Temporal trends and practice variation of paediatric diagnostic tests in primary care
Authors: Thomas Elizabeth T , Withrow Diana R , Gill Peter J , Perera Rafael , Heneghan Carl 
Published: May 2024

AbstractObjectiveThe primary objective was to investigate temporal trends and between-practice variability of paediatric test use in primary care.Methods and analysisThis was a descriptive study of population-based data from primary care consultation records from January 1, 2007, to December 31, 2019. Children aged 0 to 15 who were registered to one of the 1,464 practices and had a diagnostic test code in their clinical record were included. The primary outcome measures were: 1) temporal changes in test rates measured by the average annual percent change (AAPC), stratified by test type, gender, age group, and deprivation level and 2) practice variability in test use, measured by the coefficient of variation (CoV).Results14,299,598 diagnostic tests were requested over 27.8 million child-years of observation for 2,542,101 children. Overall test use increased by 3.6%/year (95% CI 3.4 to 3.8%) from 399/1,000-child-years to 608/1,000 child-years, driven by increases in blood tests (8.0%/year, 95% CI 7.7 to 8.4), females aged 11-15 (4.0%/year, 95% CI 3.7 to 4.3), and the most socioeconomically deprived group (4.4%/year, 95% CI 4.1 to 4.8). Tests subject to the greatest temporal increases were fecal calprotectin, fractional exhaled nitric oxide (FeNO), and vitamin D. Tests classified as high use and high practice variability were iron studies, vitamin D, vitamin B12, folate, and coeliac testing.ConclusionsIn this first nationwide study of paediatric test use in primary care, we observed significant temporal increases and practice variability in testing. This reflects inconsistency in practice and diagnosis rates, and a scarcity of evidence-based guidance. Increased test use generates more clinical activity with significant resource implications, but conversely may improve clinical outcomes. Future research should evaluate whether increased test use and variability is warranted by exploring test indications and test results, and directly examine how increased test use impacts on quality of care.Key MessagesWhat is already known on this topicPrevious research has shown that test use in adults within UK primary care sharply increased since 2000 and that there is a high degree of practice variation in test use. To date, no population-based studies have analysed paediatric test use in this setting.What this study addsIn England between 2007 and 2019, diagnostic test use increased by 4% per year, from 399 tests/1,000 child-years to 608 tests/1000-child years. Test increases were driven blood tests, especially in females aged 11-15 years of age, and children in the most deprived socioeconomic group. Specific tests that increased by the greatest margin include faecal calprotectin, fractional exhaled nitric oxide (FeNO), and vitamin D testing. Tests subject to the greatest practice variation by 2019 were FeNO, hearing tests, and vitamin D levels.How this study might affect research, practice or policyVariability in test use highlights a lack of standardised guidance and evidence in pediatric diagnostics, which has significant implications for downstream diagnostic activity, treatment, referrals and healthcare costs.