Primary Care Pharmacy September 2000 Vol 1 No 4 p99-102

Disease management

A clinic for managing neurogenic pain

By John Hamley MSc, MRPharmS

This article looks at the setting up of a pharmacist-led clinic for managing patients with pain associated with nerve damage

Acute pain is a common complaint in general practice and many patients will go on to experience chronic pain. Pain that is associated with nerve damage (neurogenic pain) is particularly debilitating and may occur following herpes zoster infection (shingles), as a result of diabetic neuropathy or as post-traumatic injury. Atypical facial pain, trigeminal neuralgia and fibromyalgia also have a neurological component.
Systematic reviews of randomised trials indicate that tricyclic antidepressants and anticonvulsants are more effective than conventional analgesics in reducing pain associated with nerve damage. It was once believed that tricyclics were appropriate where "burning" was a characteristic feature of the pain experienced, while "shooting pain" responded to anticonvulsants. However, both types of pain have since been shown to respond to tricyclics and, since these have fewer serious adverse effects than anticonvulsants, trying these drugs first is a sensible option.¹ Anticonvulsants can be tried where "shooting pain" is unresponsive to tricyclics.
The Bandolier pain website provides useful information on pain sensation and transmission, and includes systematic reviews of evidence for treatment, including numbers-needed-to-treat (NNTs).² Anyone requiring further evidence for the rationale behind setting up a pain clinic will find this a useful and informative source.

Why set up a specialised clinic?

Chronic nerve damage pain is underdiagnosed and many patients are treated inappropriately with traditional analgesics, which provide minimal pain relief. In addition, waiting times for anaesthetist-led hospital pain clinics are often upwards of six months. Early intervention with adequate doses of antidepressants or anticonvulsants not only provides faster relief for the patient but may also obviate the need for hospital referral, reducing waiting times for those who genuinely need specialist intervention.
The hospital pain clinic staff in Tayside were keen to assess how well patients could be managed in primary care. This was in order to reduce their waiting list time while maintaining appropriate hospital referral. Patient compliance may be affected by unpleasant side effects associated with antidepressants or anticonvulsants. However, careful dosage titration, together with patient counseling and the setting of realistic targets for pain relief, are essential if maximum benefit is to be achieved. This can be a time-consuming process and is unlikely to be achieved within a normal surgery consultation. The multidisciplinary practice team at Downfields surgery in Dundee, therefore, decided to set up a pharmacist-led clinic that offered support to patients with neurogenic pain.

The process

A management protocol was developed and agreed with the anaesthetist who managed the local hospital pain clinic (see Figure 1). In addition, referral criteria were drawn up for the GPs (see Figure 2). It was essential that patients referred for pharmacist management had been assessed and diagnosed appropriately to rule out any important physical causes of the pain that might require surgery or alternative intervention.
It is difficult to assess pain because tolerance varies between individuals and there is no objective way to measure pain levels. However, a clinic was held weekly to see patients from four categories:

• Patients presenting at the surgery with new nerve-related pain
• Patients who were not well controlled on current therapy and were usually managed by a GP
• Patients attending the physiotherapist or consultant orthopaedic clinic and were suitable for review of therapy
• Patients identified by practice computer searches as being on long-term medication for pain (eg, non-steroidal anti-inflammatory drugs and/or conventional analgesics), who had evidence of a neurogenic component to their pain

At the patient's first appointment, a pain history was recorded, including the site, intensity and a description of the pain. In addition, medication previously tried and its effects/outcomes were recorded (see Figure 3). Although at the Downfield practice we used an analogue pain scale to assess current levels, the patient's previous experience is the most accurate method available. Baseline liver function tests (LFTs) were measured to monitor for possible future adverse effects from carbamazepine or sodium valproate. This process could take up to 30 minutes, but time spent at the first appointment was essential for successful future management. Follow-up appointments lasting 15 to 20 minutes were booked at increasing time intervals, with patients encouraged to telephone for advice in between, if required. Patients were encouraged to telephone the pharmacist whenever they needed advice or information and could self-refer at any time.
A prescription was computer generated by the pharmacist in line with the agreed protocol and signed by the GP. (I hope that "dependent prescribing" status will eventually enable pharmacists to sign prescriptions themselves.)
Since it is not always possible to eliminate pain completely, adequate patient education and involvement is vital to achieving good pain management. Discussing their pain allows patients to set realistic targets of pain relief and to learn what action it is appropriate to take to make it more manageable. An information leaflet has been developed in conjunction with the hospital anaesthetist and a nurse at the hospital pain clinic. It is used to reinforce verbal information about medicines prescribed and is given to the patient during the consultation. The information given includes common side effects and ways to control or minimise them.
We sometimes give patients a trial of transcutaneous electrical nerve stimulation (TENS) when other treatments are inappropriate or have failed to provide adequate pain relief. TENS stimulates certain nerve fibres and blocks pain impulses to the brain. Evidence for effectiveness is lacking but individual patients do seem to respond to this treatment. Patients are referred to the physiotherapist for instruction on where and how to apply the electrodes and how to operate the equipment to achieve maximum benefit.

Clinic assessment

Peer review was used to assess the quality of pharmacist-led management of patients with neurogenic pain. Case histories were summarised and reviewed by the consultant who recorded how he would have treated the same patient. The pharmacist and anaesthetist then got together to discuss these cases. So far, little variation in management has been identified. The hospital tended to initiate TENS at an earlier stage, possibly because it had more equipment available. In addition, the hospital did not measure baseline LFTs but conceded that this should become standard practice.

What do patients think?

The clinic has proved to be popular with patients. To be seen within two weeks of initial GP presentation has improved the quality of care for the patient and enabled many to achieve adequate management of their condition before the consequences of long-term suffering, including depression and even deterioration in family relationships, has set in.
Patients who have suffered from pain for a number of years are pleased to have an interest shown in a condition that they have accepted as permanent. Some of this group may respond to trials of tricyclics and anticonvulsants. Others, who have tried these medicines before and stopped because of side effects, have subsequently benefited from starting at a low dosage, which is then titrated up to a dose that maximises pain relief, while keeping side effects at a level the patient can tolerate. Elderly patients seemed to respond to nortriptyline, rather than amitriptyline, experiencing fewer side effects. Explaining the goals of therapy and working together to achieve them has been an important step forward in managing patients with chronic pain.

What did the anaesthetist think?

Patients referred from the pharmacist-led clinic to the hospital pain clinic were known to have had an adequate trial of appropriate medication at the maximum dose the patient could tolerate. This allowed specialist services only available via the hospital (eg, nerve blocks, and surgical intervention) to be undertaken at an earlier stage after referral. Expansion of appropriate pain management in primary care would reduce the waiting times for patients requiring this specialist input.

What did the GPs think?

GPs benefited from having more time to see other patients, while knowing that patients with chronic nerve damage pain were being cared for, were receiving more appropriate medicines and were more likely to take the medicines recommended to them. Improved safety monitoring for liver and renal adverse effects was also achieved.

Conclusion

Improving pain control does not necessarily mean more work for GPs. A pharmacist-led service can significantly improve outcomes and provide a great deal of job satisfaction for the pharmacist.

Mr Hamley is the primary care trust chief pharmacist from Tayside

References