Huw T.O. Davies

Cut and thrust : antecedent surgery and trauma among patients attending a chronic pain clinic

&NA; Surgery and trauma are recognised as important causes of chronic pain, although their overall contribution has not been systematically studied. This paper reports on the contribution of surgery and trauma to chronic pain among 5130 patients attending 10 outpatient clinics located throughout North Britain. Surgery contributed to pain in 22.5% of patients, and was particularly associated with the development of pain in the abdomen and with anal, perineal and genital pain. Trauma was a cause of pain in 18.7% of patients, and was most common in pain in the upper limb, the spine and the lower limb. Patients with chronic pain associated with trauma are on average younger than those with chronic post‐surgical pain. Further, and unusually for pain conditions, the trauma patients show an excess of males over females. These findings indicate that it can be unhelpful for pain classification systems to combine surgery and trauma in a single category. The results also point to areas for potentially fruitful research into the aetiology of chronic pain. In particular, studies are needed to identify the operative procedures associated with the development of pain so that preventive measures can be implemented.

Simulating health systems: modelling problems and software solutions

Discrete event simulation is well suited to modelling health systems, providing valuable information for operational or strategic purposes. Simulation packages provide facilities for creating models in which individuals pass through a series of queues and activities. Modelling problems arise in health systems because patients renege from queues, take part in multiple activities, prematurely terminate activities, and change activities midstream. Simulation structures have been developed in Pascal to facilitate the description of these modelling complexities. Illustrations of the softwares use are taken from an example of a simulation of patients with renal failure.

Consensus and contention in the treatment of chronic nerve-damage pain

&NA; A postal questionnaire survey was carried out to investigate beliefs in the efficacy of specific treatments held by consultants involved in the treatment of chronic nerve‐damage pain. One hundred eighty‐eight consultants experienced in the treatment of chronic pain were identified by local Pain Clinic consultants in 5 centres. The specialties represented were neurology, neurosurgery, orthopaedic surgery, oncology/radiotherapy, plastic surgery and anaesthesia. Replies were received from 181 consultants (96%). Over one fifth of the consultants expressed no opinion about half of the treatments assessed. Widely divergent views were held by those who did give an opinion. Many clinicians assessed some treatments as ‘poor’ while other clinicians assessed the same treatments as ‘excellent’ (neurolytic nerve block, somatic nerve block, cortodomy and opioids). For some treatments divergence of opinion can be explained in part by differences between specialties. For other treatments marked diversity was seen within as well as between specialties. There is a clear need for education in the use of particular treatments, even amongst those clinicians who regularly see this type of patient.

Polarised views on treating neurogenic pain

&NA; This study aimed to identify areas of disagreement in the management of neurogenic pain. A short questionnaire was mailed to 179 consultants with an interest in chronic pain (response rate 89%). The questionnaire listed 11 specific conditions involving nerve pain (e.g., post‐herpetic neuralgia, causalgia) together with 11 treatments (e.g., antidepressants, neurectomy). Consultants were asked to rate the use of each treatment for each condition as ‘appropriate’, ’no value or positively harmful’ or ‘no opinion’. Much disagreement emerged about the value of each therapy for each condition: in almost every instance at least some consultants disagreed with the majority view. The dissenting minority was greater than 20% of those who gave an opinion for 48 of the 121 applications of therapy asked about. The appropriateness of treatments for trigeminal neuralgia, amputation stump pain and phantom pain was most often in dispute and there was little consensus on the value of nerve blocks. There were a few areas of near agreement. Antidepressants and anticonvulsants were mostly identified as appropriate for all the conditions listed and there was some agreement that strong opioids and the neuroablative techniques were appropriate for cancer pressure or infiltration of nerves but, with a few exceptions, of no value for all other neurogenic pain conditions. Divergence of views about treatments may indicate a lack of credible evidence on the value of therapies or a lack of professional knowledge. Where published evidence is clear, the consequences for patients may be under‐use of useful therapies or potential iatrogenic harm.

Why use a pain clinic? Management of neurogenic pain before and after referral.

Pain arising from damage or malfunction of the nervous system (for example postherpetic neuralgia, peripheral nerve injuries and the neuropathies) is often severe and resistant to standard analgesics. These patients are commonly seen in pain clinics where they receive a variety of treatments including psychotropic drugs (such as antidepressants and anticonvulsants), nerve blocks and stimulation. There is concern that the management of these difficult patients may be less than optimal where they are not seen by pain specialists. We examined a cohort of 703 patients with long-established nerve-damage pain seen in ten outpatient pain clinics. We compared their use of treatments prior to referral with the management given in the pain clinic. The majority of patients (79%) had had their pain for over 1 year before being seen in the pain clinic, yet many had not tried simple and effective treatments prior to referral. Less than a quarter had received an adequate trial of antidepressants; only one in seven had been appropriately treated with anticonvulsants; and only one in 10 had tried a nerve stimulator. All these treatments were frequently provided in the pain clinic. Referral of patients with nerve-damage pain to a pain clinic may greatly increase their access to therapies of proven value.

Waiting in pain. Delays between referral and consultation in outpatient pain clinics.

Patients with chronic pain may benefit from referral to a pain specialist. This study describes the delay between referral and first appointment of 3386 new referrals seen in ten outpatient pain clinics between 1990 and 1992. We then assess the follow‐up patterns of the pain clinics and how these relate to waiting times. Patients wait in pain for long periods before being seen in a pain clinic. In 1992 about half of patients waited more than 3 months for an appointment at a teaching hospital pain clinic; and half waited 9 weeks or longer to be seen at a district general hospital pain clinic. In many clinics the situation is worsening. Pain clinics differ widely in their patient follow‐up, with patients averaging more than twice as many visits in some clinics than others. Clinic practice on reappointing patients largely determines the number of new referrals who can be accepted for management, and hence affects waiting lists. Thus our data suggest that pain clinics themselves can help reduce waiting times, by changing the extent and nature of patient follow‐up. Ultimately, however, additional consultant sessions may be needed to enable pain clinics to meet the increasing demands placed on them.

Shaping attitudes to postoperative pain relief: The role of the acute pain team

Postoperative pain relief is often inadequate. Ignorance and misconceptions about opioids by ward staff contribute to this poor management. The introduction of acute pain teams has done much to improve pain relief for patients. It may also have contributed to changes in attitudes and knowledge of medical and nursing staff. We questioned 48 doctors and nurses on their knowledge and beliefs about postoperative pain relief. Staff members were questioned on two units, one with access to an acute pain team and one without. Over half those on the unit using traditional postoperative care thought patients did not receive adequate pain relief (58%). In comparison, only one respondent from the unit with the pain team thought this was the case (P < 0.001). More staff members that had experience of patient-controlled analgesia (PCA) were optimistic about its benefits than those in the unit with no experience; they were also less concerned about possible side effects. Only one respondent on the unit using PCA thought it carried a risk of drug dependence, compared to over half (55%) of those on the unit with no experience in this technique (P < 0.001). Over two-thirds of staff familiar with PCA thought nursing workload had decreased. Acute pain teams have an important role in educating ward staff. The impact of establishing such teams on staff knowledge and attitudes needs further study to ensure that they can carry out this role most effectively.

Entering the loop: assessing the contribution of pain clinics in northern Britain

A survey of patients attending ten outpatient pain clinics throughout northern Britain was undertaken to identify opportunities for improving the treatment of pain patients. A short data collection form was designed to obtain information at every patient consultation. The patients were found to be a diverse group, many with complex pain problems. For many patients meaningful diagnoses could not be obtained. The focus of the study was altered to address a selected group of patients: those with neurogenic pain. This group was selected because it was comparatively easy to define, and previous studies suggested that nerve damage pain might not always be well managed. Many patients were found not to have had adequate trials of potentially effective therapies prior to attendance at the pain clinics. Some of these therapies, such as antidepressants and anticonvulsants, could have been prescribed by general practitioners. However, there were also substantial differences between the clinics in the proportion of patients receiving particular therapies. Finally, although many patients had psychological morbidity few were offered psychological assessment and management. These studies have shown that the pain clinics provide a range of therapies which patients are unlikely to receive elsewhere. But there is scope for improvement in the management of patients in pain clinics and efforts are currently being directed towards this.

Interpretation and Uses of Medical Statistics

This fifth edition has undergone major restructuring, with some sections completely rewritten; it is now more logically organized and more user friendly (with the addition of summary boxes throughout the text). It incorporates new statistical techniques and approaches that have made an appearance since the last edition. In addition, some chapters or chapter headings are specifically marked to signify material that is more difficult than the material in which it is embedded such sections or chapters can be omitted at first reading.