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#MyPTArticleOfTheMonth – what is Cornelia Barth reading?
Cornelia A Barth is a physiotherapist with Master of Science qualifications from University College London. She spent the last decade in humanitarian missions in countries in Africa and the Middle East. Cornelia is currently the Physiotherapy Advisor for the International Committee of the Red Cross in Geneva. This position involves supervising physiotherapists in about 150 rehabilitation projects world-wide. These projects are being conducted in the most challenging contexts of low resources and protracted crisis. Cornelia has recently done some reading to inform her work in the prevention of diabetes and cardiovascular disease.
Shirinzadeh M, et al. The effect of community-based programs on diabetes prevention in low- and middle-income countries: a systematic review and meta-analysis. Global Health 2019;15(10):Epub
The prevalence of type 2 diabetes mellitus is increasing in low-income and middle-income countries. While community-based programs that address diet, physical activity and health behaviour have been shown to prevent or manage diabetes in high-income countries, effectiveness in lower income countries has not been systematically evaluated. The aim of this systematic review and meta-analysis was to determine if community-based programs can reduce the risk of developing diabetes in at-risk populations in low- and middle-income countries. Six trials published in 2008-2018 were included in the analysis. There was moderate quality evidence that community-based interventions reduced body weight, fasting blood glucose and HbA1C compared to control interventions. The effects on the incidence of diabetes were less clear because the 95% confidence interval for the risk ratio included a harmful effect (1.06) and a very large beneficial effect (0.03). More well-designed and long-term trials are required to improve the precision of this estimate. Cornelia says: “it is encouraging to read that the same simple and low-cost interventions that are effective in high-income countries were also effective in low- and middle-income countries. This is important because medication and patient education interventions are scarce and the prevalence of diabetes is increasing at an alarming rate in low- and middle-income countries. We should promote these evidence-based interventions among the global physiotherapy community as well as at the primary health care level world-wide.”
van de Vijver S, et al. Review of community-based interventions for prevention of cardiovascular diseases in low- and middle-income countries. Ethn Health 2012;17(6):651-76
Cardiovascular disease is also on the rise in low- and middle-income countries. This review aimed to identify the kinds of interventions used to prevent cardiovascular disease in low- and middle-income countries. The second aim was to evaluate the effectiveness of these interventions, but meta-analysis was not performed. The interventions used included education, health promotion, training of health care staff, and implementation of treatment guidelines. Many of the studies reported improvements in weight, physical activity, diet or smoking, but the lack of control groups and the diversity of the settings make generalisation of results difficult. Cornelia says: “this review indicates that a variety of health professionals need to work hand in hand to prevent cardiovascular disease in low- and middle-income countries. But we need better research so that we can design and implement evidence-based programs.”
#MyPTArticleOfTheMonth #PhysicalTherapy #physio
#MyPTArticleOfTheMonth resource – the dance of the p-values
One of issues that has prompted statisticians and journals to call for the use of significance testing and hypothesis testing to be discontinued is that p-values are not replicable. That is, if you repeat an experiment (each time randomly drawing a new sample from the population) you are likely to get a very different p-value. Emeritus Professor Geoff Cumming from La Trobe University (in Melbourne, Australia) has illustrated this nicely in a video titled “dance of the p-values”. Viewed nearly 50,000 times, this video illustrates just how unpredictable p-values are.
Many people think about p-values as being a measure of how strong the evidence is in a study. For example, very small p-values like p < 0.01 have been called ‘highly significant’, 0.01-0.05 ‘significant’, 0.05-0.10 ‘approaching significance’, and > 0.10 ‘non-significant’. The problem is that p-values tell us almost nothing about what will happen if an experiment is replicated. When computer simulation is used to replicate an experiment, the p-value varies widely.
Professor Cumming, like many other statisticians, recommends that p-values no longer be at the centre of our thinking about drawing conclusions from research because no single p-value can be trusted. A much better alternative is using confidence intervals. Estimation using confidence intervals is much more informative because confidence intervals tell us what is likely to happen if we repeat the experiment. For example, 95% confidence intervals from a sample tell as that if we repeat the experiment 100 times, in about 95 of the 100 repeats the confidence interval will include the mean difference for the population.
You may also be interested in viewing two more recent videos on this topic from Professor Cumming: “Significance Roulette 1” and “Significance Roulette 2”.
If you are interested in perusing the numbers and formulas on which the “dance of the p-values” is based, we recommend you read the following article:
Cumming G. Replication and p intervals: p values predict the future only vaguely, but confidence intervals do much better. Perspect Psychol Sci 2008;3(4):286-300.
Your ability to read scientific articles will improve with practice. Make the commitment to read at least one article per month and share your reading with the global physiotherapy community in #MyPTArticleOfTheMonth.
PEDro celebrates World Physical Therapy Day
World Physical Therapy Day was on 8 September, the theme for 2019 is chronic pain. Chronic pain is a significant global health burden. It is estimated that 1.5 billion people, around 20% of the world’s population, experience a chronic pain condition. Physiotherapists play a key role in the prevention and management of chronic pain. There are 4,600+ articles reporting the results of clinical practice guidelines, systematic reviews and randomised controlled trials evaluating the effects of physiotherapy interventions for chronic pain. To stay up to date with the latest research, physiotherapists can subscribe to PEDro’s Evidence In Your Inbox feed for ‘chronic pain’.
To celebrate World Physical Therapy Day, PEDro has produced a graphic to show how physiotherapists from around the globe have been using PEDro to inform their practice. The graphic illustrates the proportion of PEDro searches conducted by each country since 2010. In absolute terms, physiotherapists from Brazil have performed the largest number of searches (23%), followed by the USA (9%), Spain (8%), and Australia (7%). Countries with less than 1% usage are signified by the white jerseys.
#worldptday #PhysicalTherapy #physio
PEDro update (2 September 2019)
PEDro contains 44,597 records. In the 2 September 2019 update you will find:
- 34,835 reports of randomised controlled trials (34,015 of these trials have confirmed ratings of methodological quality using the PEDro scale)
- 9,089 reports of systematic reviews, and
- 673 reports of evidence-based clinical practice guidelines.
PEDro update (September 2019)
PEDro was updated on 2 September 2019. For latest guidelines, reviews and trials in physiotherapy visit Evidence in your inbox.
Next PEDro update (September 2019)
The next PEDro update is on Monday 2 September 2019.
Time to move from significance testing to estimation
A Research Note published in the latest issue of the Journal of Physiotherapy argues the case for moving away from significance tests and hypothesis tests in health research. The central reason is that p-values and claims of statistical significance (that is, the products of null hypothesis statistical tests), have some inherent flaws and are often misused and misinterpreted. The problems are difficult to describe succinctly. The Research Note addresses each of them under the headings: p-values do not indicate the probability that a hypothesis is true (or not), p-values are not evidence, significance findings are not replicable, and the null hypothesis is false in most clinical research.
For a long time, leading statisticians have argued that the concept of statistical significance should be abandoned. However, researchers in laboratory and clinical settings have continued to use null hypothesis statistical tests – presumably because it was what they are taught, it is what many journals expect, and because they were unaware of the benefits of alternative approaches to analysis. This year, however, articles in The American Statistician and Nature have strongly recommended that it is time to stop using ‘statistically significant’ and related terms.
One widely recommended alternative to significance tests and hypothesis tests in randomised controlled trials is to report the size of the effect (or point estimate) and the precision of the effect (or confidence interval). Trialists could then interpret the size of the point estimate, that is, is the point estimate large enough to be clinically worthwhile. The lower and upper values for the confidence interval can then be considered in the same way. For example, if both the lower and upper values for the confidence interval are large enough to be clinically important, the trial provides a clear answer.
The migration to confidence intervals has already begun in many journals. The proportion of physiotherapy trials that are using confidence intervals instead of (or as well as) reporting statistical significance and p-values has been increasing steadily over the past few decades. The migration from p-values to confidence intervals is more common among higher quality trials. This increases the need for physiotherapists to understand confidence intervals if they are to keep abreast of the available evidence.)
Stopping using ‘statistically significant’ and related terms has implications for many groups. These include journal editors and editorial policies, reporting checklists (eg, CONSORT Checklist), and critical appraisal tools that include a reporting component (eg, PEDro scale). A group of member journals of The International Society of Physiotherapy Journal Editors will soon be releasing their new policy on this issue. We will keep PEDro users informed of developments in this area.
Please consider reading the Research Note, which is freely available in full text via the link below, to ensure you understand the reasons for this shift in the approach to statistical analysis.
Herbert R. Research note: significance testing and hypothesis testing: meaningless, misleading and mostly unnecessary. J Physiother 2019;65(3):178-81
Systematic review found that exercise may have similar effects to antihypertensive medications in reducing blood pressure
This systematic review evaluated how different types and intensities of exercise compared against different classes and doses of antihypertensive medications in lowering systolic blood pressure levels. The review included randomised controlled trials that were conducted in adults with or without hypertension but no cardiovascular disease, cerebrovascular disease, diabetes or other chronic condition such as cancer. Any form of structured exercise and antihypertensive medication was considered to be included as the experimental intervention. Interventions were compared against usual practice (no exercise), other exercise regimens, or medications. Risk of bias was evaluated with the Cochrane risk of bias tool. A network meta-analysis was performed to compare the multiple interventions simultaneously.
The review included 197 trials of exercise (n = 10,461 participants) and 194 trials testing antihypertensive drugs (n = 29,281), totalling 391 trials included in the analysis (n = 39,742). No trials directly compared exercise and antihypertensive drugs. The average systolic blood pressure at baseline was 132 mmHg for participants in trials of exercise interventions, whereas in trials of antihypertensive medications it was consistently over 150 mmHg. The majority of trials tested endurance interventions (n = 135), such as walking, running, cycling or aquatic exercise.
Across all populations, both exercise interventions (mean difference -5 mmHg, 95% confidence interval -6 to -4) and antihypertensive medications (-9 mmHg, -10 to -8) were effective in lowering systolic blood pressure compared with control. Populations receiving medications achieved greater reductions in systolic blood pressure compared with those participating in exercise interventions (-4 mmHg, -5 to -3). All types of exercise lowered blood pressure in a similar fashion, with exception of the combination of endurance and resistance training which was more effective than dynamic resistance exercise alone (-3 mmHg, -5 to -1). A dose-response effect was observed for medications, but there was substantial uncertainty for effects of different intensities of exercise.
This review showed that the effect of exercise on lowering systolic blood pressure appears to be similar to that of commonly used antihypertensive medications across diverse populations and settings. The possibility of confounding due by the observed differences in trial populations and characteristics cannot be ruled out.
Network meta-analysis is explained in a PEDro blog from 2018.
Naci H, et al. How does exercise treatment compare with antihypertensive medications? A network meta-analysis of 391 randomised controlled trials assessing exercise and medication effects on systolic blood pressure. Br J Sports Med 2019;53(14):859-69
Read more on PEDro.
Lancet series on gender equality, norms and health
One of the United Nation's ‘Sustainable Development Goals of 2030’ is gender equality. The focus is on equitable access to economic independence, technology, education, as well as general and reproductive healthcare for all.
The Lancet recently published a series of five papers on ‘Gender Equality, Norms, and Health’. The series provides in depth analysis about health inequalities related to gender, with calls to action for governments and institutions, leaders in the health sector, researchers, and the community.
Gender inequity and restrictive gender norms (ie, the often unspoken rules that govern the attributes and behaviours that are valued and considered acceptable for men, women, and gender minorities) are determinants of health. However, the relationship between gender and health is complex because gender interacts with other social determinants (including race, class, age, and ability), and these interactions are commonly multiplicative rather than additive. The series illustrates several examples of this. Families living in poverty are less likely to seek treatment for daughters for communicable diseases, and adolescent women in developing countries are at particularly increased risk of maternal mortality due to inadequate access to healthcare.
Gender norms result in differential exposure to disease, disability, and injury. Men are more likely to experience work-related and road accidents, as well as traumatic injuries. They are more likely to experience substance abuse and develop lung cancer, due to a perceived sense of masculinity related to alcohol, smoking, and risk-taking behaviour. Health promotion activities aimed at dispelling these stereotypes are essential in reducing harm to the individual and burden on healthcare systems.
As physiotherapists, it is important to be aware of our own gender biases in how we interact with our patients, as well as the systemic gender bias in our healthcare systems. The series provides evidence that women around the world receive poorer pain management, are screened for disease less often, receive less aggressive treatment, and substandard follow-up. It is our role as physiotherapists to advocate for adequate assessment and treatment of women in pain, and promote appropriate screening for neglected conditions such as heart disease in women.
Research supports the notion that more equal and diverse societies result in better health outcomes and life expectancy for both men and women. This should inform the design and implementation of healthcare programs worldwide. Increasing equitable gender representation in positions of leadership and governance, as well as integrating modules of sex and gender-based medical concepts in medical and public health training would contribute to the United Nation’s goal of gender equality.
Researchers also need to consider gender bias in health research at various stages. Sampling, design and analysis of randomised controlled trials as well as population-based surveys needs to ensure equitable representation, unbiased framing of survey questions, and consideration of gender as a significant variable in health research.
A podcast of Lancet Executive Editor Jocalyn Clark talking with Gary Darmstadt (Stanford University, USA), the lead author of the Lancet series on gender and health, is available here.