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PubMed1995

Sex-specific causal factors and effects of common environment for symptoms of anxiety and depression in twins.

Two thousand five hundred seventy intact pairs and 724 single responders from Norwegian twins aged 18-25 years completed questionnaires with information about anxiety and depression and perceived cotwin closeness. The aim of the study was the univariate estimation of sex-specific genetic and environmental effects on an index tapping symptoms of anxiety and depression. An index of social closeness between cotwins was significantly related to the cotwin correlation for anxiety/depression scores. MZ pairs were reported to be closer than DZ pairs, and like-sexed DZ pairs were closer than unlike-sexed pairs. The symptom data were adjusted for this apparent violation of the "equal-environment" assumption in twin studies, but the adjustment did not dramatically affect the parameter estimates of genetic and environmental effects on anxiety/depression. A model specifying male (aM) and female (aF) genetic additive effects, shared environment for males (cM), and individual environmental effects (eM and eF) fitted the adjusted data very well. An alternative model, specifying aM = aF, cM = cF, and eM = eF, and no correlation between those environmental factors shared by brothers and those shared by sisters, fitted equally well. Estimated proportions of total variance from the first model were aM2 = .30, aF2 = .52, and cM2 = .21. The estimates from the second model were aM2 = aF2 = .43 and cM2 = cF2 = .11.

Adolescent↗
PubMed2002

Long-chain n-3-to-n-6 polyunsaturated fatty acid ratios in breast adipose tissue from women with and without breast cancer.

Animal studies suggest that dietary polyunsaturated fatty acids (PUFAs) of the n-6 class, found in corn and safflower oils, may be precursors of intermediates involved in the development of mammary tumors, whereas long-chain (LC) n-3 PUFAs, found in fish oil, can inhibit these effects. This case-control study was designed to examine the relationship between the PUFA composition of breast adipose tissue and the risk of breast cancer. Using fatty acid levels in breast adipose tissue as a biomarker of past qualitative dietary intake of fatty acids, we examined the hypothesis that breast cancer risk is negatively associated with specific LC n-3 PUFAs (eicosapentaenoic acid and docosahexaenoic acid) and positively associated with n-6 PUFAs (linoleic acid and arachidonic acid). Breast adipose tissue was collected from 73 breast cancer patients and 74 controls with macromastia. The fatty acid levels were determined by gas-liquid chromatography. A logistic regression model was used to obtain odds ratio estimates while adjusting for age. The age-adjusted n-6 PUFA (linoleic acid and arachidonic acid) content was significantly higher in cases than in controls (P = 0.02). There was a trend in the age-adjusted data suggesting that, at a given level of n-6 PUFA, LC n-3 PUFAs (eicosapentaenoic acid and docosahexaenoic acid) may have a protective effect (P = 0.06). A similar inverse relationship was observed with LC n-3-to-n-6 ratio when the data were adjusted for age (P = 0.09). We conclude that total n-6 PUFAs may be contributing to the high risk of breast cancer in the United States and that LC n-3 PUFAs, derived from fish oils, may have a protective effect.

Adipose Tissue↗
PubMed2004

Comparison between creatinine and pregnanediol adjustments in the retrospective analysis of urinary hormone profiles during the human menstrual cycle.

Measurement of reproductive hormones in urine is a practical way of obtaining large amounts of information; however, there is still controversy on how to overcome problems derived from volume fluctuations between samples. Creatinine adjustment is a widely accepted solution, however, it introduces an extra cost, and large studies involving multiple sequential determinations would benefit from more economical solutions. We determined the value of creatinine adjustment, and compared it with a mathematical method that uses the smoothed profile of pregnanediol (PdG) as a reference to adjust other hormonal markers. To do this, we investigated the effects on three major urinary reproductive hormonal markers (luteinizing hormone (LH), estrone 3-glucuronide (E1G) and PdG) in 17 complete menstrual cycles. Detection of the day of LH peak did not differ between raw and adjusted data. Creatinine adjustment reduced variation in pre-ovulatory E1G levels between individuals, though the effect was negligible within individuals. No significant differences were found regarding post-ovulatory PdG rise. Although creatinine adjustment significantly reduces variability, producing smoother profiles, an equivalent degree of smoothness is obtained using the PdG adjustment. We conclude that under the current technology, for the retrospective study of urinary hormonal profiles in the human menstrual cycle, PdG adjustment is a valid alternative to creatinine.

Adult↗
PubMedDate not supplied

Cohort survival in ageing populations: a model life table approach.

"In populations where higher proportions are surviving longer, cohort life tables are a valuable means of measuring changes and anticipating future developments. Yet cohort life tables are calculated only infrequently from national mortality statistics because of difficulties in adjusting observed data and projecting cohort survival. To facilitate regular updating, an approach to cohort life table construction is needed that circumvents the problems of data adjustment and projection. This paper proposes a method based on model life tables which provides information consistent with official life tables and projections of life expectancy. The paper also compares the results with those obtained by other methods and discusses some implications of trends in cohort survival." (SUMMARY IN ITA AND FRE)

Cohort Studies↗
PubMed1992

Family functions and children's postdivorce adjustment.

Data on school-age children of divorced parents were examined to determine which dimensions of family dynamics were most associated with the children's socioemotional adjustment. Those factors found to be most significant were family roles, behavior control, and affective involvement, as well as children's reaction to and insight into the divorce, and conflict in the home after the divorce. Implications for parent education and early intervention are discussed.

Adaptation, Psychological↗
PubMed2002

Adjustments and measures of differential expression for microarray data.

MOTIVATION: Existing analyses of microarray data often incorporate an obscure data normalization procedure applied prior to data analysis. For example, ratios of microarray channels intensities are normalized to have common mean over the set of genes. We made an attempt to understand the meaning of such procedures from the modeling point of view, and to formulate the model assumptions that underlie them. Given a considerable diversity of data adjustment procedures, the question of their performance, comparison and ranking for various microarray experiments was of interest. RESULTS: A two-step statistical procedure is proposed: data transformation (adjustment for slide-specific effect) followed by a statistical test applied to transformed data. Various methods of analysis for differential expression are compared using simulations and real data on colon cancer cell lines. We found that robust categorical adjustments outperform the ones based on a precisely defined stochastic model, including some commonly used procedures.

Colonic Neoplasms↗
PubMedDate not supplied

Meta-analysis of failure-time data with adjustment for covariates.

The objective of this study was to present and illustrate a technique for combining failure-time data from various sources, adjusting for differences in case-mix among studies. Based on the proportional-hazards model and the actuarial life-table approach, the method used assumes that the variation across studies is in part due to heterogeneity of the case-mix and adjusts for the case-mix before pooling results. As an example, the technique is applied to life-table data from six selected papers reporting patency of affected arteries following femoropopliteal angioplasty. Published 4- and 5-year patency results ranged from 25% to 58%, with a pooled five-year cumulative patency rate (without adjustment for case-mix) of 45% (+/- 2%). The populations in these studies, however, differed markedly in the prevalence of factors with prognostic value: type of lesion and distal runoff vessels. After adjustment for these differences in case-mix, the pooled five-year patency rates ranged from 60% (+/- 2%) for patients with stenotic lesions and good runoff to 24% (+/- 9%) for those with occlusion and poor runoff. The authors conclude that pooling studies without considering the effect of case-mix yields an average result with inappropriately narrow confidence intervals that does not reflect the variability across subgroups. The presented technique provides a method for combining failure-time data, adjusting for case-mix.

Analysis of Variance↗
PubMed1991

Socioeconomic factors and cancer incidence among blacks and whites.

Findings from previous studies suggest that differences in socioeconomic status may be responsible for some, if not all, of the elevated incidence of cancer among blacks as compared with whites. Using incidence data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program, we tested this hypothesis by correlating black and white cancer incidence rates in three US metropolitan areas between 1978 and 1982 with data from the 1980 census on socioeconomic status within individual census tracts. The study analyzed data on the incidence of cancer at all sites combined (greater than 100 cancer sites) and at seven major sites separately. As in other studies, income and educational levels served as surrogates for socioeconomic status. The present study also used census-tract data on population density as a surrogate factor. Each of these measures of socioeconomic status was analyzed independently. Before correlation with census-tract data, age-adjusted data on cancer incidence showed statistically significant elevated risks among blacks for cancer at all sites combined and at four of the seven separate sites; whites showed an elevated risk for cancer at two sites. Cancer at only one site, the colon, showed no significant association with race. When age-adjusted incidence data were correlated with socioeconomic status, the comparative black-white risks changed: Whites showed an elevated risk of cancer at all sites combined and at three of the seven separate sites; blacks maintained their elevated risk at three sites. These findings suggest that the disproportionate distribution of blacks at lower socioeconomic levels accounts for much of the excess cancer burden among blacks. They also suggest that for both blacks and whites unidentified racial factors, which may be either cultural or genetic and which are not closely linked to socioeconomic status, may play a role in the incidence of some cancers.

Black or African American↗
PubMed2003

Evaluating two adjustment methods to extrapolate HIV prevalence from pregnant women to the general female population in sub-Saharan Africa.

OBJECTIVE: To evaluate two methods for estimating HIV prevalence among the general female population of reproductive age by adjusting data observed among antenatal clinic (ANC) attendees. METHODS: We adjusted the HIV prevalence among ANC attendees in Fort Portal (Uganda; 1994-1995), Mwanza municipality (Tanzania; 1990-1991), rural Mwanza (Tanzania; 1991-1993), Mposhi district (Zambia; 1994), Chelston (Lusaka, Zambia; 1994, 1996 and 1998) and Ndola (Zambia; 1998), using firstly a method that accounts for differences in age-specific fertility by HIV serostatus and secondly a method that accounts for differences in HIV prevalence by fertility risk category and parity. RESULTS: The non-adjusted HIV prevalence among ANC attendees underestimates the prevalence among the general female population by 8.0% in Chelston in 1998 and by between 20.7% and 31.9% in all other cases. The adjusted prevalence obtained using the first method underestimates the prevalence among the general female population by about 0.5% in Fort Portal and Mposhi; it overestimates that observed in Chelston in 1994 and 1996 by about 3.5%, and that observed in Ndola, urban Mwanza and rural Mwanza, by 6.5%, 10.6% and 12.8%, respectively. The second method (applied for only four sites) provides an overestimate of 7.0% in Chelston in 1994 and an underestimate of 3.8% and 2.1% in Ndola and rural Mwanza, respectively. Both adjustment methods overestimate the 1998 prevalence in Chelston, producing less accurate estimates than the non-adjusted data. CONCLUSIONS: The HIV prevalence among women in the general population could be estimated fairly accurately by these methods in settings with mature epidemics.

Adolescent↗
PubMed2007

Genetic evaluation of beef carcass data using different endpoint adjustments.

Carcass data from 6,795 Simmental-sired animals born from 1992 to 2001 were used to determine whether adjustment to a constant age, back-fat, HCW, or marbling score would result in differences in heritability of the carcass traits and, correspondingly, if EPD calculated using those variance components and adjustments would result in sire reranking. The endpoints were age (EPA), backfat (EPF), HCW (EPC), or marbling (EPM). The traits analyzed were 12th-rib backfat (FAT), HCW, marbling (MRB), LM area (LMA), and percentage retail cuts (PRC). The data were analyzed using an animal model, where contemporary group was included as a fixed effect and was composed of slaughter date, sex, and herd. Random effects included in the model were direct genetic and residual. Estimates of heritability ranged from 0.12 to 0.14, 0.32 to 0.34, and 0.26 to 0.27 for FAT, HCW, and LMA, respectively, for the corresponding endpoints. Heritability for MRB was estimated to be 0.27 at all endpoints. For PRC, estimates of heritability were more variable, with estimates of 0.23 +/- 0.05, 0.32 +/- 0.05, 0.21 +/- 0.05, and 0.20 +/- 0.04 for EPA, EPF, EPC, and EPM, respectively. However, because the EPF and EPC adjustments adjust for a component trait of PRC (FAT and HCW, respectively), they may be altering the trait to one different from PRC. Spearman rank correlations between EPD within a trait using EPA compared with the other endpoints were >0.90 (P < 0.01) for FAT, HCW, MRB, and LMA. For PRC, Spearman rank correlations with EPA EPD were 0.73 (P < 0.01), 0.93 (P < 0.01), and 0.95 (P < 0.01) for EPF, EPC, and EPM, respectively. For most traits and endpoints, there was little reranking among sires when alternative endpoints were used. However, adjusting PRC to EPF appears to result in a greater heritability and substantial re-ranking of sires, potentially due to the adjustment changing the trait to one other than PRC.

Animals↗
PubMed1989

Estimating age incidence from survey data with adjustments for recall errors.

In this paper we propose a method and discuss the type of data required to estimate age incidence rates from population survey data. While surveys are typically designed to estimate the prevalence of a disease or medical condition, they can also be used to estimate incidence rates. A limitation of survey data, however, is that recall is prone to errors. Three types of errors are common: telescopic, false negative, and false positive reports. Telescopic reports are thought to be the most common. We propose a method to adjust for recall errors by modeling the reported age of onset (ONST) and the time interval since the reported first occurrence of the medical condition (LAG). A number of models were examined using migraine headache data from over 10,000 subjects in Washington County, Maryland. Population surveys should be considered as a relatively inexpensive means for estimating the age incidence of medical conditions, especially for symptom based problems like back pain, asthma, mental illness, and serious headache. We recommend that data be collected on variables which can be used as surrogates for the different types of recall errors. Specifically, the age at interview, the date when the condition was cured or in remission, the severity of the condition, and possibly a specific inquiry as to how certain the respondent is in reporting the date of medical events, should be considered for this purpose.

Adolescent↗
PubMed1994

Case-mix adjustment, claims data quality, and physician profiling.

On the surface, there are many ways in which case mix may be considered, but the key to any successful system often lies below the surface, in the way in which the available data feed the systems, and in the operational environment in which the output is to be used. This article will review terminology used in case-mix adjustment and profiling techniques, highlight some dangerous (and avoidable) data pitfalls, and emphasize reasonable goals that can be achieved through the use of case-mix adjusted profiling.

Data Collection↗
PubMed1990

Surviving hematological malignancies: stress responses and predicting psychological adjustment.

Within the adolescent survivor sample, the psychosocial response of having been diagnosed and successfully treated for cancer is not universal as evidenced by the variability in psychosocial adjustment. Data from the MHI suggests that adolescent cancer survivors do experience more global psychological distress than a comparison group of healthy adolescents. In addition, the majority of these patients reported persistent, intrusive thoughts about their illness and its treatment. Conversely, the adolescent cancer survivors did not differ from a normative sample on social competence, manifestation of problems behaviors, or school achievement. Thus, our data suggest that adjustment in this population is multi-dimensional with variability. While they are functioning quite adequately at school and in social situation, they continue to experience heightened and persistent distress of both a global and illness-specific quality. A number of factors that are conducive to psychosocial intervention appear to be related to adjustment. Family communication and family cohesion were significantly related to the mental health of the adolescent survivors, suggesting a need to further explore the family context of adolescent adjustment. The present work also represents the first attempt to directly examine the psychosocial functioning of young adult, acute leukemia survivors. When compared with normative samples of nonpatients, these survivors (taken as a whole group), reported heightened levels on several indicators of psychological distress. While not entirely consistent across different psychological measures, these young people were generally one standard deviation above the mean for psychological distress. But when compared to normative samples of psychiatric outpatients, our survivors reported significantly less psychological distress. For instance, leukemia survivors reported less intrusive and avoidant cognitions associated with the stressor of being diagnosed and treated for cancer than those associated with patients experiencing traumatic stress disorders. In aggregate, these findings again suggest that the psychosocial adjustment of leukemia survivors is quite variable. Finally, while group comparisons shed light on the psychosocial functioning of leukemia survivors, in general, wide variability in psychosocial adjustment may mask identification of a cohort of cancer survivors most at-risk for psychosocial dysfunction. Sociodemographic, disease/treatment and psychological distress variables only partially explain this variability. The findings from our data suggest several clinical recommendations. First, the prevalence of persistent, psychiatric comorbidity is quite low among long-term survivors of hematologic malignancies survivors. Second, if survivors do experience some psychological distress, usually, it is of non-psychopathological proportions.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Psychological↗
PubMedDate not supplied

Statistical approaches to experimental design and data analysis of in vivo studies.

The objective of any experiment is to obtain an unbiased and precise estimate of a treatment effect in an efficient manner. Statistical aspects of the design, conduct, and analysis of the experiment play a major role in determining whether this goal is met. We highlight some of the more important statistical issues that pertain to in vivo studies. Particular emphasis is placed on the role of randomization, the number of animals, the utilization of repeated measures data, adjustments for missing data, and dealing with multiple causes of death or treatment failure. The discussion is not intended to be a comprehensive guide to all the statistical issues that can occur in animal experiments. Rather, the objective is to acquaint researchers with components of the experiment that will require careful statistical thought.

Animals↗
PubMed1996

Use of risk-adjusted outcome data for quality improvement by public hospitals.

In 1993 the California Office of Statewide Health Planning and Development (OSHPD) began public release of risk-adjusted monitoring of outcomes (RAMO) under the California Hospital Outcomes Project. We studied how 17 acute are public hospitals in California used these RAMO data for quality improvement purposes following their initial distribution, first by analyzing the outcome data for San Francisco General Hospital Medical Center as recommended by OSHPD and, second, by querying the departments at the other 16 public hospitals to determine how their own analyses compared. We found that the hospitals generally did minimal analyses of the OSHPD RAMO data and considered the data of little value to them. Only 3 hospitals initiated quality improvement activities based on their data review. The major reasons given by the hospitals for not using the RAMO data were that their outcomes were adequate, as verified by a comparison of their observed outcomes and those expected after risk-adjustment; that the hospitals had too few patients in the diagnostic categories; that they had too few resources; and that they were not concerned with the data's public release. Other possible explanations were that awareness of the California Hospital Outcomes Project was not widespread at the time of the study, that the RAMO data were not distributed in a way that encouraged their use, and that public hospitals were not inclined to use the outcome data because the project was imposed on them. Whatever the explanation, our study suggests that the California Hospital Outcomes Project has had little effect on quality improvement in public hospitals.

California↗
PubMed2000

Three-dimensional nasolabial displacement during movement in repaired cleft lip and palate patients.

The objective of this study was two-fold: (1) to explore the suitability of a novel modified Procrustes fit method to adjust data for head motion during instructed facial movements, and (2) to compare the adjusted data among repaired unilateral (n = 4) and bilateral (n = 5) cleft lip and palate patients and noncleft control subjects (n = 50). Using a video-based tracking system, three-dimensional displacement of 14 well-defined nasolabial landmarks was measured during four set facial animations without controlling for head motion. The modified Procrustes fit method eliminated the contributions of head motion by matching the most stable landmarks of each video-recorded frame of the face during function to frames at rest. Its effectiveness was found to approximate that of a previous method (i.e., use of a maxillary occlusal splint to which stable dentition-based markers were attached). Data from both the unilateral and bilateral cleft lip and palate patients fell outside the normal range of maximum displacements and of asymmetry, and individual patients demonstrated greater right-versus-left asymmetry in maximum displacement than did individual noncleft subjects. It is concluded that the modified Procrustes fit method is fast, is easy to apply, and allows subjects to move the head naturally without the inconvenience of a splint while facial movement data are being collected. Results obtained using this method support the view that facial movements in cleft patients may be severely hampered and that assessment of facial animation should be strongly considered when contemplating surgical lip revisions.

Adolescent↗
PubMed2006

Adjustments for heterogeneous herd-year variances in a random regression model for genetic evaluations of Polish Black-and-White cattle.

The study investigated the existence of heterogeneous variance in first-lactation daily milk yield of Polish Black-and-White cows across herds in different years. Bayesian Information Criterion was used to show that the model with unequal residual variances for different herd-years was more plausible than the model assuming equal variances. A method of adjusting phenotypic records was developed to account for unequal variability in herd-years. Factors used for the data adjustment considered variation of general residuals and residuals for specific herd-years. The size of herd-year was also taken into account. Varied power of corrections was used to analyze the effect of adjustment on estimated breeding values. The method was applied to daily milk records of 817,165 primiparous cows. The effectiveness of the data adjustment was evaluated by the analysis of differences between each bull's breeding value and its parental index. Data correction reduced the average difference and variance of differences between breeding values and parental indices. Accounting for the size of herd-year classes in correction factors improved the efficiency of heterogeneous variance adjustment.

Analysis of Variance↗
PubMed2004

Initial experience with a new method for the dynamic assessment of pelvic floor function in women: the Kolpexin Pull Test.

The aim of this study was to evaluate a newly developed, simple test for assessing pelvic floor muscular function in women. Pelvic floor strength in women with symptomatic pelvic floor dysfunction was evaluated with a newly developed assessment tool, the Kolpexin Pull Test, and compared to a clinically validated digital pelvic floor strength assessment scale (DPA). A 36-mm Kolpexin sphere was inserted into the vagina above the levator plate and connected to a digital tensiometer/force gauge. The force required to remove the sphere was recorded for three resting trials and three maximum pelvic floor contractions. Results of the DPA and Kolpexin Pull Test were analyzed using ANOVAs of contrast variables, intraclass correlations, and regression analyses. Twenty-one women participated in the study. Age range was 36-85 years, parity range was 2-5. All six trials required less than 5 min to perform in each patient. Intraperson maximum contraction data were correlated at 0.96 (95% CI: 0.91, 0.98), and were greater at higher DPA scores ( p=0.016). There were positive correlations between the maximum contraction and DPA data (adjusted R(2)=0.52; p <0.001), and the maximum contraction minus resting vs DPA data (adjusted R(2)=0.54; p< 0.001). The Kolpexin Pull Test is reproducible, rapid, and correlates with digital clinical assessment of pelvic floor strength during maximal contractions.

Adult↗