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Open Access Research article

The test characteristics of head circumference measurements for pathology associated with head enlargement: a retrospective cohort study

Carrie Daymont1234*, Moira Zabel34, Chris Feudtner356 and David M Rubin356

Author Affiliations

1 Department of Pediatrics and Child Health, The University of Manitoba, Winnipeg, Manitoba, Canada

2 The Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada

3 Department of Pediatrics, The University of Pennsylvania, Philadelphia, Pennsylvania, USA

4 Children's National Medical Center, Washington DC, USA

5 Center for Clinical Epidemiology and Biostatistics, The University of Pennsylvania, Philadelphia, Pennsylvania, USA

6 PolicyLab, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA

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BMC Pediatrics 2012, 12:9  doi:10.1186/1471-2431-12-9

Published: 23 January 2012

Abstract

Background

The test characteristics of head circumference (HC) measurement percentile criteria for the identification of previously undetected pathology associated with head enlargement in primary care are unknown.

Methods

Electronic patient records were reviewed to identify children age 3 days to 3 years with new diagnoses of intracranial expansive conditions (IEC) and metabolic and genetic conditions associated with macrocephaly (MGCM). We tested the following HC percentile threshold criteria: ever above the 95th, 97th, or 99.6th percentile and ever crossing 2, 4, or 6 increasing major percentile lines. The Centers for Disease Control and World Health Organization growth curves were used, as well as the primary care network (PCN) curves previously derived from this cohort.

Results

Among 74,428 subjects, 85 (0.11%) had a new diagnosis of IEC (n = 56) or MGCM (n = 29), and between these 2 groups, 24 received intervention. The 99.6th percentile of the PCN curve was the only threshold with a PPV over 1% (PPV 1.8%); the sensitivity of this threshold was only 15%. Test characteristics for the 95th percentiles were: sensitivity (CDC: 46%; WHO: 55%; PCN: 40%), positive predictive value (PPV: CDC: 0.3%; WHO: 0.3%; PCN: 0.4%), and likelihood ratios positive (LR+: CDC: 2.8; WHO: 2.2; PCN: 3.9). Test characteristics for the 97th percentiles were: sensitivity (CDC: 40%; WHO: 48%; PCN: 34%), PPV (CDC: 0.4%; WHO: 0.3%; PCN: 0.6%), and LR+ (CDC: 3.6; WHO: 2.7; PCN: 5.6). Test characteristics for crossing 2 increasing major percentile lines were: sensitivity (CDC: 60%; WHO: 40%; PCN: 31%), PPV (CDC: 0.2%; WHO: 0.1%; PCN: 0.2%), and LR+ (CDC: 1.3; WHO: 1.1; PCN: 1.5).

Conclusions

Commonly used HC percentile thresholds had low sensitivity and low positive predictive value for diagnosing new pathology associated with head enlargement in children in a primary care network.