Body mass index trends over four years in persons with multiple sclerosis

The role of obesity in persons with multiple sclerosis (PwMS) is incompletely understood. Obesity predisposes individuals to a pro-inflammatory state and cardiovascular comorbidities, both of which can negatively impact MS disease course. A better understanding of weight trends in PwMS will inform optimal management of those who are overweight or obese.

To determine body mass index (BMI) trends in newly diagnosed PwMS and individual characteristics associated with weight gain after diagnosis. Also, to determine the impact of physical disability on BMI changes in PwMS.

We conducted two longitudinal retrospective cohort analyses using the Multiple Sclerosis Partners Advancing Technology Health Solutions (MS PATHS) database. The first characterized BMI trends in newly diagnosed PwMS. Multivariable linear regression was used to determine characteristics associated with baseline BMI. Multivariable logistic regression was used to determine characteristics associated with annualized BMI changes of ≥ 0.5 kg/m²/year and ≥ 2.0 kg/m²/year in PwMS who were overweight or obese at baseline. The second analysis evaluated BMI trends in individuals with more longstanding MS to determine the impact of disability on weight changes. Multivariable logistic regression was used with consolidated Patient Determined Disease Steps (PDDS) categories as a disability measure.

There were 942 PwMS in the newly diagnosed cohort, of whom 265 (27.9 %) were overweight and 403 (42.4 %) were obese. The average follow-up time was 2.1 years, and the average annualized BMI change was 0.19 kg/m²/year (SD=1.5). Greater education was associated with lower baseline BMI (β=-0.31, p = 0.003) but no other characteristics were significantly associated. Greater education was also associated with lower odds of rapid weight gain at ≥ 2.0 kg/m²/year (OR=0.88, p = 0.001), while female sex was associated with higher odds of rapid weight gain (OR=1.84, p = 0.047) at the same threshold. The disability analysis included 10,394 PwMS, of whom 5,699 (54.8 %) had low disability (PDDS 0-1), 3,221 (31.0 %) had moderate disability (PDDS 2-4), and 1,474 (14.2 %) had high disability. The average annualized BMI change was 0.08 kg/m²/year for all subjects (SD=1.7), 0.10 kg/m²/year (SD=1.6) for those with low baseline disability, 0.06 kg/m²/year (SD=1.9) for those with moderate baseline disability, and 0.04 kg/m²/year (SD=1.9) for those with high baseline disability. Relative to those with low disability, moderate disability (β=1.09, p < 0.001) and severe disability (β=1.274, p < 0.001) were both associated with higher baseline BMI. Greater disability was not associated with odds of meeting thresholds for annualized BMI increases. However, women had 22 % higher odds of a ≥ 0.5 kg/m²/year increase (p = 0.002) and 31.6 % higher odds of a ≥ 2.0 kg/m²/year increase (p = 0.01).

Being overweight or obese is common at MS diagnosis. Women with MS are especially susceptible to rapid weight gain, both at diagnosis and later in the disease course. Greater education is protective against rapid weight gain in newly diagnosed MS patients. Baseline disability did not have a significant relationship with annualized BMI change, but the relationship appears to vary according to the patient's age. The frequency of overweight and obese PwMS suggests that weight management is an important part of MS care.