Epidemiological study of multiple sclerosis in Israel: Part III Multiple sclerosis and socio-economic status

Abstract

The frequency of multiple sclerosis increases with latitude both in the northern and southern hemisphere (Dean, 1949;Kurland, Mulder, and Westlund, 1955;Acheson, Bachrach, and Wright, 1960;Sutherland, Tyrer, and Eadie, 1962). This peculiar distribution suggests that an environmental factor (or factors) whose distribution is also correlated with latitude plays a role in the aetiology of the disease. The nature of the environmental factor remains obscure, although a wide variety of factors, including climatic variables, e.g., sunlight, temperature, and cultural factors, e.g., diet, have been considered over the years. In view of the apparent difficulty in determining the nature of the aetiological agent in multiple sclerosis, attempts to narrow the range of possibilities have merit. In this regard, the observations of Miller, Ridley, and Schapira (1960) that multiple sclerosis is more common among individuals in the higher socio-economic classes deserves attention. It is generally true that the socio-economic level of populations in temperate zones where multiple sclerosis is common tends to be higher than in tropical regions where the disease is rare. Therefore, a relation between socio-economic level and the distribution of multiple sclerosis seems feasible and the aetiological agent could conceivably be some condition related to socio-economic status.Data collected in Israel afforded an opportunity to evaluate the suggestion of Miller et al. (1960) that there was a relation between socio-economic status and risk of multiple sclerosis, and Israel offers a number of advantages for studies of socio-economic factors in relation to chronic illnesses like multiple sclerosis. The country is small and its population is of a size permitting collection of data from the nation as a whole. Bias introduced by studying one region or another may thus be avoided in Israel. Moreover,

Is high socioeconomic status a risk factor for multiple sclerosis? A systematic review

“…Twelve case–control studies and one cohort study did not find an association between SES and MS risk. The cohort study included all incident cases in Denmark over a 26‐year period and benefited from contemporaneous collection of data on childhood SES.…”

“…Despite this strength, many of the case–control studies suffered from small sample sizes, resulting in wide confidence intervals which included large effect sizes along with the null value . Additionally, many studies used prevalent rather than incident cases . This increases the risk of bias as recall of events or exposures in the pre‐morbid state might be distorted by the length of time since diagnosis and the effect of disease .…”

Epidemiologic evidence for multiple sclerosis as an infection

“…Most retrospective case-control comparisons by a number of workers have revealed no significant associations, other than the accepted geographic variations (11,12,20,115,120,206,220,222,(224)(225)(226)282). Poskanzer (220,222) reported that patients had had a tonsillectomy in more instances than had either their spouses or their nearest siblings; however, these results have not been replicated.…”

“…Poskanzer (220,222) reported that patients had had a tonsillectomy in more instances than had either their spouses or their nearest siblings; however, these results have not been replicated. In the Israeli studies, there were possible inverse relationships with indices of poor sanitation and a direct relationship to some features of urbanization (12,20). Reports implicating canine distemper or dog exposure have been published, but to date these also remain unverified (see reference 151 for information up to 1983; later data do not seem to alter this conclusion).…”

Risk of Multiple Sclerosis in Relation to Industrial Activities: An Ecological Study in Four European Countries

“…Var ious approaches have been used to settle this The investigation of urban or rural origin of patients revealed conflicting results [1][2][3][4]. Evaluation of the occupational pattern of patients in comparison with the general pop ulation [5][6][7] or with control groups [8] showed either no, or no consistent, devia tion. When the time course of MS incidence was followed in defined regions over several years or decades during which industrializa tion took place, some authors found a fairly constant rate [9,10] whereas a considerable 1 Supported by the Hertie Foundation.…”