SEARCH · PubMed Health

Results for “multiple linear regression”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 469 records · Page 26Linked to original sources

PubMed1995

Spirometric reference values in school children from Dalmatia.

Data on spirometric reference values in children are based on small, selected populations. We performed spirometric testing (forced vital capacity (FVC); forced expiratory volume in one second (FEV1); forced mid-expiratory flow rate (FEF25-75%)) in 2,500 healthy nonsmoking school children (1,250 boys and 1,250 girls) in the region of Dalmatia, Croatia. Significantly higher FVC and FEV1 values were noted in boys. Standing and sitting heights correlated significantly with FVC and FEV1 in boys and girls. Regression equations were derived, utilizing the multiple linear regression analysis, for FVC, FEV1 and FEF25-75% related to five (sex, age, weight, standing and sitting heights) or three (sex, age and standing height) variables. The reference spirometric values in the Dalmatian school boys were in close agreement with Knudson et al., while the values in girls were closest to those of Knudson et al. and Cotes et al. It is suggested that for calculation of ventilatory reference values in boys and girls the age and the standing height should be used.

Adolescent↗

PubMed1997

[Factors associated with the incidence of hospital readmission].

BACKGROUND: To identify factors associated with hospital readmission, especially those potentially avoidable. This information could be useful to reduce the incidence of hospital readmissions. METHODS: A paired (1:1) case-control study nested into the cohort of first admissions at the Granada University Hospital, Spain, in 1990. All patients readmitted at the hospital within 3 years after release from the index-admission by the same diagnostic or complications of it comprised the case group. For each case, a control patient was matched for both primary diagnosis on admission and index-admission date. Information on risk factors associated with hospital readmission was obtained retrospectively from medical records. The relation between these risk factors and readmission was estimated from odds ratio both crude and adjusted using conditional logistic regression analysis. For the readmitted subsample, multiple linear regression models were applied to identify factors associated to the length of time between the index episode and the first readmission. RESULTS: Variables with consistent positive associations with readmission include male sex (odds ratio = 2.86, 95% confidence interval = 1.37-5.88), widowed or single status (2.66, 10.7-6.59) and severity at index admission (3.20, 1.57-6.51). Factors related to quality of health care did not influence readmission risk. CONCLUSIONS: Factors depending of the patient seem to be the most important variables associated to the incidence of hospital readmission.

APACHE↗

PubMed2026

Multi-locus allelic architecture underlying natural variation in leaf rolling in japonica rice.

Leaf rolling is a key component of rice canopy architecture that affects light interception, microclimate formation, and planting density. The contribution of naturally occurring allelic variation to quantitative variation in leaf rolling within cultivated rice remains poorly understood, while extreme leaf rolling caused by loss-of-function mutations often results in detrimental pleiotropic effects. Herein, we examined how multi-locus allelic variation contributes to natural variation in leaf rolling within japonica rice. Leaf rolling was quantified based on the leaf rolling index (LRI) using a panel of 201 japonica accessions. The phenotype was transformed using the Yeo-Johnson method to reduce strong right skewness and improve the distributional properties of the data, thereby facilitating subsequent regression modeling. Haplotype analyses were performed for previously reported leaf rolling-associated genes and genome-wide association study (GWAS) lead loci, leading to the identification of five loci exhibiting substantial haplotype-dependent phenotypic variation. Phenotypically defined allelic groups represented these loci were subsequently evaluated using multiple linear regression (MLR), with the first two principal components derived from genome-wide SNP data included as covariates to account for population structure. The final MLR model identified four loci (qALR1, OsYABBY1, OsSLL2, and OsSRL10) as the independent contributors to leaf rolling variation, collectively explaining 21% of the variance in the transformed phenotype after accounting for population structure. Model diagnostics and ten-fold cross-validation supported the statistical validity of the framework and indicated stable model performance across validation folds. Analysis of multi-locus allelic combinations showed 13 distinct configurations that clustered into three phenotypically differentiated groups. This reflected the cumulative dosage of high-leaf rolling alleles. Thus, the natural variation in leaf rolling in japonica rice is governed by the additive effects of multiple moderate-impact loci. The multi-locus allelic framework established here provides a statistically sound and biologically interpretable basis for dissecting polygenic canopy traits and practical guidance for developing genetic materials aimed at optimizing rice plant architecture.

cross-validation↗

PubMed2004

Contributions of weekly mean blood glucose values to hemoglobin A1c in insulin-treated type 2 diabetes: the Diabetes Outcomes in Veterans Study (DOVES).

BACKGROUND: Daily self-monitored blood glucose testing is recommended for patients with insulin-treated type 2 diabetes. However, most patients do not test frequently enough for optimal glycemic control. Less frequent testing may be sufficient for assessing glycemic control among stable patients as well as improving patient compliance. The study objective was to evaluate the weekly contribution of glucose readings to hemoglobin (Hb)A1c during an 8-week period of intensified self-monitored blood glucose testing. METHODS: The authors randomly selected stable, insulin-treated subjects with type 2 diabetes. Subjects monitored their blood glucose four times daily for 8 weeks; the authors then downloaded glucose meters and measured an HbA1c. Mean blood glucose values were calculated for each of the 8 weeks. Multiple linear regression analyses examined the contribution of these mean values to the HbA1c. RESULTS: A total of 182 subjects completed the monitoring protocol; mean HbA1c was 7.63 +/- 1.42%, mean glucose was 9.78 +/- 2.27 mmol/L, the regression correlation was 0.77, P < 0.001. A fitted multiple linear model using all 8 weekly mean blood glucose values showed large variation in their independent contributions to the HbA1c. Mean blood glucose values from consecutive weeks were highly correlated and did not provide independent information about glycemic control. Stepwise regression showed that the mean blood glucose values from weeks 4, 6, and 8 significantly and equally influenced HbA1c. CONCLUSIONS: Glycemic control can be efficiently assessed by reviewing at least 5 weeks' worth of monitoring results, focusing on alternate weeks and giving less weight to more remote readings.

Aged↗

PubMedDate not supplied

Synchronous assessment of sperm motility and fertilizing ability in the hamster following treatment with alpha-chlorohydrin.

To investigate the relationship between sperm motion parameters and fertilizing ability, a model was developed to assess both of these endpoints synchronously using a toxicant that inhibits sperm motion. alpha-Chlorohydrin (ACH) was administered daily for 4 days to male hamsters at 0, 33, 49, 66, and 83 mg/kg body weight. These males were then allowed a 45-minute breeding period with untreated estrus females on the morning of day 5. One hour after breeding, sperm samples were surgically recovered from the uteri of the females for motility analysis. Six hours later, eggs were flushed from the oviducts and evaluated for fertilization. Cauda epididymal sperm were also collected from the males shortly after breeding. Proportions of motile and progressively motile sperm were manually quantified, and overall sperm velocity and the velocity of representative vigorously swimming sperm in both the uterine and epididymal samples were measured by computer-aided sperm analysis. Significant decreases in in vivo fertilization rates and epididymal sperm motion parameters were observed at 66 and 83 mg/kg ACH, whereas uterine sperm motion was adversely affected at all ACH dosages used. All sperm motion parameters except the percentage of motile sperm in the epididymis were significantly correlated with fertilization rates by both linear and logistic regression. Overall, uterine and epididymal sperm endpoints predicted fertilizing ability comparably well. Stepwise multiple linear regression gave a model containing epididymal sperm velocity (EVCL) and uterine sperm percent motility (UMOT) with an R2 value of 0.649. Stepwise multiple logistic regression gave models containing EVCL alone and EVCL and UMOT in binary (fertile/infertile) and quantal models, respectively.

Acetylcholine↗

PubMed1997

[Relationship between air pollution due to traffic, decreased lung function and airway symptoms in children].

OBJECTIVE: To assess whether air pollution by traffic was related to lung function and chronic respiratory symptoms in children living. DESIGN: Descriptive. SETTING: The province of South Holland, the Netherlands. METHODS: In the period May through July of 1995 pulmonary function tests and questionnaires were obtained from 1,092 and 1,068 children respectively in six city districts near busy motorways in the province of South Holland. In the same period, indoor measurements were performed at 12 schools of NO2, black smoke and PM10 dust density. Lung function data were analysed by multiple linear regression and respiratory symptoms were analysed by multiple logistic regression. As independent variables, distance between motorway and home, passenger car traffic density and lorry traffic density on the motorway, and black smoke and NO2 concentrations in schools were taken. RESULTS: Significant differences in lung function and respiratory symptoms were found between children living in different city districts. Lung function as well as symptoms were associated with lorry traffic density on the motorway. The validity of these findings was supported by associations between black smoke concentrations (representative for diesel soot) and lung function as well as respiratory symptoms. In contrast, there was no association between passenger car traffic counts or NO2 and lung function or respiratory symptoms. CONCLUSION: The results suggest that air pollution by lorry traffic can lead to reduced lung function and to an increased prevalence of chronic respiratory symptoms in children living near major motorways.

Air Pollutants↗

PubMed1999

Quantitative structure-retention relationships of polychlorinated naphthalenes in gas chromatography.

A quantitative structure-retention relationship (QSRR) model has been developed for the gas chromatographic relative retention indices (RRis) of 62 polychlorinated naphthalene (PCN) congeners in a non-polar column, DB-5 (5% phenyl, methylpolysiloxane). Chemical descriptors were calculated from the molecular structures of PCNs and related to their gas chromatographic RRis by multiple linear regression analysis. The proposed model had a multiple square correlation coefficient R2 = 0.995, and standard error SE = 16.7. A QSRR reveals that the gas chromatographic retention of PCNs is associated with the number of chlorine substitutions, influenced by electronic descriptors such as heat of formation, maximum value for atomic valence, and the minimum value for electronic orbital population.

Chromatography, Gas↗

PubMed1993

Insulin-stimulated glucose utilization and borderline hypertension in young adult blacks.

The purpose of this investigation was to determine whether there is a relation between impaired insulin-stimulated glucose utilization, or insulin resistance, and blood pressure (BP) in a young adult black population. Clinically well, young black men and women, including normotensive (BP < 135/85 mm Hg, n = 23) and borderline hypertensive (BP > or = 135/85 mm Hg, n = 27) individuals, were studied. Each subject had an oral glucose tolerance test (OGTT) and underwent a euglycemic hyperinsulinemic clamp procedure. A two-way analysis of variance demonstrated a significantly greater fasting insulin plasma concentration (P < .02) and sum of insulin levels during the OGTT (P = .04) in the borderline hypertensive compared with normotensive subjects. In both BP groups, women had significantly higher fasting plasma insulin levels than men (P < .02 and P = .009). Body mass index was a significantly covariate of the plasma insulin concentration. Data obtained from the clamp demonstrated significant insulin resistance in borderline hypertensive compared with normotensive subjects (4.69 +/- 0.50 versus 6.57 +/- 0.63 mg/kg per minute, P = .002). A stepwise multiple linear regression analysis demonstrated that there are significant multiple correlations of insulin resistance with body mass index, clamped insulin level, BP group, and systolic BP (multiple R = .7862, P < .001). Application of this analysis to the nonobese sample (n = 33) found significant correlations of insulin resistance with sex, BP group, and systolic BP (multiple R = .6817, P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2004

Non-contact skin moisture measurement based on near-infrared spectroscopy.

Non-contact skin moisture measurement based on near-infrared (NIR) spectroscopy is proposed in the spectral range from 1300 to 2000 nm. A gap is introduced between the optical fiber probe and the skin surface in order to avoid occluding surface vapor. In vitro and in vivo experiments for measuring the water content of skin are implemented. The measured absorbance spectra are processed by multivariate analyses. Processed results are compared with the water content values obtained by a capacitance method. The correlations between the optical method and the capacitance method obtained by partial-least squares regression are higher than those obtained by multiple linear regression. In addition, a Monte Carlo simulation is implemented to evaluate measurement depths of the optical methods. It is presented that the measurement depth of the optical method depends largely on the water absorption. The simulation result also shows that the measurement depth of the optical method is much deeper than the depth of the capacitance method, especially in the spectral range where water absorption is relatively weak.

Algorithms↗

PubMed2002

Quantitative structure retention relationship studies for predicting relative retention times of chlorinated phenols on gas chromatography.

A new method of quantitative structure-retention relationship (QSRR) studies was reported for predicting gas chromatography (GC) relative retention times (RRTs) of chlorinated phenols (CPs) using a DB-5 column. Chemical descriptors were calculated from the molecular structure of CPs and related to their gas chromatographic RRTs by using multiple linear regression analysis. The proposed model had a multiple square correlation coefficient R2 = 0.970, standard error SE = 0.0472, and significant level P = 0.0000. The QSRR model also reveals that the gas chromatographic relative retention times of CPs are associated with physicochemical property interactions with the stationary phase, and influenced by the number of chlorine and oxygen in the CP mOlecules.

Chlorine Compounds↗

PubMed1975

Surgical resection of tumor bulk in the primary treatment of ovarian carcinoma.

The effect of tumor bulk resection on survival was studied in 102 patients with stages II and III ovarian cancer. A multiple linear regression equation provuded both simultenaous control of multiple confounding variables and an assessment of these variables as independent predictors of survival. The most important factors were the histologic grade of the tumor and the size of the largest residual tumor mass after operation. Survival time was uniformly poor if the diameter of the largest residual tumor mass exceeded 1.5 cm irrespective of total tumor volume (mean=12.7 months, SE=1.6 mo). Survival time was inversely proportional to residual mass size under 1.6 cm, and surgery improved survival relative to reduction in mass size below this limit. Extensive resections of tumor bulk with failure to remove all masses greater than 1.5 cm in diameter did not influence survival. Surgery provides optimum benefit when all gross tumor can be excised safely.

Adult↗

PubMed2006

Waiting times for cataract surgery in ten European countries: an analysis using data from the SHARE survey.

AIMS: To assess waiting times for cataract surgery and their acceptance in European countries, and to find explanatory, country-specific health indicators. METHODS: Using data from the survey of health, ageing and retirement in Europe (SHARE), waiting times for cataract surgery of 245 respondents in ten countries were analysed with the help of linear regression. The influence of four country specific health indicators on waiting times was studied by multiple linear regression. The influence of waiting time and country on the wish to have surgery performed earlier was determined through logistic regression. Additional information was obtained for each country from opinion leaders in the field of cataract surgery. RESULTS: Waiting times differed significantly (p<0.001) between the ten analysed European countries. The length of wait was significantly influenced by the total expenditure on health (p<0.01) but not by the other country specific health indicators. The wish to have surgery performed earlier was determined by the length of wait (p<0.001) but not by the country where surgery was performed. CONCLUSION: The length of wait is influenced by the total expenditure on health, but not by the rate of public expenditure on health, by the physician density or by the acute bed density. The wish to have surgery performed earlier depends on the length of wait for surgery and is not influenced by the country.

Aged↗

PubMed2000

The work lives of women physicians results from the physician work life study. The SGIM Career Satisfaction Study Group.

OBJECTIVE: To describe gender differences in job satisfaction, work life issues, and burnout of U.S. physicians. DESIGN/PARTICIPANTS: The Physician Work life Study, a nationally representative random stratified sample of 5,704 physicians in primary and specialty nonsurgical care (N = 2,326 respondents; 32% female, adjusted response rate = 52%). Survey contained 150 items assessing career satisfaction and multiple aspects of work life. MEASUREMENTS AND MAIN RESULTS: Odds of being satisfied with facets of work life and odds of reporting burnout were modeled with survey-weighted logistic regression controlling for demographic variables and practice characteristics. Multiple linear regression was performed to model dependent variables of global, career, and specialty satisfaction with independent variables of income, time pressure, and items measuring control over medical and workplace issues. Compared with male physicians, female physicians were more likely to report satisfaction with their specialty and with patient and colleague relationships (P <.05), but less likely to be satisfied with autonomy, relationships with community, pay, and resources (P <.05). Female physicians reported more female patients and more patients with complex psychosocial problems, but the same numbers of complex medical patients, compared with their male colleagues. Time pressure in ambulatory settings was greater for women, who on average reported needing 36% more time than allotted to provide quality care for new patients or consultations, compared with 21% more time needed by men (P <.01). Female physicians reported significantly less work control than male physicians regarding day-to-day aspects of practice including volume of patient load, selecting physicians for referrals, and details of office scheduling (P <.01). When controlling for multiple factors, mean income for women was approximately $22,000 less than that of men. Women had 1.6 times the odds of reporting burnout compared with men (P <.05), with the odds of burnout by women increasing by 12% to 15% for each additional 5 hours worked per week over 40 hours (P <.05). Lack of workplace control predicted burnout in women but not in men. For those women with young children, odds of burnout were 40% less when support of colleagues, spouse, or significant other for balancing work and home issues was present. CONCLUSIONS: Gender differences exist in both the experience of and satisfaction with medical practice. Addressing these gender differences will optimize the participation of female physicians within the medical workforce.

Adult↗

PubMed2000

The determination of certain major and minor elements in geological samples by inductively coupled plasma atomic emission spectrometry. Some interference problems with the analysis of geological standard reference materials and nutrition supplements.

Direct ICP-AES measurements of the digested geological standard reference material samples yielded the wrong information about their composition. The differences between certified and measured concentrations of the samples were due to the complicated sample matrix. The measured concentrations can be successfully corrected by using a multiple linear regression technique. The correction is based on the multiple regression line calculated from the analytical results at synthetic mixtures of matrix elements, where concentrations varied on five levels. There were no significant (P = 0.05) differences between certified and measured concentrations in standard reference materials after the correction. The same method was used in the analysis of nutrition supplements.

Calibration↗

PubMed2002

Radial basis function neural network based QSPR for the prediction of critical pressures of substituted benzenes.

The Quantitative Structure-Property Relationship (QSPR) method is used to develop the correlation between structures of a great number of substituted benzenes and their critical pressure. Molecular descriptors calculated from structure alone were used to represent molecular structures. A subset of the calculated descriptors selected using forward stepwise regression was used in the QSPR model development. Multiple Linear Regression and Radial Basis Function Neural Networks are utilized to construct the linear and non-linear prediction model, respectively. To obtain good prediction ability, both topological structure and training parameters of radial basis function neural networks are optimized. The prediction result agrees well with the experimental value of these properties.

Journal Article↗

PubMed2004

Relationship between exhaled carbon monoxide and airway hyperresponsiveness in asthmatic patients.

The study objectives were to analyze the changes in exhaled carbon monoxide (COex) induced by histamine provocation challenge in asthmatic patients and to evaluate the relationship between COex and airway sensitivity and reactivity. Levels of COex were measured in 105 nonsmoking mildly asthmatic subjects before and after histamine provocation challenge. Dose-response curves were characterized by their sensitivity (PD20) and reactivity. Dose-response slope (DRS), continuous index of responsiveness (CIR), and bronchial reactivity index (BRI) were determined as reactivity indices. Bronchial challenge was positive for 47 subjects and negative for 58. The COex levels rose significantly after bronchial challenge in the positive response group (4.49 +/- 0.4 vs. 5.74 +/- 0.57 ppm, p = 0.025) and in the negative response group (2.84 +/- 0.25 vs. 4.00 +/- 0.41 ppm, p = 0.000). An inverse relation between basal COex and PD20 was found (r = -0.318, p = 0.030). In all subjects, a proportional direct relationship between COex and DRS (r = 0.214, p = 0.015), CIR (r = 0.401, p = 0.000), and BRI (r = 0.208, p = 0.012) was observed. On stepwise multiple linear regression analysis, COex only significantly correlated with CIR (multiple r2 = 0.174, p = 0.000). In conclusion, exhaled CO determination is a noninvasive inflammatory marker of the respiratory tract, which shows an acceptable association with airway hyperresponsiveness.

Adult↗

PubMed1998

Associations among caregiving difficulties, burden, and rewards in caregivers to older post-rehabilitation patients.

The associations between self-reported rewards and difficulties of caregiving and burden were examined in a sample of 200 informal caregivers to older post-rehabilitation patients. Sixteen percent (16%) of caregivers reported that caregiving was physically difficult only, 15% reported emotional difficulties only, 11% reported social difficulties only, 17% reported multiple difficulties, and 40% had no difficulties. Each type of difficulty (e.g., social, emotional, and physical) was significantly associated with burden in univariate and multiple linear regression analyses, controlling for confounding characteristics. Caregivers reporting multiple types of difficulty experienced higher levels of burden than caregivers who reported only one type of difficulty. Caregivers who received more rewards from caregiving reported fewer difficulties. Caregiving rewards had no independent effect on burden but modified the associations between social and emotional difficulties and burden. In summary, caregiving rewards and difficulties were not mutually exclusive, and their relationship in turn affected burden.

Affect↗

PubMed1996

Structure-activity relationship studies on benzofuran analogs of propafenone-type modulators of tumor cell multidrug resistance.

A series of benzofurylethanolamine analogs of propafenone (1a) have been prepared and evaluated for multidrug resistance-reversing activity in two in vitro assay systems. As for propafenones, an excellent correlation of biological data with calculated lipophilicity values was found for benzofurans, whereby the latter generally had lower activity/lipophilicity ratios. Almost identical slopes of the regression lines were obtained for both propafenones and benzofurans. Multiple linear regression analysis of the complete data set yielded an equation with excellent predictive power (r2 cross-valid = 0.968). Interaction measurements with artificial membranes indicated that the differences in activity between these two series of compounds are not due to differences in the interaction pattern with biological membranes.

ATP Binding Cassette Transporter, Subfamily B, Mem↗