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Biomedical subjects

L Letenneur

Publications and source records attributed to L Letenneur.

At least 55 records · Page 3Linked to original sources
PubMed1999

Are sex and educational level independent predictors of dementia and Alzheimer's disease? Incidence data from the PAQUID project.

OBJECTIVES: To examine the age specific risk of Alzheimer's disease according to sex, and to explore the role of education in a cohort of elderly community residents aged 65 years and older. METHODS: A community based cohort of elderly people was studied longitudinally for 5 years for the development of dementia. Dementia diagnoses were made according to the DSM III R criteria and Alzheimer's disease was assessed using the NINCDS-ADRDA criteria. Among the 3675 non-demented subjects initially included in the cohort, 2881 participated in the follow up. Hazard ratios of dementia were estimated using a Cox model with delayed entry in which the time scale is the age of the subjects. RESULTS: During the 5 year follow up, 190 incident cases of dementia, including 140 cases of Alzheimer's disease were identified. The incidence rates of Alzheimer's disease were 0.8/100 person-years in men and 1.4/100 person-years in women. However, the incidence was higher in men than in women before the age of 80 and higher in women than in men after this age. A significant interaction between sex and age was found. The hazard ratio of Alzheimer's disease in women compared with men was estimated to be 0.8 at 75 years and 1.7 at 85 years. The risks of dementia and Alzheimer's disease were associated with a lower educational attainment (hazard ratio=1.8, p<0.001). The increased risk of Alzheimer's disease in women was not changed after adjustment for education. CONCLUSION: Women have a higher risk of developing dementia after the age of 80 than men. Low educational attainment is associated with a higher risk of Alzheimer's disease. However, the increased risk in women is not explained by a lower educational level.

Aged↗
PubMed1998

Modelling age-specific risk: application to dementia.

We give up-to-date methods for estimating the age-specific incidence of a disease and for estimating the effect of risk factors. We recommend taking age as the basic time scale of the analysis; then, the hazard function can be interpreted as the age-specific incidence of the disease. This choice raises a delayed entry problem. We present three methods: the person-years method; the smoothed Nelson-Aalen estimator, and the penalized likelihood approach. When explanatory variables are available, the Poisson model and the Cox model with delayed entry may be used for estimating relative risks; the penalized likelihood approach can also be used. We apply these methods to estimate the age-specific incidence of dementia using data from a large cohort study, Paquid. This 5-year study followed a random initial sample of 3675 subjects with 190 incident cases of dementia. We compare the estimates based on the three possible methods. The estimated incidences computed separately for men and women cross and it is verified that a non-proportional hazards model for gender holds; women below 75 have a lower risk than men while women above 75 have a higher risk.

Age Factors↗
PubMed1998

Illustration of analysis taking into account complex survey considerations: the association between wine consumption and dementia in the PAQUID study. Personnes Ages Quid.

Epidemiologists are increasingly looking to large-scale sample surveys to provide data for studies of the associations between known or suspected risk factors and disease. More often than not, widely available statistical software packages have been used to analyze such data, particularly when multivariable modeling is involved. Such packages assume that the data have resulted from simple random samples. However, when the survey design incorporates such features as clustering and stratification, the results of statistical analyses based on this assumption can be incorrect. The authors utilized data from the PAQUID (Personnes Agees Quid) study, collected periodically from 1988 to 1996, to illustrate the ease of performing a "design-based" (vs. a "model-based") analysis of complex survey data, and they compared the results obtained using both approaches. The PAQUID study is a stratified cluster sample of elderly community residents in the southwestern departments of Gironde and Dordogne, France. In the illustration presented-in which 3,777 community residents aged 65 years or older were selected to permit identification of baseline and lifetime factors that might be related to cognitive loss, dementia, and Alzheimer's disease--measures of association (such as odds ratios and their associated standard errors) were comparable for both analytical strategies. However, this may not be the case for other examples. Descriptive measures (such as estimates of means and proportions) may be more seriously compromised by the decision to ignore the sampling design. The availability of modern statistical packages with survey analysis capabilities should encourage data analysts to perform design-based analyses whenever possible.

Aged↗
PubMed1998

B-mode-guided vector-A-mode versus A-mode biometry to determine axial length and intraocular lens power.

PURPOSE: To compare prospectively the reproducibility and accuracy of B-mode-guided biometry with those of A-scan biometry using a conventional A-mode probe to calculate intraocular lens (IOL) power. SETTING: Department of Ophthalmology, Hôtel-Dieu de Paris, France. METHODS: The axial length (AL) in 87 eyes of 72 candidates for cataract surgery was determined by B-mode-guided vector-A-mode and A-mode biometry using an Ophthascan S Ultrasound imager. Patients were assigned to one of two groups based on the B-mode biometry: nonmyopic (AL < 24.5 mm; n = 54) or myopic (AL > 24.5 mm; n = 33). Postoperative refractive results were compared with attempted values. RESULTS: Mean AL variance was significantly greater when using the A-mode than the B-mode: 0.157 mm +/- 0.260 (SD) versus 0.015 +/- 0.018 mm in the myopic group (P < .001) and 0.024 +/- 0.024 +/- 0.045 versus 0.009 +/- 0.011 mm in the nonmyopic group (P < .001). More eyes having B-mode biometry achieved a final refraction within +/- 0.50 diopter (D) of the attempted refraction (63 and 43%, respectively; P < .05). No deviation greater than 1.60 D was observed with the B-mode in the myopic or nonmyopic group. Three cases with a such a deviation (up to 2.24 D) would have been observed had A-mode-based biometry been chosen for the IOL power calculation. In the myopic group, attempted postoperative refraction was within +/- 0.50 D in 78% of eyes having B-mode biometry compared with 65% having A-mode. This difference was not statistically significant. CONCLUSION> These results suggest that the reproducibility and accuracy of AL measurements are significantly better with B-mode-guided A-mode biometry than with A-mode biometry in myopic and nonmyopic eyes.

Biometry↗
PubMed1998

Cognitive process in preclinical phase of dementia.

Several recent prospective studies have demonstrated the existence of a preclinical stage of dementia, identifiable by neuropsychological assessment showing impairments with a great variety of cognitive tests. However, test scores are often colinear, largely because common cognitive components are involved in different tests; in spite of an apparent heterogeneity, it is still possible that a common cognitive component may be responsible for the deterioration shown in different tests in the preclinical phase. We studied the cognitive performances of 1159 elderly residents in the PAQUID (Personnes Agées quid) cohort, at a fixed lag time of 2 years before the clinical diagnosis of dementia. Seven neuropsychological tests were administered (Mini-Mental Status Examination, Benton Visual Retention Test, Wechsler Paired-Associates Test, Isaacs Set Test, Zazzo's Cancellation Task, Digit Symbol Substitution Test and Wechsler Similarities Test). Among the initially non-demented 1159 subjects, 25 developed a dementia 2 years later, of whom 16 were classified as cases of Alzheimer's disease. In order to dissect the multicolinearity of the tests we used a multivariate approach with principal component analysis (PCA). The patients' loading on each of the first four PCA factors were subsequently correlated with the risk of dementia and Alzheimer's disease 2 years later. The logistic regression with backward stepwise selected only the first factor as an independent predictor of dementia or Alzheimer's disease. Analysis shows that there are good reasons to suspect that the first PCA factor represents a general factor corresponding to aspects of control in the tasks used. Our results therefore seem to show that preclinical deficits in dementia and Alzheimer's disease reflect the deterioration of a general cognitive factor, which may be interpreted as the disturbance of central, control processes.

Aged↗
PubMed1998

Intrafamilial clustering and 4-year follow-up of asymptomatic human T-cell leukaemia virus type I (HTLV-I) infection in Benin (West Africa).

BACKGROUND: Few data exist concerning familial human T-cell leukaemia virus type I (HTLV-I) carrier states and transmission in African countries. Two previous surveys performed in Benin in 1989 and 1990 using a three-level cluster sampling method allowed us to identify HTLV-I positive subjects. The evolution of HTLV-I within the families of these subjects is described over a 4-year period, 1991-1995. METHODS: Since 1991, 37 HTLV-I seropositive subjects, six subjects with indeterminate Western-Blot pattern, and their relatives have been followed up once a year clinically and biologically. RESULTS: Twenty-three mothers in the study group gave birth to 27 children between 1991 and 1995. Among the 13 infants born to the 12 seropositive mothers, two seroconverted before their second birthday. One adult woman whose husband was seropositive developed seropositivity 4 years after marriage. In March 1992, a family case-control study (proband study) was conducted. A seroprevalence of 27.5% was found among 138 relatives of 32 infected subjects and 1.4% among 142 relatives of 32 control subjects. CONCLUSIONS: There is clearly an intrafamilial clustering of HTLV-I in Benin. The annual incidence density of HTLV-I in this cohort is estimated at 6 per thousand.

Adolescent↗
PubMed1998

A penalized likelihood approach for arbitrarily censored and truncated data: application to age-specific incidence of dementia.

The Cos model is the model of choice when analyzing survival data presenting only right censoring and left truncation. There is a need for methods that can accommodate more complex observation schemes involving general censoring and truncation. In addition, it is important in many epidemiological applications to have a smooth estimate of the hazard function. We show that the penalized likelihood approach gives a solution to these problems. The solution of the maximum of the penalized likelihood is approximated on a basis of splines. The smoothing parameter is estimated using approximate cross-validation; confidence bands can be given. A simulation study shows that this approach gives better results than the smoothed Nelson-Aalen estimator. We apply this method to the analysis of data from a large cohort study on cerebral aging. The age-specific incidence of dementia is estimated and risk factors of dementia studied.

Age Factors↗
PubMed1998

[Major statistical software usable in epidemiology].

Quality assurance of biostatistical data analysis is becoming mandatory. The aim of this review of statistical software was to guide uses who are faced with the increasing number of these tools. A list of softwares was obtained from statisticians and computer scientists, computerized databases, computer science lay press, and commercial documents. The softwares were described and their possibilities measured. The following functions were studied: functions considered as essential (descriptive analysis, Student's t, Mann-Whitney or Wilcoxon, ANOVA, Kruskall-Wallis, Pearson's chi 2, Fisher's exact test, Pearson's r), survival and multivariate analysis (logistic regression, proportional hazards modelling, times series). User-friendliness and quality of graphs were also studied. Among the 220 listed softwares, 26 could be considered as general softwares and were extensively analyzed. Statistical softwares may be classified into four categories: easy-to-use general public softwares with limited functions, such as EPI INFO; simple reference softwares with satisfactory user-friendliness and performing most of the statistical analyses, such as PCSM, STATISTICA or STATA; complex reference softwares intended for statisticians (EPILOG PLUS, SAS); specific cases such as EGRET performing only multivariate analysis or SUPERANOVA performing only analysis of variance. Such a review should be regularly updated.

Analysis of Variance↗
PubMed1997

[Progressive multifocal leukoencephalopathy. Study of the demyelination by magnetization transfer].

PURPOSE: magnetization transfer imaging (MT) has been used to study the degree of demyelination in progressive multifocal leukoencephalopathy (PML). MATERIAL AND METHOD: two groups were studied: a group of 10 HIV + patients with clinical, MR features, biological and/or biopsy proven PML, and a group of 11 normal volunteers with matched age. MT ratio (MTR) were obtained from the center of the PML lesions and 11 areas of normal appearing white matter (NAWM) in the control group. RESULTS: the mean MTR of NAWM in the control group was 46.6% (SD = 2,3). PML lesions demonstrated a strong and significant (p = 0) decreased of the MTR with mean MTR value of 22.4% (SD = 2,3). CONCLUSION: MT characterized the demyelinating process in PML, and can be used to improve diagnosis. Furthermore, MT allowed a quantification of the degree of demyelination which can be helpful in other demyelinating process of CNS such as multiple sclerosis.

Adult↗
PubMed1997

Magnetization transfer study of HIV encephalitis and progressive multifocal leukoencephalopathy. Groupe d'Epidémiologie Clinique du SIDA en Aquitaine.

PURPOSE: To ascertain whether the use of magnetization transfer (MT) in MR imaging can characterize tissue destruction in human immunodeficiency virus (HIV)-positive patients with presumed progressive multifocal leukoencephalopathy (PML) or HIV encephalitis. METHODS: Brain MR studies that included MT were obtained in three groups: 11 healthy control subjects, 10 HIV-positive patients with clinical and radiologic findings of PML, and 13 HIV-positive patients with HIV encephalitis. MT ratios (MTRs) were calculated in PML and HIV encephalitis lesions and in normal-appearing white matter in the patients and control subjects. RESULTS: PML lesions revealed a dramatic decrease in MTR (22% +/- 2.3). HIV encephalitis lesions had statistically significantly higher MTR values (40% +/- 3.8) than PML lesions. The MTR of normal-appearing white matter was significantly higher in the control subjects (47% +/- 2.3) than in the PML group (46% +/- 3.3) or the HIV encephalitis group (44% +/- 2.6). CONCLUSION: MTR determinations suggest the possibility of distinguishing PML from HIV encephalitis and of indicating whether HIV encephalitis is involved in white matter that appears normal on conventional MR images.

Adult↗
PubMed1997

[Predictive factors for institutionalization in the context of geriatric planning in the Gironde department (France)].

The objective of this study was to investigate the predictive factors over five years follow-up of institutionalization, relevant for starting interventions in the area of Gironde (South Western France). This study deals with a longitudinal study of community residents aged 65 years and older. Of the 2792 subjects initially included in the cohort in year 1988, 2493 were selected for this study, leading to the subjects whose type of housing was known at least once over the five year follow-up (1989-1993). The statistical analysis was made with a discrete Cox proportional hazard model. Of the 2493 subjects, 150 entered an institution during the five years of follow-up, leading to a cumulative incidence of 7.1%. In the multivariate analysis, the predictive factors found in this study were age, absence of phone in the house, living in home for the aged, cognitive decline evaluated with the Mini-Mental-Status-Examination (MMSE), dependency for one item of the Lawton's scale (Instrumental Activities of Daily Living or IADLs), namely the inability to do shopping, and limited social contact with the family. These different indicators are a basis for decision making to target home care services fitted to the needs of the area.

Activities of Daily Living↗
PubMed1997

Wine consumption and dementia in the elderly: a prospective community study in the Bordeaux area.

Alcoholism is a possible cause of dementia, mainly through associated nutritional deficiencies and, rarely, through acute direct toxicity. However alcohol consumption was not found to be a risk factor in previous epidemiologic studies. We prospectively studied 3,777 community residents aged 65 and over, in the districts of Gironde and Dordogne. Average daily alcoholic consumption was recorded at baseline. Incident cases of dementia and Alzheimer's disease were screened at follow-up with explicit criteria. At 3 years, 2,273 subjects not demented at baseline were still available for follow-up. Wine was the only alcoholic beverage reported by more than 95 p. 100 of regular drinkers. In the 318 subjects drinking 3 to 4 standard glasses per day (> 250 and up to 500 ml), categorized as moderate drinkers, the crude odds ratio (OR) was 0.18 for incident dementia (p < 0.01) and 0.25 for Alzheimer's disease (p < 0.03), as compared to the 971 non-drinkers. After adjusting for age, sex, education, occupation, baseline MMSE and other possible confounders, the ORs were respectively 0.19 (p < 0.01) and 0.28 (p < 0.05). In the 922 mild drinkers (< 1 to 2 glasses per day) there was a negative association only with AD, after adjustment (OR = 0.55; p < 0.05). The inverse relationship between moderate wine drinking and incident dementia was explained neither by known predictors of dementia nor by medical, psychological or socio-familial factors. Considering also the well documented negative associations between moderate wine consumption and cardiovascular morbidity and mortality in this age group, it seems that there is no medical rationale to advise people over 65 to quit drinking wine moderately, as this habit carries no specific risk and may even be of some benefit for their health. Advising all elderly people to drink wine regularly for prevention of dementia would be however premature at this stage.

Aged↗
PubMed1996

Nonsteroidal antiinflammatory drug use and cognitive function in the elderly: inconclusive results from a population-based cohort study.

As part of the cohort Paquid, we studied the relationship between the use of NSAID, incidence of dementia, and evolution of cognitive functions. Dementia was diagnosed by DSM-III criteria and cognitive functions was assessed through the Mini-Mental Status Examination (MMSE). During 2 years of follow-up, the incidence rate of dementia was 3.84% among 53 NSAID users as compared with 3.77% in 1199 nonusers (OR, 0.98; 95% CI, 0.23-4.16). Using a cutoff of -3 points for the MMSE score and taking into account age and educational status in a logistic regression model, NSAID use was related to an unfavourable variation of the MMSE score (OR, 2.84; 95% CI, 0.99-8.1).

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1996

Prevalence of self-reported asthma symptoms in a French elderly sample.

The aim of this study was to estimate the prevalence of reported asthma symptoms in French elderly people according to age, sex and principal lifetime occupation. PAQUID (Personnes Agées QUID) is a cohort of 3777 subjects, aged 65 years and over, living at home in the south-west of France. The aim of PAQUID is to study factors of cerebral and functional ageing. This cross-sectional study took place during the third year of the PAQUID follow-up, and concerned 2406 subjects (63.7% of the initial sample). Two questions were introduced into the PAQUID general questionnaire: "have you ever had asthma?' (cumulative asthma), and "did you have at least one asthma attack in the last 12 months?' (current asthma). Of 2355 subjects, 144 (6.1%) reported asthma history at some point in their life. For 58 (40.3%) subjects, it was in the previous 12 months. In men, the prevalence rate was 7.3% for cumulative asthma and 2.8% for current asthma. In women, rates were 5.2% and 2.2%, respectively. The rates were lower at advanced ages (> 85 years) for both males and females. They were particularly high in former farm workers; 13% reported cumulative asthma and 11% reported at least one asthma attack in the previous 12 months. Farmers appear to have a higher risk of both cumulative [odds ratio (OR): 2.30; 95% confidence interval (CI): 1.00-5.47] and current asthma (OR: 5.35; 95% CI: 1.33-21.50) compared to white collar workers, despite adjustments on age, sex and smoking history. The risk was also significant for manual workers, but only for cumulative asthma.

Age Factors↗
PubMed1996

Comparison of the efficacy of amphotericin B and fluconazole in the treatment of cryptococcosis in human immunodeficiency virus-negative patients: retrospective analysis of 83 cases. French Cryptococcosis Study Group.

We retrospectively analyzed clinical outcome of meningeal and extrameningeal cryptococcosis in HIV-negative patients treated with amphotericin B (43 patients) or fluconazole (40 patients). Amphotericin B and fluconazole were prescribed equally to patients with neoplastic diseases and no risk factor, but organ transplant recipients and patients with other diseases were mostly given fluconazole and amphotericin B, respectively. Patients with more severe infections (i.e., meningitis, neurological disorders, or higher levels of antigen in cerebrospinal fluid) were more frequently treated with amphotericin B. A cure rate of > 70% was achieved regardless of the initial treatment and the severity of the infection. A Cox regression analysis showed that age of > 60 years, neoplastic disease, abnormal mental status, disseminated infection at the time of diagnosis, and therapeutic failure were independent predictors of death. Although fluconazole appears to be as effective as amphotericin B, only a prospective multicenter study will determine the best treatment regimen for patients with cryptococcal meningitis who do not have AIDS.

Adult↗