Heart failure and fluid overload, with or without pulmonary congestion, can be clinically indistinguishable. On these pages we explore hospitalization for fluid overload and the related complication of pleural effusion. The set of diagnosis codes marking such admissions is concise and, among prevalent dialysis patients in 2011, admissions with primary discharge diagnoses of fluid overload outnumbered those for pleural effusion by a ratio of about four to one.
Unlike the rate of hospitalization for heart failure, the rate for fluid overload has tended to increase, especially since 2006. Once again, the evolution of reimbursement likely plays an important role. Both before and after the advent of MS-DRGs, the principal diagnosis of fluid overload (ICD-9-CM diagnosis code 276.6) has been mapped to DRGs regarding miscellaneous disorders of nutrition, metabolism, fluid, and electrolytes — entirely distinct from those regarding heart failure. Importantly, the advent of MS-DRGs substantially increased the relative weight (i.e., reimbursement rate) of the DRGs regarding miscellaneous disorders of nutrition, metabolism, fluid, and electrolytes, although only to a level that remained substantially below the relative weight of DRGs regarding heart failure. Interestingly, the ordering of Census Divisions by rate of hospitalization for fluid overload and pleural effusion appears quite different than that for heart failure and cardiomyopathy. In short, the story of heart failure and fluid overload appears to be frayed at the edges. There is evidence of coding shifts between the two diagnoses during the study era, and of regional variation in coding practices. Further analyses are needed to examine methodologies for identifying these admissions, so trends can be reliably estimated. As it stands, there is clear potential for regulatory agencies and researchers to arrive at conflicting conclusions about trends in admission rates for this important source of cardiovascular morbidity among dialysis patients.
Rates of admission with a principal diagnosis of fluid overload appear to have increased in all Census Divisions, with particularly high rates in the West North Central, West South Central, and Mountain states. The high rate during the first month of dialysis probably reflects the challenge of achieving volume control and appropriate dry weight in the new dialysis patient, while at least some of the seasonality in admissions among prevalent dialysis patients may be attributable to excessive sodium and fluid intake during holiday seasons.