Publications

OBJECTIVES

The study compared health care utilization and costs among homeless veterans randomly assigned to peer mentors or usual care and described contacts with peer mentors.

METHODS

Homeless patients at four Department of Veterans Affairs clinics were randomly assigned to a peer mentor (N=195) or to usual care (N=180). Administrative data on utilization and costs over a six-month follow-up were combined with peer mentors' reports of patient contacts.

RESULTS

Most patients (87%) in the peer mentor group had at least one peer contact. Patients in this group spent the largest proportions of time discussing housing and health issues with peer mentors and had more outpatient encounters than those in usual care, although differences were not significant. No other between-group differences were found in utilization or costs.

CONCLUSIONS

Although significant impacts of peer mentors on health care patterns or costs were not detected, some patients had frequent contact with peer mentors.

Multiple sclerosis (MS) is an autoimmune disease with both genetic and environmental risk factors. Recent studies indicate that childhood and adolescent obesity double the risk of MS, but this association may reflect unmeasured confounders rather than causal effects of obesity. We used separate-sample Mendelian randomization to estimate the causal effect of body mass index (BMI) on susceptibility to MS. Using data from non-Hispanic white members of the Kaiser Permanente Medical Care Plan of Northern California (KPNC) (2006-2014; 1,104 cases of MS and 10,536 controls) and a replication data set from Sweden (the Epidemiological Investigation of MS (EIMS) and the Genes and Environment in MS (GEMS) studies, 2005-2013; 5,133 MS cases and 4,718 controls), we constructed a weighted genetic risk score using 97 variants previously established to predict BMI. Results were adjusted for birth year, sex, education, smoking status, ancestry, and genetic predictors of MS. Estimates in KPNC and Swedish data sets suggested that higher genetically induced BMI predicted greater susceptibility to MS (odds ratio = 1.13, 95% confidence interval: 1.04, 1.22 for the KPNC sample; odds ratio = 1.09, 95% confidence interval: 1.03, 1.15 for the Swedish sample). Although the mechanism remains unclear, to our knowledge, these findings support a causal effect of increased BMI on susceptibility to MS for the first time, and they suggest a role for inflammatory pathways that characterize both obesity and the MS disease process.