Throughout the years when working with and on hospital coding of inpatient encounters, I have found that the principal diagnosis was always a topic of discussion when it comes to coding accuracy determination. It certainly is important to understand the guidelines for the selection of the principal diagnosis for the Health Information Management (HIM) coding professional as well as for the Clinical Documentation Integrity (CDI) specialist. The process of reviewing statistics, patterns and trends of diagnoses (ICD-10-CM codes) can be helpful and useful for hospitals, HIM and CDI staff.

The Healthcare Cost and Utilization Project (H-CUP) released in July another interesting report regarding the frequency of hospital inpatient principal diagnoses that sheds some light on nonmaternal, nonneonatal stays from 2018 data. This report or “statistical briefing”, number 277, was prepared by Kimberly W. McDermott, Ph.D., and Marc Roemer, M.S., and provides a variety of details and data on hospital inpatient encounters.  

The HCUP uses the National (Nationwide) Inpatient Sample (NIS), which is a nationwide database of hospital inpatient stays. The NIS is a representative of all community hospitals (i.e., short-term, non-Federal, nonrehabilitation hospitals). The NIS includes all payers, country regions, ages and both genders. It is drawn from a sampling time frame that contains hospitals comprising more than 95 percent of all discharges in the United States.

The HCUP NIS indicates the following top 20 Principal Diagnoses for 2018:

  1. Septicemia
  2. Heart Failure
  3. Osteoarthritis
  4. Pneumonia (except that caused by tuberculosis)
  5. Diabetes Mellitus with complication
  6. Acute Myocardial Infarction
  7. Cardiac Dysrhythmias
  8. COPD and bronchiectasis
  9. Acute and Unspecified Renal Failure
  10. Cerebral Infarction
  11. Skins and subcutaneous tissue infections
  12. Depressive Disorders
  13. Spondylopathies/Spondyloarthropathy
  14. Urinary Tract Infection
  15. Respiratory Failure; Insufficiency; Arrest
  16. Schizophrenia spectrum and Other Psychotic Disorders
  17. Coronary Atherosclerosis and Other Heart Disease
  18. Biliary Tract Disease
  19. Fluid and Electrolyte Disorders
  20. Complication of Select Surgical and Medical Care

Additional statistics released in the briefing include:

  • The top 20 principal diagnoses constituted nearly half of all nonmaternal, nonneonatal inpatient stays and nearly half of aggregate costs for these stays in 2018.
  • Data on Septicemia, which accounted for 8 percent of all nonmaternal, nonneonatal stays in 2018. Heart failure and osteoarthritis each accounted for 4 percent.
  • Indications that Septicemia was the first or second most common diagnosis among both males and females for each adult age group
  • Of the top 10 most common principal diagnosis in 2018, septicemia was both the most frequent (2,218,800 stays) and the costliest (441.5 billion in aggregate), Septicemia as the first and second most common diagnosis among adults, both male and female.
  • Data showing that Medicare was the primary expected payer for nearly 60 percent of inpatient stays involving the 20 most frequent principal diagnoses.
  • For three of the five top diagnoses, the rates of stays were lowest in the West compared with other regions.

You may ask why is this information and these statistics important? Well, according to the briefing, knowing the frequency of hospital principal diagnosis can help establish national health priorities, initiatives, and action plans. Additionally, alternative payment models, such as hospital value based purchasing programs, often focus on condition-specific metrics. At the hospital level, administrators can use diagnosis related information to inform planning and resource allocation, such as optimizing subspecialty services or units for the care of high-priority conditions. In addition, from my professional experience, this information can really benefit our compliance, audits, education and coding accuracy efforts.

The following is the link to this briefing: Most Frequent Principal Diagnoses for Inpatient Stays in U.S. Hospitals, 2018 #277 (ahrq.gov)

Some key questions to ask yourself and your organization or department about is:

  1. What was my hospital/organizations top hospital principal diagnosis in the years 2018, 2019 and 2020?
    • Run a report on the top 20 principal diagnoses
    • Include payer (Medicare, Medicaid, Private Insurance, Self-Pay, Other)
    • Include age and gender of the patient
    • Include length of stay, charges and the MS-DRG
  2. What were the highest and lowest charges for that specific diagnosis.
    • Determine the mean
  3. What was the highest and lowest length of stay for that specific diagnosis?
    • Determine the mean
  4. Was there a documentation and coding audit/review conducted on at least 5% or more of the top 20 principal diagnosis encounters?  
    • If yes, what did the results indicate?
    • Compare the results/accuracy from year to year
  5. Does your coding compliance audit plan include auditing the most frequent (top 20) hospital principal diagnosis encounters? (and determine …What MS-DRGs do these represent?)

As we look over this report/briefing and the above questions, we must REMEMBER, that the principal diagnosis coding and reporting guidelines (found in Section II of the Official Guidelines for Coding and Reporting), which tell us that the circumstances of the admission govern the selection the principal diagnosis. In addition, according to the Uniform Hospital Discharge Data Set (UHDDS) the principal diagnosis is defined as “that condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care.” When coding and reporting the principal diagnosis for inpatient hospital encounters (stays), both of these guidelines need to be applied with the utmost accuracy.

In conclusion, you will want to take the next step, which is to take the time to discuss this HCUP briefing and your specific coding audit plan with your Compliance Team, Revenue Cycle, HIM Coding staff and Internal/External Auditing leadership.

Written by Gloryanne Bryant, RHIA, CDIP, CCS, CCDS, AHIMA Approved ICD-10-CM/PCS Trainer

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