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The smallest worthwhile effect (SWE) is the smallest beneficial effect of an intervention that justifies the costs, risks, and inconveniences. The objective is to establish the SWE of spinal manipulative therapy (SMT) for the treatment of low back pain (LBP), and to gain insight into how different attributes of the treatment are traded among each other when choosing SMT. Part 1. A mixed-methods study will be conducted to establish and prioritize a list of attributes influencing choices for those who consider SMT for the treatment of LBP. Individual interviews and consensus groups with chiropractors, manual therapists, and osteopaths and their patients will be conducted. Interviews and consensus groups will be voice-recorded and transcribed verbatim. Part 2. A Discrete Choice Experiment (DCE) will be conducted among people with LBP who have limited to no experience with SMT. Participants will be recruited through an online independent panel company. The survey will consist of several choice sets with attributes and their levels established from Part 1. The DCE will be preceded by a short survey to understand the clinical aspects (i.e. presentation, history and previous treatment for LBP) as well as socio-demographic characteristics of the participants.

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BACKGROUND: The minimal important difference (MID) is defined as the smallest difference that the patient perceives as important. Furthermore, the smallest worthwhile effect (SWE) is the important change measured with the benefit-harm trade-off method. The aim of this study was to evaluate the MID in orthodontic treatment duration to inform the decision regarding seeking procedures to accelerate orthodontic tooth movement and reduce treatment duration. METHODS: We constructed a survey eliciting views of the MID from adult participants from four countries undergoing orthodontic treatment. Ten questions addressed reduction in the treatment duration for both durations 12 and 24 months, and four questions were related to the reduction in treatment duration that the patients would require to undergo surgical or non-surgical adjunctive procedures. We applied a univariable random effects logistic regression model to examine the association between the participants' characteristics and the MID. Then, we fitted a multivariable logistic random effects regression including significant predictors. RESULTS: Four hundred and fifty adults, with a median age of 21 (interquartile range: 19-24), undergoing orthodontic treatment participated in the survey. Of the respondents, 60% considered 15 days as a trivial reduction from 12 months duration of therapy and 70% considered 15 days a trivial reduction from 24 months. Of the respondents, 48% considered the period of 2 months a moderate reduction from 12 months, and 60% considered 2 months a moderate reduction from 24 months. From these results, we inferred that patients considered reductions of approximately 1 month as the MID in the treatment duration for both 12 and 24 months. However, SWE was considerably more than the MID for most of the participants to decide undergoing surgical adjunctive procedures to reduce the time of therapy. The participants required smaller SWE to undergo non-surgical procedures compared to surgical procedures. CONCLUSION: The MID in the treatment duration is one month for both treatment durations 12 and 24 months. Patients require a greater SWE than the MID to undergo adjunctive procedures to shorten the duration, particularly for surgical procedures.

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OBJECTIVE: To identify the smallest worthwhile effect (SWE) of exercise therapy for people with non-specific chronic low back pain (CLBP). DESIGN: Discrete choice experiment. METHODS: The SWE was estimated as the lowest reduction in pain that participants would consider exercising worthwhile, compared to not exercising i.e., effects due to natural history and other components (e.g., regression to the mean). We recruited English-speaking adults in Australia with non-specific CLBP to our online survey via email obtained from a registry of previous participants and advertisements on social media. We used discrete choice experiment to estimate the SWE of exercise compared to no exercise for pain intensity. We analysed the discrete choice experiment using a mixed logit model, and mitigated hypothetical bias through certainty calibration, with sensitivity analyses performed with different certainty calibration thresholds. RESULTS: Two-hundred and thirteen participants completed the survey. The mean age (±SD) was 50.7±16.5, median (IQR) pain duration 10 years (5-20), and mean pain intensity (±SD) was 5.8±2.3 on a 0-10 numerical rating scale. For people with CLBP the SWE of exercise was a between-group reduction in pain of 20%, compared to no exercise. In the sensitivity analyses, the SWE varied with different levels of certainty calibration; from 0% without certainty calibration to 60% with more extreme certainty calibration. CONCLUSION: This patient-informed threshold of clinical importance could guide the interpretation of findings from randomised trials and meta-analyses of exercise therapy compared to no exercise.

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Clinical relevance and statistical significance are different concepts, linked via the sample size calculation. Threshold values for detecting a minimal important change over time are frequently (mis)interpreted as a threshold for the clinical relevance of a difference between groups. The magnitude of a difference between groups that is considered clinically relevant directly impacts the sample size calculation, and thereby the statistical significance in clinical study outcomes. Especially in non-inferiority trials the threshold for clinical relevance, i.e. the predefined margin for non-inferiority, is a crucial choice. A truly inferior treatment will be accepted as non-inferior when this margin is chosen too large. The magnitude of a clinically relevant difference between groups should be carefully considered, by determining the smallest effect for each specific study that is considered worthwhile. This means taking into account the (dis)advantages of both study interventions in terms of benefits, harms, costs, and potential side effects. This article clarifies common sources of confusion, illustrates the implications for clinical research with an example and provides specific suggestions to improve the design and interpretation of clinical research.

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QUESTION: What are the smallest worthwhile effects of nonsteroidal anti-inflammatory drugs (NSAIDs) for people with acute and chronic low back pain (LBP)? What is the smallest worthwhile effect of individualised exercise for people with chronic LBP compared with no intervention? DESIGN: Benefit-harm trade-off study. PARTICIPANTS: Participants were recruited by advertisement on social media and included if they were English-speaking adults in Australia who had non-specific LBP. OUTCOME MEASURE: Pain intensity. RESULTS: A total of 116 people with acute LBP and 230 people with chronic LBP were recruited. For acute LBP, the smallest worthwhile effect of NSAIDs additional to no intervention was a 30% (IQR 10 to 40%) reduction in pain intensity. For chronic LBP, the smallest worthwhile effect of NSAIDs additional to no intervention was a 27.5% (IQR 10 to 50%) reduction in pain intensity. For chronic LBP, the smallest worthwhile effect of exercise additional to no intervention was a 20% (IQR 10 to 40%) reduction in pain intensity. There were small associations between baseline pain, duration of pain and level of exercise and the smallest worthwhile effect of NSAIDs for acute LBP. There were no other clear associations. CONCLUSIONS: For people with LBP, the smallest worthwhile effect of exercise and NSAIDs additional to no intervention is approximately a 20 to 30% reduction in pain. These results can inform the interpretation of the effects of NSAIDs and exercise in randomised trials and meta-analyses, incorporating consumers' perspectives. Further research on comparisons between different interventions and on other core LBP outcomes may inform decision-making. REGISTRATION: OSF osf.io/3erjx/.

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OBJECTIVES: To determine and compare estimates of the smallest worthwhile effect (SWE) for physiotherapy in neck, shoulder, and low-back pain patients and to investigate the influence of sociodemographic, clinical, and psychological factors on these estimates. METHODS: A structured telephone interview was conducted before treatment was commenced in 160 patients referred for primary care physiotherapy. The benefit-harm trade-off method was used to estimate the SWE of physiotherapy for the following outcomes; pain, disability, and time to recovery, compared with the improvement achieved without any treatment (natural course). Regression analyses were used to assess the influence of sociodemographics, clinical variables, and intake scores on pain, disability, and psychological scales. RESULTS: The median SWE for improvements on pain and disability was 20% (interquartile range 10%-30%), and the SWE for time to recovery was 10 days (interquartile range 7-14 days) over a period of 6 weeks. These estimates did not differ with respect to pain location (neck, shoulder, or back) and were generally unaffected by sociodemographic, clinical, and psychological factors. CONCLUSION: People with neck, shoulder, and low-back pain need to see at least 20% of additional improvement on pain and disability compared with natural recovery to consider that the effect of physiotherapy is worthwhile, given its costs, potential side effects, and inconveniences.

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BACKGROUND: the smallest worthwhile effect (SWE) of an intervention is the smallest treatment effect that justifies the costs, risks and inconveniences associated with that health intervention. OBJECTIVE: to estimate the SWE of exercise programs designed to prevent falls among older people and to compare estimates derived by two methodological approaches. STUDY DESIGN AND SETTING: discrete choice experiment (n = 220) and benefit-harm trade-off (subsample n = 66) methods were used. PARTICIPANTS: community-dwelling older people who reported a past fall or a mobility limitation answered online or face-to-face questionnaires. RESULTS: a substantial proportion of participants (82% in the discrete choice experiment and 50% in the benefit-harm trade-off study) did not consider that participation in the proposed exercise programs would be worthwhile, even if it reduced their risk of falling to 0%. Among remaining participants, the average SWE of participation in an exercise program was an absolute reduction in the risk of falling of 35% (standard deviation [SD] = 13) in the discrete choice experiment and 16% (SD = 11) in the benefit-harm trade-off study. CONCLUSIONS: many participants did not consider the hypothetical falls' risk reduction of the proposed exercise programs to be worth the associated costs and inconveniences. Greater community awareness of the fall prevention effects of exercise for older people is required.

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