Investigators Describe the MS Prodrome

The prodrome of multiple sclerosis (MS) may include an increased risk of nervous system, sensory, and musculoskeletal disorders, according to research published online ahead of print July 1 in Multiple Sclerosis Journal. Patients who later develop MS also may be more likely to have genitourinary and psychiatric symptoms in the five years before diagnosis.

Helen Tremlett, PhD

“The existence of such warning signs is well-accepted for Alzheimer’s disease and Parkinson’s disease, but there has been little investigation into a similar pattern for MS,” said Helen Tremlett, PhD, Professor in the Division of Neurology at the University of British Columbia in Canada. “We now need to delve deeper into this phenomenon, perhaps using data-mining techniques. We want to see if there are discernible patterns related to sex, age, or the type of MS they eventually develop.”

Clinical and Administrative Matched Cohorts

Dr. Tremlett and colleagues analyzed data from a matched-cohort record-linkage study to examine the MS prodrome. The investigators used population-based health administrative data and clinical data from the Canadian provinces of British Columbia, Saskatchewan, Manitoba, and Nova Scotia. The information included demographics, hospital visits, physician encounters, and prescriptions filled. Clinical data were for patients diagnosed by a neurologist at an MS clinic and included first clinical visit (or date of diagnosis) and date of symptom onset. Data were collected from April 1984 to April 2014.

Using the data, Dr. Tremlett and colleagues created a health-administrative cohort and a clinical cohort. The clinical cohort did not include data from Saskatchewan. To create the cohorts, the investigators identified patients with MS and matched them by sex, year of birth, and postal code with as many as five controls. The index date was the earliest recorded claim for a demyelinating disease for the health-administrative cohort and the date of MS symptom onset for the clinical cohort. Study outcomes were the number of physician and hospital encounters per ICD-10 chapter, the number of physician encounters per physician specialty, and the percentage of people with one or more prescriptions per drug class in the five years before the index date.

Clinical Cohort Results May Be More Accurate

The administrative cohort included 13,951 cases and 66,940 controls. The clinical cohort included 3,202 cases and 16,006 controls. Compared with controls, people with MS had more physician and hospital encounters for the nervous (rate ratio [RR], 2.31 to 4.75), sensory (RR, 1.40 to 2.28), musculoskeletal (RR, 1.19 to 1.70), and genitourinary systems (RR, 1.17 to 1.59) in the five years before the first demyelinating claim or symptom onset. Cases had more visits with psychiatrists and urologists (RR, 1.48 to 1.80) and higher proportions of musculoskeletal, genitourinary, or hormonal-related prescriptions (1.1–1.5 times higher), compared with controls. People with MS had fewer pregnancy-related encounters than controls, however (RR, 0.78 to 0.88).

The “more conservative” results for the clinical cohort are more likely to reflect the MS prodrome accurately because they are “unlikely to be influenced by a physician’s suspicion or consideration of MS,” said Dr. Tremlett and colleagues. “Although not all individuals with MS attend an MS specialty clinic, the clinical cohort represents a subgroup of the population that may differ with respect to demographic and clinical characteristics from nonclinic attendees (eg, have fewer comorbidities),” they added. NR

—Erik Greb

Suggested Reading

Wijnands JM, Zhu F, Kingwell E, et al. Five years before multiple sclerosis onset: Phenotyping the prodrome. Mult Scler. 2018 Jul 1 [Epub ahead of print].