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Biomedical subjects

A Blinowska

Publications and source records attributed to A Blinowska.

13 recordsLinked to original sources
PubMed1995

Fuzzy classification of patient state with application to electrodiagnosis of peripheral polyneuropathy.

A methodology which accounts for uncertainty or imprecision in experimental observations and both norm and pathology definitions is developed on the basis of a distance measure between fuzzy numbers. These fuzzy numbers may represent, respectively, the measurements, norm, and pathology. The distance measure, called normalized fuzzy pathology index (NFPI), evaluates the difference of distance between observed experimental values for a given patient and norm on the one hand, and pathology on the other hand. The NFPI characterizes patient state as a continuous index; however, to conform to medical usage, categories of values are defined. Each of these categories corresponds to a linguistic variable. The case study used to illustrate the methodology is the electrodiagnosis of peripheral polyneuropathy in diabetic patients. Here, four initial linguistic categories are defined by a physician, namely: normal state, borderline state, clear-cut, and severe pathology. The NFPI is calculated in three cases that provide a sensitivity analysis on measurement fuzziness and distance function weighting. The model is calibrated using 203 cases and validated using 291 different cases. The results correspond very closely to the physician's diagnosis. The loss of information in discretizing the continuous state of patients is discussed. Transferring this fuzzy approach to other cases where the concept of distance is relevant offers no difficulty.

Diabetic Neuropathies↗
PubMed1995

Do physicians estimate reliably the cardiovascular risk of hypertensive patients?.

For hypertension management, it is increasingly recommended to individualize treatment according to the individual patient's characteristics. However, the ability of physicians to predict the patient's risk in the absence of a computer aid is unknown. Our aim was to determine if senior hypertension specialists were able to assess reproducibly cardiovascular disease (cvd) risk in hypertensive patients. The records of 100 patients were selected at random from the ARTEMIS database. The group comprised 53% of males, mean age was 43.7 (15), blood pressure 160 (25) / 99 (12) mmhg and serum cholesterol 5.6 (1.1) mmol/l. The records were summarized on a standardized form. Nineteen items were devoted to general characteristics and medical history of patients, 15 to clinical examination and 7 to biological tests. These items have been chosen because they were used in the framingham cvd risk prediction equation and/or had decisional value in a bayesian program designed for secondary hypertension diagnosis. Six physicians, twice at one month intervals, assigned each patient to one of the three categories of risk (low, moderate, high). The order of cases was randomized. Chance corrected agreement (intra-physician agreement) between the two estimations was only moderate except for one expert (kappa values: 0.658, 0,543, 0.439, 0.363, 0.328 and 0.207 for each expert, respectively). The proportion of patients assigned by each physician to each category ranged from 22.7% to 77.3% for the low risk, and from 4.5% to 43.9% for the high risk category. One physician overestimated risk, one underestimated it and the three others were in keeping with framingham predictions. Bias and lack of reproducibility influence physician judgment in assessing cvd risk of hypertensive patients. Application of computer aids could result in more rational assessments and better decision making.

Adolescent↗
PubMed1993

Diagnostica--a Bayesian decision-aid system--applied to hypertension diagnosis.

"Diagnostica" is a Bayesian statistical tool designed to collect and store the patient's data, suggest a diagnosis, and explain the decision in terms of density distributions. The program is written in C language on MacIntosh support. It is described using the case study of differential diagnosis between essential and secondary hypertensions (i.e., fibrodysplastic renal artery stenosis, atheromatous renal artery stenosis, Conn's syndrome, nephropathy and pheochromocytoma). Seventeen experimental parameters were taken into consideration, all of them available during the first medical examination. The density distributions of all items were established from the ARTEMIS experimental database. Both a priori probabilities of different types of hypertension and loss coefficients are taken into account in the calculations. Diagnostica can be used in a "make diagnosis" mode or in an "edition" mode. In the first case it can serve a physician in everyday practice; in the second it becomes a tool for medical research.

Bayes Theorem↗
PubMed1991

Bayesian statistics as applied to hypertension diagnosis.

This paper deals with the following hypertension diagnoses: essential hypertension and five types of secondary hypertension: fibrodysplasic renal artery stenosis, atheromatous renal artery stenosis, Conn's syndrome, renal cystic disease, and pheochromocytoma. Only blood pressures, general information and general biochemical data are taken into account. Nineteen items were finally selected, by statistical investigation of experimental data, as being both discriminative and independent. The marginal density distributions of every item, and then joint density distribution functions were determined within six types of hypertension. The frequency of a given hypertension type within the hypertensive patients was used as prior probability of this state. The loss matrix was established by medical arguments. The expected loss corresponding to six possible decisions could thus be calculated for all cases. Both the ratio of secondary hypertensions that could be inferred from our set of data (not including the results of complementary tests) and that of correct "essential" hypertension diagnosis proved to be satisfactory.

Bayes Theorem↗
PubMed1990

Somatosensory evoked potentials from median nerve; normative data.

The somatosensory evoked potentials from median nerve were studied in a group of 127 normal adults aged from 19 to 79. The latencies of elbow, Erb's, cervical N11 and N13 as well as cortical N20 and P25 potentials were analyzed as a function of height and age. Two central conduction times, N20-N11 and N20-N13, were equally studied. The corresponding regression formulae were calculated and can be used to predict normative values of these parameters over a wide range of height and age. Standard error estimates are given for all parameters.

Adult↗
PubMed1986

[Effect of marathons on neuromuscular excitability; comparison of electromyographic and biochemical findings].

The aim of this paper is to study the neuromuscular excitability of a group of marathon runners and to see how it can be modified right after the marathon. Spontaneously appearing multiplets in EMG signal under ischaemia served as a test of the neuromuscular hyperexcitability. The percentage of positive tests is much higher than in the control population; as a rule, the effect of the marathon is to diminish the neuromuscular hyperexcitability. The concentrations of Ca, Mg and P in the plasma as well as the globular concentration of Mg have been determined several times, both before and after the marathon; no correlation has been found with the neuromuscular hyperexcitability.

Adult↗
PubMedDate not supplied

Bayesian statistics as applied to multiple sclerosis diagnosis by evoked potentials.

This study deals with the multiple sclerosis diagnosis by visual, somatosensory and brain stem auditory evoked potentials. By a statistical investigation of experimental data, four items have been selected as being both discriminative and independent: P100, N20, P40 latencies and the auditory central conduction time. The Bayesian approach was then attempted, i.e. the marginal density distributions of every item, and the joint density distribution functions have been established within both normal and multiple sclerosis population. No loss function consideration have been taken into account, as the final diagnosis is established by a neurologist who disposes of additional clinical and paraclinical information. The discrimination, as given by posterior Bayesian probability, is very satisfactory since the ratio of recognized multiple sclerosis among MS patients is over 90%, while no normal subject is diagnosed as MS.

Bayes Theorem↗
PubMedDate not supplied

Somatosensory evoked potentials from posterior tibial nerve; normative data.

The somatosensory evoked potentials from posterior tibial nerve were studied in a group of normal adults. The latencies of popliteal fossa potential, L3, N33 and P40 waves as well as central conduction time were analyzed as a function of height and age. The correlation of the peripheral conduction velocity with the subject's age was also studied. The corresponding regression formulae were calculated and can be used to predict normal values of these parameters over a wide range of height and age. Standard error estimates are given for all parameters.

Adult↗