HCAP: What's the organism?

Correct coding requires documentation of the presumed or confirmed causative organism.


Health care-associated pneumonia (HCAP) is defined as pneumonia acquired in the setting of high-risk health care contact, which includes the circumstances in the sidebar. The diagnosis of pneumonia (including HCAP) is clinical and not based on cultures. Cultures of blood and sputum are usually negative; when positive, the spectrum of antibiotic therapy can be narrowed.

Unfortunately, the correct coding of HCAP disregards these accepted diagnostic standards and terminology and requires documentation of the presumed or confirmed causative organism. However, when cultures are negative, CMS’ ICD-9-CM Official Guidelines for Coding and Reporting permit physicians to identify the probable, possible, suspected, or likely cause using their reasonable medical judgment, as long as antibiotics and other management are consistent with the documented organism. Other acceptable terminology in this instance includes “consistent with,” “compatible with,” “comparable with,” “indicative of,” “suggestive of,” and “appears to be.” “Evidence of” and “coverage for” do not qualify.

Photo from Thinkstock
Photo from Thinkstock.

According to the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS), the predominant organisms causing HCAP are gram-negative bacteria and/or Staphylococcus, similar to hospital-acquired and ventilator-associated pneumonia. Studies of more than 1,400 patients with culture-positive HCAP have consistently shown gram-negative bacteria (other than Haemophilus) in 54% to 56% of cases and methicillin-resistant or methicillin-susceptible Staphylococcus aureus (MRSA/MSSA) in 44% to 47% of cases. All other organisms (including Haemophilus and Streptococcus pneumoniae) accounted for 15% to 27%. Totals exceeded 100% due to cases of mixed infection.

Most patients with HCAP also receive a full course of broad-spectrum antibiotics targeted at gram-negative bacteria and/or Staphylococcus. In such circumstances, documentation linking HCAP to the likely organism(s) is warranted to ensure correct coding that reflects the clinical reality of the patient's condition and management. Physicians should also verify the probable or suspected diagnosis in the discharge summary (or final progress note) to confirm it did not change. It is not necessary to specify the particular gram-negative organism, although in some cases Pseudomonas is highly likely and may be identified as the probable cause.

Examples of diagnostic statements linking HCAP to the presumed cause that might be used include:

  • HCAP—suspect gram-negative,
  • HCAP likely due to staph and/or gram-negative organisms,
  • HCAP consistent with MRSA, or
  • Similar terminology identifying the likely, suspected, or probable organism(s) causing HCAP.

HCAP should be classified in a “complex” pneumonia DRG having high severity, mortality, complexity, intensity, complications, and costs. Failure to document the presumed organism(s) causing HCAP will result in assignment to a “simple” pneumonia DRG expected to have low severity, mortality, complexity, intensity, complications, and costs. The result will be the reporting of falsely high adverse outcomes for simple pneumonia and unfavorable quality rankings for both the hospital and the physician, as well as inadequate reimbursement to cover the costs of care for patients with HCAP.