Database queries for hospitalizations for acute congestive heart failure: flexible methods and validation based on set theory

Background and objective Electronic health records databases are increasingly used for identifying cohort populations, covariates, or outcomes, but discerning such clinical ‘phenotypes’ accurately is an ongoing challenge. We developed a flexible method using overlapping (Venn diagram) queries. Here we describe this approach to find patients hospitalized with acute congestive heart failure (CHF), a sampling strategy for one-by-one ‘gold standard’ chart review, and calculation of positive predictive value (PPV) and sensitivities, with SEs, across different definitions. Materials and methods We used retrospective queries of hospitalizations (2002–2011) in the Indiana Network for Patient Care with any CHF ICD-9 diagnoses, a primary diagnosis, an echocardiogram performed, a B-natriuretic peptide (BNP) drawn, or BNP >500 pg/mL. We used a hybrid between proportional sampling by Venn zone and over-sampling non-overlapping zones. The acute CHF (presence/absence) outcome was based on expert chart review using a priori criteria. Results Among 79 091 hospitalizations, we reviewed 908. A query for any ICD-9 code for CHF had PPV 42.8% (SE 1.5%) for acute CHF and sensitivity 94.3% (1.3%). Primary diagnosis of 428 and BNP >500 pg/mL had PPV 90.4% (SE 2.4%) and sensitivity 28.8% (1.1%). PPV was