MOST BACK PAIN GETS BETTER

by Prof Peter Croft MD, MRCGP, Professor of Epidemiology, North Staffs Medical Institute, Stoke-on-Trent

It is commonly assumed that most patients with low back pain will recover. The author reviews the evidence as to whether this is true.

The hypothesis that "most low back pain is not life-threatening" is the basis for the triage approach to patients with low back pain recommended in a recent Government report.(1) Clinical history, examination, and observation over time will enable the general practitioner to identify the unusual patient with a progressive, serious reason for their low back pain. But what happens to the majority of patients who have non-specific low back pain?

On the basis of an article written more than twenty years ago, reviews and government reports have assumed that most patients with low back pain get better. The world of back sufferers was neatly divided into the mountain of acute cases and the molehill of chronic problems (the minority who generate most of the costs of back pain, use most of the resources, and make up most of the referrals).

Evidence to support this came in an elegant French paper published in the British Medical Journal in 1994. (2) Consecutive attenders in French general practices who presented with acute low back pain were followed up after their initial consultation. Two weeks later, 90% of the 103 patients had recovered (that is, they had no pain and no disability related to the back problem). These are impressive figures, but they do not easily square with other published evidence.

Low back pain starts early and recurs

A population survey of low back pain was completed recently in Manchester. (3) The questionnaire used in this survey showed a body chart with shading of the low back area. Patients were asked whether they had "ever experienced pain in the shaded area which had lasted for longer than 24 hours".

By the age of 30 years, nearly half of the population had experienced a significant episode of low back pain. Surveys of schoolchildren and young adults from elsewhere in Europe have confirmed that low back pain is a common experience in these age groups. (4) If backache does get better, this occurs mostly before and during young adulthood.

The strongest predictor of a new episode of low back pain is a previous episode. (5) This is a universal finding, and does not depend on whether studies are based in the general population, in primary care or in hospital. The 45% of adults aged under 30 years who have already had significant low back pain are therefore more likely than the rest of the population to experience it in the future. And each new episode increases the likelihood of a further recurrence. More than one-third of all adults taking part in the Manchester study recalled having low back pain during the month prior to the survey. For 80% of these sufferers, however, this was not their first experience of low back pain.

According to a recent Government survey, one-third of people with low back pain will have the pain for a total of more than three months in the year. (6) This may not be a continuous period of three months, but represents a chronic problem nevertheless. The survey authors calculated that, in the course of one year, such chronic pain affects 10% of the adult population in the UK, half of whom will have had periods of more than one month away from work.

Piecing together the evidence

How do we explain these different pictures? Although the French study looked at consecutive attenders with acute low back pain, they were very particularly defined. They had to be patients who referred themselves to the general practitioner within 72 hours of the start of an episode, and they had to have been free of low back pain for at least three months beforehand. In other words, these were patients with a very acute onset of symptoms who had recently been pain-free. Most general practitioners would agree that they do see such patients, but that they represent a minority of patients consulting about low back pain.

In a study in a Manchester practice, all patients with low back pain who presented during a 12-month period (whether with a new episode, an exacerbation or a recurrence) were contacted three months after their initial consultation. Only 25% reported complete recovery, while most of those with continuing problems had not consulted again in the intervening period.

The true picture

The neat division into acute and chronic back pain is false. Most low back pain is intermittent, up and down, episodic, with periods of low-grade persistence punctuated by acute exacerbations. "Chronicity", argues Deyo, "needs to be summarised over time". It should be seen as a pool of experience over months or years, rather than a persistent problem from day to day.

Day-to-day variation in pain

Perhaps low back pain is best perceived as behaving like blood pressure. It is a universal experience, and any one individual cannot be characterised by what happens on a single day (or by a single measurement).

By and large, if the day in question is a bad day for pain, the pain is likely to get better in the short-term (just as a high blood pressure will tend to settle on repeated measurement). This is partly a matter of settling back from a bad day to an average day for that person ("regression to the mean", or returning to the individual's average pain experience), but it also reflects the fact that pain, like blood pressure, responds to positive attention.

Positive action helps

Although low back pain often recurs, the adage in the consultation is often: "if we do nothing, this episode will get better". This is misleading. Most randomised trials show that doing something (it does not matter too much what it is, as long as it is positive rather than restrictive)is better in the short-term than doing nothing. Simple measures are best. In a recent Finnish trial, active encouragement of everyday activity in patients with new low back pain resulted in a better outcome three months later than bed-rest or specific back exercises. (8)

If a patient consults the doctor at the top of one of the peaks in the back pain experience, things are likely to improve. The higher the background level of pain and disability, and the fewer the peaks and troughs, the closer the patient comes to having a persistent, chronic problem, with less relief in the short-term.

Treating acute episodes

The unanswered question is this: if vigorous attention were directed towards non-specific low back pain when the episode was acute, and when the long-term experience of pain and disability was not yet set too high, would the frequency of future episodes be reduced sufficiently to decrease the burden of low back pain over time? If the answer is yes, active treatment of those acute episodes which will "get better any way" would pay dividends (not only in short-term relief, but in an eventual decline in low back pain prevalence and its associated disability).

Consultation with the GP

In any one year, about 20% of people who experience low back pain for more than one day will consult their general practitioners about it, and 10% of these patients will be referred to hospital. There appear to be regional variations in the proportion of people who consult their doctors (9), as well as the expected variations in practice referral rates to hospital.

Despite the growing popularity of complementary therapies, general practitioners are far more likely to be consulted than osteopaths and chiropractors, (6) although this bald statement hides large social class and regional variations. In the USA more money is now spent by the public on complementary therapy than on "conventional" office visits, with low back pain heading the list of reasons for seeking alternative care. (10)

The role of X-Rays

Most of the referrals from general practice are for plain lumbar spine x-rays. Classification of low back pain continues to promote controversy and disagreement. By contrast, the Clinical Standards Advisory Group's triage of low back pain on clinical grounds seems to be acceptable to general practitioners because of its commonsense approach to the question of whether it is an urgent problem.

All the evidence suggests that the use of imaging must come second to this clinical triage. An American study reported that, out of 2,000 consecutive patients presenting with back pain in primary care without clinical "red flags" (such as weight loss or constant, progressive pain (1)) which would suggest possible serious pathology, there were no cases of malignancy or other serious pathology. (11) The use of plain lumbar radiography or magnetic resonance imaging (MRI) scanning would therefore appear to be unjustified. Furthermore, in the absence of suspicious symptoms or signs, x-ray or MRI results bear little relationship to the presence or absence of low back pain. In a study of the utility of MRI scans in diagnosing disc degeneration, most patients with low back pain had an abnormality of their discs on the scan. Unfortunately, most people in a control group with no low back pain also had abnormalities on their scans. (12) Such findings emphasise the truism that low back pain seen in primary care does not indicate spinal disease.

Despite this evidence, many low back pain patients have an x-ray. The proportion of back pain sufferers who are referred for a lumbar spine x-ray within three months of a consultation is between 10 and 20%, with large variations between practices. This rate suggests that the majority of back sufferers will have an x-ray of their spine at some time in their lives. There are reasons for this which cannot be ignored - patient anxieties, the reassurance that a negative x-ray brings, the general practitioner who recalls the tumour in the patient with initially uncomplicated low back pain, and so on. The challenge is to find ways to deal with uncertainty and anxiety, and with the status of the radiograph in our culture, before translating arguments based on what happens to most patients into what should happen to the individual.

References

1. Clinical Standards Advisory Group on Back Pain. Back pain. London: HMSO, 1994.
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3. Papageorgiou A, Croft P, Ferry S, Silman A. Estimating the prevalence of low back pain in the general population. South Manchester low back pain survey. Spine 1995; 20(17): 1889-94.
4. Loboeuf-Yde C, Lauritsen JM. The prevalence of low back pain in the literature. A structured review of 26 Nordic studies from 1954 to 1993. Spine 1995; 20: 2112-8.
5. Roland MO, Morrell DC, Morris RW. Can general practitioners predict the outcome of episodes of back pain? Br Med J 1983; 286: 523-5.
6. Mason V. The prevalence of back pain in Great Britain. Office of Population Censuses and Surveys Social Survey Division. London: HMSO, 1994.
7. Deyo RA. Practice variations, treatment fads, rising disability. Spine 1993; 18: 2153-62.
8. Malmivaara A, Hakkinen U, Aro T et al. The treatment of acute low back pain - bed rest, exercises or ordinary activity. N Engl J Med 1995; 332: 351-5.
9. Walsh K, Cruddas M, Coggon D. Low back pain in eight areas of Britain. J Epidemiol Community Health 1992; 46: 227-30.
10. Eisenberg DM, Kessler RC, Foster C, Norlock FE, Calkins DR, Delbanco DL. Unconventional medicine in the United States. N Engl J Med 1993; 328: 246-52.
11. Deyo RA, Rainville J, Kent DL. What can the history and examination tell us about low back pain? JAMA 1992; 268: 760-5.
12. Jensen MC, Brant-Zawadske MN, Obuchowski N, Modic MT, Malkasian D, Ross JS. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med 1994; 331: 69-73.

This article first appeared in UPDATE.