Sampling and non-response bias on health-outcomes in surveys of the oldest old.
Ontology highlight
ABSTRACT:
SUBMITTER: Kelfve S
PROVIDER: S-EPMC5549131 | biostudies-other | 2013 Sep
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Reliable hunting bag statistics are a prerequisite for sustainable harvest management based on quantitative modeling. Estimating the total hunting bag for a given game species is faced with a multiplicity of error sources. Of particular concern is the nonresponse error. We consider that the major cause of nonresponse bias is when the reluctance to respond is related to a null harvest, which leads to a potentially important overestimation. For tackling the nonresponse bias issue, we advocate the repeated subsampling of nonrespondents, with a final phase of personal interview by phone, intended to be without nonresponse. When a 100% response rate is actually reached at the last phase, both total and sampling variance can be estimated without bias, whatever the response rates at the previous phases. The actual case of imperfect response at the last phase is studied using Monte Carlo simulations. For imperfect response at the last phase, we show that the estimators we advocate are biased downwards but that these bias remain very moderate if the response rate at the last phase is high enough, depending on the circumstances. Furthermore, we illustrate that increasing the number of phases improves the nonresponse bias attenuation. In case of a hunting bag collecting scheme prone to a high nonresponse rate, for obtaining a very satisfying nonresponse bias attenuation we advocate relying on the multiphase sampling strategy with two- or three-phases, and a response rate in the last phase of at least 90%.
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Project description:Most studies on health trends in the elderly population focus on specific conditions, studied one at a time. However, health problems are often interrelated and exist simultaneously in late life. Individuals with health problems in several domains present special challenges to care services. To estimate future needs for care it may be relevant to study trends of complex health problems as well as single health items. This study identified serious problems in three domains (diseases/symptoms, mobility, cognition/communication) in two representative samples of the Swedish population aged 77 and older (1992: n=537; 2002: n=561). People with serious problems in two or three domains were considered to have complex health problems. Changes between 1992 and 2002 in the prevalence of persons having serious problems in no, one and two/three domains were analyzed with logistic regressions. When examining each domain separately all three showed a significant increase of serious problems. For diseases/symptoms the increase remained significant after controlling for different age and gender distributions in the two surveys. Results showed a significant increase in the prevalence of having problems in one domain, as well as having problems in two or three domains (complex problems). Results persisted when adjusting for different distributions in age, gender and education between 1992 and 2002. Results suggest a worsening of health during the 10-year period and an increase of complex problems. This emphasizes the necessity of cooperation and collaboration between different kinds of medical and social services for elderly people.
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Project description:Public health practitioners are often called upon to make inference about a health indicator for a population at large when the sole available information are data gathered from a convenience sample, such as data gathered on visitors to a clinic. These data may be of the highest quality and quite extensive, but the biases inherent in a convenience sample preclude the legitimate use of powerful inferential tools that are usually associated with a random sample. In general, we know nothing about those who do not visit the clinic beyond the fact that they do not visit the clinic. An alternative is to take a random sample of the population. However, we show that this solution would be wasteful if it excluded the use of available information. Hence, we present a simple annealing methodology that combines a relatively small, and presumably far less expensive, random sample with the convenience sample. This allows us to not only take advantage of powerful inferential tools, but also provides more accurate information than that available from just using data from the random sample alone.
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Project description:IntroductionSubstantial gaps in research remain across oldest-old ethnic populations while the burden of dementia increases exponentially with age among Mexican and Mexican American older adults.MethodsPrevalence and correlates of dementia among individuals ≥82 years of age were examined using two population-based cohort studies: The Mexican Health and Aging Study (MHAS, n = 1078, 2012) and the Hispanic Established Populations for the Epidemiologic Study of the Elderly (HEPESE, n = 735, 2012-2013). The analytic MHAS and HEPESE samples had an average age of 86.4 and 88.0 years, 1.2 and 1.8 women to men, and 2.7 and 5.1 average years of education, respectively.ResultsWe identified 316 (29.2%) and 267 (36.3%) cases of likely dementia in the MHAS and HEPESE cohorts, respectively. For Mexicans but not Mexican Americans, age-adjusted prevalence rates of likely dementia were higher in women than men. For both populations prevalence rates increased with age and decreased with education for Mexican Americans but not for Mexicans. In both populations, odds of likely dementia increased with age. Health insurance for the low-income was significantly associated with higher odds of likely dementia for Mexican American men and women and Mexican women but not men. Living in extended households increased the odds of likely dementia in women, but not in men for both studies. Multiple cardiovascular conditions increased the odds of likely dementia for Mexicans but not for Mexican Americans.DiscussionOur study provides evidence of the high burden of dementia among oldest-old Mexicans and Mexican Americans and its association with health and social vulnerabilities.
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Project description:BackgroundInformation on the extent to which older people's increasing life expectancy is characterized by good or poor health is important for policy and fiscal planning. This study explores trends in health expectancies among the oldest old in Sweden from 1992 to 2011.MethodsCross-sectional health expectancy estimates at age 77 were obtained for 1992, 2002, 2004 and 2011 by Sullivan's method. Health expectancy was assessed by severe disability, mild disability and mobility problems. Changes in health expectancies were decomposed into the contributions attributed to changes of mortality rates, and changes in disability and mobility prevalence. Mortality data were obtained from Statistics Sweden and prevalence data from two nationally representative surveys, the Swedish Panel Study of Living Conditions of the Oldest Old and the Survey of Health, Ageing and Retirement in Europe.ResultsYears free from severe disability, mild disability and mobility problems increased in both men and women. Decomposition analysis indicates that the increase was mainly driven by the change in health status rather than change in mortality. In relation to total life expectancy, the general patterns suggest that women had a compression of health problems and men an expansion.ConclusionMen's life expectancy increased more than women's; however, the increased life expectancy among men was mainly characterized by disability and mobility problems. The results suggest that the gender gap in health expectancy is decreasing.
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Project description:We looked for the presence of prostatic cells and RNAs (cellular and acellular) of prostatic origin in the ejaculate semen from fertile and sterilized men and from men with prostate cancer, to ascertain the suitability of ejaculate semen for studying and monitoring prostate health. Methods. For prostatic cells, semen from fertile and sterile men and men with prostate cancer were subjected to density gradient centrifugation on a 60% cushion of Suprasperm™ and fractions containing somatic cells were washed and cytospun onto coated slides prior to fixation and immunocytochemistry with antibodies recognizing prostatic markers. Small RNAs were isolated from liquefied semen clarified of all cellular and other insoluble material by high-speed ultra-centrifugation. Sequencing libraries were prepared from fractions isolated by PAGE, corresponding to small non-coding (snc) RNAs in the 18-23 nt and 30-35 nt size ranges. Libraries were interrogated by next generation sequencing and analysed to generate lists of differentially expressed RNAs associated with cancer and sterility. Results. Cells positive for cytokeratin 18, PSMA, NKX3.1 and CD24 were observed in most ejaculate samples by indirect immunocytochemistry as either discrete cellular entities or within clumps of cell containing material (DAPI+; antigen positive and negative) and cytoplasmic fragments (DAP–; antigen positive and negative). RNA from populations of cells enriched by differential density gradient centrifugation supported their immunocytochemical designation as prostatic cells. Small RNAs (18 - 43 nt) from seminal plasma were highly heterogeneous although tRNAs and 5SRNAs were the dominant forms. A degree of overlap between the respective differential expression profiles of small RNAs from sterile and cancer samples, suggested a common feature, perhaps indicating an inflammatory response. Conclusion. This study supports a wider appraisal of ejaculate semen for studying and monitoring prostate health.
2020-03-31 | GSE117968 | GEO
Project description:BackgroundMost health surveys have experienced a decline in response rates. A structured approach to evaluate whether a decreasing - and potentially more selective - response over time biased estimated trends in health behaviours is lacking. We developed a framework to explore the role of differential non-response over time. This framework was applied to a repeated cross-sectional survey in which the response rate gradually declined.MethodsWe used data from a survey conducted biannually between 1995 and 2017 in the city of Rotterdam, The Netherlands. Information on the sociodemographic determinants of age, sex, and ethnicity was available for respondents and non-respondents. The main outcome measures of prevalence of sport participation and watching TV were only available for respondents. The framework consisted of four steps: 1) investigating the sociodemographic determinants of responding to the survey and the difference in response over time between sociodemographic groups; 2) estimating variation in health behaviour over time; 3) comparing weighted and unweighted prevalence estimates of health behaviour over time; and 4) comparing associations between sociodemographic determinants and health behaviour over time.ResultsThe overall response rate per survey declined from 47% in 1995 to 15% in 2017. The probability of responding was higher among older people, females, and those with a Western background. The response rate declined in all subgroups, and a faster decline was observed among younger persons and those with a non-Western ethnicity as compared to older persons and those with a Western ethnicity. Variation in health behaviours remained constant. Prevalence estimates and associations did not follow the changes in response over time. On the contrary, the difference in probability of participating in sport gradually decreased between males and females, while no differential change in the response rate was observed.ConclusionsProviding insights on non-response patterns over time is essential to understand whether declines in response rates may have influenced estimated trends in health behaviours. The framework outlined in this study can be used for this purpose. In our example, in spite of a major decline in response rate, there was no evidence that the risk of non-response bias increased over time.
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Project description:Surveys are key means of obtaining policy-relevant information not available from routine sources. Bias arising from non-participation is typically handled by applying weights derived from limited socio-demographic characteristics. This approach neither captures nor adjusts for differences in health and related behaviours between participants and non-participants within categories. We addressed non-participation bias in alcohol consumption estimates using novel methodology applied to 2003 Scottish Health Survey responses record-linked to prospective administrative data. Differences were identified in socio-demographic characteristics, alcohol-related harm (hospitalisation or mortality) and all-cause mortality between survey participants and, from unlinked administrative sources, the contemporaneous general population of Scotland. These were used to infer the number of non-participants within each subgroup defined by socio-demographics and health outcomes. Synthetic observations for non-participants were then generated, missing only alcohol consumption. Weekly alcohol consumption values among synthetic non-participants were multiply imputed under missing at random and missing not at random assumptions. Relative to estimates adjusted using previously derived weights, the obtained mean weekly alcohol intake estimates were up to 59% higher among men and 16% higher among women, depending on the assumptions imposed. This work demonstrates the universal value of multiple imputation-based methodological advancement incorporating administrative health data over routine weighting procedures.
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Project description:OBJECTIVES:The oldest old population has become the fastest growing segment with excess need of care and social support, it is crucial to improve the health-related quality of life (HRQoL) of these populations. This study seeks to evaluate the health status and to investigate modifiable factors associated with health-related quality of life for oldest old adults in China. DESIGN:A cross-sectional population-based study. SETTING:Hainan Province in the south of China. PARTICIPANTS:1,278 adults aged 80 years or older. METHODS:HRQoL was assessed by three-level EuroQol-5D scale (EQ-5D-3L) and a visual analogue scale (VAS). Demographic and health-related variables were analysed by estimating mean values and standard deviations for continuous variables, percentages and standard deviations for categorical variables. Tobit regressions, ordinary least Squared (OLS) regressions and ordered probit regressions were adopted to determine the associated factors for overall HRQoL and for each health dimension. RESULTS:Anxiety/depression was the least reported problem while mobility was the most frequently reported with problem. Female respondents had lower EQ-5D score (0.76 vs. 0.86) and VAS score (66.55 vs. 69.84) than male respondents. Better health-related quality of life was significantly associated with higher BMI, no drinking habit, more leisure activities, living with family members, good sleeping quality, closer social and family connections, fewer numbers of drugs consumed per day, without having hearing or visual impairment, and fewer chronic conditions, after controlling for potential confounders. CONCLUSION:Findings from this study suggested that quality of life was not only associated with age-related diseases, but also correlated with a range of health-related lifestyles, and factors indicating social and family support.
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Project description:Individuals who live to 85 and beyond without developing major age-related diseases may achieve this, in part, by lacking disease susceptibility factors, or by possessing resistance factors that enhance their ability to avoid disease and prolong lifespan. Healthy aging is a complex phenotype likely to be affected by both genetic and environmental factors. We sequenced 24 candidate healthy aging genes in DNA samples from 47 healthy individuals aged eighty-five years or older (the 'oldest-old'), to characterize genetic variation that is present in this exceptional group. These healthy seniors were never diagnosed with cancer, cardiovascular disease, pulmonary disease, diabetes, or Alzheimer disease. We re-sequenced all exons, intron-exon boundaries and selected conserved non-coding sequences of candidate genes involved in aging-related processes, including dietary restriction (PPARG, PPARGC1A, SIRT1, SIRT3, UCP2, UCP3), metabolism (IGF1R, APOB, SCD), autophagy (BECN1, FRAP1), stem cell activation (NOTCH1, DLL1), tumor suppression (TP53, CDKN2A, ING1), DNA methylation (TRDMT1, DNMT3A, DNMT3B) Progeria syndromes (LMNA, ZMPSTE24, KL) and stress response (CRYAB, HSPB2). We detected 935 variants, including 848 single nucleotide polymorphisms (SNPs) and 87 insertion or deletions; 41% (385) were not recorded in dbSNP. This study is the first to present a comprehensive analysis of genetic variation in aging-related candidate genes in healthy oldest-old. These variants and especially our novel polymorphisms are valuable resources to test for genetic association in models of disease susceptibility or resistance. In addition, we propose an innovative tagSNP selection strategy that combines variants identified through gene re-sequencing- and HapMap-derived SNPs.
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