
Home Review results by therapeutic healthcare area About evidence-based healthcare The Cochrane Collaboration About health consumer participation Terminology Process
Evidence based health care requires evidence Evidence-based health care is a combination of current best research evidence, the expertise of the healthcare provider, and patient values – used to make decisions about health care for and with individuals, families and communities. The understanding is that evidence-based health care is for the public good and results in improvements in the quality of health care; accessibility to effective health care and health promotion interventions; and, overall, improved health. The Australian Council for Safety and Quality in Health Care (2003) developed 10 tips for safer health care that are directed at health consumers. These are ‘What everyone needs to know, a guide to becoming more involved in your health care’. A booklet explaining 'Modern Medicine' A booklet with some useful websites for quality health information You can improve your health care through an active and positive partnership. It’s okay to ask your health care professional questions and to expect answers you understand. Some people find it helpful to write their questions down before an appointment and to take notes. Others like to have a family member or a carer with them (or an interpreter). Be actively involved in your health care. Speak up if you have any questions or concerns. Learn about your condition or treatments. About health information The general public has access to large amounts of health information from television, newspapers, magazines, freely available handouts and brochures, through their personal interactions with others and the internet. Consumers are increasingly becoming engaged in their own health care. Many people want to know more about their health and to be involved in treatment and healthcare decisions. Positive outcomes may include better adherence to treatment due to increased understanding, and involvement in the process, quality use of medicines, effective behaviour changes and changes in lifestyle, improved health care, increased patient safety and ultimately better health and wellbeing. Consumers receive so much information that it may actually mislead, create anxiety and cause confusion rather than inform and guide them. Moreover, the accuracy and inherent value of much of the information can be questionable or even inappropriate. People have limited opportunity or inclination to assess the information and without adequate background knowledge on how to discern which information is reliable or applicable, a person can easily gather information which ultimately has no relevance to their condition and which potentially consumes valuable consultation time for patient and doctor. On the other hand, the information could be useful in highlighting concerns which are relevant to the way a person might proceed with their healthcare management. Communicating health information Communication problems between healthcare providers and patients are common and many patients are dissatisfied with the information they are given by their healthcare providers. Indeed, healthcare providers may focus on disease and its management rather than on the person, their life and how they address their healthcare problems. When individuals seek medical care they are unusually open to accepting guidance from an authority to whom they have entrusted their wellbeing. There is abundant evidence that when healthcare professionals converse with their patients about risk reduction, illness management, and pharmacy use, in a trusted relationship, there is a greater likelihood they will listen. Information relevant to the consultation may include the likely effectiveness of treatment; side effects; alternative treatments; and how a treatment is applied – for example doses, the minimal time permitted between treatments, what to do if a dose is missed, and lifestyle changes. What counts as evidence? Evidence is defined as any systematic observation of the apparent relation between events – considered that evidence of the higher order supersedes that of the lower order (cf contribute value). Evidence, in a patient’s mind, consists of ideas and observations that support or oppose an ‘argument’, say for adopting a healthcare intervention – these they hear from their family and contacts, read, or are exposed to in the media or on the internet. The gold standard, or ‘best’ evidence, is from randomised clinical trials and cost-benefit studies; and from systematic reviews of this evidence. It is important, therefore, to ask what relevant questions the evidence addresses and also what questions it raises, including how it can be applied to health consumers, patients and carers; that is the public or civil society. There is a lack of an evidence-based culture in the healthcare community, with providers adhering to business as usual, and expert culture, and believing they do not have the time to look for ‘evidence’. Looking for this evidence might reduce trust. Yet it is important to be transparent about where recommendations for treatment come from. The provision of health care is decided by structural, cultural and financial restraints; vested interests; values; habits; knowledge attitudes and skills – on the part of health systems, healthcare providers and the public. Some consider that evidence-based medicine is for management rather than patient-related performance. Researchers believe that if we follow strict rules for doing research it will produce evidence that minimises biases, playing favourites, and can be repeated in similar conditions to produce the same results. And if enough research evidence is collected, ‘the truth’ about something can be discovered. About evidence-based healthcare We define evidence-based health care as the> combination of current best research evidence, the expertise of the healthcare provider, and patient values. >Evidence-based health care is about making decisions about health care for and with individuals, families and communities; informed, shared decision making; and patient-centred health care. When you have a cold, you decide about how to treat it. Maybe you know already what to do or you ask somebody you trust, if she or he has a good recommendation for an effective treatment. Effective means it will probably help you, even if there is no 100% guarantee for its effectiveness or that you will be totally cured. Finding out what is the most effective treatment for most people is the goal of health care research about drugs, medical devices or other treatments. This is done with clinical studies. The results of these studies should be the basis for every decision about a treatment. Researchers call these results the evidence about the healing or harmful effects of a treatment. The Cochrane Collaboration collects existing high-quality evidence about a health care treatment and puts it together in research articles, so called systematic reviews. Each of these articles has a short summary, written in plain language, which is meant to inform consumers and lay people about the review findings. These articles are published in The Cochrane Library, an electronic library on the internet. The consumer summaries are free to access. You can use the evidence from these reviews to make your decision about your healthcare. This we call evidence-based health care because it is grounded in the most reliable information and should support you and your general practitioner or GP in your daily decisions about health care. To enable you and your GP to find this evidence quickly and in a readable form the Cochrane Collaboration and its Consumer Network aims to present the evidence also in printable plain language summaries. Sometimes the studies give us no proof or only a weak proof for the effectiveness of a treatment compared with non-active or dummy (placebo) treatment. Then you will find sentences like ‘further research is needed’. The Cochrane Library The Cochrane Library is an electronic collection of databases published on the internet and also available on CD-Rom. It is updated quarterly in an effort to add to and keep the information current. The Library is made up of a number of parts. The Cochrane Database of Systematic Reviews (CDSR) is the actual database that contains the published Cochrane reviews and protocols. >The Cochrane Collaboration is an international, not-for-profit organization which produces and disseminates high quality evidence on healthcare interventions. Evidence is published in the form of systematic reviews (Cochrane reviews), which summarise the current evidence on a topic. Reviews are published quarterly in The Cochrane Library, available free to all Australians online: www.cochranelibrary.org. Authors of reviews are usually health professionals, and are often preparing reviews in addition to their normal work. They collect all clinical trials on the topic, assess the quality of the clinical trials, and summarise the findings to make a conclusion about how effective the intervention is for the illness. >Cochrane reviews are generally updated every two years. Bringing together the evidence The information on this website is based on careful reviews of clinical trials that compared complementary and non-medical treatments with a placebo (inactive treatment) or a known treatment in a particular health setting. Evidence is gathered and summarised in a systematic review. A systematic review uses set methods to identify the best evidence from individual clinical trials and, when possible, collects the results into an overview or synthesis. Trials are included in the review if they meet specific, pre-specified criteria that are designed to minimise biases in the findings of a trial, making the trial inaccurate. Randomly assigning trial participants to an intervention group is an important part of these criteria. By concealing who is to receive what intervention, the intent is that the comparison groups are made up of similar people who are treated in the same way, other than the test treatment given. This helps to ensure that any observed differences in outcomes can be attributed to the intervention alone. Some included trials may still have insufficient numbers of participants to be able to distinguish the effects(s) of the intervention from chance events, because of the natural variation between people and their responses to treatments (the trials are said to be underpowered). Blinding also helps to minimise the effects of bias in the findings of a trial. It is important that the participants, trialists and people assessing the outcomes do not know who is receiving what intervention (blinding). Participants who receive a placebo may still have treatment benefits (and harms). Sometimes the studies give us no proof or only a weak proof for the effectiveness of a treatment compared with non-active or dummy treatment. For example, this may occur if all the clinical trials on the topic are of low quality. Then you will find sentences like ‘further research is needed’ because the intervention may well be effective but there is not strong evidence proving this. Evidence-based health care is dependent on a system to gather, synthesise and disseminate evidence The Cochrane Collaboration is a not-for-profit organisation that prepares systematic reviews of healthcare interventions in a way that minimizes biases, as much as is possible. These reviews summarise for the healthcare provider, researcher, policy makers and other the current research on whether or not a healthcare intervention really works. The organisation involves consumers in its work as a way of making the reviews more accessible and relevant to the receivers of health care. The ‘gold standard’ for producing evidence on healthcare interventions is the double-blind, randomised clinical trial (RCT). An RCT randomises people to different treatments, as a way of trying to make the different groups as similar as possible. The intervention that is being tested is compared to a non-active (placebo), a known treatment or usual care. The people who give the treatment and assess the results of giving the treatments do not know who is receiving what intervention (double blinded). The larger the trial the more the influence of things we do not know about, including biological variations and behaviours from one person to another, can be reduced and the assessment of the effect of the treatment more accurate. What an RCT does is measure the likely efficacy of a treatment – can the intervention be shown to work in this situation with carefully selected participants, a defined healthcare setting and careful follow up? The evidence from an RCT needs to be translated into everyday use in a social context and in busy healthcare systems. Furthermore, RCTs are usually short-term, so they tell us little about long-term benefits or harms of a healthcare intervention. A systematic review of RCTs gathers individual trials and summarises them in a single review. A systematic review uses set methods to identify this best evidence and, where possible, pools the results in an overview or statistical meta-analysis. Studies are only included in the review if they meet specific, pre-specified criteria defined to minimise introducing biases and influencing the findings of both the individual studies and the review. Randomly assigning trial participants to an intervention group in a way that no-one is aware what group the person is in is an important part of these criteria. Many trials have insufficient numbers of participants to be able to distinguish intervention effects - because of natural variations between people and their responses to treatments (they are underpowered). Limitations of RCTs In trials, measures of effectiveness of treatments often utilise numbers (statistics) - to simplify complex matters into easily presented objective results. To achieve this, they may utilise ‘surrogate measures’ rather than events that are of clinical important to consumers, for example blood pressure or cholesterol measures rather than heart attacks and strokes. Sometimes outcomes, such as heart attacks and strokes, are pooled (composite measures) in order to give statistical significance to the results of a trial. It is important, therefore, to consider the endpoints that are of particular relevance to the participants themselves. This might be ability to function and wellbeing. It is important also to retain participants in the trials, for the statistical measures to be meaningful. This is an important factor in how long a trial lasts. On the other hand, the people who drop out of the trial may be a measure of difficulties in adherence to treatment and of adverse effects. Not all research on health and health care can use RCTs. For public health issues such as vaccination against disease it would be impossible and unethical to conduct an RCT. Adverse effects are also best identified with studies other than RCTs, with greater numbers of participants and which cover longer time periods of use of the intervention. In other situations the interventions are complex, being made up of many components, making it difficult to identify the contribution of each to an effective intervention (as with psychosocial interventions). All of us exist in a community and a culture, a time and a place that affects how we think, act and understand the world. This is also the case for researchers and the organizations (including governments and pharmaceutical companies) that fund researchers. The problem that one person or group thinks is important in one time and place may be very different from the problem that another person or group thinks is a priority in another context. Many women now survive breast cancer and are, rightly, vocal about its effects. Women experiencing heart disease may not have the same opportunity because when it hits it hits hard. Health advocacy started with AIDs, where survival at almost any cost was all important. That is, there are also different cultures with different illnesses. For the above reasons, the question is often asked: how informative are randomised controlled trials? 1. Randomised controlled trials (RCTs) make it clear if it is reasonable to assume a certain intervention produces an identified benefit, or harm; that is, it can clarify relationships between interventions and outcomes. On the other hand, this is tested at group level and not every participant in the intervention group of a successful trial benefited. Similarly, even if the intervention did not work some participants would have shown a benefit (the placebo effect). That is, RCTs allow prognoses but they do not predict whether an intervention will work for an individual. 2. RCTs use carefully selected participants who are known to have the health condition under investigation, are within a set age range and generally do not have other existing illnesses. They are carried out in countries and care settings that can support the clinical trial. This has consequences for disadvantaged groups, different cultures, people with special needs, those with the most severe problems and highly vulnerable people. For this reason, some trials look at specific populations or ‘subgroups’. 3. RCTs are the method of choice for the effectiveness of medicines but may not be as suitable or conclusive for complex interventions or for complex healthcare problems and situations. 4. Many RCTs do not report whether the intervention was carried out as designed, or consistently. How the intervention is applied and who applies it (for example an experienced provider compared with someone new to the intervention and level of training) are also important. 5. RCTs run over relatively short time periods and in very specific settings, can the results from these trials be generalised to real life? Side effects are important or unintended consequences – which are important when one intervenes purposefully to change a situation. 6. RCTs can measure outcomes of an intervention that are objective but which do not clearly relate to hospitalisations and healthcare needs for individuals and healthcare systems. Care can be considered appropriate when the chances are maximised that the care will contribute to the wellbeing of the person who needs it, at reasonable cost for society: It is important we are aware of these limitations of ‘evidence’. The Cochrane Collaboration is an international, not-for-profit organisation which produces and disseminates high quality evidence on healthcare interventions. Evidence is published in the form of systematic reviews (Cochrane reviews), which summarise the current evidence on a topic. Reviews are published quarterly in The Cochrane Library, available free to all Australians online: www.cochranelibrary.org. The Cochrane Collaboration also has a website (www.cochrane.org) for people who want to know more about how the Collaboration works. This website is useful for easy access to the plain language summaries and more scientific abstracts of reviews (www.cochrane.org/reviews) with access to the Library, and information on the groups that make up the Collaboration. You will find the consumer web pages here (www.cochrane.org/consumers). Top Copyright © ccnet

Evidence based health care requires evidence

Evidence-based health care is a combination of current best research evidence, the expertise of the healthcare provider, and patient values – used to make decisions about health care for and with individuals, families and communities.

The understanding is that evidence-based health care is for the public good and results in improvements in the quality of health care; accessibility to effective health care and health promotion interventions; and, overall, improved health.

The Australian Council for Safety and Quality in Health Care (2003) developed 10 tips for safer health care that are directed at health consumers. These are ‘What everyone needs to know, a guide to becoming more involved in your health care’.

A booklet explaining 'Modern Medicine'
A booklet with some useful websites for quality health information

You can improve your health care through an active and positive partnership.
It’s okay to ask your health care professional questions and to expect answers you understand. Some people find it helpful to write their questions down before an appointment and to take notes. Others like to have a family member or a carer with them (or an interpreter).
Be actively involved in your health care.
Speak up if you have any questions or concerns.
Learn about your condition or treatments.

About health information

The general public has access to large amounts of health information from television, newspapers, magazines, freely available handouts and brochures, through their personal interactions with others and the internet. Consumers are increasingly becoming engaged in their own health care. Many people want to know more about their health and to be involved in treatment and healthcare decisions. Positive outcomes may include better adherence to treatment due to increased understanding, and involvement in the process, quality use of medicines, effective behaviour changes and changes in lifestyle, improved health care, increased patient safety and ultimately better health and wellbeing.

Consumers receive so much information that it may actually mislead, create anxiety and cause confusion rather than inform and guide them. Moreover, the accuracy and inherent value of much of the information can be questionable or even inappropriate. People have limited opportunity or inclination to assess the information and without adequate background knowledge on how to discern which information is reliable or applicable, a person can easily gather information which ultimately has no relevance to their condition and which potentially consumes valuable consultation time for patient and doctor. On the other hand, the information could be useful in highlighting concerns which are relevant to the way a person might proceed with their healthcare management.

Communicating health information

Communication problems between healthcare providers and patients are common and many patients are dissatisfied with the information they are given by their healthcare providers. Indeed, healthcare providers may focus on disease and its management rather than on the person, their life and how they address their healthcare problems.

When individuals seek medical care they are unusually open to accepting guidance from an authority to whom they have entrusted their wellbeing. There is abundant evidence that when healthcare professionals converse with their patients about risk reduction, illness management, and pharmacy use, in a trusted relationship, there is a greater likelihood they will listen. Information relevant to the consultation may include the likely effectiveness of treatment; side effects; alternative treatments; and how a treatment is applied – for example doses, the minimal time permitted between treatments, what to do if a dose is missed, and lifestyle changes.

What counts as evidence?

Evidence is defined as any systematic observation of the apparent relation between events – considered that evidence of the higher order supersedes that of the lower order (cf contribute value).
Evidence, in a patient’s mind, consists of ideas and observations that support or oppose an ‘argument’, say for adopting a healthcare intervention – these they hear from their family and contacts, read, or are exposed to in the media or on the internet.
The gold standard, or ‘best’ evidence, is from randomised clinical trials and cost-benefit studies; and from systematic reviews of this evidence.
It is important, therefore, to ask what relevant questions the evidence addresses and also what questions it raises, including how it can be applied to health consumers, patients and carers; that is the public or civil society.
There is a lack of an evidence-based culture in the healthcare community, with providers adhering to business as usual, and expert culture, and believing they do not have the time to look for ‘evidence’. Looking for this evidence might reduce trust. Yet it is important to be transparent about where recommendations for treatment come from. The provision of health care is decided by structural, cultural and financial restraints; vested interests; values; habits; knowledge attitudes and skills – on the part of health systems, healthcare providers and the public. Some consider that evidence-based medicine is for management rather than patient-related performance.
Researchers believe that if we follow strict rules for doing research it will produce evidence that minimises biases, playing favourites, and can be repeated in similar conditions to produce the same results. And if enough research evidence is collected, ‘the truth’ about something can be discovered.

About evidence-based healthcare

We define evidence-based health care as the> combination of current best research evidence, the expertise of the healthcare provider, and patient values.

>Evidence-based health care is about making decisions about health care for and with individuals, families and communities; informed, shared decision making; and patient-centred health care.

When you have a cold, you decide about how to treat it. Maybe you know already what to do or you ask somebody you trust, if she or he has a good recommendation for an effective treatment. Effective means it will probably help you, even if there is no 100% guarantee for its effectiveness or that you will be totally cured.

Finding out what is the most effective treatment for most people is the goal of health care research about drugs, medical devices or other treatments. This is done with clinical studies. The results of these studies should be the basis for every decision about a treatment. Researchers call these results the evidence about the healing or harmful effects of a treatment.

The Cochrane Collaboration collects existing high-quality evidence about a health care treatment and puts it together in research articles, so called systematic reviews. Each of these articles has a short summary, written in plain language, which is meant to inform consumers and lay people about the review findings.

These articles are published in The Cochrane Library, an electronic library on the internet. The consumer summaries are free to access. You can use the evidence from these reviews to make your decision about your healthcare.

This we call evidence-based health care because it is grounded in the most reliable information and should support you and your general practitioner or GP in your daily decisions about health care.

To enable you and your GP to find this evidence quickly and in a readable form the Cochrane Collaboration and its Consumer Network aims to present the evidence also in printable plain language summaries.

Sometimes the studies give us no proof or only a weak proof for the effectiveness of a treatment compared with non-active or dummy (placebo) treatment. Then you will find sentences like ‘further research is needed’.

The Cochrane Library

The Cochrane Library is an electronic collection of databases published on the internet and also available on CD-Rom. It is updated quarterly in an effort to add to and keep the information current. The Library is made up of a number of parts. The Cochrane Database of Systematic Reviews (CDSR) is the actual database that contains the published Cochrane reviews and protocols.

>The Cochrane Collaboration is an international, not-for-profit organization which produces and disseminates high quality evidence on healthcare interventions. Evidence is published in the form of systematic reviews (Cochrane reviews), which summarise the current evidence on a topic. Reviews are published quarterly in The Cochrane Library, available free to all Australians online: www.cochranelibrary.org. Authors of reviews are usually health professionals, and are often preparing reviews in addition to their normal work. They collect all clinical trials on the topic, assess the quality of the clinical trials, and summarise the findings to make a conclusion about how effective the intervention is for the illness.

>Cochrane reviews are generally updated every two years.

Bringing together the evidence

The information on this website is based on careful reviews of clinical trials that compared complementary and non-medical treatments with a placebo (inactive treatment) or a known treatment in a particular health setting.

Evidence is gathered and summarised in a systematic review. A systematic review uses set methods to identify the best evidence from individual clinical trials and, when possible, collects the results into an overview or synthesis. Trials are included in the review if they meet specific, pre-specified criteria that are designed to minimise biases in the findings of a trial, making the trial inaccurate.

Randomly assigning trial participants to an intervention group is an important part of these criteria. By concealing who is to receive what intervention, the intent is that the comparison groups are made up of similar people who are treated in the same way, other than the test treatment given. This helps to ensure that any observed differences in outcomes can be attributed to the intervention alone. Some included trials may still have insufficient numbers of participants to be able to distinguish the effects(s) of the intervention from chance events, because of the natural variation between people and their responses to treatments (the trials are said to be underpowered).

Blinding also helps to minimise the effects of bias in the findings of a trial. It is important that the participants, trialists and people assessing the outcomes do not know who is receiving what intervention (blinding). Participants who receive a placebo may still have treatment benefits (and harms).

Sometimes the studies give us no proof or only a weak proof for the effectiveness of a treatment compared with non-active or dummy treatment. For example, this may occur if all the clinical trials on the topic are of low quality. Then you will find sentences like ‘further research is needed’ because the intervention may well be effective but there is not strong evidence proving this.

Evidence-based health care is dependent on a system to gather, synthesise and disseminate evidence

The Cochrane Collaboration is a not-for-profit organisation that prepares systematic reviews of healthcare interventions in a way that minimizes biases, as much as is possible. These reviews summarise for the healthcare provider, researcher, policy makers and other the current research on whether or not a healthcare intervention really works. The organisation involves consumers in its work as a way of making the reviews more accessible and relevant to the receivers of health care.

The ‘gold standard’ for producing evidence on healthcare interventions is the double-blind, randomised clinical trial (RCT). An RCT randomises people to different treatments, as a way of trying to make the different groups as similar as possible. The intervention that is being tested is compared to a non-active (placebo), a known treatment or usual care. The people who give the treatment and assess the results of giving the treatments do not know who is receiving what intervention (double blinded). The larger the trial the more the influence of things we do not know about, including biological variations and behaviours from one person to another, can be reduced and the assessment of the effect of the treatment more accurate.

What an RCT does is measure the likely efficacy of a treatment – can the intervention be shown to work in this situation with carefully selected participants, a defined healthcare setting and careful follow up? The evidence from an RCT needs to be translated into everyday use in a social context and in busy healthcare systems. Furthermore, RCTs are usually short-term, so they tell us little about long-term benefits or harms of a healthcare intervention.

A systematic review of RCTs gathers individual trials and summarises them in a single review. A systematic review uses set methods to identify this best evidence and, where possible, pools the results in an overview or statistical meta-analysis. Studies are only included in the review if they meet specific, pre-specified criteria defined to minimise introducing biases and influencing the findings of both the individual studies and the review. Randomly assigning trial participants to an intervention group in a way that no-one is aware what group the person is in is an important part of these criteria. Many trials have insufficient numbers of participants to be able to distinguish intervention effects - because of natural variations between people and their responses to treatments (they are underpowered).

Limitations of RCTs

In trials, measures of effectiveness of treatments often utilise numbers (statistics) - to simplify complex matters into easily presented objective results. To achieve this, they may utilise ‘surrogate measures’ rather than events that are of clinical important to consumers, for example blood pressure or cholesterol measures rather than heart attacks and strokes. Sometimes outcomes, such as heart attacks and strokes, are pooled (composite measures) in order to give statistical significance to the results of a trial. It is important, therefore, to consider the endpoints that are of particular relevance to the participants themselves. This might be ability to function and wellbeing.

It is important also to retain participants in the trials, for the statistical measures to be meaningful. This is an important factor in how long a trial lasts. On the other hand, the people who drop out of the trial may be a measure of difficulties in adherence to treatment and of adverse effects.

Not all research on health and health care can use RCTs. For public health issues such as vaccination against disease it would be impossible and unethical to conduct an RCT. Adverse effects are also best identified with studies other than RCTs, with greater numbers of participants and which cover longer time periods of use of the intervention. In other situations the interventions are complex, being made up of many components, making it difficult to identify the contribution of each to an effective intervention (as with psychosocial interventions).

All of us exist in a community and a culture, a time and a place that affects how we think, act and understand the world. This is also the case for researchers and the organizations (including governments and pharmaceutical companies) that fund researchers. The problem that one person or group thinks is important in one time and place may be very different from the problem that another person or group thinks is a priority in another context. Many women now survive breast cancer and are, rightly, vocal about its effects. Women experiencing heart disease may not have the same opportunity because when it hits it hits hard. Health advocacy started with AIDs, where survival at almost any cost was all important. That is, there are also different cultures with different illnesses.

For the above reasons, the question is often asked: how informative are randomised controlled trials?

1. Randomised controlled trials (RCTs) make it clear if it is reasonable to assume a certain intervention produces an identified benefit, or harm; that is, it can clarify relationships between interventions and outcomes. On the other hand, this is tested at group level and not every participant in the intervention group of a successful trial benefited. Similarly, even if the intervention did not work some participants would have shown a benefit (the placebo effect).

That is, RCTs allow prognoses but they do not predict whether an intervention will work for an individual.

2. RCTs use carefully selected participants who are known to have the health condition under investigation, are within a set age range and generally do not have other existing illnesses. They are carried out in countries and care settings that can support the clinical trial. This has consequences for disadvantaged groups, different cultures, people with special needs, those with the most severe problems and highly vulnerable people. For this reason, some trials look at specific populations or ‘subgroups’.

3. RCTs are the method of choice for the effectiveness of medicines but may not be as suitable or conclusive for complex interventions or for complex healthcare problems and situations.

4. Many RCTs do not report whether the intervention was carried out as designed, or consistently. How the intervention is applied and who applies it (for example an experienced provider compared with someone new to the intervention and level of training) are also important.

5. RCTs run over relatively short time periods and in very specific settings, can the results from these trials be generalised to real life? Side effects are important or unintended consequences – which are important when one intervenes purposefully to change a situation.

6. RCTs can measure outcomes of an intervention that are objective but which do not clearly relate to hospitalisations and healthcare needs for individuals and healthcare systems. Care can be considered appropriate when the chances are maximised that the care will contribute to the wellbeing of the person who needs it, at reasonable cost for society:

It is important we are aware of these limitations of ‘evidence’.

The Cochrane Collaboration is an international, not-for-profit organisation which produces and disseminates high quality evidence on healthcare interventions. Evidence is published in the form of systematic reviews (Cochrane reviews), which summarise the current evidence on a topic. Reviews are published quarterly in The Cochrane Library, available free to all Australians online: www.cochranelibrary.org.

The Cochrane Collaboration also has a website (www.cochrane.org) for people who want to know more about how the Collaboration works. This website is useful for easy access to the plain language summaries and more scientific abstracts of reviews (www.cochrane.org/reviews) with access to the Library, and information on the groups that make up the Collaboration. You will find the consumer web pages here (www.cochrane.org/consumers).

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