Small proportions: what to report for confidence intervals?

The original article to which this Erratum refers was published in Pharmacoepidemiology and Drug Safety 2005; 14: 239–247.     

Using mark-recapture methodology to estimate the size of a population at risk for sexually transmitted diseases.

To study the spread of sexually transmitted diseases (STDs) using social/sexual mixing models, one must have quantitative information about sexual mixing. An unavoidable complication in gathering such information by survey is that members of the surveyed population will almost certainly have sexual contacts outside that population. The number of these outsiders may be substantial and, hence, important for the modelling process. In this paper, we develop a mark-recapture model for estimating the size of the population at risk for contracting a STD due to direct sexual contact with a specified population targeted by a survey. This mark-recapture methodology provides a reliable method of estimating the number of outsiders. Because not everyone in the targeted population may be sexually active, the size of the sexually active subset, used as the number marked in our tag-recapture formulation, must be estimated, which introduces extra variability. We derive an estimator of the variance of the estimated total number at risk that accounts for this extra variability and an expression for the bias of that estimator. We extend the methodology to stratified surveys and illustrate its use with data collected from a population of university undergraduates to estimate sexual mixing parameters of a deterministic model of the spread of STDs.     

Methodenrelevanz in der Nachsorge des Mammakarzinoms

Ohne Zusammenfassung     

同种异体黑素细胞移植治疗白癜风

0　引言　白癜风患者免疫紊乱 ,黑素细胞 (melanocyte,MC)异体移植有可能不被排斥 ,治疗如成功将有很大临床前景 [1 ] .探索同种异体黑素细胞移植后的效果很有意义 .1　病例报告　女 ,2 7岁 ,确诊白癜风 (稳定期 ) ,患者皮肤自幼出现色素脱失斑 ,逐渐增多扩大 . 1996年外用“敏白灵”,前2 mo有效 . 1999- 0 7外用补骨酯酊 ,日服 5 g· L- 1 硫酸铜 10m L和中药 1剂 ,转移因子 4m L ,sc,1· 2 d- 1 .皮损缩小 ,4mo后稳定 .用健康男青年环切的包皮培养 MC,第 4代大约80 %融合时 ,用 2 .5 g· L- 1 胰酶消化 5 min,加入含 2 0 0 g·L- 1小…     

Two tests of association for a susceptibility locus for families of variable size: an example using two sampling strategies

A two-stage approach was used to analyze Problem 2 simulated data from Genetic Analysis Workshop 11. In the first stage, we tested for linkage with the Haseman-Elston test in SIBPAL. Markers that were significant in the first stage were followed up with two types of association tests. These association tests differ in the type of family information used: 1) parental transmissions to affected children or 2) differences in marker allele frequencies between affected and unaffected siblings. We also explored how the conclusions changed when different sampling strategies were used. Of particular interest was whether the entire data set should be used to test for both linkage and association or whether the data set should be halved to allow for replication of the initial association results.     

Choosing a retrospective design to assess joint genetic and environmental contributions to risk

The authors consider issues that should be weighed when designing a retrospective study in which a focus of interest is the joint role of genetic and environmental factors in causing a disease. In place of the classical case-control design, in which controls are sampled from the same population that gives rise to the cases, one could study cases only. The case-only approach can be usefully extended by genotyping the two biologic parents of each case and in effect letting the parental genotype data provide the genetic control. Alternatively, one could carry out a case-control study in which the controls are siblings or cousins of the cases and inference is based on within-family parameters. The authors compare and contrast the parameters that can be estimated and the assumptions that must be made when each of these designs is used. The investigator must also consider certain practical issues, such as the availability of parents or sibling controls.     

Experiences with the human tumor colony-forming assay in gynecologic malignancies

Summary Tumor samples from 74 patients with gynecologic malignancies including breast cancer were processed in a soft agar colony-forming assay. None of the samples resulted in a pure single cell suspension. Of the 10 samples meeting our criteria of evaluability for chemosensitivity testing, only 5 samples showed in vitro sensitivity to any drug. Of the 3 evaluable correlations between in vitro and in vivo results, 2 were correct. Due to the low rate of evaluable samples the assay has only limited value in the assignment of chemotherapeutic drugs for patients treated at our institution.This work was supported in part by the Gesellschaft zur Bekämpfung der Krebskrankheiten Nordrhein-Westfalen     

Are general surgeons able to accurately self-assess their level of technical skills?

Introduction

Self-assessment is a way of improving technical capabilities without the need for trainer feedback. It can identify areas for improvement and promote professional medical development. The aim of this review was to identify whether selfassessment is an accurate form of technical skills appraisal in general surgery.

Methods

The PubMed, MEDLINE^®, Embase^™ and Cochrane databases were searched for studies assessing the reliability of self-assessment of technical skills in general surgery. For each study, we recorded the skills assessed and the evaluation methods used. Common endpoints between studies were compared to provide recommendations based on the levels of evidence.

Results

Twelve studies met the inclusion criteria from 22,292 initial papers. There was no level 1 evidence published. All papers compared the correlation between self-appraisal versus an expert score but differed in the technical skills assessment and the evaluation tools used. The accuracy of self-assessment improved with increasing experience (level 2 recommendation), age (level 3 recommendation) and the use of video playback (level 3 recommendation). Accuracy was reduced by stressful learning environments (level 2 recommendation), lack of familiarity with assessment tools (level 3 recommendation) and in advanced surgical procedures (level 3 recommendation).

Conclusions

Evidence exists to support the reliability of self-assessment of technical skills in general surgery. Several variables have been shown to affect the accuracy of self-assessment of technical skills. Future work should focus on evaluating the reliability of self-assessment during live operating procedures.