Epidemiology of breast cancer in a Mexican-American population.

This is a historical cohort study of breast cancer mortality in the Mexican-American community of Laredo, Texas. Included in this study were virtually all breast cancer deaths recorded in Laredo since 1875; controls matched to cases by age and birth year were drawn from the total population. Fertility history and family history of disease for cases and controls were retrieved from the genealogical data base reconstructed by our group from church and civil records for the whole city of Laredo. The findings of this study show an association between breast cancer risk and age at first birth. This study confirms familial risk to be a factor in breast cancer risk. Unlike postmenopausal breast cancer mortality in the total U.S. population, which has increased only slightly in the last 30-40 years, postmenopausal breast cancer death rates in Laredo have almost tripled since the 1940's.

Epidemiology of Rett syndrome: a population-based registry.

The Texas Rett Syndrome Registry maintains the largest population-based registry of cases and potential cases of Rett syndrome in the world. The most precise estimate of the prevalence of Rett syndrome of 1 per 22800 (0.44/10000) females aged 2 through 18 years of age was generated from this Registry. In addition, the first prevalence figures for black and Hispanic female cases were estimated. Registry cases are actively ascertained from multiple sources. Registry staff identify presumptive cases from review of information provided to the Registry by the parent or guardian. Preliminary diagnostic evaluation includes standardized review of medical records and videotape of key behaviors. Diagnosis is confirmed at clinical evaluation. The active surveillance system is monitored with the two-source capture-recapture methodology and case ascertainment is projected. The 1990 prevalence estimate of Rett syndrome indicates that the syndrome occurs less frequently than previously estimated. Until a biologic marker for Rett syndrome is identified or a standard definition for an incident case of Rett syndrome is designated, the prevalence of Rett syndrome will remain a major investigative issue of its epidemiology, and the Registry will be an important, systematic mean to gather case material for clinical and laboratory studies providing the foundation for the development of preventive interventions.

Population-based registries using multidisciplinary reporters: a method for the study of pediatric neurologic disorders.

Few registries are available for evaluating population differences for rare, newly, or ill-defined pediatric neurologic disorders. The purpose of this article is to present standard methodologies for establishing a population-based registry and evaluating the completeness of a registry's case ascertainment. The Texas Rett Syndrome Registry (TRSR) is used as a model. The combination of health care and education resources has identified approx. 89-100% of the Rett syndrome cases in Texas. Cases reported by non-physician sources, although older on average (10.7 vs 7.7 years of age), did not differ by other demographic characteristics from those reported by physicians. Non-physician health and education professionals participated with the TRSR at a significantly higher rate than physicians, 89 and 37% (p < 0.05), respectively. Capture-recapture techniques, both two-sample and log-linear modeling, were used to quantitatively evaluate case ascertainment. Standardized national and international population-based registries could be the basis of an initiative to identify the etiology and perhaps preventive measures for pediatric neurologic disorders.

Rett syndrome: an analysis using Sartwell's incubation period model.

Evidence suggests that Rett syndrome is a genetic disorder; however, an etiologic genetic model has yet to be identified. The purpose of this study was to apply a statistical model, Sartwell's incubation period model, to estimate the incubation period of Rett syndrome and postulate further on the etiology of Rett syndrome. Sartwell's model was used to test the hypothesis that the age of onset of developmental regression distributions approximate a logarithmic normal model and thus the etiologic factors of Rett syndrome occur in utero or prior to conception. Data from three case-series of Rett syndrome from different geographic regions were used for the analyses. Curves resulting from the analyses demonstrated a good approximation to the logarithmic normal distribution, indicating a good fit of the data to Sartwell's model. In conclusion, the incubation period of Rett syndrome fits the logarithmic normal model, which is consistent with the theory that a major causal factor for Rett syndrome most likely occurs in utero or prior to conception, eg, a defective gene.

Emergency department patient classification system.

Very little has been reported about costing out nursing services in emergency departments. In this study, an emergency care unit (ECU) worked with consultants to adapt the hospital patient classification system to provide more accurate ECU service charges for nursing care.

Reconstruction of genealogies from vital records: the Laredo Epidemiology Project.

The Laredo Epidemiology Project is a study of the patterns of degenerative disease, particularly cancer, in the families of Laredo, Texas. The genealogical history of Laredo was reconstructed by the grouping of 350,000 individual church and civil vital event records into multigenerational families, with record linkage based on matching names. Mortality data from city death records are mapped onto these pedigrees for analysis. This paper describes the creation of the data base and evaluation of the links.

Ascertainment of pesticide exposures of migrant and seasonal farmworker children: findings from focus groups.

BACKGROUND: To design questionnaires for epidemiologic research among children of migrant farmworkers, researchers need to consider ways to best solicit information about pesticide exposures. METHODS: Bilingual facilitators conducted five focus groups with either migrant farmworker mothers or their children (age range 8-16 years) in southern Texas and northeastern Colorado. Guided questions were used to assess activities of migrant farmworker children and the ways to best elicit information about exposure to pesticides. RESULTS: Participants reported a large number of activities that may potentially expose children to pesticides through both direct and indirect routes. Prompting, indirect questions about chemical use, and use of local and trusted facilitators increased information elicited from focus group participants. CONCLUSIONS: These focus groups helped to provide information for developing questionnaire items related to pesticide exposure among migrant farmworker children, and highlighted the importance of using bilingual community interviewers and including children as respondents.

Tracing migrant farmworkers in Starr County, Texas.

BACKGROUND: In response to The National Cancer Institute (NCI) concerns about the ability to conduct studies among migrant farmworkers, this study evaluated the feasibility of identifying migrant farmworkers in their home state and tracing them over an extended period of time. METHODS: In 1995, a group of 196 persons who had classified themselves as "migrant farmworkers" in two earlier chronic disease studies was identified. The primary objective of the current study was to determine the proportion of these farmworkers who could be located in 1995-1996. RESULTS: Of these farmworkers, 163 were located and were living (83.2%), 15 had died (7.6%), and 18 (9.2%) were lost to follow-up. CONCLUSIONS: The excellent follow-up rate was due in part to the high participation rates among persons contacted for information, stability of the farmworkers' permanent homes, predictable timing of migration, and a longstanding health research program with established community contacts.

Development of a life events/icon calendar questionnaire to ascertain occupational histories and other characteristics of migrant farmworkers.

BACKGROUND: Specialized methods are necessary to collect data from migrant farmworkers for epidemiologic research. METHODS: We developed a questionnaire that collected lifetime occupational histories and other lifestyle risk factors via a life events/icon calendar, and administered the questionnaire to a convenience sample of 162 migrant farmworkers in nine areas of the U.S. RESULTS: The average duration of the interviews was about 1 h 30 min, with an average of 45 min for the work history section. The occupational histories covered a median of 27.6 years per person for men and 20.8 years per person for women. The median number of years spent in farm jobs was 11.3 for men and 5.8 for women. The median number of farm jobs (crop/task combination) per person was 59 among men and 27 among women. Many farmworkers performed the same crop/task combinations at multiple times throughout their lives, yielding a median of 13 unique farm jobs and 8 unique crops among men and 7 jobs and 5 crops among women. CONCLUSIONS: The project demonstrated that it is feasible to collect detailed work histories and other risk factor data from farmworkers, documented the complexity of work histories encountered among farmworkers, and yielded recommendations for refining a questionnaire that will facilitate future epidemiologic research on farmworkers.