June 23, 2024

What reduction in treatment time is important to our patients?

Rarely, a research paper is published that makes me think about the findings and holds great value for clinicians and researchers. If you are a clinician who takes research seriously, please read this post, as it is highly relevant to our specialty.

Orthodontic research must reflect outcomes that are meaningful for our patients. Failing to do so could result in us overlooking the important impacts of our treatments, which would impede the growth of our knowledge. For this simple reason, we need to identify differences in outcomes that are significant to patients. This was the main focus of the fascinating study.

Most orthodontic research focuses on clinician-centred outcomes and interprets the findings according to their statistical significance rather than their benefit to the patient. Additionally, most of these outcomes are irrelevant to our clinical practice (e.g., the canine retraction rate). Thus, it is challenging to make an evidence-based decision in clinical practice and interpret the magnitude of the effect in light of patients’ preferences. As such, the authors of this paper emphasised the importance of using patient-reported outcomes and considering the smallest differences in outcomes that patients find significant.

The minimal important difference (MID)

This is the smallest difference in outcome that the patient thinks is important.

Smallest worthwhile effect (SWE)

This is the patient’s perception of the important change derived from considering the trade-off of benefit and risk.

A multinational team did this research. The EJO published the paper.

What did they ask?

“How long is the Minimal Important Difference in the duration of orthodontic treatment that adult patients perceive and the Smallest Worthwhile Effect in reduction of treatment duration to warrant the use of an intervention to accelerate their treatment”?

What did they do?

They conducted a cross-sectional survey of adult patients who had been receiving orthodontic treatment with fixed appliances for at least six months.

The team recruited patients from orthodontic institutes based in Syria, Pakistan, Switzerland and Saudi Arabia.

They designed their survey in several well-defined stages. In the first, they formulated the questions and got feedback from a panel of experts in evidence-based practice. The final survey had four domains

  • Demographic questions
  • The MID for treatment duration of 12 months. They asked the participants to assess the importance of reducing treatment duration by 15 days, 45 days, 2, 3 and 4 months.
  • The MID for treatment of 24 months. This was the perception of a reduction of 15 days, 1, 2, 4 and months.
  • SWE for treatment duration. The team asked the patients to consider the threshold period of reduction at which they would require an intervention, considering the potential costs and harms. Then, the team provided them with a detailed description of the surgical or non-surgical intervention.

They distributed paper and electronic versions of the survey.

What did they find?

A total sample of 450 adults completed the survey. Most (63%) were females treated in the University sector.

MID for treatment.

The patients felt a reduction of 1 month as the MID in treatment duration for both the 12- and 24-months treatment.

SWE reduction.

This was considerably longer than the MID. Most participants felt a reduction in treatment duration of 4 months was necessary to have a surgical adjunct in the 12-month treatment group. In the 24-month duration group, this was at least 6 months to justify a surgical procedure.

When they looked at non-surgical adjuncts, they found that the participants required a smaller SWE to undergo the additional procedure.

Their final conclusion was

“The MID was 1 month for both durations of treatment.  Patients require a greater SWE to undergo treatment adjuncts”.

What did I think?

This study presented clinically important findings that indicate the need to consider larger effect sizes when designing and interpreting studies related to accelerating treatment. After reviewing many such studies on my blog, I generally found that the effect sizes were not clinically significant. This study reaffirms my previous conclusions.

Importantly, this study provides evidence to discuss interventions’ effectiveness with patients, enabling them to make evidence-based decisions.

Final thoughts

You may believe that this study is overly academic and has limited value. However, I disagree. This paper is a significant contribution as it’s the first study to explore these crucial concepts relevant to our patients.  

My overall impression is that we should aim to reduce treatment time by 4-6 months for these interventions to be worthwhile for our patients. Unfortunately, no good studies have achieved this level of reduction.

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Have your say!

  1. Dear Prof. Kevin,
    Thank you for the extensive review and this blog post.
    The authors greatly appreciate your efforts and are highly motivated by your insightful feedback.
    Best regards,

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