Q&A: Two principal diagnoses

Q: When two conditions are both present on admission, both meet definition to be the principal diagnosis, and are “equally treated,” my understanding is that the condition does not have to be "equally treated" in the sense of duration/frequency. Can you provide the actual verbiage of the coding rule and explain?

A: The instruction can be found in Section II of the Official Guidelines for Coding and Reporting for Selection of Principal Diagnosis. It states that the circumstances of inpatient admission always govern the selection of principal diagnosis. Furthermore, the Guidelines refer to the rules outlined in CMS’ Uniform Hospital Discharge Data Set (UHDDS) as “that condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care.” (The UHDDS definitions are used by hospitals to report inpatient data elements in a standardized manner.)

The Guidelines further state that “in determining principal diagnosis, coding conventions in the ICD-10-CM, the Tabular List and Alphabetic Index take precedence” over the Guidelines. Section II.C., contains rules governing code assignment for two or more conditions that equally meet the definition for principal diagnosis. It states that “in the unusual instance when two or more diagnoses equally meet the criteria for principal diagnosis as determined by the circumstances of admission, diagnostic workup and/or therapy provided, and the Alphabetic Index, Tabular List, or another coding guidelines does not provide sequencing direction, any one of the diagnoses may be sequenced first.”

CDI professionals need to read the Official Guidelines for Coding and Reporting, in its entirety, particularly the sections governing principal diagnosis selection.

To reiterate, first and foremost the selection of the principal diagnosis is based on the circumstances of the admission as stated above, followed by any instructions received in the coding conventions, such as a “code first” note (these instructions or conventions are only found in a code book, you will not find them in the DRG Expert), followed by the advice found in the Official Guidelines for Coding and Reporting, and lastly by any instruction/advice given in the America Hospital Association’s Coding Clinic for ICD-10-CM/PCS published every year on a quarterly bases.

There is no rule as to treatment having to be “equal.”  Sometimes the provider may determine no treatment (such as medication or surgery) is the best course of action for a patient, maybe monitoring the patient at a different level of care, for instance in the ICU versus placement on a medical/surgical floor is best. It really would depend on the circumstances of the admission.

Editor’s Note: Sharme Brodie, RN, CCDS, CCDS-O, CDI education specialist and CDI Boot Camp instructor for HCPro in Middleton, Massachusetts, answered this question. For information, contact her at sbrodie@hcpro.com. For information regarding CDI Boot Camps, click here.