Slower disease progression and prolonged survival in contemporary with amyotrophic patients lateral sclerosis - Is the natural history of amyotrophic lateral sclerosis changing?

Background: In recent years, considerable effort has been made to improve the treatment of patients with amyotrophic lateral sclerosis (ALS). However, despite the increased use of supportive measures, controversy still exists about overall trends in disease progression and survival. Objective: To analyze whether survival and disease progression in patients with ALS have changed during the past 20 years. Design: By using the Kaplan-Meier life-table method, we compared disease progression (measured as time to a 20-point increase in the Appel ALS score) and survival in 1041 patients diagnosed as having ALS between January 1, 1984, and January 1, 1999 (historical group, n = 647), and between January 2, 1999, and November 1, 2004 (contemporary group, n = 394). The Cox proportional hazards model was used for univariate and multivariate analyses. Results: The median survival from symptom onset was 4.32 years (95% confidence interval [CI], 3.81-4.84 years) in the contemporary group compared with 3.22 years (95% CI, 3.04-3.41 years) in the historical group (P <.001). The contemporary patients progressed more slowly (10 months to a 20-point increase; 95% CI, 9-13 months) compared with patients in the historical group (9 months to a 20-point increase; 95% CI, 8-9 months) (P <.001). In the multivariate Cox proportional hazards model, the observed outcome improvement over time was independent of confounding factors, such as age, sex, diagnostic delay, site of symptom onset, baseline forced vital capacity, and baseline Appel ALS score, and independent of the use of potentially outcome-modifying therapies (riluzole, noninvasive ventilation, and percutaneous gastrostomy). Conclusions: Contemporary patients had significantly prolonged survival and slower disease progression compared with patients from the historical group. The improved outcome seemed independent of specific ALS outcome-modifying therapies, but we cannot rule out an effect of comorbid conditions, which could have influenced medical treatment and survival. Nevertheless, our observations suggest the possibility that disease course has changed and that ALS is becoming less aggressive over time. Further studies are needed to determine whether there has been a fundamental change in the natural history of the disease or whether our results are because of other unmeasured aspects of improved multidisciplinary care.