Systemic inflammation and subsequent risk of amyotrophic lateral sclerosis: prospective cohort study.

IMPORTANCE

While systemic inflammation has been implicated in the aetiology of selected neurodegenerative disorders, its role in the development of amyotrophic lateral sclerosis (ALS) is untested.

OBJECTIVE

To quantify the relationship of C-reactive protein (CRP), an acute-phase reactant and marker of systemic inflammation, with ALS occurrence.

DESIGN SETTING PARTICIPANTS

UK Biobank, a prospective cohort study of 502,649 participants who were aged 37 to 73 years when examined at research centres between 2006 and 2010.

EXPOSURE

Venous blood was collected at baseline in the full cohort and assayed for CRP. Repeat measurement was made 3-7 years later in a representative subgroup (N=14,514) enabling correction for regression dilution.

MAIN OUTCOMES AND MEASURES

ALS as ascertained via national hospitalisation and mortality registries. We computed multi-variable hazard ratios with accompanying 95% confidence intervals for log-transformed CRP expressed as standard deviation and tertiles.

RESULTS

In an analytical sample of 400,884 individuals (218,203 women), a mean follow-up of 12 years gave rise to 231 hospitalisations and 223 deaths ascribed to ALS. After adjustment for covariates which included health behaviours, comorbidity, and socio-economic status, a one standard deviation higher log-CRP was associated with elevated rates of both ALS mortality (hazard ratios; 95% confidence intervals: 1.32; 1.13, 1.53) and hospitalisations (1.20; 1.00, 1.39). There was evidence of dose-response effects across tertiles of CRP for both outcomes (p for trend≤0.05). Correction for regression dilution led to a strengthening of the relationship with CRP for both mortality (1.62; 1.27, 2.08) and hospitalisations (1.37; 1.05, 1.76) ascribed to ALS.

CONCLUSIONS AND RELEVANCE

Higher levels of CRP, a blood-based biomarker widely captured in clinical practice, were associated with a higher subsequent risk of ALS.

KEY POINTS

Is C-reactive protein (CRP), a marker of systemic inflammation widely used in clinical practice, associated with later risk of amyotrophic lateral sclerosis (ALS)? Following 11 years disease surveillance in 400,884 individuals (218,203 women), after adjustment for covariates and correction for regression dilution, a one standard deviation higher CRP levels were associations with both mortality (hazard ratio; 95% confidence interval: 1.62; 1.27, 2.08) and hospitalisations (1.37; 1.05, 1.76) ascribed to ALS. In the present study, CRP has a dose-response relationship with the risk of later ALS.