Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “missing data”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources

Children's television viewing, body fat, and physical fitness.

PURPOSE: The study examines the relationship between children's television (TV) viewing and physical fitness. DESIGN: Cross-sectional data from questionnaires and objective measures were analyzed. SETTING: Data were collected during the fall of 1990 from public elementary school students in a suburban California city. SUBJECTS: Approximately 98% of eligible students participated. Of these, 10% were dropped due to missing data, yielding a final sample of 284 girls and 304 boys. MEASURES: Children reported their amount of TV viewing on a typical summer day; parents reported their child's TV viewing on a typical weekday during the school year. Cardiovascular fitness was the 1-mile run/walk. Body fat was both the child's body mass index (BMI) and skinfolds. Additional measures included muscular strength/endurance and flexibility. RESULTS: Mile run/walk times were associated with both parental (eta 2 = .051 and .031 for boys and girls, respectively) and child reports (eta 2 = .020 and .028) of the child's amount of TV viewing. Parental reports, but not child reports, of the child's TV viewing were related to BMI (eta 2 = .041 and .058) and skinfolds (eta 2 = .050 and .029). Neither measure of children's TV viewing was related to muscular strength/endurance or flexibility. CONCLUSIONS: Children's TV viewing seems to be weakly and inconsistently related to various components of physical fitness. However, given the tracking of cardiovascular disease risk factors from childhood into adulthood and the high proportion of children who watch television, these relationships are worthy of further study.

Analysis of Variance↗

Universal newborn hearing screening: summary of evidence.

CONTEXT: Each year, approximately 5000 infants are born in the United States with moderate-to-profound, bilateral permanent hearing loss (PHL). Universal newborn hearing screening (UNHS) has been proposed as a means to speed diagnosis and treatment and thereby improve language outcomes in these children. OBJECTIVES: To identify strengths, weaknesses, and gaps in the evidence supporting UNHS and to compare the additional benefits and harms of UNHS with those of selective screening of high-risk newborns. DATA SOURCES: We searched the MEDLINE, CINAHL, and PsychINFO databases for relevant articles published from 1994 to August 2001, using terms for hearing disorders, infants or newborns, screening, and relevant treatments. We contacted experts and reviewed reference lists to identify additional articles, including those published before 1994. STUDY SELECTION: We included controlled and observational studies of (1) the accuracy, yield, and harms of screening using otoacoustic emissions (OAEs), auditory brainstem response (ABR), or both in the general newborn population and (2) the effects of screening or early identification and treatment on language outcomes. Of an original 340 articles identified, 19 articles, including 1 controlled trial, met these inclusion criteria. DATA EXTRACTION: Data on population, test performance, outcomes, and methodological quality were extracted by 2 authors (D.C.T., H.M.) using prespecified criteria developed by the US Preventive Services Task Force. We queried authors when information needed to assess study quality was missing. DATA SYNTHESIS: Good-quality studies show that from 2041 to 2794 low-risk and 86 to 208 high-risk newborns were screened to find 1 case of moderate-to-profound PHL. The best estimate of positive predictive value was 6.7%. Six percent to 15% of infants who are missed by the screening tests are subsequently diagnosed with bilateral PHL. In a trial of UNHS vs clinical screening at age 8 months, UNHS increased the proportion of infants with moderate-to-severe hearing loss diagnosed by age 10 months (57% vs 14%) but did not reduce the rate of diagnosis after age 18 months. No good-quality controlled study has compared UNHS with selective screening of high-risk newborns. In fair- to poor-quality cohort studies, intervention before age 6 months was associated with improved language and communication skills by ages 2 to 5 years. These studies had unclear criteria for selecting subjects, and none compared an inception cohort of low-risk newborns identified by screening with those identified in usual care, making it impossible to exclude selection bias as an explanation for the results. In a mathematical model based on the literature review, we estimated that extending screening to low-risk infants would detect 1 additional case before age 10 months for every 1441 low-risk infants screened, and result in treatment before 10 months of 1 additional case for every 2401 low-risk infants screened. With UNHS, 254 newborns would be referred for audiological evaluation because of false-positive second-stage screening test results vs 48 for selective screening. CONCLUSIONS: Modern screening tests for hearing impairment can improve identification of newborns with PHL, but the efficacy of UNHS to improve long-term language outcomes remains uncertain.

Evidence-Based Medicine↗

Linked markers and age at diagnosis.

This paper examines the relationship between age at diagnosis and markers linked to a disease trait using 100 replicates from Problem 2A in Genetic Analysis Workshop 10. After establishing the relationship between age and the quantitative trait used to define affection status, Q1, we evaluated the relationship between age at diagnosis and a marker which was linked with Q1. We found that the presence of an F allele at marker 15 on chromosome 5 was significantly associated with delayed age of diagnosis. When we evaluated 100 replicates, we found that the regression coefficients in the survival analyses were separated into two approximately normal distributions. The location of these distributions was solely reflective of the presence of affected individuals with the F allele in a particular replicate. In the replicates in one of the distributions, we found tremendous changes in the variance after employing survival models for dependent data. While we suggest that survival analysis of dependent data may be an important tool in investigating genotype specific alterations in age at event, the findings of this study indicate that the method used may be very sensitive to certain types of missing data.

Adult↗

High levels of plasma C-reactive protein and future risk of age-related cataract.

PURPOSE: Chronic intraocular inflammation, with or without systemic inflammation, is associated with increased risk of cataract. Whether systemic inflammation alone is associated with cataract is unknown. This study examined the association between plasma C-reactive protein (CRP), a marker of systemic inflammation, and risk of cataract. METHODS: In the Physicians' Health Study, we recently analyzed plasma CRP levels in baseline blood specimens from 543 men who later developed cardiovascular disease, and 543 who did not. These data provided a cost-efficient means to explore whether baseline plasma CRP is associated with future risk of age-related cataract. After excluding 252 men with prior diagnosis of cataract or missing data, we followed the remaining 834 men defined by baseline CRP level for 11 years for incident cataract. We used proportional hazards regression models, stratified by cardiovascular disease status. RESULTS: Baseline CRP was significantly higher among men who later developed cataract than levels among those who remained free of cataract, P = 0.02 (median 1.53 versus 1.23 mg/L). In a multivariable model adjusted for cardiovascular disease, randomized aspirin and beta carotene assignments, age, diabetes, cigarette smoking, alcohol consumption, body mass index, exercise, and parental history of myocardial infarction, the levels of CRP remained significantly associated with development of cataract (P = 0.001); but the association was less significant in a model using log CRP levels (P = 0.038). In exploratory analyses of a threshold effect, the excess risk was significant only among men with levels at or above the 97.5th centile (6.17 mg/L); compared to those with lower levels, the relative risk in these men was 3.00 (95% confidence interval, 1.53 to 5.91; P = 0.002). Relative risks associated with CRP levels at or above versus below the 85th, 90th, and 95th percentiles were not significant (relative risks 1.29, 1.50, and 1.77, respectively). CONCLUSIONS: Overall, our results suggest that elevated levels of CRP are associated with future risk of cataract in these apparently healthy men. This early report raises the possibility that systemic inflammation may play a role in the pathogenesis of age-related cataract.

Adult↗

Power in randomized group comparisons: the value of adding a single intermediate time point to a traditional pretest-posttest design.

Adding a pretest as a covariate to a randomized posttest-only design increases statistical power, as does the addition of intermediate time points to a randomized pretest-posttest design. Although typically 5 waves of data are required in this instance to produce meaningful gains in power, a 3-wave intensive design allows the evaluation of the straight-line growth model and may reduce the effect of missing data. The authors identify the statistically most powerful method of data analysis in the 3-wave intensive design. If straight-line growth is assumed, the pretest-posttest slope must assume fairly extreme values for the intermediate time point to increase power beyond the standard analysis of covariance on the posttest with the pretest as covariate, ignoring the intermediate time point.

Humans↗

Manipulative therapy versus education programs in chronic low back pain.

STUDY DESIGN: A randomized trial was conducted on a representative sample of patients with untreated low back pain lasting 7 weeks or longer, or having more than 6 episodes in 12 months. OBJECTIVES: To contrast the effectiveness of manipulation, a manipulation mimic, and a back education program. Methodologic criticisms of earlier studies were addressed. SUMMARY OF BACKGROUND DATA: Published meta-analyses suggest clinical benefit from manipulation for acute patients. Data are inconclusive for patients having symptoms for longer than 1 month. METHODS: A total of 1267 consecutive patients were screened. Block randomization was used to assign 209 qualifying patients to treatment groups. Self-reported pain and activity tolerance served as primary outcome measures. Patients were assessed at enrollment, after 2 weeks of treatment, and again after 2 weeks without treatment. Multiple teams conducted recruitment, randomization, assessment, treatment, and data analysis independently without sharing information. Treatments were carefully described, monitored, and balanced for physician attention and physical contact effects. RESULTS: A total of 81.3% of subjects completed the study. Confounding factors and missing data were identified in approximately 20% of those completing the final follow-up. Analysis of the remaining data was carried out. A strong time effect under treatment was observed. Greater improvement was noted in pain and activity tolerance in the manipulation group. Immediate benefit from pain relief continued to accrue after manipulation, even for the last encounter at the end of the 2-week treatment interval. CONCLUSION: Time is a strong ally of the low back pain patient. In human terms, however, there appears to be clinical value to treatment according to a defined plan using manipulation even in low back pain exceeding 7 weeks' duration.

Adult↗

Statistical issues in interpreting clinical trials.

Randomized clinical trial is an important research tool in evaluating new therapeutic agents, devices and procedures. In order to obtain reliable and unbiased results, careful consideration must be given in the design and conduct of the trial. However, bias can be introduced in the analysis of the final data if certain principles are not followed. Several issues are described that make interpretation of analyses challenging. These include the intent-to-treat principle, the use of surrogate outcome measures, subgroup analyses, missing data and noninferiority trials.

Bias↗

Multimodal CustOmics: A unified and interpretable multi-task deep learning framework for multimodal integrative data analysis in oncology.

Characterizing cancer presents a delicate challenge as it involves deciphering complex biological interactions within the tumor's microenvironment. Clinical trials often provide histology images and molecular profiling of tumors, which can help understand these interactions. Despite recent advances in representing multimodal data for weakly supervised tasks in the medical domain, achieving a coherent and interpretable fusion of whole slide images and multi-omics data is still a challenge. Each modality operates at distinct biological levels, introducing substantial correlations between and within data sources. In response to these challenges, we propose a novel deep-learning-based approach designed to represent multi-omics & histopathology data for precision medicine in a readily interpretable manner. While our approach demonstrates superior performance compared to state-of-the-art methods across multiple test cases, it also deals with incomplete and missing data in a robust manner. It extracts various scores characterizing the activity of each modality and their interactions at the pathway and gene levels. The strength of our method lies in its capacity to unravel pathway activation through multimodal relationships and to extend enrichment analysis to spatial data for supervised tasks. We showcase its predictive capacity and interpretation scores by extensively exploring multiple TCGA datasets and validation cohorts. The method opens new perspectives in understanding the complex relationships between multimodal pathological genomic data in different cancer types and is publicly available on Github.

Deep Learning↗

[PHOLY: a pilot study of drug utilization in civil hospitals in Lyon. Results].

As shown in many studies, up-to-date knowledge is not reflected in prescribing behaviours. The aim of pilot study PHOLY (Prescription aux Hospices civils de LYon) was to study methodological and technical conditions of a drug utilization study in a large university medical centre and to evaluate the discrepancy between drug prescribing and up-to-date knowledge. Data of 1115 in-patients of Hospices Civils de Lyon were collected. We have shown the feasibility of such a study in spite of many difficulties (52.15 per cent of questionnaires received, missing data...). Reference treatments such as ACE inhibitors in heart failure treatment or betablockers for high blood pressure represent respectively only 14.6 per cent and 6.7 per cent of the prescriptions in these indications. Within the framework of quality of care improvement, the study of the appropriateness of the treatments enables identification of domains where better therapeutic information is necessary.

Adrenergic beta-Antagonists↗

Statistical analysis of spatial data in the presence of missing observations: a methodological guide and an application to urban census data.

"In this paper a simple introduction and guide to a widely applicable method for estimating missing data in fields of enquiry such as census maps or LANDSAT images are presented. The method given is a maximum likelihood procedure.... The algorithm is presented in the form of a simple tutorial guide. An example, of median income levels in Houston [Texas], is worked through in detail for missing cells in census data. The example is characterised by a variable mean and a general variance-covariance matrix."

Americas↗

Auricular acupuncture for cocaine dependence.

BACKGROUND: Auricular acupuncture (insertion of acupuncture into a number, usually five, of specific points in the ear) is a widely-used treatment for cocaine dependence. OBJECTIVES: To determine whether auricular acupuncture is an effective treatment for cocaine dependence, and to investigate whether its effectiveness is influenced by the treatment regimen. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2004); MEDLINE (January 1966 to October 2004) , EMBASE (January 1988 to October 2004); PsycInfo (1985 to October 2004); CINAHL (1982 to October 2004); SIGLE (1980 to October 2004) and reference lists of articles. SELECTION CRITERIA: Randomised controlled trials comparing a therapeutic regimen of auricular acupuncture with sham acupuncture or no treatment for reduction of cocaine use in cocaine dependents. DATA COLLECTION AND ANALYSIS: Two authors independently extracted data from published reports and assessed study quality using the Drug and Alcohol CRG checklist. All authors were contacted for additional information; two provided data. Separate meta-analyses were conducted for studies comparing auricular acupuncture with sham acupuncture, and with no treatment. For the main cocaine use outcomes, analyses were conducted by intention to treat, assuming that missing data were treatment failures. Available case analyses, using only individuals who provided data, were also conducted. MAIN RESULTS: Seven studies with a total of 1,433 participants were included. All were of generally low methodological quality. No differences between acupuncture and sham acupuncture were found for attition RR 1.05 (95% CI 0.89 to 1.23) or acupuncture and no acupuncture: RR 1.06 (95% CI 0.90 to 1.26) neither for any measure of cocaine or other drug use. However, the number of participants included in meta-analyses was low, and power was limited. Moderate benefit or harm is not ruled out by these results. Methodological limitations of the included studies may have also made the results open to bias. AUTHORS' CONCLUSIONS: There is currently no evidence that auricular acupuncture is effective for the treatment of cocaine dependence. The evidence is not of high quality and is inconclusive. Further randomised trials of auricular acupuncture may be justified.

Acupuncture, Ear↗

A comparison of three approaches to estimate exposure-specific incidence rates from population-based case-control data.

In population-based case-control studies, an attempt is made to identify all incident cases diagnosed in a specified population during a fixed time interval. Assuming that this goal is met allows one to obtain measures of risk other than relative risks. In this paper, we describe three approaches to estimate exposure-specific incidence rates. Approach 1 relies on estimating crude incidence rates of the disease in strata defined, for instance, by age and geographic area, and combining them with relative risk estimates from the case-control data. In approaches 2 and 3, baseline incidence rates and relative risks are estimated jointly. Approach 2 is based on a pseudo-likelihood, while, in approach 3, the problem is regarded as a missing data problem and a full likelihood is maximized. We applied these three approaches to a study of bladder cancer. Our three sets of estimates of exposure-specific incidence rates were in close agreement, while there appeared to be greater precision with approaches 2 and 3.

Adult↗

[Computer-assisted system for analysis of heart rate variability in clinical studies].

This paper describes an adaptable framework that facilitates exploratory analysis, interpretation and classification of beat-to-beat data extracted from the electrocardiogram (ECG). The system supports a variety of user-defined annotations and allows the definition of analysis programs. Special care is taken on the correct treatment of corrupted and missing data, ubiquitously found in real world problems. Besides the computation, the performance of single features can be inspected using different kinds of diagrams provided by the system. Combinations of features can be evaluated using a polynomial classifier. Both the computation and combination of features are defined as tasks that can be dispatched by a server to various clients. The framework is easily adaptable to different problem structures and has been used successfully in three studies.

Atrial Fibrillation↗

Population and vital statistics, 1981.

"For various reasons some of the data relating to population estimates, vital statistics and causes of death in 1981 were not included in the Statistical Abstract of Israel No. 33, 1982. The purpose of this [article] is to complete the missing data and to revise and update some other data." Statistics are included on population by age, sex, marital status, population group, origin, continent of birth, period of immigration, and religion; marriages, divorces, live births, deaths, natural increase, infant deaths, and stillbirths by religion; characteristics of persons marrying and divorcing, including place of residence, religion, age, previous marital status, and year and duration of marriage; live births, deaths, and infant deaths by district, sub-district, and type of locality of residence; deaths by age, sex, and continent of birth; infant deaths by age, sex, and population group; and selected life table values by population group and sex.

Age Distribution↗

Hospital adoption of medical technology: an empirical test of alternative models.

OBJECTIVE: This study examines hospital motivations to acquire new medical technology, an issue of considerable policy relevance: in this case, whether, when, and why hospitals acquire a new capital-intensive medical technology, magnetic resonance imaging equipment (MRI). STUDY DESIGN: We review three common explanations for medical technology adoption: profit maximization, technological preeminence, and clinical excellence, and incorporate them into a composite model, controlling for regulatory differences, market structures, and organizational characteristics. All four models are then tested using Cox regressions. DATA SOURCES: The study is based on an initial sample of 637 hospitals in the continental United States that owned or leased an MRI unit as of 31 December 1988, plus nonadopters. Due to missing data the final sample consisted of 507 hospitals. The data, drawn from two telephone surveys, are supplemented by the AHA Survey, census data, and industry and academic sources. PRINCIPAL FINDING: Statistically, the three individual models account for roughly comparable amounts of variance in past adoption behavior. On the basis of explanatory power and parsimony, however, the technology model is "best." Although the composite model is statistically better than any of the individual models, it does not add much more explanatory power adjusting for the number of variables added. CONCLUSIONS: The composite model identified the importance a hospital attached to being a technological leader, its clinical requirements, and the change in revenues it associated with the adoption of MRI as the major determinants of adoption behavior. We conclude that a hospital's adoption behavior is strongly linked to its strategic orientation.

Capital Expenditures↗

Does the goose really lay golden eggs? A methodological review of Workmen's Compensation studies.

OBJECTIVE: To assess the value of workmen's compensation (WC) studies to determine the effectiveness of chiropractic. Therefore, the results of the available WC studies are summarized and the methodological quality of WC studies is discussed. DATA SOURCES: All studies were eligible without time restriction. Studies were identified by a Medline search from 1966 to 1990 (key words: chiropractic, and manipulation-orthopedic in combination with comparative studies, follow-up studies, evaluation studies) by manual examination of the most important chiropractic reference systems (CRAC and Index to Chiropractic Literature), by tracking the reference lists of identified (reviews of) WC studies and by correspondence with researchers. STUDY SELECTION: Studies were regarded as WC studies if by means of databases of WC boards, a comparison was made between claimants treated by chiropractors and those treated by other health care professionals. At least one of the following outcomes should be reported: compensated days, compensation paid or treatment costs. DATA EXTRACTION: Relevant data (authors, year, state, study population, number of patients, days compensated, compensation paid, number of treatments, consultation costs, additional treatment costs and total cost per case) were extracted by one nonblinded observer. The methodological value was reviewed narratively. DATA SYNTHESIS: The retrospective character of WC studies and the use of large WC databases harbor severe methodological problems like incomparability of study groups, absence of information on prognostic indicators, insufficient outcome measures and missing data. The results of older WC studies (before 1980) and the more recent WC studies, which were of better methodological quality, are presented separately. The older studies are in favor of chiropractic. Two of the six more recent WC studies challenge chiropractic effectiveness. CONCLUSIONS: WC studies in general report positive results for chiropractic. Recent results are more ambiguous. Because of the methodological drawbacks identified, WC studies are insufficient to enable a valid study made of chiropractic effectiveness. Therefore, chiropractic (cost-) effectiveness is not yet convincingly proven. More effort should be directed at establishing randomized clinical trials including the question of (cost-) effectiveness.

Accidents, Occupational↗

XML-based visualization of design and completeness in medical databases.

PURPOSE: mdplot (medical database plot) visualizes both structure and quality of data in medical databases by means of a summary representation of design and completeness in XML format. The goal is to identify attributes suitable for evaluation and to aid in creating open data models. METHODS: A three-stage visualization approach is applied. First, an overview of all classes in a database, second a detailed view of a specific class and third an analysis of individual attributes. Missing data is identified to enable specific efforts to improve data quality prior to analysis. For each class number of patients, attributes, and records per patient are provided. A condensed bar chart for each category of attributes (categorical, numerical, text and other) visualizes available content: The abscissa corresponds to the sequence of attributes; the ordinate represents completeness per attribute. By selection of a specific class, a detailed description is provided including mean completeness in each category as well as completeness per attribute. To analyse attributes that are collected at several time points per patient, a frequency distribution of records per patient can be generated. RESULTS: The new methodology was applied to two clinical research databases consisting of 292 attributes (955 patients) and 224 attributes (610 patients), respectively, and resulted in major restructuring of the systems. A public website is provided for generation of mdplots.

Data Collection↗

BNArray: an R package for constructing gene regulatory networks from microarray data by using Bayesian network.

UNLABELLED: BNArray is a systemized tool developed in R. It facilitates the construction of gene regulatory networks from DNA microarray data by using Bayesian network. Significant sub-modules of regulatory networks with high confidence are reconstructed by using our extended sub-network mining algorithm of directed graphs. BNArray can handle microarray datasets with missing data. To evaluate the statistical features of generated Bayesian networks, re-sampling procedures are utilized to yield collections of candidate 1st-order network sets for mining dense coherent sub-networks. AVAILABILITY: The R package and the supplementary documentation are available at http://www.cls.zju.edu.cn/binfo/BNArray/.

Algorithms↗