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Biomedical subjects

E Lesaffre

Publications and source records attributed to E Lesaffre.

At least 19 recordsLinked to original sources
PubMed1999

Assessing the goodness-of-fit of the Laird and Ware model--an example: the Jimma Infant Survival Differential Longitudinal Study.

The Jimma Infant Survival Differential Longitudinal Study is an Ethiopian study, set up to establish risk factors affecting infant survival and to investigate socio-economic, maternal and infant-rearing factors that contribute most to the child's early survival. Here, a subgroup of about 1500 children born in Jimma town is examined for their first year's weight gain. Of special interest is the impact of certain cultural practices like uvulectomy, milk teeth extraction and butter swallowing, on child's weight gain; these have never been thoroughly investigated in any study. In this context, the linear mixed model (Laird and Ware) is employed. The purpose of this paper is to illustrate the practical issues when constructing the longitudinal model. Recently developed diagnostics will be used herefor. Finally, special attention will be paid to the two-stage interpretation of the linear mixed model.

Adult↗
PubMed1999

A note on the number needed to treat.

The concept of the average number of patients needed to treat to prevent a single bad outcome is becoming increasingly popular among clinicians. Defined as the inverse of the absolute risk reduction (delta), its sample estimate is denoted as NNT. Here we discuss the mathematical and statistical properties of NNT and show that simple calculations, like taking sums of different NNTs, can give nonsensical results. The implication for a meta-analysis expressed in NNTs is that we can best calculate the combined NNT by taking the inverse of the combined estimate for delta. Simulations illustrate the better performance of the combined NNT estimate on the delta-scale (NNT(P)) in comparison with the combined estimate of NNT on the NNT-scale (NNT(O)), even in cases where it is reasonable to take sums. The calculations are illustrated using data from anti-epileptic trials.

Anticonvulsants↗
PubMed1999

Consequences of MRSA carriage in nursing home residents.

A prospective cohort study with 1 year follow-up evaluated the relation between MRSA carriage and mortality, likelihood of hospitalization and functional status in residents of a nursing home for the elderly. Included were all 447 residents living in the home in early June 1994. From all patients, swabs were taken from nose, throat and perineum. Additional swabs (sputum, urine or wounds) were taken when indicated. The relative risk (RR) of dying within 6 months in MRSA carriers compared to non-carriers was 2.29 (95% CI = 1.04-5.04). This RR remained stable (1.57-2.40) after adjustment for co-variables using Mantel-Haenszel stratified analysis. After I year, the RR was reduced to 1.30 (95% CI = 0.65-2.58). Univariate survival analysis confirmed a difference in survival between carriers and non-carriers after 6 months (log-rank P = 0.04) and no difference after 1 year. Cox regression analysis resulted in a hazard ratio for dying within 6 months of 1.73 (95% CI = 0.72-4.17). No relation was found between carriage and either likelihood of hospitalization or indicators of functional status. These results are compatible with a possible relation between 6 months mortality and MRSA carriage in nursing home patients. It calls for a large scale, multicentre cohort study in order to either confirm or refute these findings.

Aged↗
PubMed1999

Plantar force distribution in Parkinsonian gait: a comparison between patients and age-matched control subjects.

This study aimed to ascertain whether roll-off of the feet during gait was essentially different in patients with Parkinson's disease from that of elderly control subjects. Twenty-two patients, belonging mainly to Hoehn & Yahr grades III and IV, and 30 elderly people participated in the study. Plantar force distribution data were collected of two consecutive strides using pressure-sensitive insoles as part of the pododynograph system. Results showed that when correcting for gait speed and sex differences, patients with Parkinson's disease walked with significantly lower relative peak forces at the forefoot and heel and increased load at the midfoot. The onset of peak forces indicated slower load acceptance on the heel and early forefoot loading which was confirmed by a reduced amplitude of the centre of force along the length of the foot compared with healthy controls. Roll-off was significantly reduced in patients with Parkinson, a feature which was specific for the disease rather than a result of reduced gait speed alone.

Aged↗
PubMed1999

Association of hyperdense middle cerebral artery sign with clinical outcome in patients treated with tissue plasminogen activator.

BACKGROUND AND PURPOSE: The hyperdense middle cerebral artery sign (HMCAS) is a marker of thrombus in the middle cerebral artery. The aim of our study was to find out the frequency of the HMCAS, its association with initial neurological severity and early parenchymal ischemic changes on CT, its relevance to clinical outcome, and the efficacy of intravenous recombinant tissue plasminogen activator (rtPA) in patients with the HMCAS. METHODS: Secondary analysis of the data from 620 patients who received either rtPA or placebo in the European Cooperative Acute Stroke Study I (ECASS I), a double-blind, randomized, multicenter trial. The baseline CT scans were obtained within 6 hours from the onset of symptoms. Functional and neurological outcomes were assessed using the modified Rankin Scale and the Scandinavian Stroke Scale at day 90. RESULTS: We found an HMCAS in 107 patients(17.7%). The initial neurological deficit was more severe in patients with the HMCAS than in those lacking this sign (P<0.0001). Early cerebral edema and mass effect were also more common in patients with the HMCAS (P<0.0001). The HMCAS was related to the risk of poor functional outcome (grade of 3 to 6 on the modified Rankin Scale) on univariate analysis: 90 patients (84%) with the HMCAS and 310 patients (62%) lacking this sign were dependent or dead at day 90 (P<0.0001). However, this association was no longer significant in a logistic model accounting for the effect of age, sex, treatment with rtPA, initial severity of neurological deficit and early parenchymal ischemic changes on CT. Patients with the HMCAS who were given rtPA had better neurological recovery than those who received placebo (P=0.0297). CONCLUSIONS: The HMCAS is associated with severe brain ischemia and poor functional outcome. However, it has no significant independent prognostic value when accounting for the effect of initial severity of neurological deficit and of early parenchymal ischemic changes on CT. Patients with the HMCAS may benefit from intravenous rtPA.

Acute Disease↗
PubMed1998

The detection of residual serial correlation in linear mixed models.

Diggle (1988) described how the empirical semi-variogram of ordinary least squares residuals can be used to suggest an appropriate serial correlation structure in stationary linear mixed models. In this paper, this approach is extended to non-stationary models which include random effects other than intercepts, and will be applied to prostate cancer data, taken from the Baltimore Longitudinal Study of Aging. A simulation study demonstrates the effectiveness of this extended variogram for improving the covariance structure of the linear mixed model used to describe the prostate data.

Analysis of Variance↗
PubMed1998

Variceal pressure is a factor predicting the risk of a first variceal bleeding: a prospective cohort study in cirrhotic patients.

Predictive criteria for a first variceal hemorrhage lack substantial accuracy. Cross-sectional studies suggest a close relationship between variceal pressure (VP) and the occurrence of variceal bleeding. In the present prospective cohort study, the significance of VP measurement for prediction of a first variceal bleed was assessed. Eighty-seven patients with cirrhosis and large esophageal varices who had never developed variceal bleeding were followed for 12 months. The endpoint of the study was the presentation or not of a variceal hemorrhage. Thirty-four patients (39%) were in Child's class A, 37 in class B (43%), and 16 in class C (18%). The median interval between endoscopic diagnosis of varices and the beginning of the study was 15 months. Twenty-eight patients (32%) developed a variceal hemorrhage with a bleeding-related mortality of 18% (n=5). The 1-year mortality overall was 16% (n=14). Variables predictive of a first bleed identified by Cox proportional hazards regression model were: the level of VP, the North Italian Endoscopic Club (NIEC) score, and the interval between the diagnosis of varices and the start of the study. By adding VP to NIEC, a significant gain in prognostic accuracy was obtained (P = .003). In conclusion, the present study provides evidence that the level of VP is a major predictive factor for variceal hemorrhage, and that it provides further prognostic information in addition to the NIEC index.

Adult↗
PubMed1998

Twelve weeks of continuous oral therapy for toenail onychomycosis caused by dermatophytes: a double-blind comparative trial of terbinafine 250 mg/day versus itraconazole 200 mg/day.

BACKGROUND: Dermatophyte infections of the toenail have been difficult to treat, requiring long courses of therapy and having high recurrence rates. New oral antifungal agents with better outcomes and minimal adverse events are needed. OBJECTIVE: The purpose of this study was to compare two newer antifungal compounds, terbinafine and itraconazole, for efficacy and safety in toenail onychomycosis caused by dermatophytes. METHODS: The study was randomized and double-blind. It compared 12 weeks of continuous oral treatment with terbinafine 250 mg/day or itraconazole 200 mg/day for confirmed toenail dermatophyte onychomycosis. Clinical symptoms and mycologic outcome were assessed at weeks 4, 8, 12, 24, 36, and 48. A total of 372 patients (186 in each group) with dermatophyte infection confirmed by microscopy and culture were included in the intent-to-treat analysis. RESULTS: At week 48, a statistically significantly greater percentage of the terbinafine group than itraconazole group showed negative mycology (73% [119 of 163] vs 45.8% [77 of 168]; p < 0.0001) (difference = 27.2%; 95% CI = [17.0%, 37.3%]). The difference was also confirmed clinically (p = 0.001) in the patients who were clinically cured or had only minimal symptoms at the end of the study (76.2% [125 of 164] vs 58.1% [100 of 172]) (difference = 18.1%; 95% CI = [8.24%, 27.9%]). The geometric mean length of healthy nail of the big toe was significantly greater in the terbinafine than itraconazole group (8.1 vs 6.4 mm; p = 0.026). Tolerability was good to very good in almost 90% of patients in both groups, and all reported adverse events were known for these compounds. CONCLUSION: Terbinafine produced higher rates of clinical and mycologic cure at follow-up than did itraconazole.

Administration, Oral↗
PubMed1998

A frequency and correlation analysis of motor deficits in Parkinson patients.

PURPOSE: The present study explored the frequency and pattern of functional motor problems of a group of Parkinson patients, as a first step towards developing a rational approach to rehabilitation intervention addressing the primary symptoms of the disease. METHOD: Sixty patients, consisting of 40% women and 60% men with a mean age of 63.5 years and of which 88% were taking L-dopa, underwent a number of standardized clinical tests including part III of the UPDRS. They were also interviewed about the frequency of motor problems occurring at home. RESULTS: Loss of trunk rotation as expressed in rolling in supine and reduced arm swing were the most frequently registered motor disorders (73%, 75%). Freezing at the start of, or during, walking was not observed during clinical testing but was frequently claimed to occur at home (48%, 23%). A broad spectrum of deficits regarding gait, posture, transfers and distal motor problems formed a cluster, which was strongly correlated with bradykinesia (p < 0.001). Principal component analysis identified four distinct problem areas: (1) axial motor performance; (2) akinetic gait problems; (3) rigidity; and (4) tremor. CONCLUSIONS: Parkinson patients, particularly in the later stages of the disease, presented with significant levels of functional disability which was mainly linked with the underlying impairment of bradykinesia.

Adult↗
PubMed1998

Local influence in linear mixed models.

The linear mixed model has become an important tool in modelling, partially due to the introduction of the SAS procedure MIXED, which made the method widely available to practising statisticians. Its growing popularity calls for data-analytic methods to check the underlying assumptions and robustness. Here, the problem of detecting influential subjects in the context of longitudinal data is considered, following the approach of local influence proposed by Cook.

Age Factors↗
PubMed1997

Factors associated with cortical and trabecular bone loss as quantified by peripheral computed tomography (pQCT) at the ultradistal radius in aging women.

Peripheral quantitative computed tomography (pQCT) allows the separate determination of cortical and trabecular bone mineral density in the peripheral skeleton. This cross-sectional study was designed to examine the effects of healthy aging on pQCT measurements at the ultradistal radius. In a well-defined sample of 129 community-based women, aged 70-87 years, the differences in cortical and trabecular density over the age range were equivalent to losses of -0.41% and -0.65% per year, respectively. To investigate the mechanism of this age-related decline, we assessed relationships between both parameters and height, weight, body mass index, dietary calcium intake, grip strength, and serum concentrations of insulin-like growth factor-I (IGF-I), calcidiol (25(OH)D3), calcitriol (1,25(OH)2D3), parathyroid hormone (PTH), and sex hormone binding globulin (SHBG). Multiple regression was used to adjust for potential confounders. Age was not significant after controlling for other covariables. Body mass index, grip strength, serum IGF-I, 25(OH)D3, and PTH (1-84) were found to be independent predictors of total bone density. Including (total or free) 1,25(OH)2D3 did not improve the model precision. These findings provide evidence that, among other factors, the activity of the growth hormone-IGF-I-axis is of importance for skeletal integrity. Grip strength, serum IGF-I, and PTH (1-84) were discovered to be significantly related to cortical but not to trabecular density, suggesting that different mechanisms may be involved in compact and cancellous bone loss.

Aged↗
PubMed1997

Determinants of age-associated changes in os calcis ultrasonic indices in elderly women: potential involvement of geriatric hyposomatotropism in bone fragility.

OBJECTIVE: ultrasound measures a clinically relevant property of bone strength in addition to and distinct from bone mass. The aim of the present study was to examine the effects of healthy ageing on ultrasound measurements of the calcaneus. DESIGN: cross-sectional study. STUDY PARTICIPANTS: a sample of 177 community-dwelling healthy women aged 70-87 years. Exclusion criteria were diseases or medications known to affect the musculoskeletal system or the somatotrophic axis. MEASUREMENTS: serum levels of 1,25-dihydroxyvitamin D3 and insulin-like growth factor-I (IGF-I) were measured by radioimmunoassay, serum 25-hydroxyvitamin D3 (25(OH)D3) was determined by competitive binding assay and serum parathyroid hormone was assessed immunochemically. Isometric and isokinetic quadriceps strength were evaluated using a Cybex II system. Calcaneal ultrasound indices--broadband ultrasound attenuation (BUA) and speed of sound (SOS)--were measured with an Achilles system. RESULTS: we found a significant decrease with ageing in BUA and SOS (-0.5 and -1.3% per year, respectively), suggesting a continuing loss of bone quality. Quadriceps strength, serum IGF-I and 25(OH)D3 constituted the best predictors of BUA, while IGF-I was the only parameter found to be independently associated with SOS. CONCLUSION: these findings suggest that, among other factors, the activity of the growth hormone-IGF-I axis is of importance for skeletal integrity. Age-related bone fragility may, in part, be related to geriatric hyposomatotropism.

Aged↗
PubMed1997

Is metabolic evidence for vitamin B-12 and folate deficiency more frequent in elderly patients with Alzheimer's disease?

BACKGROUND: It is still unclear whether there is an association between Alzheimer's disease and vitamin B-12 or folate deficiency. This study was designed to investigate whether patients with Alzheimer's disease are particularly prone to metabolically significant cobalamin or folate deficiency as compared to nondemented hospitalized controls and healthy elderly controls living at home. METHODS: Evaluation for the diagnosis of Alzheimer's disease, routine laboratory tests, serum folate and vitamin B-12, serum methylmalonic acid (MMA), total homocysteine (tHcy), and radiological tests was performed in 52 patients with Alzheimer's disease (AD), 50 nondemented hospitalized controls, and 49 healthy elderly subjects living at home. RESULTS: Serum vitamin B-12 and folate levels are comparable between patients with AD, hospitalized control patients, and subjects living at home. Patients with AD have the highest serum MMA and tHcy levels. The MMA levels of patients with AD and hospitalized controls are not different, but the mean tHcy level is significantly higher in patients with AD as compared to nondemented patients or subjects living at home. CONCLUSION: The interpretation of the vitamin B-12 and folate status in patients with AD depends largely on the methodology (i.e., serum vitamin vs metabolite levels) and the selection of the control group. Although patients with AD have the highest tHcy and MMA levels, metabolically significant vitamin B-12 and folate deficiency is also a substantial problem in nondemented elderly patients.

Aged↗
PubMed1997

Short-term reproducibility of pressure pain thresholds in masseter and temporalis muscles of symptom-free subjects.

Pressure pain thresholds (PPTs) of the bilateral masseter and temporalis muscles were assessed over a single day and in between 2 days with the aid of an electronic algometer in 11 males and 11 females. Using a mixed model approach, covariance results were controlled for confounding of gender, day, time of the day and the within-session replications of the measurements. For every jaw muscle, the first PPT measurement of a session was markedly higher than the last one of that same session. Except for the right temporalis muscles, no significant systematic PPT differences could be observed between male and female subjects. The differences between morning and afternoon sessions were not significant for any of the muscles tested. Although the PPTs measured on the 1st day were systematically lower than those on the 2nd day for the left masseter and temporalis muscles, no significant difference between the time of the day could be observed when the values of the different muscles were grouped within a subject. Analysis of variance showed that the variability induced by the day or the time of the day was similar to the variability of the measurement itself. The inter-individual variability of PPTs was 2.3 to 9 x higher than the variability observed between trials, sessions or days. The results indicate that the PPT measurement will not be systematically influenced by the time of registration (morning/afternoon) or inbetween consecutive days. In addition, the important inter-individual differences favor the use of longitudinal within-subject studies.

Adult↗
PubMed1997

Time course of serum lipids and apolipoproteins after acute myocardial infarction: modification by pravastatin.

Pravastatin was administered to patients suffering an acute myocardial infarction starting with a dose of 10 mg/day at day 3 and continuing with a dose of 20 mg/day up to a period of 3 months. The study was performed on the basis of a randomized placebo-controlled double-blind trial. At the dosage used pravastatin significantly lowered the total cholesterol and LDL-cholesterol levels and increased the HDL-cholesterol levels compared to placebo. A prospective clinical trial in order to examine the possible clinical relevance of these findings is recommended.

Anticholesteremic Agents↗
PubMed1996

Effect of dropouts in a longitudinal study: an application of a repeated ordinal model.

An analysis is presented of a longitudinal study of fluvoxamine, an antidepressant drug, with ordinal responses, regressed on a combination of discrete and continuous covariates and with a substantial proportion of dropouts. Classical methods, such as weighted least squares (SAS procedure CATMOD) and logistic regression, are not suitable for the analysis of such data. Instead, we illustrate how a recently introduced model can be used to solve most of the problems posed. The method is likelihood-based and is an extension of the bivariate Dale model to an arbitrary number of outcomes. The method is suitable for several types of designs commonly employed in clinical trials.

Antidepressive Agents, Second-Generation↗
PubMed1996

Dietary salt, nitrate and stomach cancer mortality in 24 countries. European Cancer Prevention (ECP) and the INTERSALT Cooperative Research Group.

BACKGROUND: High salt and nitrate intake are considered as risk factors for stomach cancer, but little is known about possible interactions. This ecological study examines the respective importance of both factors for stomach cancer mortality at the population level using data obtained under standardized conditions and with biochemical analyses performed in the same laboratories. METHODS: Randomly selected 24-hour urine samples from 39 populations, sampled from 24 countries (N = 5756 people for sodium, 3303 for nitrate) were obtained from the INTERSALT study. Median sodium and nitrate levels were age- and sex-standardized between ages 20-49 years and averaged per country. Ecological correlation-regression analyses were done in relation to national stomach cancer mortality rates. RESULTS: The Pearson correlation of stomach cancer mortality with sodium for the 24 countries was: 0.70 in men and 0.74 in women (both P < 0.001) and with nitrate: 0.63 (P = 0.001) in men and (P < 0.005) in women. In multiple regression of stomach cancer mortality, using sodium and nitrate as independent variables the adjusted R2 was 0.61 in men and 0.54 in women (both P < 0.001). Addition of the interaction term (sodium x nitrate) to the previous model increased the adjusted R2 to 0.77 in men, and to 0.63 in women. The analysis of this model showed that the importance of nitrate as risk factor for stomach cancer mortality increased markedly with higher sodium levels. However, the relationship of stomach cancer mortality with sodium was always stronger than with nitrate. CONCLUSIONS: Salt intake, measured as 24-hour urine sodium excretion, is likely the rate-limiting factor of stomach cancer mortality at the population level.

Adult↗