Insufficient insufficiency


Physicians often use the term renal insufficiency to communicate the status of a patient's renal function. However, “insufficiency” is inadequate to achieve accurate ICD-9-CM code assignment when the medical record supports a more specific condition.

The ICD-9-CM codes for acute and/or chronic renal insufficiency do not have the designation of a complication or comorbidity (CC) in the Medicare Severity Diagnostic-Related Group (MS-DRG) methodology. Describing the patient's condition as renal insufficiency will not establish the severity of illness needed to correctly determine mortality risk and will likely result in the physician's report card reflecting a higher than expected mortality rate.

Chronic renal insufficiency is more accurately described as chronic kidney disease (CKD), stage 1 to 5. The National Institute of Diabetes and Digestive and Kidney Diseases, the National Kidney Foundation and the American Society of Nephrology classify stages of CKD according to the patient's glomerular filtration rate (GFR; see Table). ICD-9-CM diagnosis codes for CKD represent each stage, enabling researchers to monitor the disease process and clinical outcomes. http://www.acphospitalist.org/archives/2009/03/coding.jpg.htm

The physician should document the stage of CKD. Guidelines permit the following equivalent documentation:

  • mild CKD, stage II;
  • moderate CKD, stage III; and
  • severe CKD, stage IV.

Severe CKD, stage 4 and 5 also replace the term chronic renal failure. Both CKD stage 4 and CKD stage 5 are CCs in the MSDRG methodology.

End-stage renal disease (ESRD) is a federal government term indicating the need for renal dialysis or transplantation. ESRD is still an acceptable diagnosis for the purposes of ICD-9-CM coding and is considered a major CC (MCC) in the 2009 MS-DRG methodology, achieving the highest severity adjustment and reimbursement. It is interesting to note that CKD stages 4 and 5 are considered CCs but ESRD is an MCC even though the clinical condition is essentially the same.

Nephrotic syndrome or nephrosis is another kidney diagnosis that is reportable and considered a CC condition. The GFR may or may not be decreased in nephrotic syndrome (or nephrosis), a group of symptoms that include proteinuria (>3.5 g/d), low serum protein levels, low albumin, high cholesterol and edema. The urine may also contain fat on microscopic exam. Clinical practice guidelines and downloadable GFR calculators are available at the National Kidney Foundation's Web site. The GFR is based on the patient's serum creatinine concentration, age, race and gender.

The following case studies illustrate the impact of renal insufficiency terminology on MS-DRG assignment, as shown by the reimbursement. All scenarios are based on a hospital-specific rate of $5,500.

Scenario 1

Principal diagnosis: Community-acquired pneumonia

Secondary diagnosis: Chronic renal insufficiency; MS-DRG 195, simple pneumonia without CC: $4,024 The geometric mean length of stay for this MS-DRG is 3.5 days.

Scenario 2

Principal diagnosis: Community-acquired pneumonia

Secondary diagnosis: CKD stage 4 or 5 (CC); MS-DRG 194, simple pneumonia with CC: $5,532 The geometric mean length of stay for this MS-DRG is 4.4 days.

Scenario 3

Principal diagnosis: Community-acquired pneumonia

Secondary diagnosis: End-stage renal disease (MCC); MS-DRG 193, simple pneumonia with MCC: $7,881 The geometric mean length of stay for this MS-DRG is 5.4 days.

Acute renal insufficiency may not be the most appropriate terminology for a patient whose serum creatinine has significantly increased within the last two-week period. Consideration of a diagnosis of acute renal failure or acute (nontraumatic) kidney injury is appropriate. A widely accepted definition of acute renal failure is worsening of renal function over hours to days resulting in retention of nitrogenous wastes, such as urea nitrogen and creatinine, in the blood. Supporting laboratory values are an increase in serum creatinine for two weeks or less of 0.5 mg/dL if the baseline is less than 2.5 mg/dL, or an increase in serum creatinine by more than 20% if the baseline is greater than 2.5 mg/dL (JAMA. 2003;289:747-51).

Acute kidney injury is a complex disorder for which currently there is no accepted definition, but generally involves “an abrupt and sustained decrease in kidney function.” It is associated with increased mortality and resource use. The term acute kidney injury is proposed to represent the entire spectrum of acute renal failure (Crit Care. 2007;11:R31). Acute renal failure and acute kidney injury are reported with the same ICD-9-CM code.

Scenario 4

Principal diagnosis: Community-acquired pneumonia

Secondary diagnosis: Acute renal failure or acute kidney injury (MCC); MS-DRG 193, simple pneumonia with MCC: $7,881 The geometric mean length of stay for this MS-DRG is 5.4 days.

Acute renal failure or acute kidney injury may also be the principal diagnosis when it is “that condition established, after study, to be chiefly responsible for occasioning the admission of the patient to the hospital for care” (Official Coding Guidelines, 2008). Acute renal failure should also be reported when the condition is due to dehydration, rhabdomyolysis or benign prostatic hypertrophy with urinary obstruction.

Dialysis is not required for a diagnosis of acute renal failure and does not impact MS-DRG assignment.

When multiple physicians care for a patient, the risk of conflicting documentation increases. The admitting physician who documents acute renal failure may be followed by a physician who documents acute renal insufficiency. A coder may only code and report the diagnoses clearly and consistently documented by the physician responsible for the care of the patient. Any inconsistencies should result in the record being returned to the physician to obtain clarification of the diagnosis to be reported. By anticipating documentation needs, the physician can avoid retrospective queries requesting clarification in the form of an addendum to the medical record.