Emergency department use by persons with MS: A population-based descriptive study with a focus on infection-related visits.

We described emergency department (ED) visits (all visits and infection-related) by persons with multiple sclerosis (MS) in British Columbia, Canada (1 April 2012 to 31 December 2017). We identified 15,350 MS cases using health administrative data; 73.4% were women, averaging 51.4 years at study entry. Over 4.9 years of follow-up (mean), 56.0% of MS cases visited an ED (mean = 0.6 visits/person/year; total = 37,072 visits). A diagnosis was documented for 25,698 (69.3%) ED visits, and 18.4% (4725/25,698) were infection-related. Inpatient admissions were reported for 20.4% (5238/25,698) of all and 29.2% (1380/4725) of infection-related ED visits. Findings suggest that the ED plays a substantial role in MS healthcare and infection management.

Fatigue, sleep disorders, anaemia and pain in the multiple sclerosis prodrome.

BACKGROUND: There is increasing evidence of prodromal multiple sclerosis (MS). OBJECTIVE: The aim of this study was to determine whether fatigue, sleep disorders, anaemia or pain form part of the MS prodrome. METHODS: This population-based matched cohort study used linked administrative and clinical databases in British Columbia, Canada. The odds of fatigue, sleep disorders, anaemia and pain in the 5 years preceding the MS cases' first demyelinating claim or MS symptom onset were compared with general population controls. The frequencies of physician visits for these conditions were also compared. Modifying effects of age and sex were evaluated. RESULTS: MS cases/controls were assessed before the first demyelinating event (6863/31,865) or MS symptom onset (966/4534). Fatigue (adj.OR: 3.37; 95% CI: 2.76-4.10), sleep disorders (adj.OR: 2.61; 95% CI: 2.34-2.91), anaemia (adj.OR: 1.53; 95% CI: 1.32-1.78) and pain (adj.OR: 2.15; 95% CI: 2.03-2.27) during the 5 years preceding the first demyelinating event were more frequent among cases, and physician visits increased for cases relative to controls. The association between MS and anaemia was greater for men; that between MS and pain increased with age. Pre-MS symptom onset, sleep disorders (adj.OR: 1.72; 95% CI: 1.12-2.56) and pain (adj.OR: 1.53; 95% CI: 1.32-1.76) were more prevalent among cases. CONCLUSION: Fatigue, sleep disorders, anaemia and pain were elevated before the recognition of MS. The relative anaemia burden was higher in men and pain more evident among older adults.

Five years before multiple sclerosis onset: Phenotyping the prodrome.

BACKGROUND: The multiple sclerosis (MS) prodrome is poorly characterized. OBJECTIVE: To phenotype the MS prodrome via health care encounters. METHODS: Using data from a population-based cohort study linking administrative and clinical data in four Canadian provinces, we 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. Rate ratios (RRs), 95% confidence intervals (95% CIs) and proportions were estimated. RESULTS: The administrative and clinical cohorts included 13,951/66,940 and 3202/16,006 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; 95% CI: 1.05-5.10 to 4.75; 95% CI: 3.11-7.25), sensory (RR (range) = 1.40; 95% CI: 1.34-1.46 to 2.28; 95% CI: 1.72-3.02), musculoskeletal (RR (range) = 1.19; 95% CI: 1.07-1.33 to 1.70; 95% CI: 1.57-1.85) and genito-urinary systems (RR (range) = 1.17; 95% CI: 1.05-1.30 to 1.59; 95% CI: 1.48-1.70). Cases had more psychiatrist and urologist encounters (RR (range) = 1.48; 95% CI: 1.36-1.62 to 1.80; 95% CI: 1.61-2.01), and higher proportions of musculoskeletal, genito-urinary or hormonal-related prescriptions (1.1-1.5 times higher, all p < 0.02). However, cases had fewer pregnancy-related encounters than controls (RR = 0.78; 95% CI: 0.71-0.86 to 0.88; 95% CI: 0.84-0.92). CONCLUSION: Phenotyping the prodrome 5 years before clinical recognition of MS is feasible.

Infection-related health care utilization among people with and without multiple sclerosis.

BACKGROUND: Little is known about infection risk in multiple sclerosis (MS). OBJECTIVE: We examined infection-related health care utilization in people with and without MS. METHODS: Using population-based health administrative data from British Columbia, Canada, people with MS were followed from their first demyelinating claim (1996-2013) until death, emigration, or study end (2013). Infection-related hospital, physician, and prescription data of MS cases were compared with sex-, age-, and geographically matched controls using adjusted regression models. Sex and age differences (18-39, 40-49, 50-59, 60+ years) were explored. RESULTS: Relative to 35,837 controls, 7179 MS cases were over twice as likely to be hospitalized for infection (adjusted odds ratio: 2.39; 95% confidence interval (CI): 2.16-2.65), had 41% more physician visits (adjusted rate ratio (aRR): 1.41; 95% CI: 1.36-1.47), and filled 57% more infection-related prescriptions (aRR: 1.57; 95% CI: 1.49-1.65). Utilization was disproportionately higher in MS men than women and was elevated across all ages. MS cases had nearly twice as many physician visits and two to three times more hospitalizations for pneumonia, urinary system infections, and skin infections (aRRs ranged from 1.6 to 3.3) and over twice as many hospitalizations for intestinal infections (aRR = 2.6) and sepsis (aRR = 2.2). CONCLUSION: Infection-related health care utilization was increased in people with MS across all age groups, with a higher burden for men.

Bayesian analysis of pair-matched case-control studies subject to outcome misclassification.

We examine the impact of nondifferential outcome misclassification on odds ratios estimated from pair-matched case-control studies and propose a Bayesian model to adjust these estimates for misclassification bias. The model relies on access to a validation subgroup with confirmed outcome status for all case-control pairs as well as prior knowledge about the positive and negative predictive value of the classification mechanism. We illustrate the model's performance on simulated data and apply it to a database study examining the presence of ten morbidities in the prodromal phase of multiple sclerosis.

Disease-modifying drugs, multiple sclerosis and infection-related healthcare use in British Columbia, Canada: a population-based study.

Background: Much remains unknown surrounding the disease-modifying drugs (DMDs) used to treat multiple sclerosis and infection-related healthcare use in the 'real-world' setting. We examined if DMD exposure was associated with altered infection-related healthcare use. Methods: We assessed if DMD (versus no) exposure was associated with altered infection-related hospitalizations, physician claims, and prescriptions filled in British Columbia, Canada (1996-2017). Healthcare use was assessed using negative binomial and proportional means regression models, reported as sex-/age-/comorbidity-/calendar year-/socioeconomic-adjusted rate and hazard ratios [aRR, aHR], with 95% confidence intervals [CIs]). Findings: We identified 19,360 multiple sclerosis cases (13,940/19,360; 72.0% women; mean age at study start = 44.5 standard deviation, SD = 13.3; mean follow-up = 11.7 [SD = 7.3] years). Relative to unexposed periods, exposure to any DMD was associated with a lower infection-related rate of physician claims (aRR = 0.88; 95% CI:0.85-0.92) and hazard of hospitalization (aHR = 0.64; 95% CI:0.56-0.73), and a higher rate of infection-related prescriptions (aRR = 1.14; 95% CI:1.08-1.20). Exposure to any injectable or oral DMD was associated with a lower infection-related rate of physician claims (injectable aRR = 0.88; 95% CI:0.84-0.92, oral aRR = 0.83; 95% CI:0.77-0.90) and hazard of hospitalization (injectable aHR = 0.65; 95% CI:0.56-0.75, oral aHR = 0.54; 95% CI:0.38-0.77), whereas intravenous DMD exposure was not (aRR = 0.99; 95% CI:0.86-1.14, aHR = 0.73; 95% CI:0.49-1.09). Exposure to any injectable or intravenous DMD was associated with a higher rate of infection-related prescriptions (injectable aRR = 1.15; 95% CI:1.08-1.22, intravenous = 1.34; 95% CI:1.15-1.56), whereas oral DMDs were not (aRR = 0.98; 95% CI:0.91-1.05). Interpretation: DMD exposure for the treatment of MS was associated with differences in infection-related healthcare use. While infection-related hospitalizations and physician visits were lower, prescription fills were higher. How these differences in infection-related healthcare use affect outcomes in persons with multiple sclerosis warrants consideration. Funding: Canadian Institutes of Health Research (CIHR); German Research Foundation (DFG).