Validation of administrative case ascertainment algorithms for chronic childhood arthritis in Manitoba, Canada.

We validated case ascertainment algorithms for juvenile idiopathic arthritis (JIA) in the provincial health administrative databases of Manitoba, Canada. A population-based pediatric rheumatology clinical database from April 1st 1980 to March 31st 2012 was used to test case definitions in individuals diagnosed at ≤15 years of age. The case definitions varied the number of diagnosis codes (1, 2, or 3), time frame (1, 2 or 3 years), time between diagnoses (ever, >1 day, or ≥8 weeks), and physician specialty. Positive predictive value (PPV), sensitivity, and specificity with 95% confidence intervals (CIs) are reported. A case definition of 1 hospitalization or ≥2 diagnoses in 2 years by any provider ≥8 weeks apart using diagnosis codes for rheumatoid arthritis and ankylosing spondylitis produced a sensitivity of 89.2% (95% CI 86.8, 91.6), specificity of 86.3% (95% CI 83.0, 89.6), and PPV of 90.6% (95% CI 88.3, 92.9) when seronegative enthesopathy and arthropathy (SEA) was excluded as JIA; and sensitivity of 88.2% (95% CI 85.7, 90.7), specificity of 90.4% (95% CI 87.5, 93.3), and PPV of 93.9% (95% CI 92.0, 95.8) when SEA was included as JIA. This study validates case ascertainment algorithms for JIA in Canadian administrative health data using diagnosis codes for both rheumatoid arthritis (RA) and ankylosing spondylitis, to better reflect current JIA classification than codes for RA alone. Researchers will be able to use these results to define cohorts for population-based studies.

The prevalence of systemic autoimmune rheumatic diseases in Canadian pediatric populations: administrative database estimates.

To estimate systemic autoimmune rheumatic disease (SARD) prevalence using administrative data for pediatric populations in four Canadian provinces. Physician billing claims and inpatient hospitalizations from Alberta, Manitoba, Quebec, and Saskatchewan were used to define cases aged ≤18 years with a SARD diagnosis code in: one or more hospitalization, two or more physician visits within 2 years and at least 2 months apart, or one or more physician visit to a rheumatologist. Estimates ranged from 15.9/100,000 in Quebec [95% confidence interval (95% CI) 14.1, 18.0] to 23.0/100,000 in Manitoba (95% CI 17.9, 29.2). SARDs were more common in females than in males across all provinces. There was a slightly higher prevalence among those living in urban compared to rural areas of Alberta (rate difference 14.4, 95% CI 8.6, 20.1) and Saskatchewan (rate difference 13.8, 95% CI 1.0, 26.6). Our results provide population-based prevalence estimates of pediatric SARDs in four Canadian provinces.

Chronic inflammatory arthritis prevalence estimates for children and adolescents in three Canadian provinces.

There is a paucity of published population-based estimates of the prevalence of chronic inflammatory arthritis in the pediatric population. We used administrative health data to estimate the prevalence of chronic inflammatory arthritis in individuals ≤18 years in three Canadian provinces: Quebec, Manitoba, and Saskatchewan. Cases aged ≤18 years were identified by meeting any one of the following criteria: (a) ≥1 hospital discharge abstract with an ICD-9 code of 714 or ICD-10-CA codes of M05, M06 or M08, or (b) ≥2 ICD-9 714 billing codes ≥8 weeks apart, but within 2 years, or (c) ≥1 ICD-9 714 billing code by a rheumatologist. Crude prevalence estimates per 10,000 population were estimated with 95 % confidence intervals (CIs). Prevalence estimates were 11.7 per 10,000 individuals ≤18 years of age in Manitoba, 9.8 per 10,000 in Saskatchewan, and 8.0 per 10,000 in Quebec. In pairwise comparisons of rate differences, Manitoba and Saskatchewan had higher estimates than Quebec. Prevalence estimates were higher for females than males, with a difference of 5.9 cases per 10,000 residents (95 % CI 5.1, 6.7). Saskatchewan was the only province with a higher estimate in urban compared to rural residents (5.2, 95 % CI 2.5, 8.0). Variations in provincial estimates may be due to differences in underlying population characteristics. Although these estimates have face validity and are in keeping with the range of previously published pediatric prevalence estimates, studies to establish the empiric validity of case-finding algorithms are needed to advance research in pediatric chronic disease epidemiology.