<p><strong>PURPOSE: </strong>To examine the validity of International Classification of Diseases, 10th Revision, (ICD-10) code-based algorithms for herpes zoster (HZ) in the electronic medical record (EMR) of a large, integrated pediatric healthcare network and to examine baseline demographics and chronic comorbidities associated with HZ in a representative pediatric population.</p>

<p><strong>METHODS: </strong>We reviewed the electronic charts of all patients with a single ICD-10 for HZ (B02.xx) as their primary or secondary diagnosis in the EMR of the Children's Hospital of Philadelphia (CHOP) healthcare network from January 2010 - March 2019. The positive predictive value (PPV) for a single code for HZ was calculated and alternative algorithms were examined to determine which method resulted in the highest PPV.</p>

<p><strong>RESULTS: </strong>The PPV for a single ICD-10 code was 91.7% (95% CI 80.8-95.4) for definitive and/or probable cases of HZ and 63.9% (95% CI 53.4-75.5%) for definitive cases alone. Adding a prescription for an antiviral did not improve the PPV. However, adding a new code for rash entered within 1 week of the HZ code increased the PPV to 100% for definitive and/or probable cases but with substantial loss of sensitivity. A high proportion of children with HZ who required inpatient hospitalization had chronic disease (70%) and were on systemic immunomodulatory therapy (50%).</p>

<p><strong>CONCLUSIONS: </strong>HZ can be identified with a high PPV in electronic medical records of children using ICD-10 code alone. These findings lay the foundation for future pharmacoepidemiologic research to better understand risk factors for HZ infection.</p>

<p><strong>Background: </strong>Relatively little is known about the epidemiology of juvenile psoriatic arthritis (PsA), including clinical features associated with the development of arthritis among children with psoriasis and subsequent risk of inflammatory comorbidities.</p>

<p><strong>Objective: </strong>To identify the overall risk of arthritis among children with psoriasis and subsequent risk of inflammatory comorbidities.</p>

<p><strong>Methods: </strong>Using Clinformatics™ DataMart (OptumInsight, Eden Prairie, MN) de-identified US administrative claims data from 2000-2013, we identified children 0-16 years with an incident diagnosis of psoriasis or PsA using ICD-9-CM diagnostic, procedure and pharmacy billing codes. Cox proportional hazard regression was performed to assess clinical features associated with development of arthritis in children with psoriasis. Incidence rate ratios were used to compare the relative frequency of co-morbid diagnoses.</p>

<p><strong>Results: </strong>We identified 212 children with PsA, 4,312 with psoriasis-only, and 45,240 controls. Approximately 33% of children with PsA received a diagnostic code for psoriasis before arthritis. Median time to index code for arthritis after index code for psoriasis was 17.6 months (IQR 4.1-38.1). Older age and uveitis were associated with a significantly increased risk of developing arthritis in children with psoriasis. Children with PsA had a significantly increased risk of uveitis, diabetes, and depressive disorder when compared to patients with psoriasis and inflammatory bowel disease, uveitis, diabetes, and depressive disorder when compared to controls.</p>

<p><strong>Conclusion: </strong>Most children with PsA developed arthritis first. Older age and uveitis were risk factors for arthritis among children with psoriasis. PsA was associated with increased risk of several clinically relevant inflammatory comorbidities.</p>

<p><strong>Background: </strong>Antimicrobial prophylaxis is indicated to prevent Pneumocystis jirovecii pneumonia (PJP) in profoundly immunosuppressed children. The incidence of PJP infection in children with chronic glucocorticoid exposure is unknown, and PJP prophylaxis has been associated with adverse events. We hypothesized that PJP infection is rare in children without human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), cancer, or a transplant history who are using chronic glucocorticoids and that those exposed to PJP prophylaxis are more likely to experience a cutaneous hypersensitivity reaction or myelosuppression than unexposed patients.</p>

<p><strong>Methods: </strong>This study involved a retrospective cohort from the Clinformatics Data Mart Database (OptumInsight, Eden Prairie, MN). We identified patients ≤18 years of age who received at least 2 prescriptions for a systemic glucocorticoid within a 60-day period and excluded patients with a history of PJP infection, an oncologic diagnosis, transplant, or HIV/AIDS. PJP prophylaxis exposure was identified by using national drug codes. Cutaneous hypersensitivity reaction or myelosuppression was identified by using International Classification of Diseases, 9th Revision (ICD-9), codes. We used a discrete time-failure model to examine the association between exposure and outcome.</p>

<p><strong>Results: </strong>We identified 119399 children on glucocorticoids, 10% of whom received PJP prophylaxis. The incidences of PJP were 0.61 and 0.53 per 10000 patient-years in children exposed and those unexposed to PJP prophylaxis, respectively. In a multivariable model, trimethoprim-sulfamethoxazole was associated with cutaneous hypersensitivity reaction (odds ratio, 3.20; 95% confidence interval, 2.62-3.92) and myelosuppression (odds ratio, 1.85; 95% confidence interval, 1.56-2.20).</p>

<p><strong>Conclusions: </strong>PJP infection was rare in children using glucocorticoids chronically, and PJP prophylaxis-associated cutaneous hypersensitivity reactions and myelosuppression are more common. The use of PJP chemoprophylaxis in children without HIV/AIDS, cancer, or a transplant history who are taking glucocorticoids chronically should be considered carefully.</p>