Q&A: Choosing a principal diagnosis

Q: When a patient comes in with two diagnoses and the documentation reflects that either could be the principal diagnosis, do we choose the principal as the diagnosis that is being treated more intensely, or do we choose the higher paying DRG? Is it true that when a patient comes in with two diagnoses with both being treated equally, you can choose either as the principal diagnosis? In a case where one diagnosis is being treated more intensely, however, do you choose that one even though it is a lower weighted DRG? I usually choose the one that is being treated more intensely even though it might be lower weighted.

A: I am in 100% agreement with you. Everyone must go with the culture of their employer but speaking of CDI as an industry, it is unwise in my opinion for a CDI department to be driven by financial impact when determining which diagnoses should be principal in the scenario you outlined. I always go by the old motto of "doing the right thing for the right reasons" because good only follows that premise.

As a former auditor, I would be denying all the cases I saw where the ONLY determining factor for principal diagnosis selection was relative weight. I would be weighing the resource consumption on the two diagnoses and make my determination accordingly. I have created two patient scenarios (they are made up case examples and do not reflect actual cases) for you to compare, although I don't think you will need them.

Scenario #1:

A patient comes in with complaints of shortness of breath (SOB). A hospitalist is the attending on this case.

The patient has a past medical history of atrial fibrillation (A fib) on coumadin, hypertension (HTN), and diabetes mellitus (DM).

• Vital signs upon arrival:
  
  • Heart rate (HR): 150
  • Respiratory rate (RR): 28
  • Blood pressure (BP): 160/95
  • Saturations: 93 on room air
• EKG reveals A fib with rapid ventricular response (RVR) with a rate of 153.
• Chest x-ray reveals cardiomegaly and vascular congestion with atelectasis.
• The emergency department physician documents the following: Patient presents with worsening SOB over two days. Dyspnea noted on exertion and patient can speak in full sentences at this time. Patient reports no history of congestive heart failure (CHF).
• Physical Exam: Audible wheezing with rales in the left lower lobe. Pitting edema 2+ in bilateral ankles. Tachypneic.
• Chest x-ray: Cardiomegaly, vascular congestion and bilateral atelectasis. Possible pulmonary edema noted. Further correlation is needed.
• Labs: Brain natriuretic peptide (BNP) is drawn and results at 1200.
• Treatment: 2L oxygen via nasal cannula is applied with saturation at 96%. Foley is inserted and 40mg IV Lasix is given. Metoprolol 10mg IV x 1 dose is given. The patient is admitted for acute onset CHF and A fib RVR.
• The patient diuresed 1L UOP, HR has converted to sinus rhythm with a rate in the low- to mid-90s. The patient is receiving continuous telemetry. The patient continues on 2L oxygen with lowest saturation of 93%.
• ECHO ordered and shows ejection fraction (EF) 55%, mitral regurgitation (MR) +2, left ventricular hypertrophy (LVH).
• Cardiac consult ordered. A fib RVR and acute diastolic CHF, new onset are diagnosed. IV Lasix of 40mg x 1 (additional dose) is given with a repeat chest x-ray showing an improvement in vascular congestion and no pulmonary edema was identified on repeat film. The patient is weaned to room air with resolution of SOB.
• The patient does not return to A fib, paroxysmal and is discharged two days later on a cardiac diet, Coreg 3.375mg oral (PO) BID, 20mg Lasix PO on prescription with a follow-up appointment for the cardiologist in two weeks for a planned electrophysiology study to be performed to reevaluate the A fib.

For this scenario, I would code the principal diagnosis as the combination code for hypertensive heart disease and code the acute diastolic CHF as the MCC and then code the A fib as a secondary diagnosis (regardless of relative weights).

My rationale is that the CHF consumed most of the resources provided and the A fib resolved without return with one dose of metoprolol. Follow up therapy for both diagnoses will be ongoing on an outpatient basis.

Scenario #2:

A patient comes in with complaints of SOB and chest pain. A hospitalist is the attending on this case.

The patient has a past medical history of A fib on coumadin, HTN, DM, and chronic CHF.

• Vital signs upon arrival:
  
  • HR: 150
  • RR: 28
  • BP: 160/95
  • Saturations: 93 on room air
• EKG reveals A fib RVR with a rate of 153.
• The emergency department physician documents the following: Patient presents with worsening SOB x2 days. Dyspnea noted on exertion and patient can speak in full sentences at this time. Patient reports a history of diastolic CHF.
• Physical exam: Audible wheezing with rales in the left lower lobe. Pitting edema 2+ in bilateral ankles. Tachypneic.
• Chest x-ray: Cardiomegaly, vascular congestion and bilateral atelectasis. Possible pulmonary edema noted. Further correlation is needed.
• Labs: BNP is drawn and results at 1200. Troponin 0.02, 0.03.
• Treatment: 2L oxygen via nasal cannula is applied with saturation at 96%. Foley is inserted and 40mg IV Lasix is given. Metoprolol 10mg IV x 1 dose is given. The patient is admitted to the intensive care unit (ICU) for acute on chronic CHF and A fib RVR.
• The patient diuresed 1L UOP and HR remains between 140s and 150s. EKG continues showing A fib RVR on continuous telemetry. The patient continues on 2L oxygen with lowest saturation of 93%. The patient continues to complain of chest pain but states that it has lessened to intermittent.
• Treatment: 180mg IV Amiodarone given as bolus. The patient’s A fib RVR continues. An IV drop of Amiodarone is started.
• Cardiac consult ordered.
• Cardiology documents a prior EF of 55% done two months ago also showing MR 2+, LVH. Cardiology orders 40mg IV Lasix x 1 dose (additional dose).
• Continuous EKG shows that the patient remains in A fib RVR. 10mg Cardizem IV is ordered and administered with the Cardizem converting the rhythm to sinus rhythm. IV drop of Amiodarone is discontinued, and an IV drop of Cardizem is initiated to titrate to a target HR of 80-90.
• A fib RVR and acute diastolic CHF are diagnosed. IV Lasix of 40mg x 1 (additional dose) is given with a repeat chest x-ray showing resolution in vascular congestion and no pulmonary edema was identified on repeat film. The patient’s complaints of chest pain have resolved completely. SOB has resolved completely and the patient is weaned to room air.
• The patient is discharged two days later with a follow-up appointment with the cardiologist in one week. Electrophysiology study is ordered for outpatient.

In this scenario, A fib RVR consumed most of the resources resulting in an ICU bed which has an increase in nurse-to-patient ratio. Therefore, I would code the A fib RVR as the principal diagnosis with the combination code for the HTN and HF and the acute on chronic CHF as the MCC.

Editor’s note: Dawn R. Valdez, RN, LNC, CDIP, CCDS, manager of CDI/clinical educator at Ardent Health Services in Nashville, Tennessee, answered this question following the July 31 episode of the ACDIS Podcast. Register for the ACDIS Podcast now and avoid missing more great live episodes, click here. The entire achieves are available on the ACDIS website and as a podcast. Contact Valdez at dawnvaldez33@yahoo.com.