[Exogenous factors in the aetiology of multiple sclerosis in Cuba. A study of cases and controls].

Introduction: Descriptive epidemiological studies indicate that the prevalence of multiple sclerosis (MS) in Cuba is in the mid range of risk. It is not known what exogenous factors may be related to the aetiology of MS.

Objective: To study the exogenous factors possibly related to the aetiology of MS in the central provinces of Cuba.

Patients And Methods: We studied all the patients with definite clinical MS (Poser et al) with positive MR who came from the provinces of Cienfuegos, Villa Clara and Sancti Spiritus. The protocol was approved by the Medical Ethics Committees of each of the three institutions and reviewed by two international authorities on the subject. Each of the patients (cases) and one member of their family (control), after written consent, when they fulfilled the criteria for inclusion in the study, were personally interviewed by trained persons and the questionnaire for studying cases and controls of Boiko et al was completed. The questionnaire had been adapted for use in Cuba. The main data obtained were: demographic data, history of occupation and residence, personal medical history, exposure to possibly toxic substances, diet and nutrition, contact with animals and life style. For measurement of risk we used the risk of the results of the crossed products odds ratio (OR) with its confidence interval (CI), always insisting on precision of 95%.

Results: High educational level (OR= 2.293; 95% CI= 0.9 5.4), two or more children (OR= 2.84; 95% CI= 1.22 6.59), four or more pregnancies (OR= 3.60; 95% CI= 0.69 18.7), three or more deliveries (OR= 1.939, 95% CI= 0.44 8.4); previous measles infection (OR= 2.042; 95% CI= 0.76 5.47), a history of migraine (OR= 2.538; 95% CI= 0.81 7.94); stress (OR= 3.768; 95% CI= 1.64 8.62) and insomnia (OR= 2.95; 95% CI= 1.14 7.14) were the factors related to MS.

Conclusions: This study confirmed the existence of exogenous factors in the aetiology of patients with clinically defined MS and positive MR findings who lived in the provinces studied in Cuba. The exogenous factors found in this population of patients with MS were: high educational level, two or more children, four or more pregnancies, three or more deliveries, previous measles, a history of migraine, stress and insomnia.