Linked birth certificate–hospital discharge records are a valuable resource for examining pregnancy outcomes among women with disability conditions. Few studies relying on these data have been able to assess the accuracy of identification of preexisting disability conditions. We assessed the accuracy of International Classification of Diseases version 9 (ICD9) codes for identifying selected physical, sensory, and intellectual conditions that may result in disability. As ICD9 codes were utilized until recently in most states, this information is useful to inform analyses with these records.
We reviewed 280 of 311 (90%) medical records of pregnant women with disabilities based on ICD9 codes and 390 of 8,337 (5%) records of pregnant women without disabilities who had deliveries at a large university medical center. We estimated sensitivity, specificity, and positive predictive values (PPV) using the medical record as gold standard. We adjusted for verification bias using inverse probability weighting and imputation.
The estimated sensitivity of ICD9 codes to identify women with disabilities with deliveries 2009–2012 was 44%; PPV was 98%, improving over time. Although sensitivity was <50% for some conditions, PPVs were 87%–100% for all conditions except intellectual disability (67%). Many physical conditions had complete verification and no underreporting.
These results are helpful for new studies using historical data comparing outcomes among women with and without these conditions and to inform interpretation of results from earlier studies. Assessment of the accuracy of disabilities as identified by ICD version 10 codes is warranted.