Accuracy of the all patient refined diagnosis related groups classification system in congenital heart surgery

Abstract

Background: Administrative data are increasingly used to evaluate clinical outcomes and quality of care in pediatric congenital heart surgery (CHS) programs. Several published analyses of large pediatric administrative data sets have relied on the All Patient Refined Diagnosis Related Groups (APR-DRG, version 24) diagnostic classification system. The accuracy of this classification system for patients undergoing CHS is unclear.

Methods: We performed a retrospective cohort study of all 14,098 patients 0 to 5 years of age undergoing any of six selected congenital heart operations, ranging in complexity from isolated closure of a ventricular septal defect to single-ventricle palliation, at 40 tertiary-care pediatric centers in the Pediatric Health Information Systems database between 2007 and 2010. Assigned APR-DRGs (cardiac versus noncardiac) were compared using χ2 or Fisher's exact tests between those patients admitted during the first day of life versus later and between those receiving extracorporeal membrane oxygenation support versus those not. Recursive partitioning was used to assess the greatest determinants of APR-DRG type in the model.

Results: Every patient admitted on day 1 of life was assigned to a noncardiac APR-DRG (p<0.001 for each procedure). Similarly, use of extracorporeal membrane oxygenation was highly associated with misclassification of CHS patients into a noncardiac APR-DRG (p<0.001 for each procedure). Cases misclassified into a noncardiac APR-DRG experienced a significantly increased mortality (p<0.001).

Conclusions: In classifying patients undergoing CHS, APR-DRG coding has systematic misclassifications, which may result in inaccurate reporting of CHS case volumes and mortality.

Keywords: 20; 21; 4; APR-DRG; All Patient Refined Diagnosis Related Groups; CHS; D-TGA; DOL1; ECMO; HLHS; ICD-9-CM; PHIS; Pediatric Hospital Information Systems; TOF; VSD; congenital heart surgery; d-transposition of the great arteries, with or without VSD; day of life 1 admission; extracorporeal membrane support oxygenation; hypoplastic left heart syndrome; tetralogy of Fallot; using International Classification of Diseases, 9th Revision, Clinical Modification; ventricular septal defect.

Figure 1

Scatter plots illustrating the relationship between hospital case volume and APR-DRG coding for overall cohort (Figure 1) and individual cohorts (Figures 2a and 2b). [Lines fitted and p value obtained using linear regression]

Figure 2

a and b. Scatter plots illustrating the relationship between hospital case volume and APR-DRG coding for overall cohort (Figure 1) and individual cohorts (Figures 2a and 2b). [Lines fitted and p value obtained using linear regression]

Figure 2

a and b. Scatter plots illustrating the relationship between hospital case volume and APR-DRG coding for overall cohort (Figure 1) and individual cohorts (Figures 2a and 2b). [Lines fitted and p value obtained using linear regression]

Figure 3

Scatter plot illustrating the relationship between APR-DRG coding status and mean hospital mortality. [Lines fitted and P value obtained using linear regression. Circle sizes are proportional to the hospitals' volume of cardiac cases.]

Figure 4

Schematic representations of recursive partitioning analysis illustrating variables most predictive of non-cardiac APR-DRG status for the overall cohort (Figure 4) and for individual cohorts (Figures 5a and 5b).

Figure 5

a and b. Schematic representations of recursive partitioning analysis illustrating variables most predictive of non-cardiac APR-DRG status for the overall cohort (Figure 4) and for individual cohorts (Figures 5a and 5b).

Figure 5

a and b. Schematic representations of recursive partitioning analysis illustrating variables most predictive of non-cardiac APR-DRG status for the overall cohort (Figure 4) and for individual cohorts (Figures 5a and 5b).