Epidemiology of Multiple Sclerosis in the Counties of Northumberland and Durham
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J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.26.4.368 on 1 August 1963. Downloaded from J. Neurol. Neurosurg. Psychiat., 1963, 26, 368 Epidemiology of multiple sclerosis in the counties of Northumberland and Durham DAVID C. POSKANZER', KURT SCHAPIRA2, AND HENRY MILLER From the Department ofNeurology, the Royal Victoria Infirmary, and the Medical Research Council Research Group on Demyelinating Diseases, Newcastle upon Tyne Considerable variations in the scope and the methods The present investigation was undertaken to of ascertainment employed in different epidemiolo- study the epidemiological features of multiple gical studies, to say nothing of divergent diagnostic sclerosis in Northumberland and Durham, com- criteria, have seriously jeopardized the value of many prising a comparatively stable population of over such observations in estimating the true prevalence two million people of relatively uniform racial stock. of multiple sclerosis in various parts of the world. This population is served by two neurologists Acheson has pointed out that studies based on based on the Medical School in Newcastle upon mortality statistics (Limburg, 1950; Acheson, 1961) Tyne. Over the past 30 years only three individual are subject to misreporting and under-reporting and closely associated consultant neurologists haveguest. Protected by copyright. which reduce their accuracy and comparability. furnished this service, ensuring a uniformity in Studies of hospital records (Chiavacci, Hoff, and diagnostic standards, the lack of which has often Polvan, 1950), augmented on occasion by inter- presented one of the major difficulties in studies of views of practising physicians and examination of this kind. death certificates (Ipsen, 1950), represent further Northumberland is the most northerly English attempts to obtain more accurate data. Investigations county, bounded by Durham to the south and west- of special population groups such as U.S. veterans wards by Cumberland (see Fig. 1). It comprises (Acheson and Bachrach, 1960; Acheson, Bachrach, an area of over 2,000 square miles with a population and Wright, 1960), for which comprehensive medical of 811,400 (1958 census estimate), a large proportion records are available, have afforded opportunities of which is employed in mining and shipbuilding for more circumscribed studies. in the small but thickly peopled south-eastern part However, the personally conducted population of the county. Durham is a more densely populated survey, drawing on every available source to compile county with a population of 1,497,000 (1958 census a comprehensive register of patients, has been estimate) occupying an area of approximately 970 recognized as a superior method. Essential to the square miles. Its economy is mainly dependent on survey is the establishment of firm diagnostic criteria, heavy industry, a third of those employed being which not only lend reliability to the investigation engaged in mining, quarrying, or shipbuilding. but also permit the subsequent employment of data http://jnnp.bmj.com/ in authentic comparative studies. One such survey METHODS in the field of multiple sclerosis was published more than 30 years ago (Allison, 1931) and important CASE COLLECTION Letters were sent to all general contributions on similar lines have been made by practitioners in the two counties requesting a report on MacLean, Berkson, Woltman, and Schionneman all cases of multiple sclerosis in their practices. Most of (1950), Allison and Millar (1954), Hyllested (1956), these practitioners were working in the framework of Sutherland (1956), and Alter, Allison, Talbert, and the National Health Service but the small group engaged entirely in private practice was also included. Practitioners Kurland (1960). These observations furnish a on September 27, 2021 by valuable frame of reference for studies now under who failed to reply were circulated a second time. Those of the world. outstanding after the second letter were then offered a way in several other parts modest financial inducement to report: on this occasion 'Of the Department of Epidemiology, Harvard School of Public most replied, almost invariably waiving the fee. The Health, and Department of Neurology, Massachusetts General National Health Service lists of those replying comprised Hospital. Formerly Moseley Travelling Fellow of Harvard University. 92-5 % of the estimated population of the two counties. 2This work was based in part on a thesis for the degree of Doctor of The data concerning the response are summarized in Medicine in the University of Durham. Table I. Although 11-4% of the practices were not 368 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.26.4.368 on 1 August 1963. Downloaded from Epidemiology ofmultiple sclerosis in the counties of Northumberland and Durham 369 N guest. Protected by copyright. 'W.Hartlepool ton -on -Tees FIG. l. Counties ofNorthumberland and Durham showing cities with a population of50,000 or greater. http://jnnp.bmj.com/ TABLE I RESPONSE OF GENERAL PRACTITIONERS TO REQUEST FOR REPORTING OF PATIENTS WITH MULTIPLE SCLEROSIS Northumberland Durham Total on September 27, 2021 by General practitioners reporting 366 481 847 Practices reporting 199 277 476 Percentage practices not reporting 11-6 11-2 11-4 Cases reported as multiple sclerosis 410 604 1,0141 Total patients in practices 752,111 1,383,213 2,135,324 Census estimate of population 811,400 1,497,000 2,308,400 Percentage population represented by doctors' reports 92-7 92-4 92-5 'Of this group 260 patients were not suffering from multiple sclerosis, had onset after 1 January 1958, or resided outside the counties of Northumberland and Durham. J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.26.4.368 on 1 August 1963. Downloaded from 370 David C. Poskanzer, Kurt Schapira, and Henry Miller reported, they represented only 7-5 % of the population, lesions in time and space.' The patients were designated presumably because some physicians who failed to report as cases of 'probable' multiple sclerosis when they were no longer in practice, had left the area, or had small unequivocally satisfied these clinical criteria and when practices. The reporting was remarkably similar in the there was little reasonable doubt about the diagnosis. two counties. Of the 1,014 cases reported by practitioners, Neither was there much doubt in cases classified as 260 were eliminated because they were found later not to 'latent' multiple sclerosis. Although these patients were be suffering from multiple sclerosis, or because they asymptomatic at the time of examination, they gave a resided outside the counties of Northumberland or characteristic history of episodic multifocal neurological Durham or the onset was after prevalence day (1 January disease which defied alternative explanation. The term 1958). The first 700 cases reported (group A) were investi- 'possible' multiple sclerosis was applied in cases where gated intensively by clinical examination and an extended alternative diagnoses had been excluded as far as practic- anamnesis for use as a base-line population in clinical able and where the clinical picture was more suggestive trials. From group A, 636 cases were retained for the of multiple sclerosis than of any other recognizable study. From the remaining cases reported by practitioners neurological disorder. 118 additional patients, hereafter referred to as group B, were investigated only to establish diagnosis and to RESULTS obtain essential epidemiological information. While information was sought on cases reported by PREVALENCE After the elimination from the study general practitioners, a team of house physicians and of patients who did not suffer from the disease on final-year medical students searched the records of each 1 January 1958, who did not reside in the counties hospital in the region for patients with multiple sclerosis of Northumberland or Durham on that date, or residing in Northumberland or Durham on 1 January were believed after careful clinical evaluation not to 1958. Records of patients who had not been seen by one cases of the neurologists were investigated further. Hospital have multiple sclerosis, 1,156 remained for an- records were searched from the establishment of the alysis. The overall prevalence of established multipleguest. Protected by copyright. National Health Service in 1948 until 1960. The majority sclerosis in the two counties was 50-1 per 100,000 of these cases came from the records of the two neuro- population. This must clearly be regarded as a logists at the Royal Victoria Infirmary and the Newcastle minimal figure. We cannot estimate the number of General Hospital, which are associated with the Medical established cases which escaped our case-finding School in Newcastle. Twenty-seven other hospitals in the methods, but we believe that this figure would almost two counties were also visited and their records searched. certainly outweigh the instances in which we have When the last admission to hospital had taken place diagnosed multiple sclerosis in patients affected by before 1 January 1958, or where data were incomplete in some other disorder. Another obvious source of the hospital record, a letter and questionnaire were sent to the patient or if he was inaccessible to his practitioner, underestimation is the interval which elapses in who was traced through the National Health Service almost every case between initial symptoms, which registration records. In this way, 402 additional cases of