SEARCH · PubMed Health

Results for “Probability”

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 1,333 records · Page 74Linked to original sources

PubMed2006

[The most probable clinical diagnosis to the applicants for the intractable disease registration of Parkinson's disease, spinocerebellar degeneration and amyotrophic lateral sclerosis].

Amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD) and spinocerebellar degeneration (SCD) are included in the 45 intractable diseases" acknowledged by the Ministry of Health, Labour and Welfare of Japan. The registration of applicants is based on the attending doctors' diagnosis, and medical costs of registered patients are covered by the government. However, the accuracy of the diagnoses has not been investigated previously. The aim of the present study is to investigate the accuracy of the diagnoses of patients registered as PD, SCD and ALS in Mie prefecture of Japan. The study design was cross-sectional and the survey was carried out using an anonymous questionnaire. We asked the attending doctors the most probable clinical diagnosis in each applicant for PD, SCD or ALS at the annual renewal of application form of the specified diseases by the Ministry. The questionnaires were sent to the 57 neurologists in 20 general hospitals and 2 neurology clinics in Mie prefecture, Japan. The survey was carried out from July to September, 2003. For each disorder (PD, ALS, SCD), the accuracy rates were calculated as the ratio of the number of patients with the most probable diagnosis of the consistent disease to the number of all patients registered each disease. Questionnaires on 678 patients replied from 31 neurologists, 27 of whom were the neurology specialists approved by the Japanese Society of Neurology, were retrieved and analyzed. They covered 41.1% of the total registered PD cases, 45.4% of total SCD cases, and 54.0% of total ALS cases in Mie prefecture. The final clinical diagnosis were made by such specialists in 641 cases (94.5%). The accuracy rate of PD was 97.3% for all degenerative parkinsonisms and 90.2% for idiopathic PD, 96.0% for SCD, and 77.8% for typical ALS and 81.5% for ALS and Kennedy-Alter-Sung syndrome. Although the most probable diagnoses were performed by the attending physicians without verification by other raters, the accuracy rates were excellently high in these diseases, partly because most of the attending physicians were neurology specialists. The relatively low accuracy rate in ALS may be caused partly by the difficulty in differentiating it from spine diseases, neuropathies or myopathies at the early stage of the disease when the patients had been registered, or by inclusion of other motor neuron diseases such as Kennedy-Alter-Sung syndrome.

Amyotrophic Lateral Sclerosis↗

PubMed2006

Computation of decision levels from differentiated logistic regression probability curves.

The determination of clinical decision levels (DL) or "cut-offs" for laboratory parameters involves the analysis of sensitivity and specificity at varying levels of the predictor variable (PV). Commonly, receiver-operator characteristic (ROC) curves are used for this purpose. However, the association between a binary outcome choice and a continuous PV is often tested for statistical significance by logistic regression (LoRe), which also provides estimates of outcome probability (P) at various levels of the PV. Utilizing a graphical procedure based on the 1st [f'(P)] and 2nd [f"(P)] derivatives of the probability curve, DL were computed for simulated data sets (sims) and for actual data from a case-control study and compared with those obtained from ROC curves. Sims were constructed for 5 sets of two outcomes (n = 50, each outcome) of normally distributed data with progressive overlap and for 2 sets of fewer data (n = 15 and 9 per outcome, respectively). Additionally, data from a study of the relationship between serum Mg+2 concentration and outcomes in chronic obstructive pulmonary disease (COPD) were analyzed. DL from LoRe was taken to be the point where f"(P) = 0. For sims, the DL from LoRe correlated well with the optimum DL from ROC analysis (n = 7; r2 = 0.93; p = 0.0004). DL for Mg+2 in COPD data from LoRe was 0.83 mmol/L compared to mean of 0.82 mmol/L by ROC. These data suggest that, when the strength of association between outcomes and PV is analyzed by LoRe, DL can be determined from the probability curves. Moreover, LoRe may provide a useful method to determine DL with less ambiguity than those obtained from ROC curves, as well as provide measures of dispersion for the DL.

Decision Support Techniques↗

PubMed1991

The firing probability of single motor units following transcranial magnetic stimulation in healthy subjects and patients with neurological disease.

Magnetic stimuli applied to the scalp can cause single motor units (MUs) to discharge in intrinsic hand or more proximal arm muscles. MUs are much more likely to be fired by stimuli if they are being activated voluntarily at the same time. The changes in firing probability induced by magnetic stimuli in such tonically active MUs have been studied in healthy subjects and patients using peri-stimulus time histograms (PeSTHs). The mean firing level in the 250 msec before the stimulus, was used to define 2 peaks of increased firing after the stimulus. The first, termed the primary peak (PP), was always present, had an onset latency in first dorsal interosseous (FDI) muscle of 20-31 msec and was short in duration (mean 4.9 msec). A second increase in firing probability, the secondary peak (SP), was present in about half the FDI MUs studied, had a mean peak latency of 81.5 msec and had a duration up to about 40 msec. PP often consisted of a number of sub-peaks with intermodal intervals of around 1.5 msec. It is believed that PP is the result of activation of corticospinal (CS) fibres making monosynaptic connections and that sub-peaks within PP are due to the arrival at the motoneuron of successive CS impulses produced by the stimulus. SP is probably due to operation of other excitatory inputs to the motoneuron. In patients, a number of different abnormalities have been identified. PP has been found to be normal, absent, delayed and dispersed or having abnormally separated sub-peaks. Clearly the technique is a powerful tool for dissecting abnormalities in CS projections at the synaptic level.

Action Potentials↗

PubMed1991

Follow-up as an alternative to biopsy for probably benign mammographically detected abnormalities.

As utilization of mammographic screening increases, a large number of probably benign mammographic abnormalities are being reported. Although the primary effort of screening mammography is to detect cancer at its earliest stages, the secondary goal must be to recognize probably benign abnormalities as such and to offer prudent alternative strategies to surgical excision. Retrospective studies of false-negative mammographic findings indicated the potential for increased sensitivity of employing subthreshold findings. But this increased sensitivity is at a high cost of appropriated resources. Other retrospective studies suggested that such increased sensitivity may not be translated to improved clinical outcome. The validity of mammographic surveillance as opposed to immediate surgical referral is best evaluated through prospective trials. Three such trials have been published in the past year and offer strong reason to consider surveillance, under appropriate circumstances, as an acceptable alternative to immediate biopsy for probably benign mammographically detected lesions.

Biopsy↗

PubMed1990

Syncope and presyncope associated with probable adverse drug reactions.

The purpose of this study was to determine whether syncope and presyncope were associated with drug therapy in 70 patients referred to a tertiary care ambulatory clinic. Drug use information was obtained, validated, and classified by its potential to cause syncope and presyncope. Utilizing a standardized adverse drug reaction algorithm, nine (13%) of the 70 patients were rated as having probable drug-induced syncope and presyncope events. Overall, 12 medications were implicated. Patients with probable adverse drug reactions were older, and taking more medications, or taking an antihypertensive. Seven of the nine patients with probable adverse drug reactions were previously classified as having syncope of unknown origin after their initial clinic evaluation. Syncope and presyncope are commonly associated with adverse drug reactions, especially in the elderly and those taking multiple medications.

Accidental Falls↗

PubMed1990

How well is the probability of tumor cure after fractionated irradiation described by Poisson statistics?

The probability of tumor cure in a homogeneous population of tumors exposed to fractionated radiotherapy was modeled using numerical simulations and compared with the predictions of Poisson statistics, assuming exact knowledge of the relevant tumor parameters (clonogen number, radiosensitivity, and growth kinetics). The results show that although Poisson statistics (based on exact knowledge of all parameters) accurately describes the probability of tumor cure when no proliferation occurs during treatment, it underestimates the cure rate when proliferation does occur. In practice, however, the inaccuracy is not likely to be more than about 10%. When the tumor parameters are unknown and are estimated by fitting an empirical Poisson model to tumor-cure data from a homogeneous population of proliferative tumors, the resulting estimates of tumor growth rate and radiosensitivity accurately reflect the true values, but the estimate of initial clonogen number is biased downward. A new formula that is more accurate than Poisson statistics in predicting the probability of tumor cure when proliferation occurs during treatment is discussed.

Animals↗

PubMed1989

[Event related brain potentials and signal detection: decision confidence and signal probability].

This paper is concerned with the relation of two components of the late positive complex, P300 and slow wave, to parameters of signal detection theory. In the first experiment, basically a replication of Squires et al., signal probability was 50% and a six point rating scale was used for subjects' answers. Whereas for the P300 the well known relation to subjective confidence (and thus to response criteria) was confirmed, a similar relation could not be found for the slow wave. In the second experiment the local signal probability was varied from 25% to 75% on a trial to trial basis. Under these conditions neither the P300 nor the slow wave exhibited a relation to signal-probability, whilst the relation to decision-confidence was preserved.

Adult↗

PubMed1989

Monitoring clinical trials based on predictive probability of significance.

At a given point in a clinical trial, investigators may ask the question: "What is the likelihood of a significant result if the trial were continued?" One possible answer to this question is to examine a predictive probability of the significant difference with further patient accrual. [See, for example, Choi, Smith, and Becker (1985, Controlled Clinical Trials 6, 280-288).] This paper proposes and investigates the approach in trials for comparing the means of two normal populations. Two methods for calculating the predictive probability are examined. The results indicate that the predictive probability can be a useful conservative measure in monitoring trials.

Bayes Theorem↗

PubMed1989

Acculturation and the probability of use of health services by Mexican Americans.

How does level of acculturation affect the probability that Mexican Americans use general health, mental health, and human social services? We studied this question using data from a general population sample of Mexican Americans (N = 1,055). Data were elicited in face-to-face interviews. After controlling for sociodemographic and economic factors, health status, and insurance coverage, Mexican Americans who were less acculturated had significantly lower probabilities of an outpatient medical visit for physical health problems and of a visit to a mental health specialist or human service provider for emotional problems. The less acculturated with good perceived general health were especially unlikely to receive outpatient medical care. Having Medicaid coverage was associated with a larger increase in the probability of an inpatient medical admission for the more acculturated than for the less acculturated. Other individual characteristics had generally similar effects on use of medical and mental health services for both the more and the less acculturated Mexican Americans.

Acculturation↗

PubMed1989

Implications of probability analysis for interpreting results of leukocyte esterase and nitrite test strips.

We examined 288 urine samples, using test strips, sediment microscopy, and culture. The ability of the leukocyte esterase and nitrite test strips to detect or exclude urinary tract infection, as defined by a positive culture, was evaluated by probability analysis. We found that the diagnostic efficiency of the esterase-nitrite combination was similar to that of sediment microscopy. Moreover, once the strip test results had been obtained, little additional information was given by microscopy. The importance of estimating the prevalence, or pre-test probability, of infection before the test result is evaluated is emphasized. We conclude that, for detecting or excluding urinary-tract infection, microscopy can be replaced by the esterase and nitrite test strips. If the probability of infection predicted by the test strips is not high (or low) enough compared with medical decision limits, the samples should be cultured.

Esterases↗

PubMed1987

Teenagers' perceived and actual probabilities of pregnancy.

This study sought to determine how teenagers' actual and perceived probabilities of pregnancy are related. Data were collected from interviews with 425 women aged nineteen or younger who attended the Door, a multiservice center for youth in New York City. Subjects were asked to estimate their likelihood of becoming pregnant the last time they had intercourse, and to indicate the dates of both last intercourse and last menstrual period in order to determine their objective and subjective assessments of risk of pregnancy. It was found that the perceived probability of pregnancy was not highly correlated with actual risk: the distributions of perceived probability of pregnancy were nearly identical for both those who were and were not at actual risk. Moreover, respondents' level of knowledge about the timing of ovulation was not significantly related to the accuracy of their risk assessment. The findings also indicate that teenagers' use of contraception is guided more by their perceived risk of pregnancy than by the actual risk. Policy implications are discussed.

Adolescent↗

PubMed1979

[Comparison of four recently introduced cephalosporins with respect to probability of resistance in multiresistant strains of Escherichia coli, Proteus mirabilis and Klebsiella spec. (author's transl)].

Strains with the same number of resistances were arranged in so-called resistance classes. Nine classes of resistance (0 to greater to or equal to 8) were formed by means of ten standard chemotherapeutics; the four new cephalosporins were excluded. For every resistance class frequency of cephalosporinresistance was described as coefficient ranging from 0 to 1 (Fig. 1). In Cephalothin the coefficients were markedly rising only in 6 (7)-fold resistant strains of the species examined. Similar but somewhat reduced rising of coefficients was also observed in Cefaclor and Cefamandole. In Cefaclor this is particularly evident for E. coli, whereas in Cefamandole, it concerns Klebsiella spec. In the other species rising of coefficients of Cefaclor and Cefamandole are less marked. The probability of restance in multiresistant strains are therefore distinguished more clearly from that of Cephalothin. Cefuroxime and Cefoxitin take a special position because the probability of resistance does not rise in multiresistant strains. The coefficients of Cefoxitin do not show any recognizable dependance on multiresistance. For clinical purpose the following conclusions can be derived: Because of their effectiveness in multiresistant strains Cefoxitin and Cefuroxime are suitable for empiric use in intensive care units where many multiresistant Klebsiella-strains are to be expected. Cefamandole on the other hand is characterized by a rising probability of resistance in multiresistant strains. Therefore it should only be given after antibiotic testing. Cefaclor, a new oral cephalosporin, will be introduced specially for outpatients where multiresistant strains are rarely found.

Anti-Bacterial Agents↗

PubMed1981

[Determination of the probability of thrombocyte aggregation for evaluation of their functional state].

Basing on an analysis of the initial area of the aggregatogram a method has been suggested for determining the probability of platelet aggregation on collision. Calculation was performed in terms of a kinetic equation of coagulation according to the Smolukhovsky's approximation method and in terms of own experimental data. Good agreement of a theoretical depiction with experimental facts indicates the efficacy of the approach suggested to the appraisal of the probability of platelet aggregation, enabling the comparison of the results obtained with different plasma specimens. In contradistinction to a routine analysis of the aggregatograms (determination of the aggregation amplitude, and the time from the onset of the maximum aggregation), the probability of aggregation is determined only from platelet function.

Adenosine Diphosphate↗

PubMed1995

Probabilities of the development of ambulation for mobile children with moderate to profound mental retardation.

Development of ambulation was studied among 1,744 children, ages 3 through 10 years, with moderate to profound mental retardation. The sample was limited to children with some degree of mobility at initial testing. Evaluations over 6 years indicated that improvements in basic skills, although not probable, do occur far past the normative age for development of speech and ambulation and across all levels of mental retardation. The probability of improvement declined with age. Degree of mental retardation and severity of motor impairment had the expected negative effects on initial skill level and probability of improvement. Limiting the sample to subjects who were mobile minimized the effect of mortality.

Age Factors↗

PubMed1995

Studies on TGF-beta 1 gene expression in the intima of the human aorta in regions with high and low probability of developing atherosclerotic lesions.

Certain regions of the human aorta are at greater risk for early and more severe atherosclerotic lesions development than others. Cornhill and coworkers (Cornhill FJ et al.: Arteriosclerosis 5:415, 1985) created maps for the probability of developing atherosclerosis defining the high-probability region (HPR) in the dorsal descending thoracic aorta and the low-probability region (LPR) in the ventral descending thoracic aorta. Our study examines the hypothesis that transforming growth factor beta -1 (TGF-beta 1), a well-known suppressor of growth and function in many human cell lines, is one of the inhibitors of human atherogenesis. The present experiment analyzes the expression of mRNA for TGF-beta 1 in both the HPR and the LPR of aortas from young (age 17 to 25 y) males of black (n = 8) and white (n = 7) race. The level of TGF-beta 1 gene expression was assessed in the aortic intima in both the HPR and the LPR, using National Institutes of Health Image 1.47, an Apple Macintosh application capable of digital image processing, analysis, and morphometric measurement. There was significantly lower (P = 0.002, alpha = 0.05) TGF-beta 1 gene expression in the HPR than in the LPR in the 22- to 25-y age group. There was no significant difference in the 17- to 21-y age group and between the HPR and the LPR in the entire study group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Construction of a literature database and its use to provide probabilities for decision-analytic models of thrombolytic therapy.

Probabilities for decision-analytic models are routinely obtained from the medical literature. This study describes development and use of a literature database to facilitate obtaining probabilities for decision-analytic models of thrombolytic therapy for acute myocardial infarction. Implementation demonstrates the concept of a literature database to be both feasible and effective. Specific difficulties encountered in the evaluation of continuous variables, the potential storage of actual probabilities, and the advantage for easy growth with the literature are discussed.

Databases, Bibliographic↗

PubMed1994

High-resolution technetium-99m-HMPAO SPECT in patients with probable Alzheimer's disease: comparison with fluorine-18-FDG PET.

UNLABELLED: SPECT studies of regional cerebral perfusion with a high-resolution system were compared to PET studies of regional cerebral glucose utilization (rCMRglc) in 21 patients with probable Alzheimer's disease (AD). Ten normal subjects were also evaluated with SPECT and 10 with PET. METHODS: rCMRglc (for PET) and counts (for SPECT) in the associative cortices were normalized to the average rCMRglc, and counts in the calcarine cortex and basal ganglia were considered as a "reference area" to obtain a ratio. The ratio differences between patients and controls were tested with ANOVA performed separately for PET and SPECT. RESULTS: The difference between probable AD patients and controls was significant for both PET (p < 0.00001) and SPECT (p < 0.005); this difference was significant for the frontal, temporal and parietal cortices (p < 0.0001) for PET, and for the temporal (p < 0.005) and parietal (p < 0.001) cortices for SPECT. Temporo-parietal defects were detected in all subjects with PET and in 90% with SPECT. CONCLUSION: PET and SPECT are able to detect characteristic temporo-parietal abnormalities in probable AD. However, the presence of abnormalities in other associative areas is better evaluated with PET.

Adult↗

PubMed1996

Probability of infection with Trypanosoma cruzi of the vector Triatoma infestans fed on infected humans and dogs in northwest Argentina.

The probability that an uninfected Triatoma infestans would become infected with Trypanosoma cruzi after a single feed on people or dogs seropositive for T. cruzi was estimated in Amama, a rural village in northwest Argentina where transmission had resurged four years earlier. The prevalence of seropositivity for T. cruzi was 34.2% among 225 people tested, and 65.1% among 83 dogs tested. Parasitemia was detected by xenodiagnosis in 29.3% of 41 seropositive persons and in 85.3% of 34 seropositive dogs. Parasitemia decreased with age more sharply in seropositive people than in seropositive dogs. Seropositive humans infected 2.6% (95% confidence interval = 1.6%-3.6%) of 963 third or fourth instar nymphs fed once on them, whereas dogs infected 48.7% (44.7%-52.7%) of 610 nymphs. The probability of bug infection increased significantly with instar and was positively related to molting success. The infectivity to bugs of seropositive dogs was 12 times higher than that of seropositive children, and 100 times higher than that of seropositive adults. The weighted probability of infection of an uninfected bug fed randomly on any dog (0.3082) was about 50 times higher than that of bugs fed on any human (0.0062). Such differences in relative infectivity, combined with the relative host-feeding preference of domiciliary Triatoma infestans for dogs, reinforces the important role of domestic dogs as a risk factor for the domestic transmission of T. cruzi.

Adolescent↗