Mark Hancock one of the authors of ‘Risk of recurrences of low back pain: a prospective inception cohort study’, elaborates on this research, published in the latest issue of the Journal of Physiotherapy.

Among those who recover from low back pain, do we know much about whether it reoccurs?

It is widely believed that recurrences of back pain are common, but surprisingly there is very little quality evidence to support or refute  this belief. We recently published a systematic review investigating this topic but concluded it is not yet possible to accurately report the risk of a recurrence of low back pain, due to the poor methodological quality and small number of existing studies.

The key mythodological problem with existing studies is they include survival cohorts. This means they included people who recovered from their last episode of back pain either recently or a long time ago. The problem with this is the risk of a recurrence is likely very different in someone who recovered recently and another person who had their last episode many years ago.

An important additional limitation of previous studies is they use different definitions of an episode of low back pain, which can obviously influence the risk of a recurrence. A few years ago we published a consensus definition of a recurrence of back pain, which should produce more consistency in future studies. According to this definition a recurrence of an episode is defined as ‘a return of low back pain lasting at least 24 hours with a pain intensity of >2 on an 11-point numerical rating scale, following a period of at least 30 days pain-free’.

What sort of study would provide the best evidence about recurrence of episodes of low back pain and why?

The best study design to provide accurate estimates of how commonly recurrences take place is an inception cohort design. In an inception cohort study, patients with the condition are included at an early and uniform time point in the course of the condition. When investigating recurrences of low back pain, this involves enrolling patients who have recently recovered from an episode of back pain and then following them regularly over time to determine if and when a recurrence occurs.

Is that the study design you used?

Yes, we used an inception cohort study design. To be included in our study, participants needed to have recovered from an episode of low back pain within the last month. To achieve this was quite a challenge.

Many people who were referred to the study still had some pain, and therefore not eligible, so we followed them fortnightly until they recovered and only then did we enrol them in the study. We screened 409 patients before we enrolled the 250 participants who met the inclusion criteria and volunteered to participate for the study.

After enrolment participants were contacted monthly for one year and asked if they had experienced a recurrence of low back pain using the consensus definition mentioned before. We also asked if they had experienced a recurrence using two other stricter definitions for a recurrence. This enabled us to investigate how much the definition of recurrence impacted on the number of recurrences.

Were most patients followed up in your study?

Yes, Tatiane da Silva, the PhD student who led the trial, did a great job on this. Over 94 per cent of participants were followed up until they had a recurrence or completed the 12 month follow-up period.

Did many people have a recurrence of low back pain during the follow-up period?

We found recurrences were more common than we expected. Using the consensus definition of a recurrence, 69 per cent of participants had a recurrence within one year, 40 per cent of participants reported a recurrence severe enough to have a moderate impact on daily activities, and 41 per cent reported a recurrence that resulted in them seeking healthcare.

Were the recurrent episodes severe?

This is an interesting question and something we are continuing to investigate. As mentioned, over half of the recurrences resulted in at least moderate impact on daily activities or resulted in care being sought, but some of the recurrences were mild. We collected some other secondary data on the pain intensity and duration of the episodes. These data demonstrate substantial variability in the severity of the recurrences, but many episodes resolved over just a few days. We intend to do more analyses to further investigate the severity of the recurrences.

What information can physiotherapists use to advise patients who have had a recent episode of back pain about their likelihood of a recurrence?

Physiotherapists should educate patients about the high likelihood of recurrences of low back pain. If patients understand this, they will hopefully be less alarmed when a recurrence occurs. Patients can be reassured that many of the recurrences will be short lived, and should be provided with advice on how to self-manage minor recurrences. We also found that regular exposure to awkward postures, and sitting for more than five hours a day, increased the risk of future recurrences. Physiotherapists should discuss these risk factors with patients and ways to limit exposure to awkward postures and long periods of sitting.

If those factors indicate that a recurrence of back pain is more likely, does that mean that physiotherapy intervention with things like posture and sitting time will reduce the recurrence of low back pain?

Ideally, we need a well-conducted randomised controlled trial to provide strong evidence that reducing exposure to awkward positions or sitting will reduce risk of recurrence, but that study has not been done. Given the available evidence it is reasonable to tell patients these factors are associated with increased risk and reducing exposure to them may reduce their risk. It would seem particularly important to address these factors if they were associated with the individual patient’s past episodes of low back pain. The strongest available evidence on preventing recurrences of back pain comes from a systematic review by Daniel Steffens published in 2016 that found exercise and education programs nearly half the risk of a recurrence of low back pain.

Mark Hancock, APAM, is an associate professor of physiotherapy, Faculty of Medicine and Health Science, Macquarie University. He has more than 20 years of clinical experience as a musculoskeletal physiotherapist working in a primary care setting. Mark now works primarily as an academic/ researcher. His research focuses on the diagnosis and management of back pain.