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Background and purpose: Pediatric‐onset multiple sclerosis (PoMS) is associated with high health care use. To plan resource allocation for this patient group, knowledge of the incidence rate and prevalence is important. However, such studies are scarce, few are population‐based, and the methodology varies widely. We aimed to address this knowledge gap by performing a nationwide study of the incidence rate and prevalence of PoMS in Sweden, an area of high multiple sclerosis (MS) incidence and prevalence. Methods: MS cases were identified by linking two nationwide registers, the National Patient Register and the Swedish MS Registry. MS cases having their first central nervous system demyelinating event or MS clinical onset before age 18 years were classified as pediatric onset. Incidence rate and prevalence were estimated annually over the study period (2006–2016) for the total population and stratified by sex and age group (<12, 12–15, and 16–17 years). Temporal trends and ratios between sexes and age groups were estimated. Results: We identified 238 incident cases from 2006 to 2016, corresponding to an overall crude incidence rate of 1.12 per 100,000 person‐years and an overall crude prevalence of 2.82 per 100,000 population. There was a higher incidence rate among females and the highest age category. The overall incidence rate and prevalence estimates remained stable during the study period. Conclusions: Sweden exhibits a consistently high incidence rate and prevalence of PoMS that has remained stable over time. This knowledge serves as a tool to aid in planning resource allocation and health services for this patient population. [ABSTRACT FROM AUTHOR]

Objective: There has been interest in a possible negative association between HIV and multiple sclerosis (MS). We aimed to compare the risk of MS in a cohort of individuals living with HIV to that in the general population. Methods: Population‐based health data were accessed for 2 cohorts of HIV‐positive persons from Sweden and British Columbia, Canada. Incident MS was identified using MS registries or a validated algorithm applied to administrative data. Individuals with HIV were followed from 1 year after the first clinical evidence of HIV or the first date of complete administrative health data (Canada = April 1, 1992 and Sweden = January 1, 2001) until the earliest of incident MS, emigration, death, or study end (Canada = March 31, 2020 and Sweden = December 31, 2018). The observed MS incidence rate in the HIV‐positive cohort was compared to the expected age‐, sex‐, calendar year‐, income‐specific, and region of birth‐specific rates in a randomly selected sample of >20% of each general population. The standardized incidence ratio (SIR) for MS following the first antiretroviral therapy exposure ("ART‐exposed") was also calculated. Results: The combined Sweden‐Canada cohort included 29,163 (75% men) HIV‐positive persons. During 242,248 person‐years of follow‐up, 14 incident MS cases were observed in the HIV‐positive cohort, whereas 26.19 cases were expected. The SIR for MS in the HIV‐positive population was 0.53 (95% confidence interval [CI] = 0.32–0.90). The SIR for MS following the first ART exposure was 0.55 (95% CI = 0.31–0.96). Interpretation: This international population‐based study demonstrated a lower risk of MS among HIV‐positive individuals, and HIV‐positive ART‐exposed individuals. These findings provide support for further exploration into the relationship among HIV, ART, and MS. ANN NEUROL 2024;95:487–494 [ABSTRACT FROM AUTHOR]

Background: The absence of reliable imaging or biological markers of phenotype transition in multiple sclerosis (MS) makes assignment of current phenotype status difficult. Objective: The authors sought to determine whether clinical information can be used to accurately assign current disease phenotypes. Methods: Data from the clinical visits of 14,387 MS patients in Sweden were collected. Classifying algorithms based on several demographic and clinical factors were examined. Results obtained from the best classifier when predicting neurologist recorded disease classification were replicated in an independent cohort from British Columbia and were compared to a previously published algorithm and clinical judgment of three neurologists. Results: A decision tree (the classifier) containing only most recently available expanded disability scale status score and age obtained 89.3% (95% confidence intervals (CIs): 88.8–89.8) classification accuracy, defined as concordance with the latest reported status. Validation in the independent cohort resulted in 82.0% (95% CI: 81.0–83.1) accuracy. A previously published classification algorithm with slight modifications achieved 77.8% (95% CI: 77.1–78.4) accuracy. With complete patient history of 100 patients, three neurologists obtained 84.3% accuracy compared with 85% for the classifier using the same data. Conclusion: The classifier can be used to standardize definitions of disease phenotype across different cohorts. Clinically, this model could assist neurologists by providing additional information. [ABSTRACT FROM AUTHOR]

Objectives: We aimed at designing a nomogram, a prediction tool, to predict the individual's risk of conversion to secondary progressive multiple sclerosis (SPMS) at the time of multiple sclerosis (MS) onset. Methods: One derivation and three validation cohorts were established. The derivation cohort included 8825 relapsing-onset MS patients in Sweden. A nomogram was built based on a survival model with the best statistical fit and prediction accuracy. The nomogram was validated using data from 3967 patients in the British Columbia cohort, 176 patients in the ACROSS and 2355 patients in FREEDOMS/FREEDOMS II extension studies. Results: Sex, calendar year of birth, first-recorded Expanded Disability Status Scale (EDSS) score, age at the first EDSS and age at disease onset showed significant predictive ability to estimate the risk of SPMS conversion at 10, 15 and 20 years. The nomogram reached 84% (95% confidence intervals (CIs): 83–85) internal and 77% (95% CI: 76–78), 77% (95% CI: 70–85) and 87% (95% CI: 84–89) external accuracy. Conclusions: The SPMS nomogram represents a much-needed complementary tool designed to assist in decision-making and patient counselling in the early phase of MS. The SPMS nomogram may improve outcomes by prompting timely and more efficacious treatment for those with a worse prognosis. [ABSTRACT FROM AUTHOR]

Objective: Elevated healthcare use before multiple sclerosis (MS) onset suggests earlier opportunity to identify MS. Yet their timing and sociodemographic effects are unclear. We examined rates of healthcare use (and by age/sex) for >two decades pre-MS onset., Methods: We identified people with MS (PwMS) using administrative data from Canada (Ontario) and Sweden (1991-2020) ("administrative" cohort), and the Swedish MS Registry ("clinical" cohort). The first MS/demyelinating diagnostic code (administrative) or symptom onset (clinical) defined MS onset. We compared annual rates of healthcare use (hospital, physician, and emergency-room [ED]) pre-onset between PwMS and up to five matched population controls using negative binomial regression, and by age/sex., Results: The administrative cohort = 35,018/136,007 PwMS/controls (Ontario), and 10,269/51,297 (Sweden). Rates of healthcare use were higher for PwMS than controls up to 28 (of 29) years (Ontario) and up to 15 (of 19) years (Sweden) pre-onset. Annual healthcare use rose steadily as onset approached, particularly escalating 7 years pre-onset in Ontario (e.g., hospital visit rate ratios [RRs] exceeded 1.30), and 6 years in Sweden (physician visit RRs > 1.10). RRs peaked the year pre-onset (ED visits [Ontario] = 3.04; 95% CI: 2.94-3.13, physician visits [Sweden] = 2.51; 95% CI: 2.44-2.59). In the year pre-onset, RRs were disproportionately higher for males (ED RRs [Ontario] = 3.30; 95% CI: 3.13-3.48 vs. females = 2.90; 95% CI: 2.79-3.02), and dropped steadily by age (physician visit RRs [Sweden] = 2.61/2.27/1.97/1.72 for 50/40/30/20-year-olds). The smaller clinical cohort (7604/37,974 PwMS/controls) exhibited similar patterns, albeit more modest, with RRs elevated up to 5 years pre-onset (physician visit RR [year-5] = 1.08; 95% CI: 1.02-1.14; RR [year-1] = 1.39;1.33-1.46)., Interpretation: Higher healthcare use was evident decades before MS onset, escalating 6-7 years pre-onset, peaking the year before, being disproportionately higher for males and older PwMS., (© 2024 The Author(s). Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)