The influence of age at onset on the course of multiple sclerosis

Background/aim. Multiple sclerosis (MS) patients complain with the first symptoms of the disease in a period which varies from childhood to adult life. To date, the effective influence of age at onset on disease course is not clear. The main purposes of the present study were to evaluate and compare the influence of the age and age at onset on the disability progression in a population of sporadic and familial MS. Subjects/methods. The study population included 1744 cases of definite MS of whom 1463 sporadic (1039 from Apulia and 424 from Sardinia) and 281 familial cases (119 sibling and 36 parent/child pairs) belonging to 129 MS multiplex families (75 from Sardinia and 54 from Apulia). The analysis was performed by SPSS and SAS computing programs. Kruskall-Wallis, Kruskall-Wallis 1-Way Anova, Mann-Whitney and Wilcoxon signed-rank statistic tests were used. Results. In a sporadic MS population the current EDSS significantly correlated with the current age (P< 0.009). By grouping patients for current age classes of 5 years each, the age at onset did not influence (age< 25 years) or inversely correlated with the average EDSS (Kruskal-Wallis: P< 0.05). Using a multivariate analysis and considering disease duration as covariate, we demonstrated the significant effect of age (Kruskall-Wallis 1-Way Anova: P= 0.001) and not of age at onset on the EDSS severity. In sibling pairs the age at onset of proband (25.04 ± 7.3) was significantly lower than the age at onset of age-matched (30-50 years) sporadic patients (28.8 ± 6.9) (P< 0.0001). In parent/child pairs, age at onset of parents (43.5 ± 8.3) was significantly higher than in age-matched (45-65 years) sporadic cases (36.3 ± 9.3) (P= 0.0003), and affected children (AO: 21.7 ± 5.3) developed MS at an age significantly lower than age-matched (20-40 years) sporadic cases (24.1 ± 5.4) (P= 0.013). However, no differences were found in mean EDSS values between each familial group and the correspondent age-matched sporadic MS patients. Conclusion. The age at onset seems not to influence the MS outcome. Familial cases show an earlier disease onset than age-matched sporadic cases, suggesting even more the possible genetic influence on the disease onset.