Helen V Worthington

Bio: Helen V Worthington is an academic researcher from University of Manchester. The author has contributed to research in topics: Randomized controlled trial & Cochrane Library. The author has an hindex of 88, co-authored 453 publications receiving 26746 citations. Previous affiliations of Helen V Worthington include Manchester Royal Infirmary & Newcastle University.

Meta-analyses involving cross-over trials: methodological issues

Abstract: Background Meta-analysis of randomized controlled trials (RCTs) is usually based on trials where patients are randomized individually into two different, parallel, treatment groups. This paper concentrates on RCTs of a different design—two-period, twotreatment cross-over trials. Methods The characteristics of these trials are outlined, with detailed examples of methods for analysis for both continuous and binary data. These case studies are then extended into the context of a meta-analysis. The Cochrane Library was surveyed to assess current practice for synthesis. Results Methods are described for continuous and binary data for use both when the necessary paired data are given and also when they need to be calculated or imputed, and some suggestions are provided to help people wishing to synthesize data from cross-over trials into meta-analyses. The survey suggested that about 8% of the trials in the Cochrane library were cross-over trials and 18% of the reviews referred to such trials, although there was no consistent approach to their inclusion into the reviews. Conclusions Methods do exist for including valuable information from two-period, twotreatment cross-over trials into quantitative reviews. However, poor reporting of cross-over trials will often impede attempts to perform a meta-analysis using the available methods.

Fluoride varnishes for preventing dental caries in children and adolescents.

Abstract: BACKGROUND: Topically-applied fluoride varnishes have been used extensively as an operator-applied caries-preventive intervention for over three decades. This review updates the first Cochrane review of fluoride varnishes for preventing dental caries in children and adolescents, which was first published in 2002. OBJECTIVES: To determine the effectiveness and safety of fluoride varnishes in preventing dental caries in children and adolescents, and to examine factors potentially modifying their effect. SEARCH METHODS: We searched the Cochrane Oral Health Group's Trials Register (to 13 May 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 4), MEDLINE via OVID (1946 to 13 May 2013), EMBASE via OVID (1980 to 13 May 2013), CINAHL via EBSCO (1980 to 13 May 2013), LILACS and BBO via the BIREME Virtual Health Library (1980 to 13 May 2013), ProQuest Dissertations and Theses (1861 to 13 May 2013), and Web of Science Conference Proceedings (1945 to 13 May 2013). A search for ongoing trials was undertaken on ClinicalTrials.gov on 13 May 2013. There were no restrictions on language or date of publication in the search of the electronic databases. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials with blind outcome assessment used or indicated, comparing topically-applied fluoride varnish with placebo or no treatment in children up to 16 years during at least one year. The main outcome was caries increment measured by the change in decayed, missing and filled tooth surfaces in both permanent (D(M)FS) and primary (d(e/m)fs) teeth. DATA COLLECTION AND ANALYSIS: At least two review authors assessed all search results, extracted data and undertook risk of bias independently. Study authors were contacted for additional information. The primary measure of effect was the prevented fraction, that is the difference in mean caries increments between the treatment and control groups expressed as a percentage of the mean increment in the control group. The caries increments nearest to three years were used from each included study. Random-effects meta-analyses were performed where data could be pooled. Potential sources of heterogeneity were examined in random-effects meta-regression analyses. Adverse effects information was collected from the included trials. MAIN RESULTS: Twenty-two trials with 12,455 participants randomised (9595 used in analyses) were included. For the 13 that contributed data for the permanent tooth surfaces meta-analysis, the pooled D(M)FS prevented fraction estimate comparing fluoride varnish with placebo or no treatment was 43% (95% confidence interval (CI) 30% to 57%; P < 0.0001). There was substantial heterogeneity, confirmed statistically (P < 0.0001; I(2) = 75%), however this body of evidence was assessed as of moderate quality. The pooled d(e/m)fs prevented fraction estimate was 37% (95% CI 24% to 51%; P < 0.0001) for the 10 trials that contributed data for the primary tooth surfaces meta-analysis, also with some heterogeneity (P = 0.009; I(2) = 59%). Once again this body of evidence was assessed as of moderate quality. No significant association between estimates of D(M)FS or d(e/m)fs prevented fractions and the pre-specified factors of baseline caries severity, background exposure to fluorides, application features such as prior prophylaxis, concentration of fluoride, frequency of application were found. There was also no significant association between estimates of D(M)FS or d(e/m)fs prevented fractions and the post hoc factors: whether a placebo or no treatment control was used, length of follow-up, or whether individual or cluster randomisation was used, in the meta-regression models. A funnel plot of the trials in the main meta-analyses indicated no clear relationship between prevented fraction and study precision. In both methods, power is limited when few trials are included. There was little information concerning possible adverse effects or acceptability of treatment. AUTHORS' CONCLUSIONS: The conclusions of this updated review remain the same as those when it was first published. The review suggests a substantial caries-inhibiting effect of fluoride varnish in both permanent and primary teeth, however the quality of the evidence was assessed as moderate, as it included mainly high risk of bias studies, with considerable heterogeneity.

Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review

Abstract: OBJECTIVE: To review systematically the evidence for an effect of long chain and shorter chain omega 3 fatty acids on total mortality, cardiovascular events, and cancer. DATA SOURCES: Electronic databases searched to February 2002; authors contacted and bibliographies of randomised controlled trials (RCTs) checked to locate studies. REVIEW METHODS: Review of RCTs of omega 3 intake for (3) 6 months in adults (with or without risk factors for cardiovascular disease) with data on a relevant outcome. Cohort studies that estimated omega 3 intake and related this to clinical outcome during at least 6 months were also included. Application of inclusion criteria, data extraction, and quality assessments were performed independently in duplicate. RESULTS: Of 15,159 titles and abstracts assessed, 48 RCTs (36,913 participants) and 41 cohort studies were analysed. The trial results were inconsistent. The pooled estimate showed no strong evidence of reduced risk of total mortality (relative risk 0.87, 95% confidence interval 0.73 to 1.03) or combined cardiovascular events (0.95, 0.82 to 1.12) in participants taking additional omega 3 fats. The few studies at low risk of bias were more consistent, but they showed no effect of omega 3 on total mortality (0.98, 0.70 to 1.36) or cardiovascular events (1.09, 0.87 to 1.37). When data from the subgroup of studies of long chain omega 3 fats were analysed separately, total mortality (0.86, 0.70 to 1.04; 138 events) and cardiovascular events (0.93, 0.79 to 1.11) were not clearly reduced. Neither RCTs nor cohort studies suggested increased risk of cancer with a higher intake of omega 3 (trials: 1.07, 0.88 to 1.30; cohort studies: 1.02, 0.87 to 1.19), but clinically important harm could not be excluded. CONCLUSION: Long chain and shorter chain omega 3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer.

Interventions for treating oral mucositis for patients with cancer receiving treatment.

Abstract: BACKGROUND: Treatment of cancer is increasingly more effective but is associated with short and long term side effects. Oral side effects remain a major source of illness despite the use of a variety of agents to prevent them. One of these side effects is oral mucositis (mouth ulcers). OBJECTIVES: To evaluate the effectiveness of prophylactic agents for oral mucositis in patients with cancer receiving treatment, compared with other potentially active interventions, placebo or no treatment. SEARCH STRATEGY: Electronic searches of Cochrane Oral Health Group and PaPaS Trials Registers (to 16 February 2011), CENTRAL (The Cochrane Library 2011, Issue 1), MEDLINE via OVID (1950 to 16 February 2011), EMBASE via OVID (1980 to 16 February 2011), CINAHL via EBSCO (1980 to 16 February 2011), CANCERLIT via PubMed (1950 to 16 February 2011), OpenSIGLE (1980 to 2005) and LILACS via the Virtual Health Library (1980 to 16 February 2011) were undertaken. Reference lists from relevant articles were searched and the authors of eligible trials were contacted to identify trials and obtain additional information. SELECTION CRITERIA: Randomised controlled trials of interventions to prevent oral mucositis in patients receiving treatment for cancer. DATA COLLECTION AND ANALYSIS: Information regarding methods, participants, interventions, outcome measures, results and risk of bias were independently extracted, in duplicate, by two review authors. Authors were contacted for further details where these were unclear. The Cochrane Collaboration statistical guidelines were followed and risk ratios calculated using random-effects models. MAIN RESULTS: A total of 131 studies with 10,514 randomised participants are now included. Overall only 8% of these studies were assessed as being at low risk of bias. Ten interventions, where there was more than one trial in the meta-analysis, showed some statistically significant evidence of a benefit (albeit sometimes weak) for either preventing or reducing the severity of mucositis, compared to either a placebo or no treatment. These ten interventions were: aloe vera, amifostine, cryotherapy, granulocyte-colony stimulating factor (G-CSF), intravenous glutamine, honey, keratinocyte growth factor, laser, polymixin/tobramycin/amphotericin (PTA) antibiotic pastille/paste and sucralfate. AUTHORS' CONCLUSIONS: Ten interventions were found to have some benefit with regard to preventing or reducing the severity of mucositis associated with cancer treatment. The strength of the evidence was variable and implications for practice include consideration that benefits may be specific for certain cancer types and treatment. There is a need for further well designed, and conducted trials with sufficient numbers of participants to perform subgroup analyses by type of disease and chemotherapeutic agent.

Fluoride toothpastes of different concentrations for preventing dental caries in children and adolescents

Abstract: Background Caries (dental decay) is a disease of the hard tissues of the teeth caused by an imbalance, over time, in the interactions between cariogenic bacteria in dental plaque and fermentable carbohydrates (mainly sugars). The use of fluoride toothpaste is the primary intervention for the prevention of caries. Objectives To determine the relative effectiveness of fluoride toothpastes of different concentrations in preventing dental caries in children and adolescents, and to examine the potentially modifying effects of baseline caries level and supervised toothbrushing. Search methods A search was undertaken on Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and several other databases. Reference lists of articles were also searched. Date of the most recent searches: 8 June 2009. Selection criteria Randomised controlled trials and cluster-randomised controlled trials comparing fluoride toothpaste with placebo or fluoride toothpaste of a different concentration in children up to 16 years of age with a follow-up period of at least 1 year. The primary outcome was caries increment in the permanent or deciduous dentition as measured by the change in decayed, (missing), filled tooth surfaces (D(M)FS/d(m)fs) from baseline. Data collection and analysis Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were resolved by discussion and consensus or by a third party. The primary effect measure was the prevented fraction (PF), the caries increment of the control group minus the caries increment of the treatment group, expressed as a proportion of the caries increment in the control group. Where it was appropriate to pool data, network meta-analysis, network meta-regression or meta-analysis models were used. Potential sources of heterogeneity were specified a priori and examined through random-effects meta-regression analysis where appropriate. Main results 75 studies were included, of which 71 studies comprising 79 trials contributed data to the network meta-analysis, network meta-regression or meta-analysis. For the 66 studies (74 trials) that contributed to the network meta-analysis of D(M)FS in the mixed or permanent dentition, the caries preventive effect of fluoride toothpaste increased significantly with higher fluoride concentrations (D(M)FS PF compared to placebo was 23% (95% credible interval (CrI) 19% to 27%) for 1000/1055/1100/1250 parts per million (ppm) concentrations rising to 36% (95% CrI 27% to 44%) for toothpastes with a concentration of 2400/2500/2800 ppm), but concentrations of 440/500/550 ppm and below showed no statistically significant effect when compared to placebo. There is some evidence of a dose response relationship in that the PF increased as the fluoride concentration increased from the baseline although this was not always statistically significant. The effect of fluoride toothpaste also increased with baseline level of D(M)FS and supervised brushing, though this did not reach statistical significance. Six studies assessed the effects of fluoride concentrations on the deciduous dentition with equivocal results dependent upon the fluoride concentrations compared and the outcome measure. Compliance with treatment regimen and unwanted effects was assessed in only a minority of studies. When reported, no differential compliance was observed and unwanted effects such as soft tissue damage and tooth staining were minimal. Authors' conclusions This review confirms the benefits of using fluoride toothpaste in preventing caries in children and adolescents when compared to placebo, but only significantly for fluoride concentrations of 1000 ppm and above. The relative caries preventive effects of fluoride toothpastes of different concentrations increase with higher fluoride concentration. The decision of what fluoride levels to use for children under 6 years should be balanced with the risk of fluorosis.

The PRISMA Statement for Reporting Systematic Reviews and Meta-Analyses of Studies That Evaluate Health Care Interventions: Explanation and Elaboration

Abstract: Systematic reviews and meta-analyses are essential to summarize evidence relating to efficacy and safety of health care interventions accurately and reliably. The clarity and transparency of these reports, however, is not optimal. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users. Since the development of the QUOROM (QUality Of Reporting Of Meta-analysis) Statement—a reporting guideline published in 1999—there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Realizing these issues, an international group that included experienced authors and methodologists developed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions. The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram. The checklist includes items deemed essential for transparent reporting of a systematic review. In this Explanation and Elaboration document, we explain the meaning and rationale for each checklist item. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. The PRISMA Statement, this document, and the associated Web site (http://www.prisma-statement.org/) should be helpful resources to improve reporting of systematic reviews and meta-analyses.

Cochrane Handbook for Systematic Reviews of Interventions

Abstract: The Cochrane Handbook for Systematic Reviews of Interventions is the official document that describes in detail the process of preparing and maintaining Cochrane systematic reviews on the effects of healthcare interventions.

The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration

Abstract: Systematic reviews and meta-analyses are essential to summarise evidence relating to efficacy and safety of healthcare interventions accurately and reliably. The clarity and transparency of these reports, however, are not optimal. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users. Since the development of the QUOROM (quality of reporting of meta-analysis) statement—a reporting guideline published in 1999—there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Realising these issues, an international group that included experienced authors and methodologists developed PRISMA (preferred reporting items for systematic reviews and meta-analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions. The PRISMA statement consists of a 27-item checklist and a four-phase flow diagram. The checklist includes items deemed essential for transparent reporting of a systematic review. In this explanation and elaboration document, we explain the meaning and rationale for each checklist item. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. The PRISMA statement, this document, and the associated website (www.prisma-statement.org/) should be helpful resources to improve reporting of systematic reviews and meta-analyses.

Development of a Classification System for Periodontal Diseases and Conditions

Abstract: Classification systems are necessary in order to provide a framework in which to scientifically study the etiology, pathogenesis, and treatment of diseases in an orderly fashion. In addition, such systems give clinicians a way to organize the health care needs of their patients. The last time scientists and clinicians in the field of periodontology and related areas agreed upon a classi- fication system for periodontal diseases was in 1989 at the World Workshop in Clinical Periodontics.1 Subsequently, a simpler classification was agreed upon at the 1st European Workshop in Periodontology.2 These classification systems have been widely used by clinicians and research scientists throughout the world. Unfortunately, the 1989 classification had many shortcomings including: 1) considerable overlap in disease categories, 2) absence of a gingival disease component, 3) inappropriate emphasis on age of onset of disease and rates of progression, and 4) inadequate or unclear classification criteria. The 1993 Europea...