Estimació de variàncies de les variables de l'enquesta de salut de barcelona

ResumEl càlcul de les variàncies en els estudis de disseny mostral complex (mostreig estratificat o multietàpic) resulta esbiaxat en no tenir en compte els efectes del disseny. En aquest article es presenta el càlcul de les variàncies dels estadístics de l'enquesta de salut de Barcelona de 1986 (estudi d'una mostra de 2.205 famílies — conglomerats — i estratificada per districte municipal i per grandària familiar). S'utilitza el métode Jackknife i els resultats es comparen amb l'estimació obtinguda pel métode estàndard (és a dir, suposant un mostreig aleatori simple d'individus).El mètode Jackknife incorpora tot el disseny mostral en el càlcul de les variáncies, en formar a posteriori pseudo-estrats que són en el seu interior homogenis. Aquest mètode condueix a resultats més acurats que el mètode estándard, especialment en el càlcul de valors poblacionals totals. Les diferéncies, però, no són excessivament importants, mentre que el efecte del disseny per conglomerats és més gran per algunes variables. (Gac Sanit 1989; 12 (3): 409–20).SummaryVariance estimation of surveys with complex sampling designs (stratified or multistage design) is biased if design effects are not taken into account. In this article we estimate the variance of some of the variables included in the 1986 health interview survey of Barcelona (survey of 2,205 households—clusters—that were stratified by municipal district and by family size). We present a comparison of variance estimates using the Jackknife method and using the standard method (the one used for simple random samples).Jackknife method incorporates sampling desing effects for estimating the variance, as homogeneous pseudo-clusters are formed. This method leads to more accurate results than the other method especially when calculating global population estimates. Differences between these methods are not very important, whereas cluster design effects are more important for certain variables. (Gac Sanit 1989; 12 (3): 409–20)

Dental Caries, Fluorosis, and Fluoride Exposure in Michigan Schoolchildren

This study relates the prevalence of caries and fluorosis among Michigan children, residing in four different areas, to the various concentrations of F in the communities' water supplies. Demographic information, details of F history, and dental attendance data were collected by a questionnaire form filled out by parents. Children ages six to 12 were screened for caries by means of the NIDR criteria and for fluorosis by means of the TSIF index. Results pertain only to continuous residents and the permanent dentition. The prevalence of both caries and fluorosis was significantly associated with the F concentration in the community water supply. Approximately 65% of all children were caries-free, ranging from 55.1 % in fluoride-deficient Cadillac to 73.7% in Redford (1. 0 ppm F). About 36% of all children had dental fluorosis, ranging from 12.2 in Cadillac to 51.2 in Richmond (1.2 ppm). All of the fluorosis was very mild. From logistic regression, the prevalence of caries was significantly associated with age, dental attendance, and the use of a water supply fluoridated at 1.0 ppm. The odds of experiencing fluorosis increased at every F level above the baseline (Cadillac), with the use of topical F rinses, and with age. Results suggest that children in the four communities may be ingesting a similar level of F from sources such as dentifrices, dietary supplements, and professional applications, but the factor that differentiates them with respect to the prevalence of caries and fluorosis is the F concentration in the community water supply.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66926/2/10.1177_00220345880670050101.pd

Comparison of seven prognostic tools to identify low-risk pulmonary embolism in patients aged <50 years

publishersversionPeer reviewe

Seal or Varnish? A randomised controlled trial to determine the relative cost and effectiveness of pit and fissure sealant and fluoride varnish in preventing dental decay

Background Fissure sealant (FS) and fluoride varnish (FV) have been shown to be effective in preventing dental caries when tested against a no-treatment control. However, the relative clinical effectiveness and cost-effectiveness of these interventions is unknown. Objective To compare the clinical effectiveness and cost-effectiveness of FS and FV in preventing dental caries in first permanent molars (FPMs) in 6- and 7-year-olds and to determine their acceptability. Design A randomised controlled allocation-blinded clinical trial with two parallel arms. Setting A targeted population programme using mobile dental clinics (MDCs) in schools located in areas of high social and economic deprivation in South Wales. Participants In total, 1016 children were randomised, but one parent subsequently withdrew permission and so the analysis was based on 1015 children. The randomisation of participants was stratified by school and balanced for sex and primary dentition baseline caries levels using minimisation in a 1 : 1 ratio for treatments. A random component was added to the minimisation algorithm, such that it was not completely deterministic. Of the participants, 514 were randomised to receive FS and 502 were randomised to receive FV. Interventions Resin-based FS was applied to caries-free FPMs and maintained at 6-monthly intervals. FV was applied at baseline and at 6-month intervals over the course of 3 years. Main outcome measures The proportion of children developing caries into dentine (decayed, missing, filled teeth in permanent dentition, i.e. D4–6MFT) on any one of up to four treated FPMs after 36 months. The assessors were blinded to treatment allocation; however, the presence or absence of FS at assessment would obviously indicate the probable treatment received. Economic measures established the costs and budget impact of FS and FV and the relative cost-effectiveness of these technologies. Qualitative interviews determined the acceptability of the interventions. Results At 36 months, 835 (82%) children remained in the trial: 417 in the FS arm and 418 in the FV arm. The proportion of children who developed caries into dentine on a least one FPM was lower in the FV arm (73; 17.5%) than in the FS arm (82, 19.6%) [odds ratio (OR) 0.84, 95% confidence interval (CI) 0.59 to 1.21; p = 0.35] but the difference was not statistically significant. The results were similar when the numbers of newly decayed teeth (OR 0.86, 95% CI 0.60 to 1.22) and tooth surfaces (OR 0.85, 95% CI 0.59 to 1.21) were examined. Trial fidelity was high: 95% of participants received five or six of the six scheduled treatments. Between 74% and 93% of sealants (upper and lower teeth) were intact at 36 months. The costs of the two technologies showed a small but statistically significant difference; the mean cost to the NHS (including intervention costs) per child was £500 for FS, compared with £432 for FV, a difference of £68.13 (95% CI £5.63 to £130.63; p = 0.033) in favour of FV. The budget impact analysis suggests that there is a cost saving of £68.13 (95% CI £5.63 to £130.63; p = 0.033) per child treated if using FV compared with the application of FS over this time period. An acceptability score completed by the children immediately after treatment and subsequent interviews demonstrated that both interventions were acceptable to the children. No adverse effects were reported. Limitations There are no important limitations to this study. Conclusions In a community oral health programme utilising MDCs and targeted at children with high caries risk, the twice-yearly application of FV resulted in caries prevention that is not significantly different from that obtained by applying and maintaining FSs after 36 months. FV proved less expensive. Future work The clinical effectiveness and cost-effectiveness of FS and FV following the cessation of active intervention merits investigation

Le cauchemar de l'éducation des filles. Notes sur «Le Rêve » de Zola

Caries Patricia, Desgranges Béatrice. Le cauchemar de l'éducation des filles. Notes sur «Le Rêve » de Zola. In: Romantisme, 1989, n°63. Femmes écrites. pp. 23-28