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At least 307 records · Page 17Linked to original sources
PubMed2006

The Khatri Sikh Diabetes Study (SDS): study design, methodology, sample collection, and initial results.

Non-insulin-dependent diabetes mellitus, or type 2 diabetes (T2DM), has become a major public health problem in India. The high prevalence, relatively young age of onset, and strong familial aggregation of T2DM in some Indian communities remains to be explained. Many of the traditional risk factors established for European populations do not appear to be present in Asian Indians. Phase I of the Sikh Diabetes Study (SDS) was launched to build the population resources required to initiate a large-scale genetic epidemiological study of diabetes in an Asian Indian population. The SDS is focused on the Khatri Sikh population of North India. In all, 1,892 subjects were enrolled to participate in the family-based study; 1,623 of these subjects belong to 324 families, each of which has at least 2 siblings affected with T2DM. The sample included 1,288 individuals affected with T2DM (siblings, parents, or relatives) and 335 unaffected siblings, parents, or relatives. The remaining 269 subjects were unrelated nondiabetic control subjects, including unaffected spouses of probands or siblings. This primarily nonvegetarian, nonsmoking endogamous caste group has presented an unusual clinical picture of uneven distribution of adiposity and a high rate of T2DM with secondary complications. Such well-characterized population isolates may offer unique advantages in mapping genes for common complex diseases.

Adult↗
PubMed1981

Microbial sampling variables and recreational water quality standards.

A study was conducted at two beaches on Lake Erie to evaluate the water sampling design for the collection of several microbiological indicator organisms in relation to day, time, and location of collection. The concentrations of these organisms were generally found to vary significantly (P less than 0.05) by the specific time of day and day of weekend that collection took place. However, the concentrations of these organisms did not vary significantly (P greater than 0.05) at various locations in the bathing area. Future studies investigating the health effects of recreational water as related to microbiological variables should be designed to collect water samples at the specific time of day and day of weekend that an individual was exposed. In addition, sampling at various locations in the bathing area should probably be considered for those beaches having poor dispersion of fecal waste sources.

Bathing Beaches↗
PubMed1998

[The incidence of adenoviruses in viral conjunctivitis].

A study about the incidence of Adenovirus on viral conjunctivitis was conducted. A sample design was made and samples of conjunctival exudate were taken from 150 patients with diagnosis of apparently viral conjunctivitis at the "Ramón Pando Ferrer" Ophthalmological Hospital from July to December, 1994. Samples were inoculated in cell culture and the indirect immunofluorescence technique was applied to those with a cytopathogenic effect that suggested infection due to Adenovirus. Monoclonal antibodies were used against Adenovirus allowing to identify them as part of the Adenoviridae family. The hemagglutination technique was used with erythrocytes of monkeys and rats as an indicator system in order to group the isolates previously identified by the indirect immunofluorescence technique. Later on, it was made an analysis by restriction enzymes of the viral genome to enable typing. The results of this study showed an incidence of Adenovirus on viral conjunctivitis of 20%, with a confidence interval between 14 and 26% and a reliability index of 95%. It was proved that serotype 37 caused conjunctivitis more frequently.

Adenovirus Infections, Human↗
PubMed2003

[Prevalence of serious mental pathology in the city of San Luis].

OBJECTIVE: This work includes part of the results of the first epidemiological research on mental health held at San Luis City, aimed to estimate adult prevalence rate of mental pathology on San Luis' adult population. It has also been considered the prevalent kind of disorders. In both cases, it has been taken into account five domains of independent variables, due to sociodemographic characteristics: sex, age, educational level, occupational level, and residence zone. METHODS: The methodology is based on the epidemiological descriptive and transversal model. The assessment instrument, the Millon Clinical Multiaxial Inventory-II, was administrated to a representative adult sample, designed by a probabilistic sample methodology. RESULTS: The clinical measurement of Personality Pathology Scales and Sever Clinical Syndromes Scales showed a prevalence rate of 25,69% of serious mental pathology in general population, which is higher in women, 27,13%; than in men, 24,19%. In accordance to independent variables, there is a higher prevalence in elderly people, although there is no correlation with the number of symptoms; there is a lower prevalence among people with more years of education, with a relative correlation with number of symptoms-; and some professions showed higher scores than others, also with a relative correlation with number of symptoms. Considering the kind of mental disorders, there was a high prevalence of paranoid disorder and of alucinatory disorder, both in the women and men's samples. CONCLUSIONS: Finally, we found that the prevalence rates of serious mental pathology in San Luis population are similar to those obtained by previous studies in Argentina.

Adolescent↗
PubMed2003

Design of Phase II cancer trials evaluating survival probabilities.

BACKGROUND: Phase II cancer studies are undertaken to assess the activity of a new drug or a new treatment regimen. Activity is sometimes defined in terms of a survival probability, a binary outcome such as one-year survival that is derived from a time-to-event variable. Phase II studies are usually designed with an interim analysis so they can be stopped if early results are disappointing. Most designs that allow for an interim look are not appropriate for monitoring survival probabilities since many patients will not have enough follow-up by the time of the interim analysis, thus necessitating an inconvenient suspension of accrual while patients are being followed. METHODS: Two-stage phase II clinical trial designs are developed for evaluating survival probabilities. These designs are compared to fixed sample designs and to existing designs developed to monitor binomial probabilities to illustrate the expected reduction in sample size or study length possible with the use of the proposed designs. RESULTS: Savings can be realized in both the duration of accrual and the total study length, with the expected savings increasing as the accrual rate decreases. Misspecifying the underlying survival distribution and the accrual rate during the planning phase can adversely influence the operating characteristics of the designs. CONCLUSION: Two-stage phase II trials for assessing survival probabilities can be designed that do not require prolonged suspension of patient accrual. These designs are more efficient than single stage designs and more practical than existing two-stage designs developed for binomial outcomes, particularly in trials with slow accrual.

Clinical Trials, Phase II as Topic↗
PubMed1995

Factors related to immunization status among inner-city Latino and African-American preschoolers.

OBJECTIVE: To identify factors associated with undervaccination at 3 months and 24 months among low-income, inner-city Latino and African-American preschool children. DESIGN: Interviews with a representative sample of inner-city families using a cross-sectional, multi-stage, cluster-sample design combined with a replicated quota sampling approach. SETTING: South Central and East Los Angeles areas in inner-city Los Angeles. POPULATION: Eight hundred seventeen Latino and 387 African-American families with children between 12 and 36 months of age. MAIN OUTCOME VARIABLES: Being fully immunized or up-to-date (UTD) at 3 months (1 diphtheria-tetanus-pertussis vaccine and 1 oral polio vaccine) and 24 months of age (4 diphtheria-tetanus-pertussis vaccines, 3 oral polio vaccines, and 1 measles-mumps-rubella vaccine). METHODS: Logistic regressions of UTD immunization status at 3 and 24 months by population and health care system factors. RESULTS: Seventy percent of Latino children and 53% of African-American children were UTD at 3 months of age. At 24 months of age, 42% of Latino children and 26% of African-American children were UTD on their immunizations. Receipt of the first immunizations by 3 months was associated with smaller family size, and evidence of connection to prenatal care. Latino children were less likely to be UTD at 24 months if they obtained well child care from private providers versus public clinics (odds ratio [OR] = 0.45, 95% confidence interval [CI] = 0.26, 0.79). There was also a trend for Latino children to be less well immunized if they were in health maintenance organizations versus public clinics (0.31, 0.05 < P < .1). African-American children were more likely to be UTD at 24 months if they were UTD at 3 months (OR = 5.56, 95% CI = 1.43, 21.6), had more health visits (OR = 1.13, 95% CI = 1.01, 1.27), and were less likely to be UTD at 24 months if they were on Medicaid versus private insurance (OR = 0.26, 95% CI = 0.08, 0.90). IMPLICATIONS: Both African-American and Latino children in inner-city Los Angeles have low immunization rates at 3 and 24 months. Prenatal care and family size are strongly associated with being UTD by 3 months; however, family and child characteristics are relatively unimportant predictors of being UTD at 24 months of age. Important risk factors for underimmunization at 2 years of age in the inner-city, low-income communities studied include type of health insurance and source of well child care, with the public sector having higher rates than private doctors' offices or health maintenance organization/managed care plans.

Black or African American↗
PubMed1992

Sample size considerations in designing studies with intra-oral models.

Especially during recent years, the use of pre-clinical models for predicting the efficacy of fluoride systems has assumed greater importance within the scientific community. Originally utilized primarily to screen experimental fluoride delivery systems, preclinical models are now being considered as predictors of clinical efficacy in lieu of controlled clinical caries trials. Of the various preclinical models presently available, human intra-oral models have the greatest potential for reflecting intended usage conditions and therefore may be the most meaningful models for predicting clinical efficacy. However, only with the proper consideration of numerous critical variables can studies using intra-oral models be appropriately designed to achieve the desired objectives. Clearly, these models must provide relevant information in a manner which reflects clinically established cariostatic activity and be capable of detecting established differences in the amount of cariostatic activity, i.e., dose-response effects. Three sources of variation must be considered before an appropriate study design and sample size can be chosen. Based on fluoride uptake data from an intra-oral model with proximally-located enamel specimens, estimates of variation among subjects, within subjects, and among specimens within subjects were obtained. Multiple specimens per panelist do not affect the first two sources of variation. Thus, the number of panelists, and not the number of specimens, is of primary importance when pre-test data are used to choose the appropriate study design and calculate the required sample size.

Adult↗
PubMed1995

Estimating sample sizes for a two-stage sampling survey of seroprevalence of pseudorabies virus (PRV)-infected swine at a regional level in The Netherlands.

In the European Union, vaccination campaigns against Pseudorabies virus (PRV) in swine have been started to eradicate PRV. Specific sampling designs are needed to monitor PRV seroprevalence at a regional level. This paper demonstrates how sampling theory can be applied to design a disease seroprevalence survey, using PRV as an example. In the spring of 1994, the four regions in the Netherlands covered by the regional Animal Health Services were monitored with respect to PRV seroprevalence. Per region, blood samples from approximately 1400 herds, with two animals per herd, were collected. The sampling design accounted for stratification by fattening pig and sow population within each region. The regional PRV seroprevalence of swine in the Southern region was the highest (24.9%), closely followed by the PRV seroprevalence of swine in the Eastern region (20.5%). These regions have the highest density of swine in the Netherlands. The PRV seroprevalence in the Western and Central region (11.7%) was about half of the seroprevalence in the Southern and Eastern regions; the lowest regional PRV seroprevalence was observed in the Northern region (3.5%). The Northern part also has the lowest pig density. The PRV seroprevalence was approximately two times higher in sows than in fattening pigs.

Animals↗
PubMedDate not supplied

[Methodology of the National Seroepidemiologic Survey, Mexico].

This paper briefly describes the methodology employed in the National Seroepidemiologic Survey (NSS). Among the aspects discussed are: previous studies of this kind; the master sampling frame; the sample design, the study population and sample size; the selection of diseases for study; the variables; instruments for data collection; operational design for the survey; as well as data processing and analysis. The overall response rate of the NSS was 78.4 per cent of the surveyed homes, 40 per cent of which were from rural areas (communities of less than 2,500 persons). The non-response rate was 41.3 per cent with the highest level in Baja California Sur (RNR = 26%) and the lowest in Puebla (RNR = 50.9%). The poor response in Puebla may have been due to the fact that it was the first state surveyed and served as the pilot project. The variable estimates from the NSS were similar to those found in other national surveys and the General Population Census. Therefore, these is reason to believe that the results of the NSS were representative and comparable. The final part of the paper describes the NSS projects already published, national seroprevalences, considerations concerning inference, and the laboratory procedures utilized in each project.

Adolescent↗