Table 1.

Administrative claims-based definitions for volume overload hospital admissions

Definition number and description	Lead author (year of publication)a	ICD-9 discharge diagnosis codesb
1. Fluid overloadc	Banerjee (2007) [10]	276.6, 276.69
2. Pulmonary edema	--	514, 518.4
3. Heart failure	--	398.91, 402.x1, 404.x1, 404.x3, 428d
4. Fluid overloadc or pulmonary edema	--	276.6, 276.69, 514, 518.4
5. Fluid overloadc or pleural effusion	Weinhandl (2015) [11]	276.6, 276.69, 511.9
6. Fluid overloadc or heart failure	--	276.6, 276.69, 398.91, 402.x1, 404.x1, 404.x3, 428d
7. Fluid overloadc, pulmonary edema or heart failure	Arneson (2010) [6]	276.6, 276.69, 514, 518.4, 402.x1, 404.x1, 404.x3, 428d

Abbreviations: ICD-9 International Classification of Diseases, Ninth Revision

^aDenotes prior use of the ICD-9 diagnosis code combination to define volume overload hospitalizations

^bSeparate analyses evaluating definition validity considered ICD-9 diagnosis codes present in: 1) any billing order position, 2) the primary billing position only and 3) the primary and leading secondary billing positions

^cPrior to October 1, 2010 the ICD-9 discharge diagnosis code 276.6 (fluid overload) was the only applicable code in existence. On October 1, 2010, ICD-9 diagnosis code 276.6 (fluid overload) became invalid and was replaced by more granular codes: 276.61 (transfusion associated circulatory overload) and 276.69 (other fluid overload). For hospitalizations with a discharge date prior to October 1, 2010 the ICD-9 code 276.6 was used to construct claims-based volume overload definitions. For hospitalizations with a discharge date on or after October 1, 2010 the ICD-9 code 276.69 was used to construct claims-based volume overload definitions

^dSpecified three digit ICD-9 diagnosis categories included all existing 4th and 5th digit diagnosis codes