IS ASPIRATION PNEUMONIA EPIDEMIC IN ELDERLY AMERICANS?

SAN FRANCISCO-Aspiration pneumonia may have become a lethal and costly epidemic in elderly Americans, according to William B. Baine, MD, who presented a poster at the 39th Interscience Conference on Antimicrobial Agents and Chemotherapy.

"Pneumonitis due to inhalation of food and vomitus, commonly known as aspiration pneumonia, has become the second most frequent principal diagnosis, trailing only that broad catchall designation, 'pneumonia, organism unspecified,' among hospitalizations of Medicare patients for any of 55 different diagnoses indicating infection or inflammation of the lungs," stated Dr. Baine, who is Senior Medical Advisor at the Center for Outcomes and Effectiveness Research at the Agency for Health Care Policy and Research (AHCPR) in Rockville, Md.

"One possible explanation for the apparent increase in aspiration pneumonia is that hospitals are increasingly likely to specify aspiration pneumonia to obtain the maximum allowable reimbursement from Medicare," Dr. Baine continued. "Of greater concern is the possibility that [these diagnoses] might be revealing a smoldering epidemic of aspiration pneumonia among elderly patients."

The diagnosis of aspiration pneumonia included two different disease processes, Dr. Baine explained. In one version of the disease, regurgitated stomach acid passes down the windpipe and reaches the lung. The result can be an acid burn, which renders lung tissue susceptible to complicating infection. The other version often reflects other illnesses that compromise the patient's ability to cough or swallow. For example, patients whose throat muscles have been affected by stroke can be at high risk for aspiration pneumonia. Uncoordinated swallowing misdirects saliva, food, or drink to the airways. If the patient's cough reflex is too feeble, some of these materials may pass into the lung--along with mouth and throat bacteria.

AHCPR researchers reviewed Health Care Financing Administration computer files of Medicare hospital claims for patients discharged from 1991 through 1996 to identify inpatient stays by patients age 65 years or older with a principal diagnosis of aspiration pneumonia. "From 1991 through 1996, the number of hospital discharges of Medicare patients whose reason for admission was reported to be aspiration pneumonia increased by 76%, exceeding 100,000 cases in 1996 alone," Dr. Baine pointed out. "Over that same interval, the number of elderly persons who had Medicare coverage grew by less than 7%."

Yearly increases in the number of hospitalizations for aspiration pneumonia per 100,000 persons were most marked in the very old. Mean costs and Medicare hospital reimbursements were lowest for white women, who showed the lowest case-fatality rate in hospital (23%). This subgroup of patients had the shortest average hospital stay (10.4 days) and stay in intensive care (0.8 days) and accounted for a mean Medicare payment to the hospital of only $8,246. In contrast, black men, at highest risk of fatal outcome (26%), had the longest average stay in hospital (14.2 days) and in intensive care (1.1 days) and were responsible for the highest Medicare hospital reimbursements. An additional 22% of patients discharged alive to home or self-care were dead within 90 days of hospital admission; case-fatality rates at 90 days were even higher in patients sent to home health care, an intermediate care or a skilled nursing facility, or to another facility.

Among Medicare patients with a principal diagnosis of aspiration pneumonia, the three most common secondary diagnoses were volume depletion, congestive heart failure, and urinary tract infections. Common discharge diagnoses most strongly related to a principal diagnosis of aspiration pneumonia--compared with a diagnosis of pneumococcal pneumonia--were dysphagia, gastrostomy status, and staphylococcal pneumonia.

The question is whether this increase in aspiration pneumonia arises from an actual increase in cases or is merely an apparent increase resulting from selection pressure for the "aspiration pneumonia" diagnostic code. Most Medicare payments for pneumonia hospitalizations are covered by one of two sets of diagnosis-related groups (DRGs): "simple pneumonia and pleurisy" and "respiratory infections and inflammation." As the latter DRG covers pneumonias that may be particularly severe, the hospital payment for these is generally higher than for "simple pneumonias." Reporting a patient as having aspiration pneumonia instead of "pneumonia, organism unspecified," shifts the DRG from the lower to the higher reimbursement, which is obviously to the hospital's advantage.

If, on the other hand, Medicare bills are pointing to a real increase in aspiration pneumonia, a second question arises: What underlying processes are bringing about this increase? To find that out, further research is needed, Dr. Baine noted.

"Further investigation must concentrate upon possible causal factors," he argued, "including the possibility of previously unrecognized connections between some of these conditions or their management and the risk of aspiration pneumonia."

-Lawrence Prescott