Our Research Methods

Research Methods

Our methods follow established guidelines in the conduct of systematic reviews and evidence translation. This includes all steps of the process, from identifying relevant studies, to combining their results and translating this into the evidence categories we use.

Using established guidelines, our Expert Researchers developed a step-by-step scientific methodology tailored to the Evidence Based IVF website.

Randomised controlled trials

We only include data from randomised controlled trials because these studies provide the most reliable evidence about whether an IVF option is effective and safe.

Randomised controlled trials (RCTs) are considered the gold standard in research because they provide the most reliable evidence about whether a treatment or intervention works. In a randomised trial, participants are randomly assigned to either the treatment group or the control group (like flipping a coin). This random assignment helps to ensure that any differences between the groups are due to the treatment itself and not other factors. By comparing the treatment group to the control group, researchers can determine whether the treatment has a real effect.

Watch this video for more information about the rationale for randomised controlled trials and how they work. 

Research integrity in IVF studies

There is growing concern that some IVF studies may involve research misconduct, such as falsifying or altering data. While journals can retract studies with serious integrity issues after thorough review, this process is often very lengthy. As a result, many studies with potential integrity problems remain published and unretracted.

To help identify potential integrity concerns in the studies we evaluate, we use a tool called the Trustworthiness in Randomised Controlled Trials (TRACT) checklist.

Trial registration

One key factor we look at is whether the trial was registered on an official clinical trial registry before recruiting participants. Trial registration is important for several reasons:

• It allows researchers to see what studies are ongoing and may be published in the future.
• It helps identify "publication bias," where studies with less positive or less exciting results are less likely to be published.
• It lets us compare the methods and outcomes planned at the start of the study with what was actually reported when the results were published.

Since trial registration became standard practice in 2005, we expect all trials starting after 2010 to have been registered before recruitment began. If a study doesn’t meet this requirement, the study results from this trial will not be used unless there is other convincing evidence, such as an ethics approval letter, or a reasonable explanation from the researchers to confirm the study was conducted as claimed.

Conference abstracts

We also only include studies if they have been reported as full-length publications in peer-reviewed journals. Sometimes studies are presented at scientific conferences and information about the study is available from the conference organisers in a short description known as a ‘conference abstract’. If a study is only available as a conference abstract, it is often not possible to tell if the study was truly randomised or if the results have been accurately reported. Therefore, we only include conference abstracts if we can obtain further information about the trial from a prospective trial registration or correspondence with the study authors.

Quality of evidence in IVF

We use the GRADE approach to determine the quality or certainty of evidence

This tell us ‘How good is the evidence?’ or ‘How much do we trust this evidence?’ on a 4-point scale (very low, low, moderate, high).

It is sort like asking “Are we sure?”

We consider five different questions when assessing quality of evidence using GRADE

• What are the limitations of the studies i.e. what is the risk of bias?
• Are the results of different studies consistent?
• How directly does the evidence apply?
• Are the results precise?
• Have we found all the research that exists?

Cost of IVF optional extras

We provide an estimated range of the cost of each optional extra. This is determined by a review of IVF clinic websites and input from our Collaborators. To provide a quick overview of the approximate cost of optional extras, we created the following general guide in partnership with our patient Collaborators.

Cost information is indicative only and varies from clinic to clinic and depending on different circumstances.

Updates to the evidence

We update the information for each optional extra every 6-12 months.