Cohort Members Research Articles

Psychotic Disorders in Adolescence and Later Long-term Exclusion From Education and Employment.

Psychotic disorders have been associated with not being in education, employment, and training (NEET). There is a lack of knowledge on the importance of risk markers for NEET among people with psychotic disorders and what rehabilitation they receive. We based our research on the register-based 1987 Finnish Birth Cohort study, which included all live births in Finland during that year. The study cohort were 288 people who had been diagnosed with psychotic disorders during 2004-2007, when they were 16-20 year old, and 55 883 who had not. We looked at the national register data for those subjects in 2008-2015, when they were 20-28 year old, and compared any associations between sociodemographic factors and NEET status. NEET for more than 5 year affected 2.2% of those without psychosis, 35.8% of those with any nonaffective psychotic disorder, and 57.0% of those with schizophrenia or schizoaffective disorders. Family-related risk factors were weaker predictors of long-term NEET in subjects with psychotic disorders than other cohort members. Having a psychotic disorder plus long-term NEET was associated with not applying for upper secondary education, not finishing upper secondary education, parents receiving welfare benefits, being diagnosed with schizophrenia or schizoaffective disorders and being hospitalized for psychosis. Only 24.3% with psychotic disorders had participated in vocational rehabilitation. A diagnosis of psychosis in adolescence is independently associated with serious long term functional disability. Among those with psychotic disorders, educational problems are markers for adverse labor market outcomes. Despite this, vocational rehabilitation is seldom provided.

Social Integration of Millenial Generation in the Lithuanian Armed Forces - What Cultural Challenges are Waiting for Organization to Retain Individuals in the Military Service?

Millenialls currently are one of the largest members of the age cohorts performing military service among the world armies, also in the armed forces of Lithuania. The expectations of Millenialls individuals are far more individualistic compared to previous generations: generation X, baby boomers. Researches show that millennials more often quit their jobs if the content of jobs do not meet their individual expectations. The vast majority of early military retirees in the Lithuanian armed forces belong to the category of junior officers (senior lieutenants and captains). The aim of this research is to reveal the value features of the social integration of the individuals of the millennium generation (officers, non-commissioned officers) serving in the Lithuanian Armed Forces. The research is done by qualitative research method using a semistructural interview approach- a total of 22 informants were interviewed. The study shows that these sociocultural aspects are condition of social inclusion in the organization (or allienation): the importance of self-realization (more important than career) versus unfulfilled expectations in military service, individual expression versus restriction of individual expression, the importance of favorable conditions to be creative versus meaningless content of the service. This study shows what socio-cultural challenges are relevant when talking about the integration of people today in the Lithuanian Armed Forces and that the socio-cultural content of military service will be increasingly significant and relevant in the future.

Outcomes of a Peer Mentoring Circle: An Innovation to Improve Academic Physician Career Advancement in a Community Hospital Setting.

Faculty retention is a prominent topic in academic medicine. Investment in faculty career development supports faculty vitality, advancement, and retention. Academic physicians in community-based settings far from their academic affiliate may find identifying local career advancement mentorship challenging. In June 2018, a career advancement in-service day at The Children's Hospital of San Antonio and Baylor College of Medicine in Houston was convened to design a peer mentoring circle (PMC). Using self-determination theory, this program aimed to help PMC members develop goals; schedule and attend regular meetings; format, review, and critique member curricula vitae and portfolios; and hold one another accountable to submitting award and promotion applications. Eleven inaugural PMC cohort members attended regular monthly meetings from July 2018 to June 2019 (median, 6 members per meeting). All members were competent in accessing the PMC repository of materials. Statistically significant improvement ( P < .01) was seen in self-reported knowledge and skills relevant to award or academic promotion support and resources. Compared with no patient care or teaching awards and 1 academic promotion among non-PMC faculty, 5 PMC members (45.5%) earned a patient care award, 4 (36.4%) earned a teaching award, and 5 of 10 faculty members (50.0%) achieved academic promotion ( P < .001 for all). On the retrospective pre-post survey, members endorsed several PMC strengths, including personal and emotional support, professional support, and accountability. Next steps include establishing a local faculty development office, convening a second cohort, revising evaluation methods, expanding membership, and offering 1-on-1 career counseling. Community-based academicians who aim to replicate this program should organize a career advancement and faculty development in-service day, identify local faculty members to manage meetings, retain a repository of resources, set deadlines and hold one another accountable to them, and celebrate achievements and support one another in failure.

Left ventricular diastolic abnormalities in vegetarians compared with non-vegetarians.

Vegetarians have less hypertension, diabetes mellitus and obesity, hence possibly lower risk of congestive heart failure (HF). We studied associations between vegetarian diets and echocardiographic markers of stage B HF. In a cross-sectional study, dietary pattern was ascertained by a validated FFQ. Echocardiograms were interpreted using standardised criteria. Participants were free-living subjects in Southern California who were older Adventist Health Study-2 cohort members. After exclusions, 133 subjects aged >60 years were enrolled. Their mean age was 72·7 (sd 8·7) years, 48·1 % were female, 32 % were African American and 71 % were vegetarian. Non-vegetarians had higher body weight (80·3 (sd 15·17) kg v. 71·3 (sd 16·2), P < 0·005), body surface area (1·92 (sd 0·24) m2v. 1·81 (sd 0·22) m2, P = 0·01) and prevalence of hypertension (63 % v. 47 %, P = 0·10). Adjusting for age, sex, race and physical activity, it is found that vegetarians had greater echocardiographic mitral annular e' velocity (a measure of left ventricular (LV) relaxation) 7·44 v. 6·48 (non-vegetarian) cm/s (P = 0·011) and a yet greater contrast when vegans (7·66 cm/s, P = 0·011) were the group of interest. The ratio mid-to-late-diastolic mitral flow velocity (E/A) was also higher in vegans compared with non-vegetarians (1·02 and 0·84, respectively, P = 0·008). Mediation analyses suggested these associations may be partly related to higher blood pressures and BMI in the non-vegetarians. We conclude that vegetarians, especially vegans, appear to have better LV relaxation and fewer diastolic abnormalities than others. As dietary exposure is modifiable, one may speculate pending further investigation about the potential for reduction of stage B HF and later mortality.

Cumulative consumption of tea is associated with lower risk of liver cancer: Updated results from the Shanghai Women's Health Study.

Prospective epidemiological studies have provided limited evidence for an association between tea consumption and liver cancer risk. Based on a population-based prospective cohort study in middle-aged Chinese women, we investigated the association between tea consumption and the risk of primary liver cancer. Detailed information on tea drinking habits and other potential confounders was obtained at the baseline interview. Incident liver cancer cases were identified through record linkage with the population-based cancer registry and verified through home visits and review of medical charts by medical experts. Multiple aspects of tea drinking habits including starting age, duration, intensity and cumulative consumption of any type of tea and green tea were considered. Multivariable-adjusted hazard ratios (aHRs) and their 95% confidence intervals (CIs) were derived from the Cox regression models. After a median follow-up time of 18.12 (interquartile range=1.59) years, 253 incident liver cancer cases were identified from 71 841 cohort members. Compared with never tea drinkers, the risk of liver cancer for participants who have consumed over 30 kg of dried tea leaves cumulatively was 0.56 (95% CI: 0.32-0.97). For those who drank green tea only, the aHR was 0.54 (95% CI: 0.30-0.98). This updated study suggested an inverse association between cumulative consumption of tea, especially green tea and the risk of primary liver cancer.

A validated artificial intelligence-based pipeline for population-wide primary immunodeficiency screening

Identification of patients with underlying inborn errors of immunity and inherent susceptibility to infection remains challenging. The ensuing protracted diagnostic odyssey for such patients often results in greater morbidity and suboptimal outcomes, underscoring a need to develop systematic methods for improving diagnostic rates. The principal aim of this study is to build and validate a generalizable analytical pipeline for population-wide detection of infection susceptibility and risk of primary immunodeficiency. This prospective, longitudinal cohort study coupled weighted rules with a machine learning classifier for risk stratification. Claims data were analyzed from a diverse population (n= 427,110) iteratively over 30 months. Cohort outcomes were enumerated for new diagnoses, hospitalizations, and acute care visits. This study followed TRIPOD (Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis) standards. Cohort members initially identified as high risk were proportionally more likely to receive a diagnosis of primary immunodeficiency compared to those at low-medium risk or those without claims of interest respectively (9% vs 1.5% vs 0.2%; P< .001, chi-square test). Subsequent machine learning stratification enabled an annualized individual snapshot of complexity for triaging referrals. This study's top-performing machine learning model for visit-level prediction used a single dense layer neural network architecture (area under the receiver-operator characteristic curve= 0.98; F1 score= 0.98). A 2-step analytical pipeline can facilitate identification of individuals with primary immunodeficiency and accurately quantify clinical risk.

Altruism, Jobs, and Alternative Certification: Mathematics Teachers’ Reasons for Entry and Their Retention

This study examines the relationship between alternatively certified mathematics teachers’ stated reasons for entry and their odds of retention at the school level and at the district level. Study participants were members of the 2006 and 2007 cohorts of New York City Teaching Fellows who completed three surveys over a 9-year period. Administrative data sets from the New York City Department of Education (NYCDOE) provided employment history of cohort members as well as demographic information about the teachers and sites of employment in New York City (NYC) public schools. Drawing on retention and survey data, we found that, of the four reasons for entry factors, two were predictive of NYCTF mathematics teacher retention (i.e., job benefits and alternative certification) and two were not (i.e., altruism and meaningful job). Given the cost associated with recruiting and training alternatively certified teachers, information to improve the initial selection process and increase the rate of retention makes financial sense for districts that employ alternatively certified teachers.

Childhood onset of migraine, gender, psychological distress and locus of control as predictors of migraine in adulthood

ABSTRACT This study explored a set of psychological and socio-demographic factors in childhood and adulthood associated with migraines assessed at age 42 years. Data were drawn from a large, nationally representative, prospective longitudinal study: the 1970 British Cohort Study (BCS70). In total, 5628 cohort members with data on parental social class at birth, cognitive ability (intelligence), self-esteem and locus of control at age 10 years, psychological distress and educational qualifications at age 34, and current occupation at age 42 years were examined. We assessed whether or not they regularly experienced migraines at age 42 years. Logistic regression analysis showed that childhood migraine, gender and adult psychological distress, as well as childhood locus of control (for females only), were significant and independent predictors of the prevalence of migraine in adulthood. Childhood migraine seemed to have a long-lasting effect on adult migraine, and psychological distress also appeared to detrimentally affect adult migraine over time.

The interaction effect of CHA2DS2-VASc components on ischemic stroke risk after atrial fibrillation: a population-based cohort study

Abstract Background In the European Union, almost nine million individuals 55 years or older had atrial fibrillation in 2010. It is estimated that around a quarter of all ischemic stroke cases in individuals 80 to 89 years can be attributed to atrial fibrillation. The CHA2DS2-VASc is the most commonly used clinical tool to predict ischemic stroke and incorporates congestive heart failure, hypertension, age 75 years or older, diabetes mellitus, previous stroke/transient ischemic attack/systemic embolism, vascular disease, age 65 to 74 years, and female sex. It remains unknown whether the CHA2DS2-VASc components and atrial fibrillation interact biologically, i.e. whether the CHA2DS2-VASc components and atrial fibrillation increase ischemic stroke rate beyond their individual effects. Purpose We examined the interaction effect between CHA2DS2-VASc and atrial fibrillation and on ischemic stroke rate. Methods We conducted a population-based cohort study of all adult atrial fibrillation or flutter patients from 1996 through 2016 and a one-to-five comparison cohort from the general population. Members of the comparison cohort were matched on year of birth, sex, and the individual CHA2DS2-VASc components. We followed each individual from the index date (the date of atrial fibrillation or date of matching) until the first of ischemic stroke, death from any cause, loss-to follow-up, 10 years follow-up, or 31 December 2016. We calculated ischemic stroke rates per 1,000 person-years (PYs) and interaction contrasts, which is the proportion of the summed ischemic stroke rate of the CHA2DS2-VASc components and atrial fibrillation that is beyond their individual effects. Results After one-year follow-up, the ischemic stroke rate per 1,000 PY among individuals with CHA2DS2-VASc score zero was 5.69 (95% confidence interval [CI]: 4.68–6.69) in the atrial fibrillation cohort and 1.86 (95% CI: 1.60–2.12) in the comparison cohort. Among individuals with CHA2DS2-VASc score one, the mortality rate per 1,000 PY increased to 10.9 (95% CI: 9.75–12.0) in the atrial fibrillation cohort and 7.45 (95% CI: 7.01–7.88) in the comparison cohort. The interaction contrast in individuals with CHA2DS2-VASc score one was −0.41 (10.8 − 7.45 − 5.69 + 1.86) indicating that the ischemic stroke rate was not explained by interaction (−0.41 / 10.8 = −3.8%). The interaction effect was −2.75 in individuals with CHA2DS2-VASc score two and −2.79 in individuals with CHA2DS2-VASc score three or higher, again indicating no interaction. Interaction did not explain the ischemic stroke rate after one to five years follow-up either, but did explain 16% of the ischemic stroke rate in individuals with CHA2DS2-VASc score three or higher after five to 10 years follow-up. Conclusion Biological interaction between the CHA2DS2-VASc components and atrial fibrillation does not contribute substantially to the ischemic stroke risk. Funding Acknowledgement Type of funding sources: None.

"I am aware that this letter may be offensive": The Unapologetic Achievements of Ruth Barcan Marcus and Marjorie Glicksman Grene.

This article presents a case study in the complex of pressures and attitudes that shaped the professional lives and intellectual legacies of twentieth-century American philosophers, examining the writings and careers of two of the discipline's pioneering women: Ruth Barcan Marcus and Marjorie Glicksman Grene. As members of the small cohort of women trained in philosophy during the first half of the century who achieved permanent academic appointments, their stories illuminate the salience of gender within the professional world of mid-twentieth century American academia.

BLACK BY GOD | The West Virginian

BLACK BY GOD | The West Virginian

Preparedness for healthy ageing and polysubstance use in long-term cannabis users: a population-representative longitudinal study

SummaryBackgroundCannabis is often characterised as a young person’s drug. However, people who began consuming cannabis in the 1970s and 1980s are no longer young and some have consumed it for many years. This study tested the preregistered hypothesis that long-term cannabis users show accelerated biological ageing in midlife and poorer health preparedness, financial preparedness, and social preparedness for old age.MethodsIn this longitudinal study, participants comprised a population-representative cohort of 1037 individuals born in Dunedin, New Zealand, between April, 1972, and March, 1973, and followed to age 45 years. Cannabis, tobacco, and alcohol use and dependence were assessed at ages 18 years, 21 years, 26 years, 32 years, 38 years, and 45 years. Biological ageing and health, financial, and social preparedness for old age were assessed at age 45 years. Long-term cannabis users were compared using independent samples t tests with five groups: lifelong cannabis non-users, long-term tobacco users, long-term alcohol users, midlife recreational cannabis users, and cannabis quitters. In addition, regression analyses tested dose–response associations for continuously measured persistence of cannabis dependence from age 18 years to 45 years, with associations adjusted for sex, childhood socioeconomic status, childhood IQ, low childhood self-control, family substance dependence history, and persistence of alcohol, tobacco, and other illicit drug dependence.FindingsOf 997 cohort members still alive at age 45 years, 938 (94%) were assessed at age 45 years. Long-term cannabis users showed statistically significant accelerated biological ageing and were less equipped to manage a range of later-life health, financial, and social demands than non-users. Standardised mean differences between long-term cannabis users and non-users were large: 0·70 (95% CI 0·46 to 0·94; p<0·0001) for biological ageing, −0·72 (−0·96 to −0·49, p<0·0001) for health preparedness, −1·08 (−1·31 to −0·85; p<0·0001) for financial preparedness, and −0·59 (−0·84 to −0·34, p<0·0001) for social preparedness. Long-term cannabis users did not fare better than long-term tobacco or alcohol users. Tests of dose–response associations suggested that cannabis associations could not be explained by the socioeconomic origins, childhood IQ, childhood self-control, and family substance-dependence history of long-term cannabis users. Statistical adjustment for long-term tobacco, alcohol, and other illicit drug dependence suggested that long-term cannabis users’ tendency toward polysubstance dependence accounted for their accelerated biological ageing and poor financial and health preparedness, although not for their poor social preparedness (β −0·10, 95% CI −0·18 to −0·02; p=0·017).InterpretationLong-term cannabis users are underprepared for the demands of old age. Although long-term cannabis use appears detrimental, the greatest challenge to healthy ageing is not use of any specific substance, but rather the long-term polysubstance use that characterises many long-term cannabis users. Substance-use interventions should include practical strategies for improving health and building financial and social capital for healthy longevity.

Early-onset burdensome multimorbidity: an exploratory analysis of sentinel conditions, condition accrual sequence and duration of three long-term conditions using the 1970 British Cohort Study

ObjectivesThe prevalence of multiple long-term condition (LTC) multimorbidity is increasing with younger onset among socioeconomically deprived populations. Research on life course trajectories towards multimorbidity is limited and early-onset multimorbidity poorly...

Predictive clustering methods to identify differential toxicity of air pollutant mixtures

BACKGROUND AND AIM: Spatial misalignment between the relatively small number of locations where air pollution mixtures are measured and the locations of cohort members poses a challenge to assessing health effects. This talk presents a clustering-based approach to defining multipollutant exposure profiles that can be well predicted at unobserved locations. METHODS: Clusters are defined by combining multipollutant measurements with spatial and spatiotemporal characteristics of the monitoring location in a Gaussian mixture model. Cluster membership for cohort locations and times are then predicted using parametric and machine learning classification algorithms. RESULTS: We demonstrate this approach using PM2.5 components on a national scale and on-road multipollutant measures (including ultrafine particles and volatile organic compounds) on a regional scale. We identify mixtures associated with differing effects of air pollution exposure on atherosclerosis, blood pressure, and cancer risk. CONCLUSIONS: Cluster-based approaches for defining pollution mixtures provide an effective approach to assessing multipollutant exposures using spatially misaligned data. Incorporating location characteristics can improve predictive accuracy and power for assessing differences in health effects of ambient air pollution exposure. KEYWORDS: ambient air pollution, fine particulate matter, k-means, multipollutant exposures, spatiotemporal statistics

Radon Exposure to Community Members Living Near a Uranium Procession Plant

Background: Members of the Fernald Community Cohort (FCC, N=9782) are persons who lived within 5 miles of the uranium processing plant at Fernald, Ohio, USA. From 1951 to 1989 the site processed uranium ore and recycled materials to make highly refined uranium metal products used in the United States Department of Energy nuclear weapons production. The aqueous raffinate or waste from the chemical digestion process was pumped into two large concrete silos for storage and were found to be sources of radon decay products. Vents in the protective dome covers were not sealed until 1979. Source terms and dosimetry algorithms for exposure to both uranium particulates and radon were developed by CDC. Methods: Based on the CDC prior work, we developed a mathematical model to estimate yearly outdoor radon exposure persons in the cohort from the K-65 silos during 1952-1988. We collected and verified residential history information from members of the cohort. We used the radon source terms developed by CDC, yearly wind speed and direction data, and applied the model to the residential history for each member of the cohort. Results: 9306 members of the cohort had sufficient residential history information to be used for radon dosimetry calculations for individual cohort members. The population mean value (sd) of total cumulative exposure (over the years 1952-1988) was 460.70 (508.84) pCi/m2-years, median 299.60 pCi/m2-years, with a large range of 0-4625.75 pCi/m2-years. Arithmetic median exposure also was calculated for each person, or the median of yearly exposure, with a population mean of 20.43 pCi/m2, also with a large range 0 to 200.57 pCi/m2. Conclusions: Using reliable data and well-developed algorithms we estimated environmental (outdoor) radon exposure for members of the FCC and found a wide range of cumulative outdoor radon exposure. Key Words: uranium, radon, community cohort

Exposure to Wildfires and Cancer Incidence in Canada: A Population-Based Cohort Study

Background and Aim: Wildfires emit many carcinogenic pollutants that contaminate air, water, terrestrial and indoor environments. However, little is currently known about the relationship between exposure to wildfires and cancer risk. The aim of this study was to investigate the associations between residential exposure to wildfires and the incidence of several cancer outcomes in a national, population-based cohort in Canada Methods: We conducted a cohort study of over two million Canadians followed for cancer incidence over 20 years (approximately 34 million person-years). Exposures to wildfires were assigned based on area burned within a 20 or 50 km radius of residential locations and updated for annual residential mobility. Multivariable Cox proportional hazards models were used to estimate associations between exposure to wildfires and specific cancers associated with carcinogenic compounds released by wildfires including lung and brain cancer, non-Hodgkin lymphoma, multiple myeloma, and leukemia, adjusted for many personal and neighbourhood-level covariates. Results: Wildfire exposure was consistently associated with slightly increased incidence of lung cancer and brain tumors. For example, cohort members experiencing a wildfire within 50 km of residential locations in the past ten years had a 4.9% (adjusted HR= 1.049, 95% CI: 1.028-1.071) relatively higher incidence of lung cancer than unexposed populations, and a 10% (adjusted HR= 1.100, 95% CI: 1.026-1.179) relatively higher incidence of brain tumors. Similar associations were observed for the 20 km buffer size. Wildfires were not associated with hematologic cancers in this study, and concentration-response trends were not readily apparent when area burned was modelled as a continuous variable. Conclusions: Long-term exposure to wildfires may increase the risk of lung cancer and brain tumors. Further work is needed to develop long-term estimates of wildfire exposures that capture the complex mixture of environmental pollutants released during these events. Keyword: wildfires, cancer

Temporal factors related to diesel exhaust exposure and lung cancer mortality in the Diesel Exhaust in Miners Study II nested case-control study

BACKGROUND AND AIM: The Diesel Exhaust in Miners Study (DEMS) was an important contributor to the IARC re-classification of diesel exhaust as Group I carcinogen. We extended DEMS cohort follow-up by 18 years and the nested case-control study to include all newly identified lung cancer deaths and matched controls (DEMS II). Our purpose was to further characterize the exposure-response relationship with a focus on the effects of timing of exposure and exposure cessation. METHODS: We conducted a case-control study of lung cancer nested in a cohort of workers in eight nonmetal mines (376 lung cancer deaths, 796 controls). Controls were selected from workers who were alive when the case died, individually matched on mine, sex, race/ethnicity, and birth year (within 5 years). Based on an extensive historical exposure assessment, we estimated respirable elemental carbon (REC), an index of diesel exposure, for each cohort member. Odds ratios (ORs) were estimated by conditional regression analyses controlling for smoking and other confounders. RESULTS: ORs increased with increasing 15-year lagged cumulative exposure, peaking with a tripling of risk for exposures of about 950 to &amp;#x3c;1700 &amp;#x3bc;g/m3-y (OR = 3.23; 95% CI = 1.47 to 7.10), followed by a plateau/decline among the heavily exposed (OR = 1.85; 95% CI = 0.85 to 4.04). Patterns of risk by cumulative REC exposure varied across four exposure time windows (Phomogeneity&amp;#x3c;0.001), with ORs increasing for exposures accrued primarily 10-19 years prior to death (Ptrend&amp;#x3c;0.001). Results provided little support for a waning of risk among workers whose exposures ceased for &amp;#x2265;20 years. CONCLUSIONS: DEMS II preliminary findings provide insight into the exposure-response relationship between diesel exhaust and lung cancer mortality and the effects of timing of exposure, with important implications for the assessment of risk from diesel exhaust by regulatory agencies. KEYWORDS: Diesel exhaust, lung cancer, occupational exposure

Associations between cohort study participation and self-reported health and well-being: the Northern Finland Birth Cohort 1966 Study

AimThe aim of this study was to explore whether active participation in a longitudinal birth cohort study is associated with study participants’ health behaviour and well-being.MethodsThe subjects of this study...

Cohort profile: life with neurofibromatosis 1 – the Danish NF1 cohort

PurposeThe Danish neurofibromatosis 1 (NF1) cohort was initiated to study health-related, socioeconomic and psychological consequences of living with the monogenetic disorder NF1 using a nationwide and population-based approach.ParticipantsThe cohort includes...

Population-Based Limits of Urine Creatinine Excretion

The validity of a timed urine collection is typically judged by measurement of urine creatinine excretion, but prevailing limits may be unreliable. We sought to empirically derive population-based limits of excretion for evaluating the validity of a timed urine collection. Covariate and 24-hour urine data were obtained from 3582 participants in the Chronic Renal Insufficiency Cohort (CRIC) study, 814 participants in the Modification of Diet in Renal Disease (MDRD) study, 1010 participants in the Jackson Heart Study (JHS), and 8536 participants in the Prevention of Renal Vascular End Stage Disease (PREVEND) study. Weight, height, age, sex, and serum creatinine concentrations were evaluated as potential predictors of urine creatinine excretion using Akaike Information Criteria, R-squared values, and deviance. Bias and precision of the fitted models were assessed by analyses of residuals. Agreement between 24-hour creatinine clearance and 125I-iothalamate clearance was assessed before and after exclusion of potentially invalid urine samples. A best-fitting model to predict 24-hour urine creatinine excretion among the 9199 discovery cohort members included sex-specific terms for weight, height, and age (R-squared= 0.328). This model had a median bias of+4.3 mg creatinine/day (95% confidence interval-5.6,+13.3 mg/day) in 4599 validation cohort members, and 82% of observed values were within 30% of predicted model. Serum creatinine concentrations only marginally improved model precision but reduced bias in persons with advanced chronic kidney disease (CKD). The limits of urine creatinine excretion derived here represent the most valid and representative data for appraising the adequacy of a timed urine collection.