Risk factors in multiple sclerosis: a population-based case–control study in Sicily. Background and methods

Abstract

Incidence of multiple sclerosis (MS) has steeply increased over time during the last 30 years in the city of Catania. We carried out a population-based case-control study to evaluate the possible role of both environmental and genetic factors. From 1975 to 2004 in Catania, 367 MS patients diagnosed according to the Poser's criteria had the onset of disease. A sample of MS patients was randomly selected from this incident cohort. Three controls matched by age and sex were randomly selected from the rosters of 14 GPs. Controls were proportionally selected according to the distribution by municipality of the target population using a multistage sampling methods. All cases and controls underwent a face-to-face interview to record information concerning environmental factors and a blood sample was taken for serological and genetic analysis. 164 MS patients (64 % women; mean age of 46.4 ± 10.7) and 481 controls (69 % women; mean age of 47.7 ± 14.8) were enrolled in the study. The distribution of the whole population and the selected controls by municipalities was similar. A blood sample was taken from 150 MS cases and from 337 controls. At the end of the enrolment, we obtained a representative sample of the MS cases and population controls avoiding possible selection bias. Participation rate was very high also concerning the collection of biological specimens.

Seroprevalence of Toxocara canis in the city of Catania, Italy.

“…The study is part of a larger case-control study aimed to evaluate the role of both environmental and genetic factors and the risk of Multiple Sclerosis (MS) in the population of Catania. Background and methods have been extensively reported elsewhere 12…”

Toxoplasma gondii and multiple sclerosis: a population-based case–control study

“…The original sample of the case–control study consisted of 164 cases and 481 controls. Baseline characteristics (sex, age at onset, disease form and expanded disability status scale) of the 164 enrolled patients were not significantly different from the whole MS population (incident cohort of MS patients consisting of 367 patients) 11 . Out of the 164 MS patents a serum sample was available for 129 (78.6%) cases and 287 (59.6%) controls.…”

“…This is the first population-based case–control study carried out to evaluate the possible association between MS and T. gondii. MS patients, in fact, were randomly enrolled from a well-established cohort of incident MS patients, while controls were selected from the general population using a multistage sampling method 11 , thus reducing the risk of a possible selection bias among cases. Furthermore, along with the study carried out by Stascheit et coll.…”

“…The study gathered clinical data and serum samples from 164 MS patients and 481 age and sex matched controls. Background and methods have been extensively reported elsewhere 11 . Briefly, MS patients were randomly selected from an incident cohort of MS patients consisting of all incident cases in the city of Catania who had had the onset of disease from 1st January 1975 to 31st December 2004 and comprises 367 MS patients 12 – 14 .…”

“…All subjects have been asked the questions directly and in the case of a disability-related impairment in communication, to a proxy responder, preferably the spouse or sibling. Details of the screening instrument are reported elsewhere 11 .…”