Does a modifiable risk factor score predict disability worsening in people with multiple sclerosis?

BACKGROUND: Risk factors for chronic disease include smoking, hazardous alcohol consumption, physical inactivity, unhealthy body mass index and poor diet (SNAP factors). In multiple sclerosis (MS) SNAP factors are associated with health outcomes such as disability in cross-sectional studies, but longitudinal data are lacking. OBJECTIVE: The objective of this study was to assess whether a combined SNAP risk score predicts disability worsening. METHODS: Longitudinal self-reported data from two time-points 2.5 years apart from an international survey of 1225 people with MS were used in linear regression models adjusted for potential confounding. Disability worsening was measured using the patient-derived Multiple Sclerosis Severity Score. RESULTS: The majority (62%) had two or more risk factors, with insufficient fruit and vegetable intake (83%), unhealthy body mass index (42%) and physical inactivity (33%) most common. Some SNAP factors at follow-up were associated with disability at follow-up (cross-sectionally), and in addition there was some evidence that increasing risk factors was associated with disability worsening over the 2.5 year study period. Baseline SNAP score was not predictive of disability worsening at follow-up, however. CONCLUSION: Known risk factors for morbidity and mortality were common and associated with disability cross-sectionally, but not prospectively. Further studies using longer time frames, objective measures and interventions may elucidate potential benefits from changes in risk factors on MS outcomes.