Epidemiology and treatment of neuropathic pain: the UK primary care perspective.

The true incidence of neuropathic pain is unknown, but it is believed to be under-diagnosed and treated inadequately, despite the availability of drugs with proven efficacy. Our objective was to report the epidemiology and drug treatment of neuropathic pain as managed by UK primary care physicians. A descriptive analysis of the epidemiology of incident post-herpetic neuralgia (n=12,386); trigeminal neuralgia (8268); phantom limb pain (451) and painful diabetic neuropathy (4719) and prescription treatment at diagnosis from computerised UK general practice records (GPRD): January 1992 to April 2002. Incidences per 100,000 person years observation of 40 (95% CI 39-41) for post-herpetic neuralgia, 27 (26-27) for trigeminal neuralgia, 1 (1-2) for phantom limb pain and 15 (15-16) for painful diabetic neuropathy are reported, with rates decreasing over time for phantom limb pain and post-herpetic neuralgia and increasing for painful diabetic neuropathy. Drugs were initiated at first diagnosis record for 46-66% of conditions, usually one item, with antidepressants included in 30% of prescriptions, anticonvulsants in 20% and opioid analgesics in 20%. The most commonly prescribed items were the same across conditions; amitriptyline, carbamazepine, coproxamol, codydramol and codeine+paracetamol. Carbamazepine was prescribed to 58% of the trigeminal neuralgia cohort. In 2600 patients followed to stable therapy, there was a median of one to two drug changes. We provide the primary care managed incidence of four neuropathic pain conditions. For commonly prescribed treatments, changes in therapy are less frequent when initial therapy was with antidepressants or anticonvulsants rather than conventional analgesics.