Phenotyping the prodrome 5 years before clinical recognition of multiple sclerosis (MS) is feasible, according to a recent study. Using data from a population-based cohort study linking administrative and clinical data, researchers compared physician and hospital encounters and prescriptions filled (via International Classification of Diseases chapters, physician specialty or drug classes) for MS subjects in the 5 years before the first demyelinating claim in an administrative cohort or the clinical symptom onset in an MS clinic-derived cohort, to age-, sex- and geographically matched controls. They found:

• The administrative and clinical cohorts included 13,951/66,940 and 3,202/16,006 people with and without MS (cases/controls).
• Compared to controls, in the 5 years before the first demyelinating claim or symptom onset, cases had more physician and hospital encounters for the nervous (RR [range]=2.31), sensory (RR [range]=1.40), musculoskeletal (RR [range]=1.19), and genito-urinary systems (RR [range] =1.17).
• Cases had more psychiatrist and urologist encounters (RR [range]=1.48), and higher proportions of musculoskeletal, genito-urinary, or hormonal-related prescriptions (1.1–1.5 times higher).
• However, cases had fewer pregnancy-related encounters than controls (RR=0.78).