[RESEARCH] Internal and external validity of cluster randomised trials: systematic review of recent trials
Objectives To assess aspects of the internal validity of recently published cluster randomised trials and explore the reporting of information useful in assessing the external validity of these trials.
Design Review of 34 cluster randomised trials in primary care published in 2004 and 2005 in seven journals (British Medical Journal, British Journal of General Practice, Family Practice, Preventive Medicine, Annals of Internal Medicine, Journal of General Internal Medicine, Pediatrics).
Data sources National Library of Medicine (Medline) via PubMed.
Data extraction To assess aspects of internal validity we extracted data on appropriateness of sample size calculations and analyses, methods of identifying and recruiting individual participants, and blinding. To explore reporting of information useful in assessing external validity we extracted data on cluster eligibility, cluster inclusion and retention, cluster generalisability, and the feasibility and acceptability of the intervention to health providers in clusters.
Results 21 (62%) trials accounted for clustering in sample size calculations and 30 (88%) in the analysis; about a quarter were potentially biased because of procedures surrounding recruitment and identification of patients; individual participants were blind to allocation status in 19 (56%) and outcome assessors were blind in 15 (44%). In almost half the reports, information relating to generalisability of clusters was poorly reported, and in two fifths there was no information about the feasibility and acceptability of the intervention.
Conclusions Cluster randomised trials are essential for evaluating certain types of interventions. Issues affecting their internal validity, such as appropriate sample size calculations and analysis, have been widely disseminated and are now better addressed by researchers. Blinding of those identifying and recruiting patients to allocation status is recommended but is not always carried out. There may be fewer barriers to internal validity in trials in which individual participants are not recruited. External validity seems poorly addressed in many trials, yet is arguably as important as internal validity in judging quality as a basis for healthcare intervention.
Heart disease data may not be gender-specific
Filed under: Research, Women Heart Health, Men Heart Health
We've all heard the expression: There are lies, damn lies, and statistics. I always do my best to remember these very words as I research articles for this blog. As I've pointed out several times, there seems to be a great deal of contradictory information circulating the research field, lending credibility to the aforesaid statement regarding statistics. Understandably, research methods, treatment models, and everything else in between can be the cause of the paucity of irrefutable evidence these days. But, there's simply no excuse for overlooking something as simple as dividing test results by gender. Now being quite honest, I'm not really all up in arms about the whole thing. The Mayo Clinic, however, seems a bit ticked.
According to their own study, the Mayo Clinic determined that it is very rare that researchers will produce a sex-based analysis of their findings. In a review of 64 cardiovascular clinic trials published from July 1 through December 31, 2004, only 153 of the publications provided sex-specific reporting. This is especially dangerous when dealing with diseases that tend to affect one sex more than the other, which is the case with heart disease. Being the number one threat to a woman's health, it is imperative that they know whether published data is skewed in any way by gender involvement.
The researchers from the Mayo Clinic suggest that when female patients are recommended a certain treatment or test, they should ask whether women were included in the research. And, if so (and if known), what percentage of the sample group did they represent.
Deep belly fat not so evil after all?
Filed under: Type 2, Lifestyle, Research, Daily News
Did you hear about renowned Harvard scientist Barbara Kahn's latest published research? I blogged about it recently. Kahn and colleagues state, in a report published in Cell Metabolism (July 2007), that it's possible to use a simple blood test to detect the presence of a specific protein called RBP4. Kahn et al say the presence of RBP4 can be used to measure accumulations of deep belly fat. Underpinning this research is a belief that such accumulations of belly fat increase risk for metabolic syndrome, leading to various maladies including heart disease and diabetes.However, not everyone accepts this point of view. A Yale research team says that deep belly fat may not be so evil after all. The researchers, who are based at Yale University School of Medicine in Chevy Chase, Maryland, assert that metabolic syndrome is caused not by belly fat but by insulin resistance in skeletal muscle. This resistance, they state, makes it tough for the body to manufacture glycogen, so - in people who are insulin resistant - energy that cannot be stored as glycogen gets diverted into fatty acid production, which then contributes to metabolic syndrome.
The team compared abdominal fat levels in young and healthy individuals, some of whom were insulin sensitive and some of whom were insulin resistant. The result? "There is absolutely no difference in the volume of abdominal fat," states Yale's Gerald I. Shulman, who was lead author of the study. Abdominal fat, says Dr. Shulman, "may come later in the course of the disease [metabolic syndrome], but it's not a primary, underlying factor."
'Ole dinosaur metformin as good as new
Filed under: Type 2, Adult Onset, Drugs, Research
The first in-depth comparison of type 2 oral medications arriving on the scene over the last decade was published earlier this week in the Annals of Internal Medicine. The review determined older, cheaper diabetes drugs are as safe and effective as new alternatives. Oh boy, Big Pharma's newer drug sales teams won't like this conclusion.
Metformin, also known as Glucophage, was cited as the safest and best option, as it works as well as other oral medications, but does not cause weight gain or hypoglycemia. Bad cholesterol is also lowered on metformin, and the drug only costs about $100 a year. Newer drugs cost as much as $262 a month, stated lead researcher Dr. Shari Bolen, and there was no benefit to the newer drugs unless tolerance to an older one was at issue. They also noted taking two oral meds can improve blood sugar, but the cost and risk of side effects are both higher.
The researchers reviewed more than 200 published studies and some unpublished information from the Food and Drug Administration. Avandia's manufacturer, GlaxoSmithKline, stated this analysis was completed prior to the completion of one Avandia study that showed Avandia improved blood sugar control compared to two rival meds.
But the dinosaur Metformin does have a roar -- it can cause a rare, dangerous side effect called lactic acidosis. Read more in Globe and Mail.
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[RESEARCH] Child-parent screening for familial hypercholesterolaemia: screening strategy based on a meta-analysis
Objective To develop a population screening strategy for familial hypercholesterolaemia.
Design Meta-analysis of published data on total and low density lipoprotein (LDL) cholesterol in people with and without familial hypercholesterolaemia according to age. Thirteen studies reporting on 1907 cases and 16 221 controls were used in the analysis. Included studies had at least 10 cases and controls with data on the distribution of cholesterol in affected and unaffected individuals.
Main outcome measures Detection rates (sensitivity) for specified false positive rates (0.1%, 0.5%, and 1%) in newborns and in age groups 1-9, 10-19, 20-39, 40-59, and ≥60 years.
Results Serum cholesterol concentration discriminated best between people with and without familial hypercholesterolaemia at ages 1-9, when the detection rates with total cholesterol were 88%, 94%, and 96% for false positive rates of 0.1%, 0.5%, and 1%. The results were similar with LDL cholesterol. Screening newborns was much less effective. Once an affected child is identified, measurement of cholesterol would detect about 96% of parents with the disorder, using the simple rule that the parent with the higher serum cholesterol concentration is the affected parent.
Conclusions The proposed strategy of screening children and parents for familial hypercholesterolaemia could have considerable impact in preventing the medical consequences of this disorder in two generations simultaneously.
[RESEARCH] Interventions to promote walking: systematic review
Objective To assess the effects of interventions to promote walking in individuals and populations.
Design Systematic review.
Data sources Published and unpublished reports in any language identified by searching 25 electronic databases, by searching websites, reference lists, and existing systematic reviews, and by contacting experts.
Review methods Systematic search for and appraisal of controlled before and after studies of the effects of any type of intervention on how much people walk, the distribution of effects on walking between social groups, and any associated effects on overall physical activity, fitness, risk factors for disease, health, and wellbeing.
Results We included 19 randomised controlled trials and 29 non-randomised controlled studies. Interventions tailored to people's needs, targeted at the most sedentary or at those most motivated to change, and delivered either at the level of the individual (brief advice, supported use of pedometers, telecommunications) or household (individualised marketing) or through groups, can encourage people to walk more, although the sustainability, generalisability, and clinical benefits of many of these approaches are uncertain. Evidence for the effectiveness of interventions applied to workplaces, schools, communities, or areas typically depends on isolated studies or subgroup analysis.
Conclusions The most successful interventions could increase walking among targeted participants by up to 30-60 minutes a week on average, at least in the short term. From a perspective of improving population health, much of the research currently provides evidence of efficacy rather than effectiveness. Nevertheless, interventions to promote walking could contribute substantially towards increasing the activity levels of the most sedentary.
[RESEARCH] Prediction of citation counts for clinical articles at two years using data available within three weeks of publication: retrospective cohort study
Objective To determine if citation counts at two years could be predicted for clinical articles that pass basic criteria for critical appraisal using data within three weeks of publication from external sources and an online article rating service.
Design Retrospective cohort study.
Setting Online rating service, Canada.
Participants 1274 articles from 105 journals published from January to June 2005, randomly divided into a 60:40 split to provide derivation and validation datasets.
Main outcome measures 20 article and journal features, including ratings of clinical relevance and newsworthiness, routinely collected by the McMaster online rating of evidence system, compared with citation counts at two years.
Results The derivation analysis showed that the regression equation accounted for 60% of the variation (R2=0.60, 95% confidence interval 0.538 to 0.629). This model applied to the validation dataset gave a similar prediction (R2=0.56, 0.476 to 0.596, shrinkage 0.04; shrinkage measures how well the derived equation matches data from the validation dataset). Cited articles in the top half and top third were predicted with 83% and 61% sensitivity and 72% and 82% specificity. Higher citations were predicted by indexing in numerous databases; number of authors; abstraction in synoptic journals; clinical relevance scores; number of cited references; and original, multicentred, and therapy articles from journals with a greater proportion of articles abstracted.
Conclusion Citation counts can be reliably predicted at two years using data within three weeks of publication.
[RESEARCH] Pharmacological and lifestyle interventions to prevent or delay type 2 diabetes in people with impaired glucose tolerance: systematic review and meta-analysis
Objective To quantify the effectiveness of pharmacological and lifestyle interventions to prevent or delay type 2 diabetes in people with impaired glucose tolerance.
Data sources Medline, Embase, and the Cochrane library searched up to July 2006. Expert opinions sought and reference lists of identified studies and any relevant published reviews checked.
Study selection Randomised controlled trials that evaluated interventions to delay or prevent type 2 diabetes in individuals with impaired glucose tolerance.
Results 21 trials met the inclusion criteria, of which 17, with 8084 participants with impaired glucose tolerance, reported results in enough detail for inclusion in the meta-analyses. From the meta-analyses the pooled hazard ratios were 0.51 (95% confidence interval 0.44 to 0.60) for lifestyle interventions v standard advice, 0.70 (0.62 to 0.79) for oral diabetes drugs v control, 0.44 (0.28 to 0.69) for orlistat v control, and 0.32 (0.03 to 3.07) for the herbal remedy jiangtang bushen recipe v standard diabetes advice. These correspond to numbers needed to treat for benefit (NNTB) and harm (NNTH) of 6.4 for lifestyle (95% credible interval, NNTB 5.0 to NNTB 8.4), 10.8 for oral diabetes drugs (NNTB 8.1 to NNTB 15.0), 5.4 for orlistat (NNTB 4.1 to NNTB 7.6), and 4.0 for jiangtang bushen (NNTH 16.9 to NNTB 24.8).
Conclusions Lifestyle and pharmacological interventions reduce the rate of progression to type 2 diabetes in people with impaired glucose tolerance. Lifestyle interventions seem to be at least as effective as drug treatment.
[RESEARCH] Effectiveness of interventions to promote physical activity in children and adolescents: systematic review of controlled trials
Objective To review the published literature on the effectiveness of interventions to promote physical activity in children and adolescents.
Design Systematic review.
Data sources Literature search using PubMed, SCOPUS, Psychlit, Ovid Medline, Sportdiscus, and Embase up to December 2006.
Review methods Two independent reviewers assessed studies against the following inclusion criteria: controlled trial, comparison of intervention to promote physical activity with no intervention control condition, participants younger than 18 years, and reported statistical analyses of a physical activity outcome measure. Levels of evidence, accounting for methodological quality, were assessed for three types of intervention, five settings, and three target populations.
Results The literature search identified 57 studies: 33 aimed at children and 24 at adolescents. Twenty four studies were of high methodological quality, including 13 studies in children. Interventions that were found to be effective achieved increases ranging from an additional 2.6 minutes of physical education related physical activity to 283 minutes per week of overall physical activity. Among children, limited evidence for an effect was found for interventions targeting children from low socioeconomic populations, and environmental interventions. Strong evidence was found that school based interventions with involvement of the family or community and multicomponent interventions can increase physical activity in adolescents.
Conclusion Some evidence was found for potentially effective strategies to increase children's levels of physical activity. For adolescents, multicomponent interventions and interventions that included both school and family or community involvement have the potential to make important differences to levels of physical activity and should be promoted. A lack of high quality evaluations hampers conclusions concerning effectiveness, especially among children.
Foods to help you quit
Filed under: Research, Smoking
Nothing says sexy like a long, brown Pall Mall cigarette hanging out of someone's mouth. Oh wait, my bad, I meant 
that nothing says "bad breath, bad teeth, and a shortened life expectancy" than that same scenario.
If I seem harsh about smoking, I'm sorry. Coming from a family of smokers - but not being one - I live in constant fear of my loved one's health and spend too much time questioning why they, and millions of people worldwide, would purposely do something so unhealthy. "It's a stress release" - yeah, I've heard that one before. "I only smoke when I drink" - yup, heard that one, too. "It's just too tough to quit" - aahh, a reason that at least has some merit. But, what all the smokers out there might not know is that there are actually certain foods that will help you quit (and no, this isn't the part where I try to get all cute and tell you that one of those foods is Cold Turkey).
Based on a study published in the journal (strangely enough) Nicotine & Tobacco Research, smokers claim that fruits, vegetables, juice, and dairy products combine the worst with the flavor of their cigarette. By contrast, caffeinated beverages and alcohol seem to be flavor enhancers.
At least that explains the whole "I only smoke when I drink" excuse.
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