An Overview of ABSSSI and Its Associated Economic Burden

JANUARY 22, 2019


Experts Joe Reilly, PharmD, BS, BCGP, and Tom Lodise, PharmD, PhD, break down the logistics of acute bacterial skin and skin structure infections (ABSSSIs) and the economic burden they impose.


Joe Reilly, PharmD, BS, BCGP: Skin and soft tissue infections, or SSTIs, are bacterial infections of the skin or underlying tissues that are typically characterized as purulent or nonpurulent infections, and they can also be acute or chronic types of infections. A category of SSTI is called acute bacterial skin and skin structure infections, or ABSSSIs.

Tom Lodise, PharmD, PhD: I think that’s a good working definition of when we think about skin and soft tissue infections. In addition, defining virulent or nonvirulent, I think it’s also good to classify patients’ symptoms and whether there are underlying comorbidities. When we think about nonpurulent infections, the organism we worry about most is group A strep [Streptococcus], sometimes Staph [Staphylococcus] aureus, predominantly MSSA [methicillin-susceptible Staphylococcus aureus]. When we think about purulent infections, this is where we begin to worry about MRSA [methicillin-resistant Staphylococcus aureus], particularly the community-acquired MRSA strain. Again, in addition to thinking about skin, we take into account a patient’s symptoms as well as their comorbidities, and this really helps us to direct the initial site of care. As Joe mentioned, a subset of skin and soft tissue infections is acute bacterial skin and skin structure infections or abscesses. This was a designation created by the FDA.

So historically, if you look at package inserts for some of our older antibiotics, what you’ll see is if they were indicated for a skin infection, they were indicated for a complicated skin and skin structure infection. More recently, the indication is now acute bacterial skin and skin structure infections. The reason why the FDA made this change is 2-fold. First, with complicated skin and skin structures, it was a little bit more of an amorphic definition. And what they found is many patients who had a complicated skin and skin structure infection could be treated just by surgical intervention alone.

In contrast, we talked about an abscess. Joe said these are skin infections that are greater than 75 cm2, including abscesses, wounds, and cellulitis. And the thought here is although many of these patients do require surgical intervention, they also required antibiotics for a successful outcome. And because of this, they made this the designation within the trials, and when evaluating patients, they were deemed a success if they had a greater than 20% reduction in lesion size by 48 to 72 hours. So again, when we think about public health studies or these epidemiologic burden of illness studies, really what we’re capturing is skin and soft tissue infections, as Joe mentioned. We think about clinical trials; this is where we apply the abscesses with more recently approved drugs for skin infection.

Joe Reilly, PharmD, BS, BCGP: The economic burden, depending on data you look at, is significant for hospital systems and health care in general. There’s a lot of cost to consider. Just for hospitals in the United States in a year, those numbers are $4 billion or can be much greater. The burdens can vary from their soft costs involved, lost productivity, but in general, it’s $4 billion per year just in cost incurred by hospitals for the patients who were admitted with skin and soft tissue infections or ABSSSIs.

Tom Lodise, PharmD, PhD: I think when you think about the cost, what we find right now in the United States is about 2% of all hospital admissions are skin related, resulting in somewhere between 600,000 and 800,000 admissions per year, but that’s only part of the story. So when we think about patients with skin infection, we have about 6.5 million who show up to your doctor, and these are more your simple cellulitis, things that can largely be managed with topical antibiotics. We see about 3.5 million present to the ED [emergency department] with symptoms, and this is where we get into more those purulent and nonpurulent types of skin infections that Joe mentioned. And, of those individuals, 1 in 5 is admitted.

So when you think about that $4 billion, if you take into account both direct and indirect costs, it can be upward of $15 billion. But the 1 thing I would say is when a decision is made to admit a patient, you incur a $5000 cost. Could be upward of a $10,000 cost depending on the length of stay. And it makes sense. You think about each hospital admission for skin is somewhere between 4 and 5 days. The average hospital day for a skin patient is around $1500 to $2000. The costs are largely derived just from room and board, so basically when you admit someone for a skin infection, you’re paying $5000 for them to sit in that hospital bed, eat bad meals, and watch 3 stations of TV. So a lot of the burden we think about, this $4 billion or $15 billion, when you start thinking about the cost of skin infections, a lot of this is avoidable because of overhospitalization.

Joe Reilly, PharmD, BS, BCGP: And, as Tom said, when you look at those costs incurred by the hospital, it’s really room and board. A lot of people focus on drug acquisition costs. Depending on the estimates you look at, it’s under 20% of the cost. And a lot of these patients are admitted. It’s certainly a money loser for the hospital because their reimbursement does not exceed the actual costs. And many of these patients are readmitted. So there are frequent fliers with skin infections who can come back with the same skin infection, another skin infection, or actually disease progression. So when a patient stays for 4 days in a hospital, there’s sort of a push to get them out quicker because the hospitalization cost, the room and board, exceeds the reimbursement. And the sooner you get them out, we think, is better for the hospital, but it may not be best for the patient because now we’re depending on them to be compliant with oral antibiotic therapy in the outpatient setting or to continue the antibiotics in another setting.

Tom Lodise, PharmD, PhD: Yes. So those are several good points you raised there, Joe. And I think when we think about the cost of hospital care, my pharmacy cost is maybe 15%. Antibiotics are only 1%. So I think in the era of antibiotic stewardship where optimizing outcomes is the priority, there’s a real heavy emphasis on cost of care. And when we look at the totality of a skin admission, antibiotics are less than 5%. Also, I’m glad that you mentioned readmissions because what we’re finding is somewhere between 10% and 20% of patients with a skin infection who are hospitalized are readmitted within 30 days. That’s a high number; that’s 1 in 5. And as Joe has alluded to, for some of these patients, depending on their comorbidities and lifestyle choices, it could be a reinfection, but I think a lot of them are just progression of infections that were not adequately treated. And much of this can be related to failure to take oral drugs in the outpatient setting, which we’ll talk about in more detail later in the interview.

 

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