Prognostic significance of body weight variation after diagnosis in ALS: a single-centre prospective cohort study

Body weight reduction after disease onset is an independent predictor of survival in amyotrophic lateral sclerosis (ALS), but significance of weight variation after diagnosis remains to be established.

To investigate weight variation after diagnosis and its prognostic significance in patients with ALS as a prospective cohort study.

Seventy-nine patients with ALS were enrolled in this study. At the time of diagnosis and about 1 year later, we evaluated the following parameters: age, sex, onset age, onset region, body mass index (BMI) and premorbid BMI, forced vital capacity and the revised ALS functional rating scale. Annual BMI decline rates (∆BMI) from onset to diagnosis and from diagnosis to about 1 year later were calculated. Patients were followed to the endpoints (death or tracheostomy), and the relationships between ∆BMIs and survival were investigated.

Patients with post-diagnostic ∆BMI ≥ 2.0 kg/m²/year showed shorter survival length than those with < 2.0 kg/m²/year (log-rank test, p < 0.0001), and multivariate analysis using the Cox model revealed post-diagnostic ∆BMI as an independent prognostic factor. No correlation was identified between pre- and post-diagnostic ∆BMIs. Female patients with post-diagnostic ∆BMI < pre-diagnostic ∆BMI showed longer survival than those with the opposite ∆BMI trend (log-rank test, p = 0.0147). Female patients with post-diagnostic weight increase showed longer survival than those with weight decrease (log-rank test, p = 0.0228).

Body weight changes after diagnosis strongly predicts survival in ALS, and weight gain after diagnosis may improve survival prognosis, particularly in female ALS patients.