Yellow flags

Yellow flags are psychological and social factors that raise the chance that back pain will last or become disabling. The term was first used for psychosocial factors that predict disability after the onset of musculoskeletal pain; more recent work tends to keep it for psychological factors and to treat social and workplace factors separately (Nicholas et al., 2011).

They are the counterpart of red flags. Red flags are signs of a possible serious cause, such as a fracture, infection or cancer. Yellow flags say nothing about the spine itself; they help predict how ordinary back pain is likely to go.

What counts as a yellow flag?

The factors with the best evidence include:

• Distress and low mood. A review of prospective studies found that psychological distress and depressive mood, and to a lesser extent somatisation (physical symptoms linked with distress), predicted the move from acute to chronic pain. The evidence for catastrophising, expecting the worst about pain, was weaker (Pincus et al., 2002).
• Fear-avoidance beliefs, the belief that activity will cause harm. In back pain of less than 6 months, strong fear-avoidance beliefs were linked with more pain and disability and a lower chance of returning to work (Wertli et al., 2014). Fear of movement is covered under kinesiophobia.
• Coping style. After whiplash, a passive coping style, low mood and fear of movement were linked with slower or less complete recovery (Carroll et al., 2008).

None of this means the pain is “in your head”. The pain is real; yellow flags describe what makes it more likely to persist.

How are yellow flags screened?

The best known tool in the UK is the STarT Back tool, developed in English general practice. It has 9 questions: about leg pain, other pain, disability, how bothersome the pain is, and 5 psychosocial items on catastrophising, fear, anxiety and depression. The scores sort people into low, medium or high risk of a poor outcome (Hill et al., 2008).

NICE suggests considering a tool like this at the first contact with a health professional for each new episode of low back pain. People at low risk would get simpler support such as reassurance, advice to keep active and self-management guidance, while those at higher risk would get more intensive support such as exercise programmes, with or without manual therapy (NICE).

Does addressing yellow flags help?

It can, though not everywhere. In a trial of 851 people with back pain at ten English general practices, care matched to their STarT Back risk group improved disability more than usual best practice at 4 and 12 months, with small effect sizes, and cost less (Hill et al., 2011). When the approach was introduced in six US primary care clinics, clinicians used the tool for about half of their patients but didn’t change what they recommended, and patient outcomes didn’t change either (Cherkin et al., 2018).

Looking across studies, targeting yellow flags, especially when they are strong, has given more consistently positive results than ignoring them (Nicholas et al., 2011). Treatments that tackled fear-avoidance beliefs did better than ones based purely on a biomedical explanation (Wertli et al., 2014).

What it means if you sit at a desk with back pain

Most back pain improves within a few weeks (NHS); see non-specific low back pain and Will back pain go away on its own?. If worry about your back, stress or low mood is building alongside the pain, that is worth mentioning to a GP or physiotherapist, not keeping to yourself. The NHS says to see a GP if you’re struggling to cope, and lists cognitive behavioural therapy among the treatments that can help people cope with back pain (NHS). Can stress cause back pain? looks at that link in more detail.