Our findings do not support the widely accepted assertion that blacks have a lower risk of MS than whites. A possible explanation for our findings is that people with darker skin tones have lower vitamin D levels and thereby an increased risk of MS, but this would not explain why Hispanics and Asians have a lower risk of MS than whites or why the higher risk of MS among blacks was found only among women.

Objective: To determine whether childhood obesity is a risk factor for developing pediatric multiple sclerosis (MS) or clinically isolated syndrome (CIS).Methods: Cases were identified through the Kaiser Permanente Southern California (KPSC) Pediatric Acquired Demyelinating Diseases Cohort between 2004 and 2010. For cases, body mass index (BMI) was obtained prior to symptom onset, for the underlying cohort BMI was obtained through the KPSC Children's health study (n 5 913,097). Weight classes of normal weight, overweight, moderate obesity, and extreme obesity were assigned based on BMI specific for age and sex.Results: We identified 75 newly diagnosed pediatric cases of MS or CIS, the majority of which were in girls (n 5 41, 55%), age 11-18 (n 5 54, 72%). Obesity was associated with a significantly increased risk of MS/CIS in girls (p 5 0.005 for trend) but not in boys (p 5 0.93). The adjusted odds ratio and 95% confidence intervals for CIS/MS among girls was 1.58 (0.71-3.50) for overweight compared to normal weight (reference category), 1.78 (0.70-4.49) for moderately obese, and 3.76 (1.54-9.16) for extremely obese. Moderately and extremely obese cases were more likely to present with transverse myelitis compared with normal/overweight children (p 5 0.003). Conclusion:Our findings suggest the childhood obesity epidemic is likely to lead to increased morbidity from MS/CIS, particularly in adolescent girls. Once thought to be rare in children, multiple sclerosis (MS) and its potential precursor, clinically isolated syndrome (CIS), which encompasses optic neuritis (ON) and transverse myelitis (TM), are increasingly recognized. Pediatric MS/CIS most often affects teenage girls. While once thought to be more common in whites, one study showed that the incidence is higher in blacks compared with whites and Hispanics.1 Whether this represents increased exposure to environmental triggers that increase with age, black race, or female sex during childhood is unclear.Over the last 30 years, the prevalence of pediatric obesity has tripled. It is well-known that obesity is characterized by a low-grade inflammatory state, 2 raising the possibility that the increasing reports of pediatric MS/CIS may be due at least in part to this alarming epidemic. Yet whether obesity is a risk factor for pediatric MS/CIS is unknown. Even in adults, the relationship between obesity and MS risk is not well understood. Only 2 studies have examined this question, both of which suggest that moderate obesity at age 20 but not at other times in life double the risk of adult-onset MS in women 3,4 and men. 4 However, the studies are limited by retrospective self-report of body size, 3,4 selection bias, 3 use of volunteer controls, 4 small number of obese subjects, 3,4 and inability to examine the risk among extremely obese individuals. 3,4 The purpose of this study was to estimate the magnitude of the association between overweight, moderate, and extreme childhood obesity and the risk of pediatric MS/CIS in our population-based,

IMPORTANCE Because vaccinations are common, even a small increased risk of multiple sclerosis (MS) or other acquired central nervous system demyelinating syndromes (CNS ADS) could have a significant effect on public health. OBJECTIVE To determine whether vaccines, particularly those for hepatitis B (HepB) and human papillomavirus (HPV), increase the risk of MS or other CNS ADS. DESIGN, SETTING, AND PARTICIPANTS A nested case-control study was conducted using data obtained from the complete electronic health records of Kaiser Permanente Southern California (KPSC) members. Cases were identified through the KPSC CNS ADS cohort between 2008 and 2011, which included extensive review of medical records by an MS specialist. Five controls per case were matched on age, sex, and zip code. EXPOSURES Vaccination of any type (particularly HepB and HPV) identified through the electronic vaccination records system. MAIN OUTCOMES AND MEASURES All forms of CNS ADS were analyzed using conditional logistic regression adjusted for race/ethnicity, health care utilization, comorbid diseases, and infectious illnesses before symptom onset. RESULTS We identified 780 incident cases of CNS ADS and 3885 controls; 92 cases and 459 controls were females aged 9 to 26 years, which is the indicated age range for HPV vaccination. There were no associations between HepB vaccination (odds ratio [OR], 1.12; 95% CI, 0.72-1.73), HPV vaccination (OR, 1.05; 95% CI, 0.62-1.78), or any vaccination (OR, 1.03; 95% CI, 0.86-1.22) and the risk of CNS ADS up to 3 years later. Vaccination of any type was associated with an increased risk of CNS ADS onset within the first 30 days after vaccination only in younger (<50 years) individuals (OR, 2.32; 95% CI, 1.18-4.57). CONCLUSIONS AND RELEVANCE We found no longer-term association of vaccines with MS or any other CNS ADS, which argues against a causal association. The short-term increase in risk suggests that vaccines may accelerate the transition from subclinical to overt autoimmunity in patients with existing disease. Our findings support clinical anecdotes of CNS ADS symptom onset shortly after vaccination but do not suggest a need for a change in vaccine policy.