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C Wolfson

Publications and source records attributed to C Wolfson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Validation of a French version of an informant-based questionnaire as a screening test for Alzheimer's disease.

BACKGROUND: Development of informant-based screening tests for dementia is an emerging field. The reliability and validity of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), an instrument that screens for dementia in general, have been established. We conducted a study to validate a French version of the IQCODE as a screening test for Alzheimer's dementia in the elderly living in the community. METHOD: In the Canadian Study of Health and Aging, subjects were screened in their own homes using the modified Mini-Mental State Exam (3-MS). Those who screened positive, along with a sample of subjects who screened negative, were referred for a complete clinical examination. In Quebec, an informant was asked to complete the French version, IQCODE(F), at that time. Based on the final clinical diagnoses, performances of the IQCODE(F) and Mini-Mental State Examination (MMSE, converted from 3-MS) in screening for Alzheimer's disease were evaluated. RESULTS: Of the 237 subjects, the mean IQCODE (F) score was 3.4 (s.d. = 0.6), on a 5-point scale (1 = improvement in condition over the past 10 years, 5 = marked deterioration, 3 = no change). The mean MMSE score was 23.1 (s.d. = 4.5). The scores on the two scales were correlated (r = -0.44, P < 0.001). The IQCODE(F) scores were unrelated to education (r = -0.07, P > 0.3) in contrast to the MMSE scores (r = 0.28, P < 0.001). With respect to a diagnosis of probable Alzheimer's disease, the IQCODE(F) (cut-off point 3.6) had a sensitivity of 75% and a specificity of 95.6%. The sensitivity and specificity of the MMSE (cut-off point 23) were 70% and 82.3% respectively. CONCLUSION: The findings of the IQCODE(F) are consistent with those of the English version in correlation with the MMSE and apparent freedom from educational bias. The IQCODE is superior to the MMSE as a screening test for probable Alzheimer's disease in the elderly living in the community. It may be a useful addition to the screening tests already available, especially for the less well educated.

Aged↗
PubMed1994

Use of proton magnetic resonance spectroscopy for monitoring disease progression in multiple sclerosis.

Decreases in brain N-acetylaspartate are associated with neuronal loss or dysfunction. We report a longitudinal study in which changes in the N-acetylaspartate to creatine resonance intensity ratio measured by brain proton magnetic resonance spectroscopy were used to follow the progression of brain pathology in 7 patients with multiple sclerosis over an 18-month period. Four of the patients had a history of recurrent relapses and 3 had a secondary progressive course. All had clinical and magnetic resonance imaging evidence of persistent neurological abnormalities. At 6-month intervals proton magnetic resonance spectra were obtained and the N-acetylaspartate-creatine ratio was determined for each patient. The volumes of hyperintense signal from lesions on conventional magnetic resonance images and the Kurtzke Expanded Disability Status Scale scores were determined concurrently. At the onset of the study, the N-acetylaspartate-creatine ratio was significantly (p < 0.05) lower in the central brain volumes from the patients than in 13 normal control subjects. At 12 and 18 months of follow-up, the ratio had decreased further in all patients (p < 0.05), consistent with progressive accumulation of neuronal damage. In contrast to magnetic resonance spectra data, changes in lesion volume on magnetic resonance images or disability status did not reach significance over this period. Subgroup analysis showed that changes (increases or decreases) in the N-acetylaspartate-creatine ratio between consecutive 6-month examinations correlated significantly (r = -0.74, p < 0.005) with changes in lesion volume on magnetic resonance images in patients with a history of relapses.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspartic Acid↗
PubMed1994

Hemostatic markers in acute transient ischemic attacks.

BACKGROUND AND PURPOSE: Hemostatic abnormalities have been shown previously in stroke patients. The purpose of this study was to assess the activity of selected parameters of the coagulation system in acute reversible cerebral ischemia. METHODS: We measured fibrinopeptide A, thrombin-antithrombin III, and D-dimer in 36 patients in both the acute (< 7 days) and postacute stage (1 and 3 months) after a transient ischemic attack (TIA). The results were compared with those of 20 asymptomatic patients with a history of remote TIA and 65 age- and sex-matched controls. RESULTS: Mean fibrinopeptide A and thrombin-antithrombin III values were elevated in the acute stage after a TIA (P < .02) compared with levels at 1 month. In contrast, D-dimer was significantly increased at all three times points after the event when compared with remote TIA (P < .05) or control subjects (P < .001). No association could be found between marker levels and clinical outcome or the degree of cervical atherosclerosis as assessed by duplex ultrasonography. CONCLUSIONS: These findings suggest that after acute reversible cerebral ischemia, there is early transient activation of thrombogenesis and ongoing fibrinolysis.

Aged↗
PubMed1993

Adult children's perceptions of their responsibility to provide care for dependent elderly parents.

We examined how adult children in Canada whose parents were hospitalized in an acute care setting perceived responsibility for their parents' care. Using a visual analogue scale, adult children rated the amount of financial, emotional, and physical support families "should" and "could" give to elderly persons described in four vignettes. All scores were high, with "should" consistently higher than "could" for every vignette and for each of the three types of support. For daughters, the more aggressive the parent, the lower the "should" score for financial support. The same relationship was observed for incontinence and these findings were consistent over all four vignettes.

Adult↗
PubMed1993

The latent period of multiple sclerosis: a critical review.

It is a widely held belief that multiple sclerosis is a disease with a long latent period that is preceded by heightened susceptibility before adolescence. There has, however, been little research focused on either the estimation of the latent period or determination of the susceptibility period. In this article, we present a critical assessment of the relevant literature on migrant studies, cluster studies, the Faroe Islands "epidemic," sibling study, and novel statistical approaches as they pertain to the pre-onset natural history of multiple sclerosis. We also discuss the roles of the latent and susceptibility periods in the design, analysis, and interpretation of epidemiologic studies.

Adolescent↗
PubMed1993

Multiple sclerosis: a comparison of the latent periods of different populations.

While some research in multiple sclerosis has concentrated on the latent period of this disease in single population groups, none has attempted to carry out significance tests to compare the distributions of the latent periods of two distinct groups. Two comparisons are made here, between the populations attending the Multiple Sclerosis Clinic of the Montreal Neurological Institute and Hôpital Neurologique et Neuro-Chirurgical Pierre-Wertheimer, Lyon. We also compared the latent period separately in males and females. There were no significant differences. The significance tests and power studies were based on a nonparametric model that allows for uncertainty in the ages of disease initiation as well as in the ages of onset.

Adolescent↗
PubMed1990

Interobserver variability in the interpretation of contrast venography, technetium-99m red blood cell venography and impedance plethysmography for deep vein thrombosis.

Contrast venography (CV) is the standard technique for diagnosing deep vein thrombosis (DVT). Newer noninvasive tests have also proven efficacious. However, there is a lack of data on the level of agreement among observers in their interpretation of the results of the various tests. After agreeing on well-defined criteria, three experienced observers assessed, blindly, the results of tests performed over a 4-month period on 117 patients who were suspected clinically of having had a first episode of DVT. The kappa statistic was used to measure the level of agreement beyond chance for CV (69 patients), red blood cell venography (RBCV) (82 patients) and impedance plethysmography (76 patients). The results of CV were assigned to normal, abnormal or inadequate categories, and those of RBCV and IPG to normal, equivocal or abnormal categories. The kappa values for CV, RBCV and IPG ranged from 0.53 to 0.56, 0.42 to 0.56 and 0.90 to 0.91 respectively. Values greater than 0.75 represented excellent agreement beyond chance and those between 0.40 and 0.75 represented fair to good agreement. Excellent kappa values were obtained for IPG because interpretation of the results of this method is entirely objective. Although the values for CV and RBCV showed good to fair agreement, there was a greater degree of observer variation, despite the well-defined criteria, indicating the subjectivity of interpretation of these test results. It is concluded that the kappa statistic can be used to measure observer variation of the results of tests for diagnosing DVT and may serve as a quality control tool for studies in which more than one person interprets the results.

Contrast Media↗
PubMed1990

Is multiple sclerosis an infectious disease? Inference about an input process based on the output.

The output process of an infinite-server queue with a Poisson process input is observed starting at time 0 with an empty queue. It is assumed that the service time distribution is known. This article discusses statistical inference about the input intensity. A controversial issue in the study of multiple sclerosis is addressed as a motivation for the model and methods developed.

Adolescent↗
PubMed1989

Mathematical models and individualized outcome estimates in multiple sclerosis.

There is an urgent need for individualized outcome estimates in multiple sclerosis (MS). This is a prerequisite for selecting appropriate therapies in a disease the outcome of which may vary between malignant and benign forms. This question was addressed by using probabilistic mathematical models. The disease course is described by movements of the patient's condition through well-defined disease states. The data used are based upon 278 reports of definite and probable MS cases collected over a 20-year period (1957-1976) at l'Hôpital Neurologique de Lyon. A Markov model was first prepared. However, it only provided an overall presentation of the disease which was not very meaningful for the individual patient, and limited studies of potential prognostic variables to dichotomous variables and univariate analyses. A stochastic survival model was then elaborated. It was complex at the theoretical level but in practice, easy to use. Personalized prognosis of a patient could be ascertained by combining several single potential prognostic variables and using their actual value in the case of quantitative variables. Although these models still need to be refined and have to be validated from the present state of the patients and other patient cohorts, they provide for the first time a global description of disease course likelihood and prognosis. The survival model may be adapted to each patient.

Age Factors↗
PubMed1989

On the estimation of the distribution of the latent period of multiple sclerosis.

A widely accepted hypothesis is that the initiation of multiple sclerosis occurs many years before the clinical onset of disease. Thus far, attempts to describe the characteristics of the latent period have depended entirely on ad hoc methods relying heavily on the results of migrant studies. Here, by introducing a stochastic model to describe the initiation-onset process, the distribution of the latent period is estimated, and several important consequences for multiple sclerosis discussed.

Age Factors↗
PubMed1989

The Canadian Neurological Scale: validation and reliability assessment.

The Canadian Neurological Scale (CNS) was designed to monitor mentation and motor functions in stroke patients. We assessed its validity and reliability on a group of 157 patients with a diagnosis of acute cerebrovascular accident. We determined validity by (1) correlating scale items and total score with the standard neurologic examination; (2) exploring the scale's predictive power with different end points at 6 months--the initial CNS was a significant predictor of outcome; (3) showing that the CNS had higher correlation coefficients with the initial neurologic examination than the Glasgow Coma Scale; and (4) assessing the responsiveness of the scale to change in the neurologic status of stroke patients. Interobserver reliability, measured by kappa statistics on each scale item, was good. Accordingly, we established the validity and reliability of the CNS for its use in clinical studies and in the care of stroke patients.

Central Nervous System↗
PubMed1988

Technetium-99m red blood cell venography in patients with clinically suspected deep vein thrombosis: a prospective study.

We have compared technetium-99m (99mTc) red blood cell (RBC) venography to serial impedance plethysmography (IPG) in 110 consecutive patients with a first episode of clinically suspected deep vein thrombosis (DVT). IPG was performed at Day 0 and, if abnormal, contrast venography was also performed to rule out a falsely positive result. Patients with an initially normal IPG had the test repeated at Days 1, 3, 5 to 7, and 10 to 14. Contrast venography was not performed and anticoagulant treatment was withheld in all patients who remained normal during repeated IPG testing. Technetium-99m RBC venography was performed at Day 0 in patients with an initially abnormal IPG and during the period of serial IPG testing in those with an initially normal IPG. The sensitivity of [99mTc]RBC venography for proximal DVT was 0.68, with 95% confidence limits (CL) from 0.48 to 0.89. Specificity was 0.88 (95% CL from 0.81 to 0.95). When the findings of [99mTc]RBC venography for the entire lower extremity were compared to the reference method, the sensitivity increased to 0.90 (95% CL from 0.82 to 0.97) but the specificity decreased to 0.56 (95% CL from 0.51 to 0.62). Technetium-99m RBC venography is a sensitive but less specific method for detecting DVT of the entire lower extremity. An abnormal [99mTc]RBC venogram, particularly in the calf region, should always be confirmed by another diagnostic method.

Erythrocytes↗
PubMed1987

Improvements to a simple Markov model of the natural history of multiple sclerosis. I. Short-term prognosis.

Follow-up data from a prognostic study done at L'Hôpital Neurologique de Lyon have been reanalyzed using a new methodologic approach. A stochastic survival model which allows the course of the disease to be described through the movement of patients from one disease state to another is presented. This approach extends previous modelling work by enabling the risk of transition between pairs of states to be written as a function of any number of discrete or continuous prognostic variables. Length of the first remission, sex, and mode of onset (mono- vs. polysymptomatic) were found to be significant prognostic indicators.

Adult↗
PubMed1986

Observer variation in the classification of mammographic parenchymal patterns.

Wolfe has described different cancer risks associated with a classification of four patterns of the breast parenchyma on mammography, but there is however little information available on the ability of radiologists to agree on the classification of the different patterns. We have assessed inter-rater agreement on the assignment of films to one of the four mammographic patterns described by Wolfe. One hundred xeromammograms were selected, copied and distributed to 10 radiologists who were experts in mammography. Films were classified according to the presence or absence of several radiological signs, according to diagnosis and recommendation, and according to mammographic pattern. Agreement was assessed after correction for agreement expected by chance, using the Kappa statistic. In general, high levels of agreement were found for the classification of mammographic pattern. Agreement on the classification of mammographic pattern was substantially greater than agreement for any other feature of mammographic interpretation, including diagnosis and recommendation.

Breast Neoplasms↗
PubMed1985

A Markov model of the natural history of multiple sclerosis.

Prior research into multiple sclerosis prognosis has produced conflicting results. This paper presents an original approach in which the disease course is described by the movements of patients through well-defined disease states. A Markov model is proposed to describe these movements and to evaluate the effect of prognostic factors on transitions from state to state. The feasibility and applicability of this model is determined using data on the course of disease in 278 diagnosed patients from Lyon. Patients with older age at onset, females, and those with monosymptomatic onset are found to be at a higher risk of transition to a worse disease state.

Adult↗