Who tests for lead and why? A 10-year analysis of blood lead screening, follow-up and CNS outcomes in a statewide US healthcare system

Abstract

Objectives: This study aims to determine (1) which providers in US healthcare systems order lead tests, why and at what frequency and (2) whether current patient population lead levels are predictive of clinical outcomes. Methods: Retrospective medical record study of all blood lead tests in the Medical University of South Carolina healthcare system 2012-2016 and consequent evidence of central nervous system (CNS)-related disease across a potential 10-year window (2012-2022). Results: Across 4 years, 9726 lead tests resulted for 7181 patients (49.0% female; 0-94 years), representing 0.2% of the hospital population. Most tests were for young (76.6%≤age 3) and non-Hispanic black (47.2%) and Hispanic (26.7%) patients. A wide variety of providers ordered tests; however, most were ordered by paediatrics, psychiatry, internal medicine and neurology. Lead levels ranged from ≤2.0 μg/dL (80.8%) to ≥10 μg/dL (0.8%; max 36 μg/dL). 201 children (3.1%) had initial lead levels over the reference value for case management at the time (5.0 μg/dL). Many high level children did not receive follow-up testing in the system (36.3%) and those that did often failed to see levels fall below 5.0 μg/dL (80.1%). Non-Hispanic black and Hispanic patients were more likely to see lead levels stay high or go up over time. Over follow-up, children with high lead levels were more likely to receive new attention-deficit/hyperactivity disorder and conduct disorder diagnoses and new psychiatric medications. No significant associations were found between lead test results and new CNS diagnoses or medications among adults. Conclusions: Hospital lead testing covers a small portion of patients but includes a wide range of ages, presentations and provider specialities. Lack of lead decline among many paediatric patients suggests there is room to improve provider guidance around when to test and follow-up.