IMPORTANCE Although highly effective disease-modifying therapies for multiple sclerosis (MS) have been associated with an increased risk of infections vs injectable therapies interferon beta and glatiramer acetate (GA), the magnitude of potential risk increase is not well established in real-world populations. Even less is known about infection risk associated with rituximab, which is extensively used off-label to treat MS in Sweden. OBJECTIVE To examine the risk of serious infections associated with disease-modifying treatments for MS. DESIGN, SETTING, AND PARTICIPANTS This nationwide register-based cohort study was conducted in Sweden from January 1, 2011, to December 31, 2017. National registers with prospective data collection from the public health care system were used. All Swedish patients with relapsing-remitting MS whose data were recorded in the Swedish MS register as initiating treatment with rituximab, natalizumab, fingolimod, or interferon beta and GA and an age-matched and sex-matched general population comparator cohort were included. EXPOSURES Treatment with rituximab, natalizumab, fingolimod, and interferon beta and GA. MAIN OUTCOMES AND MEASURES Serious infections were defined as all infections resulting in hospitalization. Additional outcomes included outpatient treatment with antibiotic or herpes antiviral medications. Adjusted hazard ratios (HRs) were estimated in Cox regressions. RESULTS A total of 6421 patients (3260 taking rituximab, 1588 taking natalizumab, 1535 taking fingolimod, and 2217 taking interferon beta/GA) were included, plus a comparator cohort of 42 645 individuals. Among 6421 patients with 8600 treatment episodes, the mean (SD) age at treatment start ranged from 35.0 (10.1) years to 40.4 (10.6) years; 6186 patients were female. The crude rate of infections was higher in patients with MS taking interferon beta and GA than the general population (incidence rate, 8.9 [95% CI, 6.4-12.1] vs 5.2 [95% CI, 4.8-5.5] per 1000 person-years), and higher still in patients taking fingolimod (incidence rate, 14.3 [95% CI, 10.8-18.5] per 1000 person-years), natalizumab (incidence rate, 11.4 [95% CI, 8.3-15.3] per 1000 person-years), and rituximab (incidence rate, 19.7 [95% CI, 16.4-23.5] per 1000 person-years). After confounder adjustment, the rate remained significantly higher for rituximab (HR, 1.70 [95% CI, 1.11-2.61]) but not fingolimod (HR, 1.30 [95% CI, 0.84-2.03]) or natalizumab (HR, 1.12 [95% CI, 0.71-1.77]) compared with interferon beta and GA. In contrast, use of herpes antiviral drugs during rituximab treatment was similar to that of interferon beta and GA and lower than that of natalizumab (HR, 1.82 [1.34-2.46]) and fingolimod (HR, 1.71 [95% CI, 1.27-2.32]). CONCLUSIONS AND RELEVANCE Patients with MS are at a generally increased risk of infections, and this differs by treatment. The rate of infections was lowest with interferon beta and GA; among newer treatments, off-label use of rituximab was associated with the highest rate of serious infections. The different risk profiles sh...

Twins, full siblings, and half-siblings are increasingly used as comparison groups in matched cohort and matched case-control studies. The "within-pair" estimates acquired through these comparisons are free from confounding from all factors that are shared by the siblings. This has made sibling comparisons popular in studying associations thought likely to suffer confounding from socioeconomic or genetic factors. Despite the wide application of these designs in epidemiology, they have received little scrutiny from a statistical or methodological standpoint. In this paper we show, analytically and through a series of simulations, that the standard interpretation of the models is subject to several limitations that are rarely acknowledged.Although within-pair estimates will not be confounded by factors shared by the siblings, such estimates are more severely biased by non-shared confounders than the unpaired estimate. If siblings are less similar with regard to confounders than to the exposure under study, the within-pair estimate will always be more biased than the ordinary unpaired estimate. Attenuation of associations due to random measurement error in exposure will also be higher in the within-pair estimate, leading within-pair associations to be weaker than corresponding unpaired associations, even in the absence of confounding. Implications for the interpretation of sibling comparison results are discussed.

Our findings suggest an improved effectiveness and tolerability of rituximab compared with fingolimod in stable RRMS patients who switch from natalizumab due to JC virus antibody positivity. Although residual confounding factors cannot be ruled out, the shared reason for switching from natalizumab and the preferential use of either rituximab or fingolimod in 2 of the centers mitigates these concerns. Ann Neurol 2016;79:950-958.

BackgroundResearch suggests that suicidal behaviour is aggregated in families. However, due to methodological limitations, including small sample sizes, the strength and pattern of this aggregation remains uncertain.MethodWe examined the familial clustering of completed suicide in a Swedish total population sample. We linked the Cause of Death and Multi-Generation Registers and compared suicide rates among relatives of all 83 951 suicide decedents from 1952–2003 with those among relatives of population controls.ResultsPatterns of familial aggregation of suicide among relatives to suicide decedents suggested genetic influences on suicide risk; the risk among full siblings (odds ratio 3.1, 95% confidence interval 2.8–3.5, 50% genetic similarity) was higher than that for maternal half-siblings (1.7, 1.1–2.7, 25% genetic similarity), despite similar environmental exposure. Further, monozygotic twins (100% genetic similarity) had a higher risk than dizygotic twins (50% genetic similarity) and cousins (12.5% genetic similarity) had higher suicide risk than controls. Shared (familial) environmental influences were also indicated; siblings to suicide decedents had a higher risk than offspring (both 50% genetically identical but siblings having a more shared environment, 3.1, 2.8–3.5 v. 2.0, 1.9–2.2), and maternal half-siblings had a higher risk than paternal half-siblings (both 50% genetically identical but the former with a more shared environment). Although comparisons of twins and half-siblings had overlapping confidence intervals, they were supported by sensitivity analyses, also including suicide attempts.ConclusionsFamilial clustering of suicide is primarily influenced by genetic and also shared environmental factors. The family history of suicide should be considered when assessing suicide risk in clinical settings or designing and administering preventive interventions.

Background: Prenatal environmental factors such as maternal adiposity may influence the risk of offspring autism spectrum disorders (ASD), though current evidence is inconsistent. The objective of this study was to assess the relationship of parental BMI and gestational weight gain (GWG) with risk of offspring ASD in a population-based cohort study using family-based study designs.Methods: The cohort was based in Stockholm County, Sweden, including 333 057 individuals born 1984–2007, of whom 6420 were diagnosed with an ASD. We evaluated maternal body mass index (BMI) at first antenatal visit, GWG and paternal BMI at the time of conscription into the Swedish military as exposures using general estimating equation (GEE) models with logit link.Results: At the population level, maternal overweight/obesity was associated with increased risk of offspring ASD [odds ratio (OR)25 ≤ BMI < 30 1.31, 95% confidence interval = 1.21–1.41; ORBMI ≥ 30 1.94, 1.72–2.17], as was paternal underweight (ORBMI < 18.5, 1.19, 1.06–1.33) and obesity (ORBMI ≥ 30 1.47, 1.12–1.92) in mutually adjusted models. However, in matched sibling analyses, the relationship between elevated maternal BMI and ASD risk was not apparent. GWG had a U-shaped association with offspring ASD at the population level (ORinsufficient 1.22, 1.07–1.40; ORexcessive 1.23, 1.08–1.40). Matched sibling analyses were suggestive of elevated risk with excessive GWG (ORinsufficient 1.12, 0.68–1.84; ORexcessive 1.48, 0.93–2.38).Conclusions: Whereas population-level results suggested that maternal BMI was associated with ASD, sibling analyses and paternal BMI analyses indicate that maternal BMI may also be a proxy marker for other familial risk factors. Evidence is stronger for a direct link between GWG and ASD risk.

Objective. To estimate familial aggregation of rheumatoid arthritis (RA) in 3 large population-representative samples and to test if familial aggregation is affected by rheumatoid factor (RF)/anti-citrullinated protein antibody (ACPA) status, type of relative, sex, and age at onset of RA.Methods. A register-based nested case-control study was performed in the Swedish total population. Data on patients with RA were ascertained through the nationwide Swedish Patient Register (n ‫؍‬ 88,639), the clinical Swedish Rheumatology Quality Register (n ‫؍‬ 11,519), and the Epidemiological Investigation of Rheumatoid Arthritis case-control study (n ‫؍‬ 2,871). Data on first-and second-degree relatives were obtained through the Swedish Multigeneration Register. Familial risks were calculated using conditional logistic regression.Results. Consistent across data sources, the familial odds ratio for RA was ϳ3 in first-degree relatives of RA patients and 2 in second-degree relatives. Familial risks were similar among siblings, parents, and offspring. Familial aggregation was not modified by sex, but was higher in RA patients with early-onset disease and in RF/ACPA-positive RA patients. The observed familial risks were consistent with a heritability of ϳ50% for ACPA-positive RA and ϳ20% for ACPAnegative RA.Conclusion. The pattern of risks suggests that familial factors influence RA in men and women equally and that these factors are of less importance for lateonset RA. Familial factors are more important for seropositive RA, but there is significant familial overlap between seropositive RA and seronegative RA. Even if the familial risk is assumed to be completely due to genetics, the observed risks suggest that heritability of RA is lower than previously reported, in particular for ACPA-negative RA.

IMPORTANCE Comparative real-world effectiveness studies of initial disease-modifying treatment (DMT) choices for relapsing-remitting multiple sclerosis (RRMS) that include rituximab are lacking. OBJECTIVE To assess the effectiveness and drug discontinuation rates of rituximab among patients with newly diagnosed RRMS compared with injectable DMTs, dimethyl fumarate, fingolimod, or natalizumab. DESIGN, SETTING, AND PATIENTS This retrospective cohort study used prospectively collected data to examine specialized care of 2 Swedish county-based community samples of patients with RRMS. Patients with RRMS who received diagnoses from January 1, 2012, to October 31, 2015, who resided in Stockholm or Västerbotten Counties were identified from a Swedish multiple sclerosis registry. MAIN OUTCOMES AND MEASURES All reasons for drug discontinuation of initial treatment choice (main outcome) and specific reasons for switching (secondary outcomes) were analyzed with multivariable Cox regression, including propensity scores. RESULTS Among 494 patients (median [interquartile range] age, 34.4 [27.4-43.4] years; 158 men [32.0%]), 215 received an injectable DMT (43.5%); 86 (17.4%), dimethyl fumarate; 17 (3.4%), fingolimod; 50 (10.1%), natalizumab; 120 (24.3%), rituximab; and 6 (1.2%), other DMT. Regional preferences were pronounced, with 42 of 52 (81%) and 78 of 442 (18%) receiving rituximab in Västerbotten and Stockholm, respectively. The annual discontinuation rate for rituximab, injectable DMTs, dimethyl fumarate, fingolimod, and natalizumab were 0.03, 0.53, 0.32, 0.38, and 0.29, respectively. Continued disease activity was the main reason for discontinuation of injectable DMTs, dimethyl fumarate, and fingolimod; positive John Cunningham virus serology results were the main reason for discontinuation of natalizumab. Rate of clinical relapses and/or neuroradiologic disease activity were significantly lower for rituximab compared with injectable DMTs and dimethyl fumarate, with a tendency for lower relapse rates also compared with natalizumab and fingolimod. The annual discontinuation rate of initial treatment choice was significantly lower in Västerbotten compared with Stockholm (0.09 and 0.37, respectively). CONCLUSIONS AND RELEVANCE Rituximab was superior to all other DMT in terms of drug discontinuation and displayed better clinical efficacy compared with injectable DMTs and dimethyl fumarate with borderline significance compared with natalizumab and fingolimod. The county where rituximab constituted the main initial treatment choice displayed better outcomes in most measured variables. Collectively, our findings suggest that rituximab performs better than other commonly used DMTs in patients with newly diagnosed RRMS.

The observed familiality should be accounted for in criminological research, applied violence risk assessment, and prevention efforts.