A population-based study to develop juvenile arthritis case definitions for administrative health data using model-based dynamic classification.

Background: Previous research has shown that chronic disease case definitions constructed using population-based administrative health data may have low accuracy for ascertaining cases of episodic diseases such as rheumatoid arthritis, which are characterized by periods of good health followed by periods of illness. No studies have considered a dynamic approach that uses statistical (i.e.

Summarizing the extent of visit irregularity in longitudinal data.

Background: Observational longitudinal data often feature irregular, informative visit times. We propose descriptive measures to quantify the extent of irregularity to select an appropriate analytic outcome approach.

Methods: We divided the study period into bins and calculated the mean proportions of individuals with 0, 1, and > 1 visits per bin.

Methods for analyzing observational longitudinal prognosis studies for rheumatic diseases: a review & worked example using a clinic-based cohort of juvenile dermatomyositis patients.

Most outcome studies of rheumatic diseases report outcomes ascertained on a single occasion. While single assessments are sufficient for terminal or irreversible outcomes, they may not be sufficiently informative if outcomes change or fluctuate over time. Consequently, longitudinal studies that measure non-terminal outcomes repeatedly afford a better understanding of disease evolution.

Risk Factors for Symptomatic Avascular Necrosis in Childhood-onset Systemic Lupus Erythematosus.

Objective: To examine the frequency and risk factors for symptomatic avascular necrosis (AVN) in childhood-onset systemic lupus erythematosus (cSLE).

Methods: A single-center, nested, matched, case-control design was used. There were 617 patients with cSLE followed at the Hospital for Sick Children (SickKids) Lupus Clinic between July 1982 and June 2013 included in the study.

Longitudinal data subject to irregular observation: A review of methods with a focus on visit processes, assumptions, and study design.

When data are collected longitudinally, measurement times often vary among patients. This is of particular concern in clinic-based studies, for example retrospective chart reviews. Here, typically no two patients will share the same set of measurement times and moreover, it is likely that the timing of the measurements is associated with disease course; for example, patients may visit more often when unwell.

Systematic review of the quality of prognosis studies in systemic lupus erythematosus.

Objective: Prognosis studies examine outcomes and/or seek to identify predictors or factors associated with outcomes. Many prognostic factors have been identified in systemic lupus erythematosus (SLE), but few have been consistently found across studies. We hypothesized that this is due to a lack of rigor of study designs.

Longterm outcomes and damage accrual in patients with childhood systemic lupus erythematosus with psychosis and severe cognitive dysfunction.

Objective: (1) To describe the clinical course and response to treatment; and (2) to evaluate and compare damage accrual of distinct phenotypic subgroups of patients with clinically important psychiatric illness of pediatric systemic lupus erythematosus (pSLE).

Methods: A single-center cohort study of patients with pSLE followed at a pediatric lupus clinic from 1985 to July 2009. Clinical course and response to treatment were studied.

Psychiatric illness of systemic lupus erythematosus in childhood: spectrum of clinically important manifestations.

Objective: To determine the spectrum of manifestations in clinically important (i.e., requiring alterations of immunosuppressive therapy) psychiatric illness of pediatric systemic lupus erythematosus (pSLE) and to describe the laboratory and imaging features associated with psychiatric illness of pSLE (psySLE).

The risky business of studying prognosis.

Prognosis studies provide important healthcare information. Clinicians use prognostic factors to predict disease progress, thus allowing individualization of disease management. Prognosis is the issue in many translational studies that aim to identify biomarkers to predict outcomes.

Predicting longitudinal trajectory of bone mineral density in paediatric systemic lupus erythematosus patients.

Objectives: (1) To identify the average lumbar spine (LS) bone mineral density (BMD) trajectory in paediatric systemic lupus erythematosus (pSLE) patients, and (2) to identify predictors of BMD trajectory.

Methods: 68 consecutive newly diagnosed pSLE patients prospectively followed in our lupus cohort with three annual dual energy x-ray absorptiometry (DEXA) examinations were studied. Low LS BMD was defined as z-score ≤-2.