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Results for “Logistic Models”

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PubMed2003

[Adverse reactions to influenza vaccine in the elderly, Campinas District, SP, 2000].

Adverse reactions associated with vaccines are poorly documented in Brazil. The aim of this article was to identify the incidence of adverse effects to the influenza vaccine in the elderly of Campinas district, SP. A questionnaire was applied to a random systematic sample of people over 60 years of age (n = 206), participating in the Brazilian Vaccination Campaign during 2000. Temporal link was taken into account for general and local symptoms after vaccine. One or more symptoms were reported by 20.48% (CI 14.87-25.88) and local pain was the most frequent complaint 12.62% (CI 8.09 -17.15). A multi-regression logistic model was adjusted, considering any adverse effects after exposure as the dependent variable. The independent variable associated with adverse effects was female gender (OR = 5.89 and CI 2.08-16.68). This study reaffirms the low reactogenicity of influenza vaccine.

Aged↗

PubMed2006

Experimental simulation of transmission of an obligate aphid pathogen with aphid flight dispersal.

The wide dispersal of Entomophthorales-caused mycoses that usually regulate aphid populations is most likely to be associated with the flight of infected alates. This hypothesis was examined via simulated flight and postflight colonization of Myzus periscae alates exposed to spore showers of Pandora neoaphidis, a common obligate aphid pathogen prevalent world wide. A total number of 407 alates were showered in different batches, then individually flown in a computer-monitoring flight mill system and reared on cabbage leaves for 14-day free reproduction and contagious infection within progeny colonies at 20-23 degrees C. On average, 80.6% of them flew 2.6 km in 1-5 h, survived 3.2 days, produced 5.3 nymphs, and transmitted their infection to progeny successfully. However, 9.8% of the flown alates left no progeny although they survived at least 1 day prior to mycosis while the rest were not mycosed, producing significantly more nymphs during the first week. The flight distances of the infected (0.01-10.2 km) or uninfected alates (0.1-8.3 km) were exponentially correlated to the flight time (r( 2) >or= 0.98). When grouped by the flight ranges of <1.0, 1.0-3.0, 3.0-5.0 and >5.0 km, the number of live aphids and the proportion of mycosed individuals per progeny colony over colonization days fit well to a complex logistic model (r( 2) = 0.984) and modified Gompertz model (r( 2) = 0.978) respectively. Both models included flight distance, postflight survival time, premycosis fecundity and primary infection rate as independent variables to affect the developmental rates. The results highlight the significant role of infected alates in the wide dispersal of P. neoaphidis-caused mycoses among aphids.

Animals↗

PubMedDate not supplied

[Nosocomial sepsis and polymorphism of the NOD-2 gene].

Sepsis is a clinical syndrome resulting from a systemic inflammatory response to infection. Genetic factors may be important risk factors for sepsis. The present study determines whether the most frequent polymorphism of NOD2, a cytosol sensor of peptidoglycan, are independent risk factors for nosocomial sepsis. 80 sepsis patients and 90 unmatched controls admitted to the Campus Bio-Medico School of Medicine Hospital in Rome were studied. NOD2 polymorphisms were determined by Amplification Refractory Mutation System (ARMS) PCR, while TLR4 polymorphisms were determined by Allele-Specific PCR. 25% of sepsis patients and 7.77% of controls had NOD2 mutations. This resulted in an Odds Ratio (OR) of 3.95 for sepsis and NOD2 mutation patients and in an OR of 4.26 adjusting for cancer incidence and age in a logistic model. NOD2 mutations are an independent risk factor for nosocomial sepsis. The present study has shown, for the first time, the association between NOD2 mutations and sepsis, and it has determined NOD2 essential part of the innate immunity response to bacteria.

Aged↗

PubMed1994

Dose-effect relations for local functional and structural changes of the lung after irradiation for malignant lymphoma.

PURPOSE: To estimate the dose-effect relations for local functional (ventilation and perfusion) and structural (density) changes of the lung, 3-4 months after irradiation. METHODS: Twenty-five patients with malignant lymphoma were irradiated with a (modified) mantle field to an average dose of 38 Gy, given in 21 fractions. Single photon emission computed tomography (SPECT) ventilation (V) and perfusion (Q) scans, and CT scans were performed before and 3-4 months after radiation treatment. The three-dimensional dose distribution was calculated using the CT data. After correlation of SPECT and CT data sets, the average post-treatment value of V, Q and lung density per voxel was calculated relative to the pre-treatment value, per dose interval of 4 Gy. Subsequently, the dose-effect relations in each patient were normalized to the average value per voxel in the dose interval of 0-12 Gy. In addition, in each dose interval of 4 Gy the fraction of patients with changes larger than 20% was calculated for all three parameters. The dose-effect relations for perfusion and ventilation normalized to the low-dose regions, and the dose-incidence curves for the fraction of patients with changes larger than 20% were fitted for all three parameters, using a logistic model. RESULTS: Marked changes in the distribution of V and Q were found after irradiation. Prior to normalization to the low-dose regions, a change in V and Q was found in most patients in the dose interval of 0-12 Gy, varying from an increase of 37% to a decrease of 10%, which was followed by a decreasing trend at higher doses. The increase in the low-dose regions indicated a redistribution phenomenon, the magnitude of which was dependent of the irradiated volume. The logistic fit of the dose-effect relations for Q and V, normalized to the low-dose regions, resulted in values for D50 of 51 Gy and 54 Gy (given in 21 fractions on average), respectively, and for the steepness parameter k of 4.2 and 4.0, respectively. The logistic fit for the dose-incidence curves for Q, V and lung density resulted in values for D50 and k of 38 Gy, 37 Gy, 44 Gy and 10.3, 7.8 and 9.4, respectively. CONCLUSIONS: With the combined use of SPECT and CT scans, we have obtained dose-effect relations for local functional and structural damage in the lung, 3-4 months after irradiation.

Adolescent↗

PubMed2005

Predicting ongoing pregnancy following ovulation induction with recombinant FSH in women with polycystic ovary syndrome.

BACKGROUND: Ovulation induction with recombinant FSH (rFSH) is common in women with polycystic ovary syndrome (PCOS) not responding to clomiphene citrate treatment, despite the associated risk of multiple pregnancies. We analysed clinical, ultrasonographic and endocrine parameters during initial screening of women with clomiphene citrate-resistant PCOS as predictors of ongoing pregnancy within 12 months of treatment following ovulation induction with rFSH. METHODS: Eighty-five women were allocated to receive rFSH as part of a multicentre clinical trial. rFSH was administered in a chronic low-dose step-up protocol. The primary end-point was an ongoing pregnancy within 12 months. A logistic model was built using clinical, ultrasonographic and endocrine parameters to predict the response to rFSH treatment, adjusted for the number of cycles performed. RESULTS: In total, 85 women underwent 272 treatment cycles with rFSH, of which 57 women (67%) achieved an ongoing pregnancy. Oligomenorrhoea, shorter duration of infertility and a lower free androgen index (FAI) were associated with higher chances of an ongoing pregnancy, resulting in a predictive model with a modest discriminative power (area under the curve 0.72, 95% confidence interval 0.64-0.79) that allowed us to distinguish between women with a probability of <5% of attaining an ongoing pregnancy and women with a probability of >25% of doing so. CONCLUSION: A model consisting of oligo/amenorrhoea, duration of infertility and FAI level allowed a distinction to be made between women with a poor chance and women with a good chance of achieving an ongoing pregnancy.

Adult↗

PubMed2002

A clinical index predicting mortality with Pseudomonas aeruginosa bacteraemia.

The aim of this study was to define risk factors associated with mortality in Pseudomonas aeruginosa bactaeremia and to combine them in a clinical index predicting the risk of death. The study investigated 125 consecutive episodes of P. aeruginosa bacteraemia at this hospital. Crude mortality was 34%, corresponding to 43 patients who died, with 67% of deaths, directly attributable to bacteraemia. A regression logistic model identified five variables that were independently and significantly associated with an increased risk of death: 1) hospitalisation in the intensive care unit; 2) coagulopathy; 3) septic shock; 4) age > or = 65 years; and 5) the clinical condition of the patient. These variables were as recorded at the time that the first positive blood culture was obtained. The sensitivity and specificity of a prediction of death based on the model were 84% and 85%, respectively. An index score, calculated from these variables, divided patients into three groups with increasing likelihood of mortality resulting from P. aeruginosa bacteraemia.

Adolescent↗

PubMed1995

[Study of demographic, environmental and congenital factors in the development of nevi in children between three and fifteen years old. Early results].

A survey of benign melanocytic naevi was conducted among school children in Montpellier (France) in 1993 with the aim to assess the evolution with age of the number of naevi and the factors influencing their number. Children in different age groups (3, 6, 9, 12 and 15 years) attending randomly selected public schools where included in the study. Dermatologists examined 651 children and recorded the number of naevi of more than 2 mm of diameter. Analysis was restricted to 565 children whose parents responded to a historical questionnaire of exposure and sociodemographic data. Among these children the number of naevi per unit of area increased progressively with age although the number of naevi per unit of skin area reached a plateau at about 11 years of age for the girls and around 15 years of age for the boys. Puberty is a regulative factor for the number of naevi and the number of naevi per unit of area. Children whose parents were born in Europe were most likely to have naevi. Susceptibility to burns were also associated with few number of naevi and number of naevi per unit of skin area. The cumulative exposure to sun since birth and the cumulative exposure during the holidays increased the number of naevi and the number of naevi per unit of area but these variables are the last introduced into the logistic model. A prospective questionnaire can be used to assess the exposures and protection variables allowing a better estimation of the skin reaction to sun.

Adolescent↗

PubMed1988

Modeling bivalve diversification: the effect of interaction on a macroevolutionary system.

The global diversification of the class Bivalvia has historically received two conflicting interpretations. One is that a major upturn in diversification was associated with, and a consequence of, the Lake Permian mass extinction. The other is that mass extinctions have had little influence and that bivalves have experienced slow but nearly steady exponential diversification through most of their history, unaffected by interactions with other clades. We find that the most likely explanation lies between these two interpretations. Through most of the Phanerozoic, the diversity of bivalves did indeed exhibit slow growth, which was not substantially altered by mass extinctions. However, the presence of "hyperexponential bursts" in diversification during the initial Ordovician radiation and following the Late Permian and Late Cretaceous mass extinctions suggests a more complex history in which a higher characteristic diversification rate was dampened through most of the Phanerozoic. The observed pattern can be accounted for with a two-phase coupled (i.e., interactive) logistic model, where one phase is treated as the "bivalves" and the other phase is treated as a hypothetical group of clades with which the "bivalves" might have interacted. Results of this analysis suggest that interactions with other taxa have substantially affected bivalve global diversity through the Phanerozoic.

Animals↗

PubMed2004

Nitrification in natural waters with high suspended-solid content--a study for the Yellow River.

In this research, the mechanism regarding the effects of suspended solids on nitrification in freshwater systems with high solid contents was examined. Experimental studies were conducted for natural water of the Yellow River under laboratory conditions. Nitrification kinetics was investigated in water systems with various levels of suspended-solid contents. The associated mechanisms were analyzed through investigation of the adsorption-desorption of ammonium nitrogen, the process of bacteria growth, and the feature of nitrification kinetics. The results indicated that the presence of suspended solids could accelerate the nitrification process. The nitrification rate would increase non-linearly with the increase of suspended-solid content. When the initial concentration of ammonia nitrogen was 12.70 mg/l in the water system, the ratios of half-time duration for nitrification would be 1.88:1.23:1 under suspended-solid contents of 0, 1.84 and 5.00 g/l, respectively. When the initial concentration of ammonia nitrogen was around 1.0 mg/l in the water system, the nitrification rates in systems with suspended-solid contents of 1.81 and 3.42 g/l would then be approximately 9 and 12 times that without suspended solids, respectively. The populations of nitrifying bacteria would rise with increasing suspended-solid content. The existence of suspended solids would increase the contact chances between bacteria and nitrogen, resulting in accelerated nitrification processes; this was manifested by the increased K(4) (tau(max)/K(S)) along with the raised suspended-solid contents while fitting nitrification kinetics with the growth-based logistic model. Since the amount of ammonium nitrogen adsorbed on suspended-solid surface was non-linearly proportional to the suspended-solid content, the nitrification rate was also non-linearly proportional to the suspended-solid content.

Adsorption↗

PubMed1999

Prenatal and perinatal risk factors for Tourette disorder.

AIMS: To identify pre- and perinatal risk factors for Tourette disorder. METHODS: Case control study. We matched names of patients who met DSM criteria for Tourette disorder with their birth certificates. For each case five controls were selected. The controls were matched by sex, year and month of birth. RESULTS: Univariate analysis of the 92 cases and the 460 matched controls identified 4 risk factors; one categorical variable--trimester prenatal care begun and 3 continuous variables--apgar score at 5 minutes, month prenatal began and number of prenatal visits. Logistic modeling to control for confounding produced a three variable model (apgar score at 5 minutes (OR = 1.31), number of prenatal visits (OR = .904) and fathers age (OR = .909). The model parameters were: chi 2 = 19.76; df = 3; p < .001. CONCLUSIONS: This is an inexpensive methodology to identify potential risk factors of patients with Tourette disorder and other mental illness.

Adolescent↗

PubMed2003

Dose-volume prediction of radiation-related complications after proton beam radiosurgery for cerebral arteriovenous malformations.

OBJECT: The use of radiosurgery for the treatment of cerebral arteriovenous malformations (AVMs) and other lesions demands an accurate understanding of the risk of radiation-related complications. Some commonly used formulas for predicting risk are based on extrapolation from small numbers of animal experiments, pilot human treatment series, and theoretical radiobiological considerations. The authors studied the incidence of complications after AVM radiosurgery in relation to dose, volume, and other factors in a large patient series. METHODS: A retrospective review was conducted in 1329 patients with AVM treated by Dr. Raymond Kjellberg at the Harvard Cyclotron Laboratory (HCL) between 1965 and 1993. Dose and volume were obtained from HCL records, and information about patient follow up was derived from concurrent clinical records, questionnaires, and contact with referring physicians. Multivariate logistic regression with bootstrapped confidence intervals was used. Follow up was available in 1250 patients (94%); the median follow-up duration was 6.5 years. The median radiation dose was 10.5 Gy and the median treatment volume was 33.7 cm(3). Twenty-three percent of treated lesions were smaller than 10 cm(3). Fifty-one permanent radiation-related deficits occurred (4.1%). Of 1043 patients treated with a dose predicted by the Kjellberg isoeffective centile curve to have a less than 1% complication risk, 1.8% suffered radiation-related complications. Actual complication rates were 4.7% for 128 patients treated at Kjellberg risk centile doses of 1 to 1.8%, and 34% for 61 patients treated at risk centile doses of 2 to 2.5%. The fitted logistic model showed that complication risk was related to treatment dose and volume, thalamic or brainstem location, and patient age. CONCLUSIONS: The Kjellberg isoeffective risk centile curve significantly underpredicted actual risks of permanent complications after proton beam radiosurgery for AVMs. Actual risks were best predicted using a model that accounted for treatment dose and volume, lesion location, and patient age.

Adolescent↗

PubMed2003

The diagnostic odds ratio: a single indicator of test performance.

Diagnostic testing can be used to discriminate subjects with a target disorder from subjects without it. Several indicators of diagnostic performance have been proposed, such as sensitivity and specificity. Using paired indicators can be a disadvantage in comparing the performance of competing tests, especially if one test does not outperform the other on both indicators. Here we propose the use of the odds ratio as a single indicator of diagnostic performance. The diagnostic odds ratio is closely linked to existing indicators, it facilitates formal meta-analysis of studies on diagnostic test performance, and it is derived from logistic models, which allow for the inclusion of additional variables to correct for heterogeneity. A disadvantage is the impossibility of weighing the true positive and false positive rate separately. In this article the application of the diagnostic odds ratio in test evaluation is illustrated.

Diagnosis↗

PubMed2000

Low somatic cell count: a risk factor for subsequent clinical mastitis in a dairy herd.

A case-control study was conducted to evaluate factors measured at the udder inflammation-free state as risk factors for subsequent clinical mastitis. The factors including somatic cell count (SCC), body condition score, milk yield, percentages of milk fat and milk protein, and diseases were evaluated for their association with the results of udder inflammatory response. The results of the response were specified as presence (case) and absence (control) of clinical signs of mastitis. Data on Holstein Friesian cows calving from January 1984 to November 1996 from a commercial farm with low bulk milk SCC were used. Univariable and multivariable random-effect logistic models were used to evaluate the effect of those factors on the risk of clinical mastitis. The following variables were associated with increased odds of case versus control events in the univariable analysis: early lactation period, low SCC, high milk yield, high percentage of milk protein, high percentage of milk fat, low body condition score, retained placenta, and milk fever. For the final multivariable model of all variables used for analysis, only low SCC remained significantly associated with increased risk of subsequent clinical mastitis. The authors concluded that very low SCC during the udder inflammation-free state are associated with increased risk of clinical mastitis.

Animals↗

PubMed2000

Coagulum index predicts coagulum formation in right atrial radiofrequency energy delivery to ablate atrial fibrillation.

An ongoing multicenter U.S. clinical study evaluates the safety and effectiveness of creating linear lesions with radiofrequency (RF) energy using a 3.7 Fr microcatheter used with a 9 Fr steerable guiding catheter in the right atrium (RA) to treat paroxysmal atrial fibrillation (PAF). Study entry criteria were symptomatic, drug refractory PAF. RF energy was delivered in 60-second episodes at 30 W or 50 W power settings. Electrode tissue contact was ascertained by sharp electrograms of high amplitude. Coagulum Index (C.I.), a new calculation to predict the probability of coagulum development, was derived analytically from measurements of RF power, RF current, and time to reach maximum temperature in each ablation episode. The RF data from 398 separate ablation episodes in 15 patients were used to calculate C.I. Coagulum presence was determined by postablation visual inspection of the microcatheter electrodes. A logistic model was used to estimate the probability of coagulum occurrence, with C.I. as the predictive variable. When C.I. > or = 12, the probability of coagulum formation increased significantly in this model (P < 0.0001). Prolonging the power delivery rise time and limiting maximum RF power setting to 30 W effectively lowers C.I. and minimizes coagulum formation. These results should also apply to left atrium ablation, where minimizing coagulum formation may decrease the risk of stroke or mortality.

Atrial Fibrillation↗

PubMed1995

Patterns of health services utilization and mammography use among women aged 50 to 59 years in the Québec Medicare system.

Many studies have identified physicians' recommendation as the single most important predictor of mammography use. Health services utilization is a complex phenomenon, and the contribution of the different dimensions of health services utilization on mammography use is underresearched. This study examines the specific contribution of health services utilization variables in a multivariate model of the recency of mammography use for women aged 50 to 59 years. Subjects were respondents of the 1987 Québec Health Survey. Survey data were then linked on an individual basis to the respondent's records of Medicare physicians' claims for health care services for the 3 years before the survey. This unique data set enabled the inclusion of sociodemographic variables, risk factors, health status, healthy lifestyles, and women's patterns of utilization of general and gynecologic health care services. Multivariate predictors of the recency of mammography are: having an education higher than high school, working outside home, not living in a remote area, suffering from benign breast disease, and not perceiving one's own health as good. The volume of general and gynecologic medical care is associated with the recency of mammography in independent logistic models that include women's predisposing, enabling, and need factors. This study shows that even in a universal third-party payer health care system, physicians are missing opportunities to promote breast cancer screening.

Female↗

PubMed1993

Acute renal failure after coronary surgery--a study of incidence and risk factors in 2009 consecutive patients.

To obtain a model for the prediction of acute renal failure (ARF) after coronary surgery, 2009 consecutive patients were investigated. ARF was defined as a peak postoperative serum creatinine value exceeding the preoperative value by 50% or more or a need for dialysis. A postoperative increase in serum creatinine of less than 50% was associated with an early mortality (< or = 30 days postop.) of 0.4%. Sixteen per cent of the patients increased their serum creatinine by more than 50% and in this group there was a mortality of 1.3%. Twenty-five patients (1.2%) required postoperative haemodialysis because of ARF and of these 11 (44%) died early, whereas another 7 patients with chronic renal failure, requiring both pre- and postoperative haemodialysis, all survived. Peak postoperative serum creatinine and changes from the preoperative value were analyzed and related to clinical variables. Multivariate analysis indicated that high preoperative serum creatinine, high age and postoperative haemodynamic instability were the most important risk factors for developing renal failure. A logistic model including these risk factors versus the probability of developing ARF is presented.

Acute Kidney Injury↗

PubMed2006

Luteinizing hormone in premenopausal women may stimulate uterine leiomyomata development.

OBJECTIVE: Human chorionic gonadotropin (hCG) has proliferative effects on uterine smooth muscle and leiomyoma tissue in vitro. We hypothesized that luteinizing hormone (LH) would have the same effect by activating the LH/hCG receptor, and it would follow that premenopausal women with higher basal LH levels would be more likely to have leiomyomata. METHODS: Randomly selected women, aged 35 to 49 years, from a prepaid health plan were screened for leiomyomata with pelvic ultrasound. Urine samples collected during the first or last 5 days of the menstrual cycle were analyzed for LH by immunofluorometric assay, and concentrations were corrected for creatinine (n = 523). Logistic regression and Bayes analyses were used to evaluate the association of LH with presence and size of leiomyomata, adjusting for age, and other risk factors. RESULTS: Women with higher LH were more likely to have leiomyomata (adjusted odds ratios for second and third tertiles were 1.7 and 2.0 compared with lower tertile; 95% confidence intervals, 1.0 to 2.7 and 1.2 to 3.4, respectively). The association was stronger for large leiomyomata. Bayes analyses designed to estimate LH effects on tumor onset separately from tumor growth showed significantly accelerated tumor onset but little evidence of effects on tumor growth. Age, an independent risk factor for leiomyomata, was not affected by inclusion of LH in the logistic models. CONCLUSIONS: As hypothesized, women with higher LH were more likely to have leiomyomata, but this did not explain the age-related increase in leiomyomata during perimenopausal ages. Determining whether LH is causal or a marker for susceptibility will require further research.

Adult↗

PubMed1991

Predictors of abdominal injury in children with pelvic fracture.

During a 48-month period, 2,248 children (aged less than 15 years) were consecutively admitted to a regional pediatric trauma center with blunt trauma (ICD-9-CM code greater than or equal to 800). Fifty-four children (2.4%) had injury to the pelvic circle, as diagnosed by radiographic examination; 13 of these children had concomitant abdominal or genitourinary (GU) injury. Contingency table analysis and stepwise logistic regression were used to determine the best predictors of abdominal injury. The mean age of the children was 8.6 years. Eighty-nine percent of the injuries were motor-vehicle related (59% pedestrian; 30% crash occupant). Nine children (17%) required transfusions of packed red blood cells; 9 children (17%) required surgery. There were 6 deaths in this group, a mortality rate of 11.1%. The most common fracture sites in the pelvis were the pubic rami (59%), ilium or pelvic rim (17%), and the sacrum (6%). Ten children (19%) had multiple pelvic fractures. Location of fracture was strongly associated with the probability of abdominal injury: 80% of children with multiple pelvic fractures had concomitant abdominal or GU injury, compared with 33% with fracture of the ilium or pelvic rim, and 6% with isolated pubic fractures (p less than 0.001). The variables that best predicted abdominal or GU injury using a backward-elimination, stepwise logistic model were the presence of multiple pelvic fractures (p less than 0.002) and unweighted Revised Trauma Score (p less than 0.05); age of child, systolic blood pressure, respiration rate, Glasgow Coma Scale score, and mechanism of injury were not predictive.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Injuries↗