What is a principal diagnosis?

Answer 1

The Principal Diagnosis is defined as the condition established after study to be chiefly responsible for admission of the patient to the hospital.

In the reimbursement of hospitals by insurance companies and Medicare, the amount of contracted payments are sometimes determined using a reimbursement scheme called DRG payments. A DRG (Diagnosis Related Group) is a grouping of all the conditions that were treated while a person was hospitalized along with any surgeries they may have had. This is grouped using standardized diagnosis and procedure codes (called ICD-9-CM, which stands for International Classification of Diseases, ninth revision, Clinical Modification).

One of the most important parts of the DRG classification and assignment is the Principal Diagnosis, since the DRG grouping (and therefore the payment) is primarily determined by that diagnosis that was the reason the patient went into the hospital. There are very specific guidelines on how that diagnosis is determined to be the principal one based upon the doctor's documentation in the medical record.

Here is a simple example of a Principal Diagnosisselection:

A woman is taken to the emergency room for very severe abdominal pain with nausea and vomiting. She is admitted to the hospital to determine the cause of the symptoms and for treatment. They do studies and find that she has gallstones. She has surgery to remove the gallstones. After the surgery she recovers and is sent home. By the definition above, the Principal Diagnosis in her case is going to be Cholelithiasis (gallstones) since, after study and after surgery, her abdominal pain, nausea and vomiting were determined to have been due to the gallstones.

So, although she had initial symptoms of nausea and vomiting and abdominal pain, none of them are the Principal Diagnosis. They would be considered the Admitting Diagnoses. After study it was determined that the condition that made her sick and caused her to need to be in the hospital was the gallstones.

To take the example one step further, if after she had the surgery, she was unfortunate enough to have a heart attack while in the hospital, even though it is a more serious condition and it causes her to stay much longer in the hospital, her insurance payment will still be based on the DRG related to the Principal Diagnosis of gallstones since it was what initially got her admitted. The heart attack would be a Secondary Diagnosisand it would affect a higher payment.

But the Principal Diagnosis doesn't get changed from the condition that, after study, was determined to have caused her to go into the hospital in the first place (gallstones). In some cases, the heart attack would be called a Primary Diagnosissince it was the most serious and resource intensive condition. However, the Principal Diagnosis doesn't change even if there is a Secondary Diagnosis added that is considered a more serious Primary Diagnosis.