar openings in rat lungs and rhesus monkey lung lobes and to obtain robust estimates of average alveolar volume. The estimator of total alveolar number was based on systematic, uniformly random sampling using the fractionator sampling design. The number of alveoli in the rat lung ranged from 17.3 x 10(6) to 24.6 x 10(6), with a mean of 20.1 x 10(6). The average number of alveoli in the two left lung lobes in the monkey ranged from 48.8 x 10(6) to 67.1 x 10(6) with a mean of 57.7 x 10(6). The coefficient of error due to stereological sampling was of the order of 0.06 in both rats and monkeys and the biological variation (coefficient of variance between individuals) was 0.15 in rat and 0.13 in monkey (left lobe, only). Between subdivisions (left/right in rat and cranial/caudal in monkey) there was an increase in variation, most markedly in the rat. With age (2-13 years) the alveolar volume increased 3-fold (as did parenchymal volume) in monkeys, but the alveolar number was unchanged. This study illustrates that use of the Euler characteristic and fractionator sampling is a robust and efficient, unbiased principle for the estimation of total alveolar number in the lung or in well-defined parts of it.

Age Factors↗