Clinical tips: back pain

Ben Basger takes a look at the drug-related consequences of back pain treatment

You might be interested to know about the types of people who presented to the accident and emergency departments of Melbourne hospitals with lower back pain (Internal Medicine Journal 2019; doi:10.1111/imj.14075).

Among nearly 1,000 people who were admitted to hospital, median age was 67 and 63% were female. The most common diagnoses were musculoskeletal non-specific back pain (41%), disc-related (22%), vertebral fracture (14%) and sciatica (14%).

The most interesting findings for us from this study appeared to be that: Paracetamol and opioid-based analgesia were almost universally administered;

Non-steroidal anti-inflammatory drugs were prescribed in 51% of people;

Neuropathic pain medications (pregabalin, amitriptyline and/or gabapentin) were prescribed to 53% of patients;

32% of patients received prednisolone;

Diazepam was administered in 28% of patients; and

A physiotherapist was involved in the treatment of 92% of the admitted patients

As you would expect, co-morbidities were present, occurring in around three quarters of patients. Common ones were mental health (26%), gastroesophageal reflux disease (25%), diabetes (23%), chronic airways disease/asthma (18%), osteoporosis (16%), ischaemic heart disease (16%) and malignancy (10%).

What may all this mean to us? We may have to deal with the consequences of drug-related problems, of which there are only two; either the medicine does not work and/or the medicine causes harm: Adverse effects of gabapentin/pregabalin may add to adverse effects of opioids to increase the likelihood of unsteadiness, falls, daytime sleepiness and confusion. This is also true for diazepam. Not a great idea in older people.

The potential harm from the use of gabapentin/pregabalin in musculoskeletal non-specific back pain appears to strongly outweigh any likely benefits. A recent review reported; “There is moderate-to high-quality evidence that anticonvulsants are ineffective for treatment of low back pain or lumbar radicular pain. There is high-quality evidence that gabapentinoids have a higher risk for adverse events (CMAJ 2018 July 3;190:E786-93. doi: 10.1503/cmaj.171333).

Mental health patients with ischaemic heart disease taking certain SSRIs may have their QT interval lengthened by amitriptyline.

Paracetamol and NSAIDs may give short-term pain relief, but evidence of long-term effectiveness is lacking. NSAIDs may worsen dyspepsia in patients with GORD.

Amitriptyline is more effective than placebo in relieving pain but does not consistently improve function. Its use for greater than eight weeks has not been established.

There is insufficient evidence about the use of muscle relaxants (like diazepam) in chronic back pain. Adverse effects are frequent, a strong likelihood of dependency exists, and efficacy compared with analgesics is unknown.

Opioids are only partially effective in relieving pain and are unlikely to improve psychological or functional status. A short course (a week) may help.

Massage reduces pain and improves function and other interventions such as exercise or behavioural therapy may be beneficial, particularly with other treatments.

Patients should be advised to stay active.

Dr Ben Basger PhD MSc BPharm DipHPharm FPS AACPA is a clinical pharmacist and educator at Wolper Jewish Hospital and The University of Sydney, NSW.

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