<p><strong>Importance: </strong>Despite concerns regarding the potential deleterious physical and mental health outcomes among family members of a child with a life-threatening condition (LTC), few studies have examined empirical measures of health outcomes among these family members.</p>

<p><strong>Objectives: </strong>To examine whether mothers, fathers, sisters, and brothers of children with 1 of 4 types of pediatric LTCs have higher rates of health care encounters, diagnoses, and prescriptions compared with families of children without these conditions.</p>

<p><strong>Design, Setting, and Participants: </strong>This retrospective cohort study included US families with commercial insurance coverage from a single carrier. Children who had 1 of 4 LTCs (substantial prematurity, critical congenital heart disease, cancer, or a condition resulting in severe neurologic impairment) were identified by a diagnosis in their insurance claim data between July 1, 2015, and June 30, 2016. Each case child and their family was matched with up to 4 control children and their families based on the age of the case and control children. Data were analyzed between August 2020 and March 2021.</p>

<p><strong>Exposures: </strong>Having a child or sibling with substantial prematurity, critical congenital heart disease, cancer, or a condition resulting in severe and progressive neurologic impairment.</p>

<p><strong>Main Outcomes: </strong>Rates of occurrence of health care encounters, physical and mental health diagnoses, and physical and mental health medication prescriptions, identified from insurance claims data, were compared between case and control families using a multivariable negative binomial regression model. The statistical analysis adjusted for observed differences between case and control families and accounted for clustering at the family level.</p>

<p><strong>Results: </strong>The study included 25 528 children (6909 case children [27.1%] and 18 619 control children [72.9%]; median age, 6.0 years [IQR, 1-13 years]; 13 294 [52.1%] male), 43 357 parents (11 586 case parents [26.7%] and 31 771 control parents [73.3%]; mean [SD] age, 40.4 [8.1] years; 22 318 [51.5%] female), and 25 706 siblings (7664 case siblings [29.8%] and 18 042 control siblings [70.2%]; mean [SD] age, 12.1 [6.5] years; 13 114 [51.0%] male). Overall, case mothers had higher rates of the composite outcome of health care encounters, diagnoses, and prescriptions compared with control mothers (incident rate ratio [IRR], 1.61; 95% CI, 1.54-1.68), as did case fathers compared with control fathers (IRR, 1.55; 95% CI, 1.46-1.64). Sisters of children with LTCs had higher rates of the composite outcome compared with sisters of children without LTCs (IRR, 1.68; 95% CI, 1.55-1.82), as did brothers of children with LTCs compared with brothers of children without LTCs (IRR, 1.70; 95% CI, 1.56-1.85).</p>

<p><strong>Conclusions and Relevance: </strong>In this cohort study, mothers, fathers, sisters, and brothers who had a child or sibling with 1 of 4 types of LTCs had higher rates of health care encounters, diagnoses, and medication prescriptions compared with families who did not have a child with that condition. The findings suggest that family members of children with LTCs may experience poorer mental and physical health outcomes. Interventions for parents and siblings of children with LTCs that aim to safeguard their mental and physical well-being appear to be warranted.</p>

<p><strong>BACKGROUND: </strong>Neuromyelitis optica spectrum disorder (NMOSD) is a rare demyelinating disease in need of more studies to determine effective treatment regimens. The rarity of the disorder, however, makes large randomized-controlled trials challenging. Validation of the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) code for NMO could facilitate the use of large healthcare claims data for future research. We aimed 1) to determine the positive predictive value (PPV) of the ICD-9-CM code for NMO as well as evaluate case-finding algorithms for the identification of patients with NMO/NMOSD and 2) to compare the evaluation of and treatment for pediatric versus adult patients.</p>

<p><strong>METHODS: </strong>This was a multicenter retrospective cohort study of patients with ≥ 1 ICD-9 code for NMO seen at 3 pediatric and 2 adult United States medical centers from 2001-2016. Using a standardized data entry form, pediatric and adult neurologists and rheumatologists reviewed patients' medical records to determine whether patients fulfilled the 2006 criteria for NMO and/or the 2015 criteria for NMOSD in order to determine the positive predictive value (PPV) for the ICD-9-CM code. Demographic and clinical information was abstracted from patient medical records to ascertain variables then evaluated in case-based finding algorithms for further identification of patients with true NMO/NMOSD. We also evaluated differences in clinical characteristics between pediatric and adult patients using chi-squared or Fisher's exact tests, as appropriate, to assess for treatment variation.</p>

<p><strong>RESULTS: </strong>A single code for NMO had a PPV of 47% across all sites, with significant site variation (0-77%). The best case-finding algorithm included at least 5 codes as well as a documented hospitalization (PPV&nbsp;=&nbsp;=90% for children and PPV&nbsp;=&nbsp;92% for adults). Children were more likely to be evaluated by a rheumatologist or ophthalmologist, undergo magnetic resonance imaging of the orbits, and receive immunosuppressive and biologic agents than their adult counterparts. Rituximab was administered similarly among the two groups.</p>

<p><strong>CONCLUSION: </strong>The ICD-9 code for neuromyelitis optica (NMO) is inaccurate for identification of NMO/NMOSD. Using case-finding algorithms increases the PPV. The initial diagnostic evaluation and treatment of NMOSD differs significantly between children and adults.</p>

<p><strong>Background: </strong>Treatment algorithms for neuromyelitis optica spectrum disorder (NMOSD) vary, and sparse data exist regarding the impact of initial treatments on disease course. We aimed to determine whether administration of rituximab during first hospitalization reduces 1-year readmission rates.</p>

<p><strong>Methods: </strong>We conducted a retrospective cohort study of subjects with NMOSD using the Pediatric Health Information System database from 2005-2015. Subjects were ages 1 to 21 years who received glucocorticoids and an ICD-9-CM code indicating neuromyelitis optica (NMO) during first hospitalization. All subjects had at least 12 months of continuous enrollment. The primary exposure was ≥1 rituximab dose during first hospitalization. We tested for the association of rituximab use with all-cause re-hospitalization, the primary outcome, using survival analysis. Re-hospitalization was considered if a hospital admission occurred &gt; 30 days after initial discharge with exclusion of admissions with re-dosing of rituximab and data were censored at 12 months. Secondary outcomes included time to and median duration of re-hospitalization using 25 percentiles of survival time and the Wilcoxon-rank sum test, respectively.</p>

<p><strong>Results: </strong>Of 180 subjects who met inclusion criteria, 71.7% were female and the median age was 13 years (IQR: 10, 15). 52 subjects (28.9%) received rituximab during first hospitalization, and there was an increasing trend in rituximab use over time (p&lt;0.01). Overall, 36.7% of children were readmitted and time to readmission was a median of 365 days (IQR: 138, 365). Rituximab exposure was not associated with re-hospitalization (adjusted HR: 0.71: 95% CI: 0.38, 1.34) nor a reduced time to re-hospitalization. Median duration of re-hospitalization was 2 days shorter in the rituximab exposed group (p=0.02). Receipt of physical therapy, a surrogate marker for neurologic impairment, during first hospitalization was associated with re-admission within 12 months (adjusted HR: 4.81; 95% CI: 1.14, 20.29).</p>

<p><strong>Conclusions: </strong>Among children with NMOSD, first-line administration of rituximab was not associated with risk of or time to re-hospitalization. Rituximab use was found to be associated with a shorter duration of re-hospitalization. Need for physical therapy during first hospitalization was independently associated with an increased risk of re-admission.</p>