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Biomedical subjects

E Lesaffre

Publications and source records attributed to E Lesaffre.

At least 19 recordsLinked to original sources
PubMed2007

Caries patterns in primary dentition in 3-, 5- and 7-year-old children: spatial correlation and preventive consequences.

This study aimed to contribute to the descriptive information of oral health status in the primary dentition, especially concerning the distribution and spatial correlation of lesions. Data were obtained from two surveys. In the Signal-Tandmobiel project 4,468 7-year-old children in Flanders (Belgium) were selected by a stratified clustered random sample. In the Tandje de Voorste - Smile for Life (TDV) project, data were obtained from 1,291 3-year-old and 1,315 5-year-old children. The children were examined by trained dentists, using standardized and widely accepted criteria, based on the British Association for the Study of Community Dentistry criteria. At the population level, symmetry in the prevalence of caries experience across the midline was tested at the tooth and tooth surface levels using generalized estimating equations and alternating logistic regression (ALR) approaches. Individual symmetry was tested using an approach described by Hujoel et al. [J Dent Res 1994;73:1575-1580]. Descriptive observations suggested a symmetrical distribution of caries experience at the population level. The null hypothesis of symmetry could not be rejected at a 0.05 level, suggesting that caries experience might be symmetric in the deciduous dentition. Based on the ALR approach, 2 x 2 associations of caries experience at the tooth and surface levels, both in 5- and 7-year-olds, appeared to be strongest for the left-right pairs in the mandible, followed by the left-right pairs in the maxilla. At the individual level the hypothesis of random caries pattern was rejected (p < 0.0001). In conclusion, at the population level the null hypothesis of left-right symmetry could not be rejected, while at the individual level lesions tended to cluster on one side of the mouth.

Belgium↗
PubMed2006

The clinicopathological and prognostic relevance of cytokeratin 7 and 19 expression in hepatocellular carcinoma. A possible progenitor cell origin.

AIMS: Cytokeratin (CK) 7 and CK19 expression, present in hepatic progenitor cells (HPCs) and in cholangiocytes but not in normal hepatocytes, has been reported in some hepatocellular carcinomas (HCCs); however, the incidence and relevance of this expression in HCC in Caucasians is not known. Therefore, our aim was to study the occurrence and clinicopathological characteristics of HCC expressing CK7 and/or CK19 in 109 Caucasian patients. METHODS AND RESULTS: The expression of hepatocellular differentiation markers (Hepar, canalicular polyclonal carcinoembryonic antigen), biliary/progenitor cell markers (CK7, CK19), alpha-fetoprotein (AFP), p53 and beta-catenin in HCC was semiquantitatively assessed by immunohistochemistry. Of 109 HCCs, 78 were CK7-/CK19- (72%), 13 CK7+/CK19- (12%), seven CK7-/CK19+ (6%), 11 CK7+/CK19+ (10%). CK19 expression was significantly associated with elevated serum AFP (400 ng/ml) (P = 0.023), tumour AFP expression (P < 0.0001), presence in serum of anti-hepatitis B core (P = 0.016), less fibrosis in non-neoplastic parenchyma (P = 0.009) and less nuclear beta-catenin expression (P = 0.021). CK7 expression was significantly associated with elevated serum bilirubin (> 2 mg/dl) (P = 0.0005) and less nuclear beta-catenin expression (P = 0.003). HCC expressing CK19 had a higher rate of recurrence (P = 0.009, hazard ratio 12.5, n = 31) after liver transplantation compared with CK19- tumours. CONCLUSIONS: In our series, 28% of HCCs contained cells expressing CK7 and/or CK19. They potentially derive from HPCs. The higher recurrence rate of CK19+ HCC after transplantation suggests a worse prognosis for these HCCs compared with CK19- HCC.

Adult↗
PubMed2004

Analysis of caries experience taking inter-observer bias and variability into account.

In larger oral health surveys, clinical measurements are often obtained using several examiners. This raises the issue of inter-observer variability in measurement. Often, the problem is dealt with by reporting kappa values obtained in a calibration exercise. In the present study, the limitations of this statistic are presented, and an alternative, based on a Bayesian approach, is proposed. When the alternative approach was applied to caries experience data obtained in an oral health screening survey in seven-year-old Flemish children (Signal Tandmobiel study), it could be ruled out that the observed geographic East-West gradient was due to bias induced by variability in scoring of the different dental examiners involved. The proposed method offers an opportunity to refine existing analytical approaches and is relevant to any health outcome study.

Bayes Theorem↗
PubMed2004

Variables associated with oral hygiene levels in 7-year-olds in Belgium.

OBJECTIVES: The present investigation aimed to delineate the extent of the correlation between each of a number of possible associated variables and the amount of plaque (as measured by a plaque index) present in 7-year-old Flemish children and to investigate the potential relation between caries experience and the amount of dental plaque. PARTICIPANTS: A sample of 4,468 children representative of children living in Flanders and born in 1989 was obtained. Their mean age was 7.1 (SD = 0.4) years with a boys/girls ratio of 51.8%-48.2%. METHODS: Analyses were performed with ordinal plaque index outcome, considering the children's school (i.e. class) as a random effect. Random effect models were estimated with the SAS procedure Proc NLMIXED. RESULTS: From the multiple logistic regression analysis, it could be concluded that the older the subjects the more dental plaque was observed (OR = 1.35; CI 1.08-1.68; p = 0.0081). Moreover, four explanatory variables could be identified as significant determinants for dental plaque in the mixed dentition: 'start of brushing after the age of 2' (OR = 1.161; CI: 1.09-1.23; p < 0.0001), 'brushing frequency of < 1x/day' (OR = 1.369; CI: 1.012-1.66; p = 0.0019), 'more than two in between meal snacks' (OR = 1.18; CI: 1.023-1.36; p = 0.0111) and 'daily intake of sugar containing drinks' (OR = 1.24; CI: 1.08-1.42; p = 0.0023). Further, being male was associated with a higher amount of plaque (OR = 1.16; CI: 1.00-1.34; p = 0.0506) and finally, a weak but significant correlation (Spearmans' rho: r = 0.23, p < 0.0001) between caries experience and the amount of cervical plaque was shown. CONCLUSION: The amount of cervical plaque in the mixed dentition was significantly related to variables associated with oral hygiene and dietary habits. A low but significant correlation between the amount of dental plaque and caries experience was observed.

Age Factors↗
PubMed2003

Low back pain in Flemish adolescents and the role of perceived social support and effect on the perception of back pain.

AIM: To document the prevalence of low back pain (LBP) in Flemish adolescents and to recognize the association between perceived social support and affect and medical consultation and reduction of activities. METHODS: The study comprised 620 adolescents. A questionnaire was used to elicit the characteristics of LBP. Perceived social support and affect were investigated using the Personal Resource Questionnaire (PRQ) and the Positive Affect Negative Affect Scale (PANAS), respectively. Comparisons were made between adolescents with LBP and adolescents without LBP. Within the LBP group, answers from adolescents appealing for medical advice were compared with those who did not seek advice. Another comparison was done between adolescents who reduced their activities and those who did not. Descriptive statistics, the median test for two samples, a chi2 test or Fisher's exact probability test and logistic regression analysis were used for data analysis. RESULTS: Month prevalence of LBP was 24.7%. Thirteen adolescents visited a physician or received treatment, pain severity being the sole factor associated with the decision. Fifteen adolescents reduced their sports activities and 11 reduced or stopped other leisure activities. Pain severity and negative affect were the main associated factors. CONCLUSION: The results of the present study encourage further research on the role of pain perception and the influence of psychosocial factors on back pain in adolescents.

Adolescent↗
PubMed2002

Modelling tooth emergence data based on multivariate interval-censored data.

Studies on emergence of (permanent) teeth are published regularly in the dental literature. Besides descriptive statistics (mean or median values) on emergence times, comparisons between boys and girls are of interest. Gender comparisons are intersubject analyses, but also intrasubject questions, like 'Is there a left-right symmetry with respect to the mean (median) emergence times?' are of interest. Studies on emergence times most often are faced with interval-censored data. We will extend a GEE-type test proposed by Huster et al. for bivariate right-censored data to the multivariate setting with interval-censored data. Central to our paper is to provide appropriate statistical models to resolve some dental questions on emergence. The analyses are based on data from the longitudinal Signal-Tandmobiel study.

Age Factors↗
PubMed2001

Modelling bivariate ordinal responses smoothly with examples from ophthalmology and genetics.

A non-parametric implementation of the bivariate Dale model (BDM) is presented as an extension of the generalized additive model (GAM) of Hastie and Tibshirani. The original BDM is an example of a bivariate generalized linear model. In this paper smoothing is introduced on the marginal as well as on the association level. Our non-parametric procedure can be used as a diagnostic tool for identifying parametric transformations of the covariates in the linear BDM, hence it also provides a kind of goodness-of-fit test for a bivariate generalized linear model. Cubic smoothing spline functions for the covariates are estimated by maximizing a penalized version of the log-likelihood. The method is applied to two studies. The first study is the classical Wisconsin Epidemiologic Study of Diabetic Retinopathy. The second study is a twin study, where the association between the elements of twin pairs is of primary interest. The results show that smoothing on the association level can give a significant improvement to the model fit.

Adolescent↗
PubMed2001

Treatment of reinfarction after thrombolytic therapy for acute myocardial infarction: an analysis of outcome and treatment choices in the global utilization of streptokinase and tissue plasminogen activator for occluded coronary arteries (gusto I) and assessment of the safety of a new thrombolytic (assent 2) studies.

BACKGROUND: Early reinfarction after thrombolytic therapy is associated with adverse outcomes and increased mortality. Among patients with reinfarction in the 1992 Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO I) and the 1998 Assessment of the Safety of a New Thrombolytic (ASSENT 2) trials, we investigated temporal and regional differences in the use of repeat thrombolysis, revascularization (angioplasty and/or bypass surgery), or conservative measures and the outcomes of each management strategy. METHODS AND RESULTS: Data from the 4% of patients (n=2301) who experienced reinfarction after thrombolytic therapy were studied. Baseline characteristics, 30-day mortality, and incidence of total and hemorrhagic strokes were compared among the 3 treatment groups. The 30-day mortality did not differ between the repeat thrombolysis and revascularization groups (P=0.72), and it was significantly lower among patients treated by these 2 strategies than in those treated conservatively (11% and 11% versus 28%, respectively; P<0.001). Stroke rates did not differ significantly between the 3 treatment strategies (P=0.49). From 1992 to 1998, the percentage of reinfarction patients treated with repeat thrombolysis decreased from 29.3% to 18.5% in US centers and from 51.4% to 41.9% in all other centers (P<0.001). In contrast, use of revascularization procedures increased from 33.5% to 47.9% in US centers and from 8.1% to 23.0% in all other centers (P<0.001). CONCLUSIONS: Repeat thrombolysis and revascularization are associated with significantly lower mortality among reinfarction patients. Randomized trials are necessary to assess the exact risks and benefits of rethrombolysis versus interventional revascularization in this subset of high-risk patients presenting with reinfarction after thrombolytic therapy.

Aged↗
PubMed2001

Assessing risk indicators for dental caries in the primary dentition.

The aim of the present study was to assess indicators shown to be associated with the prevalence of caries in the primary dentition of 7-year-old Flemish schoolchildren. Cross-sectional first year data of the longitudinal Signal-Tandmobiel survey were analysed (n=4468). Gender, age, oral hygiene habits, use of fluorides, dietary habits, geographical factors and parental modelling were the considered predictors. From the multiple logistic regression analysis, including schools as a random effect, and after adjusting for the confounding variables-educational system and province (stratification variables), gender and age-it became clear that the following risk indicators remained significant (at 5% level) for the presence of caries: frequency of toothbrushing (P=0.05) with an OR 1.24 for brushing less than once a day, age at start of brushing (P<0.001) with an OR=1.22 for a delay of 1 year, regular use of fluoride supplements (P<0.001) with an OR=1.54 for no use, daily use of sugar-containing drinks between meals (P<0.001) with an OR=1.38, and number of between-meals snacks (P=0.012) with an OR=1.22 for using more than 2 between-meal snacks. There was a significant difference (P<0.05) in caries experience determined by the geographical spread, with an explicit trend of caries declining from the east to the west. In a model with an ordinal response outcome, the daily use of sugar-containing drinks between meals had a more pronounced effect when caries levels were high. From this study it became obvious that, in Flemish children, an early start of brushing and a brushing frequency of at least once a day need to be encouraged, while the use of sugar-containing drinks and snacks between meals needs to be restricted to a maximum of 2 per day. Geographical differences need to be investigated in more detail.

Age Factors↗
PubMed2001

Sensitivity analysis for nonrandom dropout: a local influence approach.

Diggle and Kenward (1994, Applied Statistics 43, 49-93) proposed a selection model for continuous longitudinal data subject to nonrandom dropout. It has provoked a large debate about the role for such models. The original enthusiasm was followed by skepticism about the strong but untestable assumptions on which this type of model invariably rests. Since then, the view has emerged that these models should ideally be made part of a sensitivity analysis. This paper presents a formal and flexible approach to such a sensitivity assessment based on local influence (Cook, 1986, Journal of the Royal Statistical Society, Series B 48, 133-169). The influence of perturbing a missing-at-random dropout model in the direction of nonrandom dropout is explored. The method is applied to data from a randomized experiment on the inhibition of testosterone production in rats.

Animals↗
PubMed2001

Parental occupational status related to dental caries experience in 7-year-old children in Flanders (Belgium).

OBJECTIVES: The study aimed to investigate differences in the oral health of 7-year-old Flemish children by the parents' occupational class and to explore behavioural and demographic factors linked to social inequalities in oral health. PARTICIPANTS: A stratified cluster sample of 1,500 primary school children in Flanders, born in 1989. METHOD: The clinical oral examination was performed in the first year of a longitudinal oral health project in Flanders (1996-2001) by 16 calibrated examiners. Information on occupational level of the parents and on oral health related behaviour was gained, respectively, by the school health care centres and the parents of the children using a structured questionnaire. RESULTS: The mean dmf values between the several SES groups, assessed by occupational status of the parents, were significantly different (P<0.001). The mean dmft and dmfs values were the lowest for the most advantaged children (1.3/2.7) and were threefold higher in the least advantaged children (3.9/9.1). The prevalence of caries-free children was 2.5 times higher among the highest SES families compared with the lowest SES families. In a logistic regression model adjusted for the stratification factors, the excess risk for caries in children increased with decreasing occupational level of the parents. There was a cumulative effect of decreasing occupational level and oral health habits on the caries prevalence. CONCLUSION: The results of the study allow the supposition that social inequalities in oral health among children exist in Flanders. Environmental factors and individual behavioural factors partially explain why social class might influence oral health.

Belgium↗
PubMed2001

[In the interests of taking one's time even when one reads a scientific article! Critical review of the literature on tooth eruption].

Nowadays everybody has access to the medical literature, not only through the libraries of the universities, but even more conveniently via Medline and Pubmed. It is very tempting only to read abstracts and summaries instead of "wasting time" by reading the whole article. Reading the article itself however enables the reader to select only these articles that have a good methodological and statistical basis. In this contribution several topics will be discussed that may help the reader to read scientific articles with a critical mind: definitions, quality of the data, study concepts, composition of the sample, control group, statistical analysis, sample size and interpretation of the results. Different items are exemplified with articles that deal with the emergence of permanent teeth.

Controlled Clinical Trials as Topic↗
PubMed2001

[Analysis of dental caries risk factors in the primary dentition].

The aim of the present study was to assess indicators shown to be associated with the prevalence of caries in the primary dentition of 7-year-old Flemish schoolchildren. Cross-sectional first year data of the Signal-Tandmobiel survey were analysed (n = 4468). Gender, age, oral hygiene habits, use of fluorides, dietary habits, geographical factors and social factors were involved in logistic regression models. There was a significant difference (P < 0.05) in caries experience determined by the geographical spread, with an explicit trend of caries declining from the east to the west. A start of brushing before the age of 2 and a brushing frequency of at least once a day need to be encouraged, while the use of sugar containing drinks and snacks between meals needs to be restricted to a maximum of 2 per day. The mean dmf-t values were the lowest for the most advantaged children and where threefold higher in the least advantaged children. There was a cumulative effect of decreasing social level and oral health habits on the caries prevalence. Social inequalities in oral health among children exist in Flanders.

Belgium↗
PubMed2001

[Factors determining dental plaque and their relation to the assessment of caries among 7-year-old Flemish children].

The present investigation aimed to assess the impact of a number of variables on the variation on the amount of dental plaque present in the mixed dentition of 7-year-old Flemish children and to investigate a potential correlation between caries experience and the amount of dental plaque. Analyses were performed with ordinal plaque index as outcome measure, considering the children's school (i.e. class) as a random effect. This random effect turned out to be of great importance when dealing with large clustered samples. From the multiple logistic regression analysis, it was concluded that the older the subjects the more dental plaque was observed (or = 1.35; CI: 1.08-1.68; P = 0.0081). Four exploratory variables, could be identified as important risk indicators for dental plaque accumulation in the mixed dentition: 'start of brushing after the age of 2 years' (or = 1.161; CI: 1.09-1.23; P < 0.0001), 'brushing frequency of < 1 x/day (or = 1.37; CI: 1.12-1.66; P = 0.0019), more than two in between meal snacks (or = 1.18; CI: 1.03-1.36; P = 0.02) and daily intake of sugar containing drinks (or = 1.24; CI: 1.08-1.42; P = 0.002). Further, being male was linked to a higher amount of plaque (or = 1.16; CI: 1.00-1.34; P = 0.0506). Finally a weak but significant correlation (spearman's rho: r = 0.23; P < 0.0001) between caries experience and the amount of cervical plaque was shown.

Belgium↗
PubMed2000

Identification of lacunar infarcts before thrombolysis in the ECASS I study.

BACKGROUND: The identification of lacunar infarcts before thrombolysis would make it possible either to exclude them from treatment or to show that they also may benefit from it. OBJECTIVE: To determine whether clinical presentation or early CT findings of patients enrolled in the first European Cooperative Acute Stroke Study (ECASS I) trial would identify lacunar infarcts before treatment. METHODS: Predictive values, sensitivity, specificity, and accuracy of clinical presentation as pure motor hemiparesis (PMH) or sensorimotor stroke (SMS) syndromes and of baseline CT findings in predicting lacunar infarcts were calculated in the ECASS I patients. RESULTS: Of 514 patients, 44 placebo (17%) and 44 recombinant tissue plasminogen activator (rt-PA) (18%) patients had PMH/SMS involving at least two of three areas. Thirty-one placebo (12%) and 32 rt-PA (13%) patients had PMH/SMS involving three areas. The 7-day CT was compatible with a lacunar infarct in 32 placebo (12%) and 44 rt-PA (18%) patients. PMH/SMS involving at least two areas had a positive predictive value of 30% both in placebo and rt-PA patients, whereas positive predictive values of the involvement of three areas were 23% and 31%. Those of absence of early CT signs were 21% and 30%, and those of leukoaraiosis or previous lacunar infarcts were 21% and 23%. Positive predictive values of PMH/SMS involving at least two areas combined with absence of early CT signs were 36% in placebo and 33% in t-PA patients, and those of PMH/SMS plus leukoaraiosis or previous lacunes were 28% and 7%, respectively. CONCLUSIONS: In the ECASS I trial, lacunar infarcts were not recognizable on clinical grounds, and early CT findings, alone or in combination with the clinical picture, added poorly to the differential diagnosis.

Cerebral Infarction↗