Epidemiological studies in the United Kingdom; incidence and lifetime prevalence rates of neurological disorders, and the prognosis of seizures

Two community-based neuroepidemiological studies in the United Kingdom constitute the basis of this thesis. I The National Hospital for Neurology and Neurosurgery General Practice Linkage Study The population of thirteen general practices was studied in order to describe the incidence and lifetime prevalence of neurological disorders. Over an eighteen month period all incident cases of neurological conditions were ascertained prospectively in this defined urban population. Multiple case ascertainment methods were employed to address the difficulties inherent in neuroepidemiological case-finding. At the end of the period all the general practice notes were hand searched. In three practices lifetime prevalence was also surveyed. Overall 0.6% of the population per year had an incident neurological condition and 6% had had a neurological diagnosis m their life. The annual incidence and lifetime prevalence rates for the individual neurological disorders are reported. II The National General Practice study of Epilepsy Patients who presented for the first time with an epileptic seizure were recruited between 1984 and 1987 forming a prospective community-based cohort. These patients have been followed subsequently in order to study the long-term prognosis for recurrence and remission of seizures. a) The prognosis for febrile convulsions Within this cohort were 220 children who had experienced febrile convulsions. The risk of subsequent development of epilepsy or neurological deficit using a Cox proportional hazards model with time-dependent co-variates was examined. In this cohort 6% had developed epilepsy by thirteen years. b) The prognosis for epilepsy from first presentation The baseline and remission data from the 792 patients recruited with seizures was analyzed using a Cox proportional hazards model to determine factors which are predictive of prognosis. A single dominant determinant was found - the higher the number of seizures occurring between first presentation and six months the lower were the chances for remission