Assessment of the Validity of Administrative Data for Gestational Diabetes Ascertainment

Published:November 14, 2022DOI:



      Administrative data, including International Classification of Disease (ICD) codes and birth certificate records, are often used for retrospective gestational diabetes mellitus (GDM) research investigations, to describe associations of GDM with perinatal complications and long-term outcomes, and to determine GDM prevalence. Research investigating the validity of using ICD codes and birth certificates for GDM ascertainment shows varying degrees of reliability.


      To evaluate the accuracy of both ICD codes and birth certificate diagnosis for GDM ascertainment in a large hospital-based cohort of pregnant individuals, using laboratory criteria for GDM as the reference.

      Study Design

      We studied individuals who received prenatal care at an academic hospital and affiliated community health centers between 1998 and 2016. In the setting of universal two-step screening for GDM, pregnant individuals were classified as having GDM if greater than or equal to two oral glucose tolerance test values met or exceeded National Diabetes Data Group (NDDG) thresholds. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for ICD code and birth certificate ascertainment of GDM, along with their exact binomial 95% confidence intervals (95% CI).


      In a cohort of 51,059 pregnancies with complete glucose screening, 1303 (2.6%) met NDDG laboratory criteria for GDM. GDM ICD codes had moderate sensitivity of 70.5% (95% CI: 67.9%, 72.9%), high specificity of 99.3% (95% CI: 99.3%, 99.4%), a PPV of 73.3% (95% CI: 70.8%, 75.8%), and a NPV of 99.2% (95% CI: 99.1%, 99.3%). In the 46,512 pregnancies linked to birth certificate data, birth certificate diagnosis had moderate sensitivity (66.3% [95% CI: 63.6%, 69.0%]), high specificity (98.9% [95% CI: 98.8%, 99.0%]), moderate PPV (62.1% [95% CI: 59.8%, 64.4%]), and high NPV (99.1% [95% CI: 99.0%, 99.2%]).


      Ascertainment of GDM using administrative data, including ICD codes or birth certificates, has moderate sensitivity, moderate PPV, high specificity, and high NPV. Our findings provide context for interpreting the validity of studies that depend on administrative data for ascertainment of GDM and comparing them to prospective studies that use laboratory-based GDM criteria.


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