Population-based Sampling Frame Research Articles

Neurogenic Lower Urinary Tract Dysfunction in the First Year After Spinal Cord Injury: A Descriptive Study of Urodynamic Findings.

We aimed to provide a real-world description of neurogenic lower urinary tract dysfunction within the first year after spinal cord injury with a focus on unfavorable urodynamic parameters that are associated with urological morbidity. Urodynamic investigations from 97 patients with traumatic or ischemic acute spinal cord injury and managed according to the European Association of Urology Guidelines on Neuro-Urology were analyzed at a single university spinal cord injury center at 1 month, 3 months, 6 months, and 12 months after injury. Unfavorable urodynamic parameters were defined as detrusor overactivity in combination with detrusor sphincter dyssynergia, maximum storage detrusor pressure of 40 cm H2O or higher, bladder compliance less than 20 mL/cm H2O, and vesicoureteral reflux of any grade. One or more unfavorable urodynamic parameter was observed in 87 out of 97 patients (90%) within the first year after spinal cord injury. Eighty-eight percent of the patients showed detrusor overactivity with detrusor sphincter dyssynergia, 39% a maximum storage detrusor pressure of 40 cm H2O or higher, and 7% vesicoureteral reflux. No patient developed a low-compliance bladder. Using a standardized urodynamic follow-up schedule, we found unfavorable urodynamic parameters in a majority of the population within the first year after spinal cord injury. As early treatment based on urodynamic findings might reduce the risk of deterioration of upper and lower urinary tract function, thereby improving long-term outcomes, there is need for further research regarding recommendations for a urodynamic follow-up schedule during the first year after spinal cord injury.

Care Continuum and Postdischarge Outcomes Among HIV-Infected Adults Admitted to the Hospital in Zambia.

BackgroundWe characterized the extent of antiretroviral therapy (ART) experience and postdischarge mortality among hospitalized HIV-infected adults in Zambia.MethodsAt a central hospital with an opt-out HIV testing program, we enrolled HIV-infected adults (18+ years) admitted to internal medicine using a population-based sampling frame. Critically ill patients were excluded. Participants underwent a questionnaire regarding their HIV care history and CD4 count and viral load (VL) testing. We followed participants to 3 months after discharge. We analyzed prior awareness of HIV-positive status, antiretroviral therapy (ART) use, and VL suppression (VS; <1000 copies/mL). Using Cox proportional hazards regression, we assessed risk factors for mortality.ResultsAmong 1283 adults, HIV status was available for 1132 (88.2%), and 762 (67.3%) were HIV-positive. In the 239 who enrolled, the median age was 36 years, 59.7% were women, and the median CD4 count was 183 cells/mm3. Active tuberculosis or Cryptococcus coinfection was diagnosed in 82 (34.3%); 93.3% reported prior awareness of HIV status, and 86.2% had ever started ART. In the 64.0% with >6 months on ART, 74.4% had VS. The majority (92.5%) were discharged, and by 3 months, 48 (21.7%) had died. Risk of postdischarge mortality increased with decreasing CD4, and there was a trend toward reduced risk in those treated for active tuberculosis.ConclusionsMost HIV-related hospitalizations and deaths may now occur among ART-experienced vs -naïve individuals in Zambia. Development and evaluation of inpatient interventions are needed to mitigate the high risk of death in the postdischarge period.

Food Allergy Is an Important Risk Factor for Childhood Asthma, Irrespective of Whether It Resolves

The risk of developing asthma in those with early food allergy is unknown, particularly when early life food allergy has resolved. To understand whether challenge-proven food allergy in infancy increases the risk of asthma at age 4 years, using data from a population-based cohort. A total of 5,276 12-month-old infants were recruited using a population-based sampling frame. Infants underwent skin prick test to egg, peanut, and sesame and those with a detectable skin prick test result had oral food challenges. At age 4 years, food challenges were repeated to determine persistence or resolution of food allergy. The association between food allergy and doctor-diagnosed asthma was examined using binomial regression in 2,789 participants. Children with food allergy at age 1 year had an increased risk of asthma (1 food allergy: relative risk [RR], 1.69; 95% CI, 1.29-2.21; 2 or more food allergies: RR, 2.76; 95% CI, 1.94-3.92). The risk of asthma was highest in children with food allergy and coexistent eczema in infancy (RR, 2.87; 95% CI, 2.22-3.70). Transient food allergy and persistent food allergy were both associated with an increased risk of asthma (transient egg allergy: RR, 1.92; 95% CI, 1.46-2.51; persistent egg allergy: RR, 2.60; 95% CI, 1.76-3.85). Asthma at age 4 years is twice as common in those with challenge-proven food allergy at age 1 year, irrespective of whether the food allergy subsequently resolves. Children with 2 or more food allergies and those with coexistent eczema were almost 3 times as likely to develop asthma compared with those with no food allergies.

Male Sexual Function in New Zealand: A Population-Based Cross-Sectional Survey of the Prevalence of Erectile Dysfunction in Men Aged 40–70 Years

BackgroundSexual function declines with age and erectile dysfunction (ED) is a common condition worldwide; however, prevalence rates vary markedly between populations and reliable data specific to New Zealand (NZ) are lacking. AimTo assess the prevalence of ED in NZ men using a population-based cross-sectional survey. MethodsPostal questionnaires were sent, according to a modified Dillman method, to a randomly selected age-stratified population-based sample of 2,000 men 40 to 70 years old obtained from the electoral roll. Self-reported erectile function was assessed using the five-item International Index of Erectile Function (IIEF-5) and the single-question self-assessment tool. OutcomesThe prevalence of ED is presented as crude, age-adjusted to the distribution of the NZ population, and standardized to the World Health Organization World Standard Population (WSP). Associations between sexual function and age were analyzed using χ2 test. ResultsThe response rate was 30% (599) and 28% (562) were complete for analysis. The crude prevalence of ED was 42% (22% mild, 10% mild to moderate, 6% moderate, and 4% severe), the age-adjusted prevalence was 38%, and the WSP-adjusted prevalence was 37%. Among men reporting ED, 16% were medically diagnosed and 22% were treated. ED affected 24% of men in their 40s, 38% in their 50s, and 60% in their 60s (P < .001). Age was associated with a significant increase in diagnosed ED (P = .001), treated ED (P = .006), dissatisfaction with current sexual function (P < .001), associated anxiety or depression (P = .023), and a decrease in sexual activity (P < .001). Clinical TranslationApproximately one in three NZ men 40 to 70 years old might have ED. Although comparable to overseas populations, this prevalence is high. Strengths and LimitationsThis study provides the most reliable, comprehensive, and current information on ED and its risk factors in NZ men. Strengths include the large sample, the use of random selection from a population-based sampling frame, established effective survey methods, and the validated IIEF-5. Limitations include the inability of cross-sectional data to determine causation, non-sampling errors associated with the population-based sampling frame, the low response rate, the inability to assess non-respondents, the possibility of men with ED who were sexually inactive not responding or not completing the IIEF-5, and the inherent inability to rule out recall bias. ConclusionED is a marker of subclinical cardiovascular disease. The high prevalence and low levels of diagnosis and treatment indicate a lost opportunity for timely intervention to delay or prevent the progression toward clinical disease.Quilter M, Hodges L, von Hurst P, et al. Male Sexual Function in New Zealand: A Population-Based Cross-Sectional Survey of the Prevalence of Erectile Dysfunction in Men Aged 40–70 Years. J Sex Med 2017;14:928–936.

Selection Bias in Population-Based Cancer Case–Control Studies Due to Incomplete Sampling Frame Coverage

Increasing numbers of individuals are choosing to opt out of population-based sampling frames due to privacy concerns. This is especially a problem in the selection of controls for case-control studies, as the cases often arise from relatively complete population-based registries, whereas control selection requires a sampling frame. If opt out is also related to risk factors, bias can arise. We linked breast cancer cases who reported having a valid driver's license from the 2004-2008 Wisconsin women's health study (N = 2,988) with a master list of licensed drivers from the Wisconsin Department of Transportation (WDOT). This master list excludes Wisconsin drivers that requested their information not be sold by the state. Multivariate-adjusted selection probability ratios (SPR) were calculated to estimate potential bias when using this driver's license sampling frame to select controls. A total of 962 cases (32%) had opted out of the WDOT sampling frame. Cases age <40 (SPR = 0.90), income either unreported (SPR = 0.89) or greater than $50,000 (SPR = 0.94), lower parity (SPR = 0.96 per one-child decrease), and hormone use (SPR = 0.93) were significantly less likely to be covered by the WDOT sampling frame (α = 0.05 level). Our results indicate the potential for selection bias due to differential opt out between various demographic and behavioral subgroups of controls. As selection bias may differ by exposure and study base, the assessment of potential bias needs to be ongoing. SPRs can be used to predict the direction of bias when cases and controls stem from different sampling frames in population-based case-control studies.

Ethnoracial variations in acute PTSD symptoms among hospitalized survivors of traumatic injury

Ethnoracial minority status contributes to an increased risk for posttraumatic stress disorder (PTSD) after trauma exposure, beyond other risk factors. A population-based sampling frame was used to examine the associations between ethnoracial groups and early PTSD symptoms while adjusting for relevant clinical and demographic characteristics. Acutely injured trauma center inpatients (N = 623) were screened with the PTSD Checklist. American Indian and African American patients reported the highest levels of posttraumatic stress and preinjury cumulative trauma burden. African American heritage was independently associated with an increased risk of higher acute PTSD symptom levels. Disparities in trauma history, PTSD symptoms, and event related factors emphasize the need for acute care services to incorporate culturally competent approaches for treating these diverse populations.

Recruiting for a Longitudinal Study of Childrenʼs Environmental Health Using a Household-Based Probability Sampling Approach

TAB1-O-03 The sampling design for the National Children's Study (NCS) calls for a population-based, multistage, clustered household sampling approach (visit our website for more information on the NCS: www.nationalchildrensstudy.gov). The full sample is designed to be representative of both urban and rural births in the United States, 2007 to 2011. While other survey research efforts have used similar designs with success, this would be a novel recruitment strategy for an environmental epidemiologic study of preconception factors and pregnancy outcomes. A comprehensive pilot study is planned for 2006 to 2009 in central North Carolina: BEFirstNC. We will screen a total of approximately 10,000 households from 4 defined geographic areas (2 urban and 2 rural). The areas were chosen to have a broad range of demographic variation with respect to race/ethnicity and income as well as urban/rural housing units. The study will enroll women planning pregnancy and those currently pregnant, with a small number of women enrolled in the hospital after delivery. The BE First NC study visits mimic the visit schedule planned for the first 2 years of the NCS. Frequent home and clinic visits will continue until the child is 18 months of age. Data collection from participants (women, partners, and children) will focus on topics that are likely to yield meaningful results in a small sample of infants (∼400 children). Participant burden associated with study visits, in-person interviews, mail-in forms, biologic specimen collection, environmental sample collection, and clinical tests will be characterized. Frequent qualitative assessments will evaluate the acceptability of the visit schedule and planned data collection methods, including likes and dislikes of study participants regarding each visit, important factors in the participant's decision making process to join the study, continue to participate or drop out. Spatial environmental monitoring data and community resource information (parks, etc.) will be combined with individual family data to assess the neighborhood as well as household environment. This pilot study can provide valuable information on the feasibility of using a household-based sampling approach to identify, enroll, and retain women and families for a longitudinal study of child health and development. Demographic differences in participant response and retention will be informative for the national study as well as the qualitative assessment of study acceptability. Using a population-based sampling frame for a study of pregnancy outcomes can avoid biases associated with recruiting volunteers who may be more health conscious than nonparticipants and/or may be more concerned about their environment. Measuring aspects of the environment before a couple becomes pregnant allows for an interesting opportunity to assess peri-conceptional factors that may relate to pregnancy outcomes as well as child development. This is an abstract of a proposed presentation and does not necessarily represent Environmental Agency policy.

Pregnancy Risk Assessment Monitoring System (PRAMS): Possible New Roles for a National MCH Data System

The Pregnancy Risk Assessment Monitoring System (PRAMS) was established by the Centers for Disease Control and Prevention (CDC) in 1987 in five states, and today 32 states participate. Using states' vital statistics (birth certificates) as its population-based sampling frame, PRAMS "follows back" a stratified sample of women several months post-partum, surveying them about their own and their infant's prenatal, birth, and post-partum behavior and experiences. It uses a standardized protocol and multiple data collection modalities. PRAMS was initiated in an era of intense state and national interest in infant mortality, racial disparities reduction, and publicly supported prenatal care program expansion-and a lack of state-specific information available to inform local and state program development and assessment. The PRAMS format allows more in-depth inquiry about reproductive health topics than is possible from the more widespread but limited set of information available on birth certificates. PRAMS carries on a long, proud tradition of follow-back studies in the maternal and child health (MCH) field. In the 1920s, the U.S. Children's Bureau conducted the nation's first major in-depth study on infant mortality using a similar follow-back methodology. In each of 10 cities, every woman whose infant had died in the past year was systematically surveyed. The results provided an initial understanding of the nature of infant mortality in the U.S., indicating that infant deaths occurred more often in lower-income than higher-income families, among bottle-fed than breast-fed infants, and among twins than singletons. Beginning in 1964 and every eight years thereafter through 1988, the National Center for Health Statistics (NCHS) conducted intensive national follow-back studies of live births and infant/fetal deaths, which has provided much of our more recent national epidemiologic information about pregnancy and births, especially concerning smoking, prenatal care usage, etc. A similar Department of Education/NCHS national follow-back and longitudinal follow-up study, the Early Childhood Longitudinal Study-Birth Cohort (ECLS-BC) was begun in 2001 and will survey 10,000 mothers and their infants through kindergarten age.

Fat consumption and HbA(1c) levels: the EPIC-Norfolk study.

To describe the relationship between total dietary fat and the pattern of fat intake and HbA(1c). In this cross-sectional study, 2,759 men and 3,464 women (40-78 years of age) without a previous diagnosis of type 2 diabetes were recruited from a population-based sampling frame. Diet was assessed using a self-reported semiquantitative food frequency questionnaire. The HbA(1c) level was negatively associated with the polyunsaturated fat-to-saturated fat ratio (P:S ratio) of the diet (beta = -0.0338 HbA(1c)% per SD change in P:S ratio; P < 0.001) and positively associated with the total level of fat intake (beta = 0.0620 HbA(1c)% per SD change in total fat intake; P < 0.001), adjusted for age and total energy intake. The associations remained significant when adjusted for each other and for total energy, protein, age, sex, family history of diabetes, BMI, waist-to-hip ratio, physical activity, and smoking (for P:S ratio, beta = -0.0200 HbA(1c)% per SD change in P:S ratio, P = 0.013; for total fat, beta = 0.420% HbA(1c)% per SD change in total fat intake, P < 0.001). The benefits from a high P:S ratio were attributed to a lower saturated fat intake. These findings demonstrate independent associations between HbA(1c) concentration across the normal range of HbA(1c) and both total fat intake and the pattern of dietary fat intake. They provide further support to efforts promoting modifications in the intake of dietary fat.

Driver's License and Voter Registration Lists a s Population-Based Sampling Frames for Rural African Americans

PURPOSE: To compare coverage of a state driver's license list and county voter registration lists as frames for sampling rural African Americans. METHODS: Name, birth date, sex, and county were extracted from records for all 18–59 year-old African Americans residing in eight rural North Carolina counties and listed in the North Carolina Driver license file [obtained as a SAS dataset from the University of North Carolina (UNC) Highway Safety Research Center] and in machine-readable text files of registered voters (obtained from county boards of elections). Files were edited, merged, and matched by last name and date of birth to produce three files for each five-year age group, sex, and county: 1) persons listed only in the driver's file; 2) persons listed only in the voter's file; and 3) persons listed in both. RESULTS: The median percentages of unique persons found only on the driver's list, only on the voter's list, and on both lists were 54%, 17%, and 30% men, and 35%, 25%, and 41% women, respectively. CONCLUSIONS: The driver's list provided better coverage than did voter registration lists. Federal legislation that prohibits states from releasing driver's license lists for use in surveys removes a valuable resource for population-based research.

Epidemiological personology: the unifying role of personality in population-based research on problem behaviors.

Epidemiological personology refers to a paradigm in which a developmental perspective on individual differences is paired with a population-based sampling frame to yield insights about the role of personality in consequential social outcomes. We review our work in epidemiological personology, linking personality to diverse, problematic social outcomes: Mental disorders, health-risk behaviors, and violence. We conclude that broad-band personality measurement is both feasible and fruitful in large-scale research on problem behaviors, and we call for increased collaboration between personality psychologists and researchers in fields such as public health, epidemiology, and sociology.

A cross-sectional study of dietary patterns with glucose intolerance and other features of the metabolic syndrome.

Previous epidemiological studies have demonstrated relationships between individual nutrients and glucose intolerance and type 2 diabetes, but the association with the overall pattern of dietary intake has not previously been described. In order to characterize this association, 802 subjects aged 40-65 years were randomly selected from a population-based sampling frame and underwent a 75 g oral glucose-tolerance test. Principal component analysis was used to identify four dietary patterns explaining 31.7% of the dietary variation in the study cohort. These dietary patterns were associated with other lifestyle factors including socio-economic group, smoking, alcohol intake and physical activity. Component 1 was characterized by a healthy balanced diet with a frequent intake of raw and salad vegetables, fruits in both summer and winter, fish, pasta and rice and low intake of fried foods, sausages, fried fish, and potatoes. This component was negatively correlated with central obesity, fasting plasma glucose, 120 min non-esterified fatty acid and triacylglycerol, and positively correlated with HDL-cholesterol. It therefore appears to be protective for the metabolic syndrome. Component 1 was negatively associated with the risk of having undiagnosed diabetes, and this association was independent of age, sex, smoking and obesity. The findings support the hypothesis that dietary patterns are associated with other lifestyle factors and with glucose intolerance and other features of the metabolic syndrome. The results provide further evidence for the recommendation of a healthy balanced diet as one of the main components of chronic disease prevention.

Genetic variance components analysis for binary phenotypes using generalized linear mixed models (GLMMs) and Gibbs sampling.

The common complex diseases such as asthma are an important focus of genetic research, and studies based on large numbers of simple pedigrees ascertained from population-based sampling frames are becoming commonplace. Many of the genetic and environmental factors causing these diseases are unknown and there is often a strong residual covariance between relatives even after all known determinants are taken into account. This must be modelled correctly whether scientific interest is focused on fixed effects, as in an association analysis, or on the covariances themselves. Analysis is straightforward for multivariate Normal phenotypes, but difficulties arise with other types of trait. Generalized linear mixed models (GLMMs) offer a potentially unifying approach to analysis for many classes of phenotype including multivariate Normal traits, binary traits, and censored survival times. Markov Chain Monte Carlo methods, including Gibbs sampling, provide a convenient framework within which such models may be fitted. In this paper, Bayesian inference Using Gibbs Sampling (a generic Gibbs sampler; BUGS) is used to fit GLMMs for multivariate Normal and binary phenotypes in nuclear families. BUGS is easy to use and readily available. We motivate a suitable model structure for Normal phenotypes and show how the model extends to binary traits. We discuss parameter interpretation and statistical inference and show how to circumvent a number of important theoretical and practical problems that we encountered. Using simulated data we show that model parameters seem consistent and appear unbiased in smaller data sets. We illustrate our methods using data from an ongoing cohort study.

Genetic variance components analysis for binary phenotypes using generalized linear mixed models (GLMMs) and Gibbs sampling

The common complex diseases such as asthma are an important focus of genetic research, and studies based on large numbers of simple pedigrees ascertained from population-based sampling frames are becoming commonplace. Many of the genetic and environmental factors causing these diseases are unknown and there is often a strong residual covariance between relatives even after all known determinants are taken into account. This must be modelled correctly whether scientific interest is focused on fixed effects, as in an association analysis, or on the covariances themselves. Analysis is straightforward for multivariate Normal phenotypes, but difficulties arise with other types of trait. Generalized linear mixed models (GLMMs) offer a potentially unifying approach to analysis for many classes of phenotype including multivariate Normal traits, binary traits, and censored survival times. Markov Chain Monte Carlo methods, including Gibbs sampling, provide a convenient framework within which such models may be fitted. In this paper, Bayesian inference Using Gibbs Sampling (a generic Gibbs sampler; BUGS) is used to fit GLMMs for multivariate Normal and binary phenotypes in nuclear families. BUGS is easy to use and readily available. We motivate a suitable model structure for Normal phenotypes and show how the model extends to binary traits. We discuss parameter interpretation and statistical inference and show how to circumvent a number of important theoretical and practical problems that we encountered. Using simulated data we show that model parameters seem consistent and appear unbiased in smaller data sets. We illustrate our methods using data from an ongoing cohort study. Genet. Epidemiol. 17:118–140, 1999. © 1999 Wiley-Liss, Inc.

Association of the health-promoting workplace with trade unionism and other industrial factors.

The study examines associations of five healthy workplace attributes with trade unionism and nine other industrial and sociodemographic factors. The aims were to illustrate the measurement of workplace health promotion indicators in Western Australia and to identify associations leading to a better understanding of determinants of the healthy workplace. Personal and telephone cross-sectional surveys were performed using population-based sampling frames. The overall response rate was 72%. Workplaces in Western Australia. Random samples of household respondents aged 16 to 69 years in 1992 (n = 1310) and 1994 (n = 1113). Measures of association between healthy workplace attributes and trade unionism were adjusted for workplace location, size, sector, and industrial classification. Trade unionism was strongly associated with healthy catering practices (adjusted OR 2.05; 95% CI 1.30 to 3.23), sun protection practices (2.66; 1.69 to 4.17), disability access (1.47; 1.10 to 1.95), and worksite health promotion programs (2.56; 2.07 to 3.17). A weak and nonsignificant association was observed with restrictive smoking policies (1.21; .95 to 1.55). Generally, healthy workplace attributes were reported less often by respondents working in rural locations, in the private sector, and at small worksites. There was no consistent relationship with sociodemographic factors, including an index of social disadvantage, but members of blue-collar occupations experienced a low prevalence of restrictive smoking policies. The study raises the hypothesis, but cannot confirm, that trade unions could provide a means for employees to pursue the creation of a health-promoting workplace. Small business represents an excellent target for health promotion activities.

The influence of family history of hip fracture on the risk of verterbral deformity in men and women: The European vertebral osteoporosis study

There are few data exploring clustering of osteoporotic fractures within families. The aim of this study was to determine on influence of maternal and paternal history of hip fracture on the risk of vertebral deformity. 12,816 men and women aged 50 to 75 years were recruited from population based sampling frames across Europe. Subjects were invited to attend by letter of invitation for an interviewer administered questionnaire and lateral spinal radiographs. Vertebral deformity was defined morphometrically using the McCloskey-Kanis method. 6.4% of men and 7.1% of women reported that their mother had suffered a hip fracture, while 1.7% of both men and women reported that their father had suffered a hip fracture. A maternal history of hip fracture was associated with a modest increased risk of vertebral deformity in men [odds ratio (OR) 1.3, 95% confidence interval (CI) 1.0–1.8], the risk being greater among those aged 65 years and over (OR = 1.5; 95% CI 1.0–2.4) and in those from low prevalence areas. There was no increased risk in women. Paternal history of hip fracture was not associated with vertebral deformity in either sex. In conclusion, maternal history of hip fracture appears to be a risk factor for vertebral deformity, particularly in men.

The influence of alcohol consumption on the risk of vertebral deformity

The influence of alcohol consumption on the risk of osteoporosis is not well established. The aim of this study was to determine the relationship between frequency of alcohol consumption and the risk of vertebral deformity across different European populations. A population survey method was used. Men and women aged 50 years and over were recruited from population-based sampling frames in 36 centres from 19 European countries. Subjects were invited to attend by letter of invitation for an interviewer-administered questionnaire and lateral spinal radiographs. Vertebral deformity was defined morphometrically using the McCloskey-Kanis method. Data from 14237 individuals were available for this analysis. Alcohol consumption was compared between the 809 men and 884 women with vertebral deformity and the 5905 men and 6639 women without vertebral deformity. The frequency of alcohol intake was greater in men than women. Overall, there was no detectable association between frequency of alcohol intake and vertebral deformity in either men or women. Stratification by age showed that women 65 years and over who took alcohol on more than 5 days per week had a reduced risk of vertebral deformity compared with those taking alcohol less than once per week. This protection was most obvious after adjusting for age, centre, body mass index, smoking, current level of physical activity and previous fractures (odds ratio [OR] = 0.65; 95% confidence intervals [CI] = 0.43, 0.99). There was a smaller and non-significant protective effect amongst men aged 65 years and over and this was most apparent amongst moderately frequent drinkers (1-4 days per week) (OR = 0.81; 95% CI = 0.62, 1.08). There was no association between the occurrence of vertebral deformity and frequency of alcohol consumption in younger men and women. Overall, the effects of the frequency of alcohol consumption on vertebral deformity were modest. In older women, regular consumption on more than 5 days per week is associated with a reduced risk. Further, prospective data are required to confirm these findings. It is also necessary to investigate, in terms of amount of alcohol consumed, at what level the benefits of regular intake are obviated by the increased risks from alcohol excess.

Age and sex influences on fall characteristics.

To investigate age and sex influences on fall characteristics. A total of 1243 subjects (517 males and 726 females) aged 50 years and over and drawn from population based sampling frames were invited to complete an interviewer administered questionnaire concerning descriptive characteristics of falls experienced in the previous four months. Information collected included details about the part of the body to strike the ground, direction of the fall, level of trauma and whether or not injury or fracture was sustained. One hundred and seventy two subjects reported a fall in the previous four months. Restricting analysis to the 142 subjects who fell from a standing height or less, females aged 50-64 years were more than twice as likely to fall onto their hand compared with older females (odds ratio (OR) = 2.2; 95% confidence interval (CI) 0.8 to 6.2) and at all ages (50+) were more than three times as likely to fall on their hip compared with males (OR = 3.4; 95% CI 1.0 to 11.5). Compared with older males, males aged 50-64 were more likely to fall sideways (OR = 5.1; 95% CI 1.5 to 17.4) and less likely to fall forwards (OR = 0.4; 95% CI 0.1 to 1.1). There is a potentially clinically important variation in fall type by age and sex. In particular, this variation might explain patterns of occurrence of hip and Colles' fracture.

The driver's license list as a population-based sampling frame in Iowa.

Driver's license lists are infrequently used for population-based sampling, presumably because of suspicions of poor population coverage. The 1990 Iowa driver's license list was compared with the 1990 census to evaluate coverage by 5-year age group, sex, resident county, and urbanicity. Coverage exceeded 90% among 15- to 74-year-old men and 15- to 64-year-old women, with uniform coverage by county and county urbanicity group in these age ranges. In Iowa, these lists are convenient and cost-effective and appear to be representative for 25- to 64-year-olds. The representativeness of driver lists in regard to other factors and in other geographic regions deserves further evaluation.

Issues and problems in Alzheimer's disease registry development

The case registry is a system for recording, storing, and updating standardized information about all individuals who acquire a particular disease or class of disorders from a specified date onwards. It may contain personal, familial, social, clinical, and genetic information. To be most informative, cases should be culled from a precisely defined geographical or administrative area. Registries produce cumulative, chronologically oriented records about people for epidemiologic and other research as well as statistics for health services planning. The historical development of case registers for cancer, congenital defects, psychiatric conditions, and other disorders has illustrated the diverse, often multipurpose functions that they may serve. Registries are, or can be, populationbased sampling frames for both retrospective and longitudinal studies, and statistical databases. Creating a registry involves addressing six common problems and issues: 1) defining objectives; 2) determining scope of coverage of populations and conditions; 3) ascertaining cases reliably and validating diagnoses; 4) choosing accurate, efficient data collection methods; 5) maintaining confidentiality of patient records and family privacy; 6) bearing the (growing) financial burden. Sites are unique, so solutions must be individualized. Registry operations are complex, expensive, and long-term. The key to their success does not lie in technical and statistical details alone, but in an essential spirit of cooperation and commitment among all participants.