Specifically, what questions did your study seek to answer? 

The study sought to answer the question of what the smallest worthwhile effect is for pain intensity when using guideline- recommended interventions for low back pain (LBP), specifically non-steroidal anti-inflammatory drugs (NSAIDs) for people with acute and chronic LBP and exercise for people with chronic LBP. 

The smallest worthwhile effect is a measure of clinical importance that overcomes many of the limitations of the minimum clinically important difference and is the only measure that accounts for patients’ perspectives on what is an important effect.

How does a benefit–harm trade-off study work?

A benefit–harm trade-off study assesses the balance between the potential benefits and harms of a medical intervention or treatment. 

Typically, the intervention comparison of interest (eg, exercise compared to no exercise) is outlined to the participant, including the costs and risks of the treatment. 

Then the participant is asked to state how much of a benefit (reduction in pain in our study) they would require to make those potential harms worthwhile. 

To ensure that the smallest worthwhile effect is reached, participants are asked whether they’d accept a benefit of less than they initially stated.

Who did you enrol in your benefit–harm trade-off study? 

We enrolled people who spoke and read English, lived in Australia and had non-specific LBP (acute or chronic). 

We recruited these people through advertisements on social media so that we did not enrol participants who had already presented to a physiotherapy clinic, making our results potentially generalise better to the general population.

What did the study find?

We found that for acute LBP, the smallest worthwhile effect of NSAIDs, in addition to no intervention, was a 30 per cent reduction in pain intensity, with an interquartile range of 10 per cent to 40 per cent. 

For chronic LBP, the smallest worthwhile effect of NSAIDs in addition to no intervention was pretty similar, a 27.5 per cent reduction in pain intensity, with an interquartile range of 10 per cent to 50 per cent.

For chronic LBP, the smallest worthwhile effect of exercise in addition to no intervention was a 20 per cent reduction in pain intensity, with an interquartile range of 10 per cent to 40 per cent.

We also identified small associations between baseline pain, duration of pain and the level of exercise with the smallest worthwhile effect of NSAIDs for acute LBP. 

However, there were no other meaningful associations found.

What further research is needed in this area?

The smallest worthwhile effect is the best patient-centred measure of clinically important effect, although it has only been estimated for a handful of interventions for LBP and a few other conditions. 

To appropriately interpret the effects of interventions, the smallest worthwhile effect must be estimated for different treatments and comparisons, especially for commonly used and tested interventions.

We also need to estimate the smallest worthwhile effect for interventions with significant risk of harm, such as opioids and surgeries for musculoskeletal conditions, to identify what benefit patients would need to make these treatments worthwhile.

These areas of research can provide a more comprehensive understanding of what patients think about the treatment and management of LBP and can help inform decision-making for individuals with LBP.

 

Harrison Hansford

Harrison Hansford is a National Health and Medical Research Council Postgraduate Scholar and accredited exercise physiologist completing his PhD at the University of New South Wales and Neuroscience Research Australia. Harrison’s PhD is titled ‘Improving the evidence- based management of musculoskeletal conditions’.