Outpatient Parenteral Antimicrobial Therapy

Ann L N Chapman (2013)

Defining OPAT

Outpatient Parenteral Antimicrobial Therapy (OPAT) is a form of antibiotic therapy which aims to provide parenteral treatment to patients that have severe infections such that they do not need to stay in the hospital overnight. Parenteral treatment is defined as any medication that needs to be administered through the veins, i.e., intravenously.

The Uses of OPAT

One of the strengths of OPAT is its applicability to many infections, these include cellulitis, infective endocarditis, septic arthritis, and osteomyelitis. Cellulitis is a soft tissue infection which can vary in severity. Around thirty percent of patients who present to the hospital will have an infection that can be treated through the use of intravenous antibiotic therapy. The use of OPAT in these instances leads to successful long and short term clinical results. More serious infections such as those of septic arthritis and infective endocarditis also yield optimistic results though a period of inpatient care usually helps to achieve this. OPAT also plays an integral part in the treatment plan for infective endocarditis which requires a more thorough evaluation to determine whether treatment is suitable for patients or not.

Assessing Patients’ Suitability for OPAT

The key criterion for OPAT is that the patients need to be clinically stable, hence the ease of use with simpler infections and issues that arise with more complex conditions. For instance, in the case of cellulitis some assessment is required in order to exclude other complications being mistaken for it. Additionally, in the case of infective endocarditis, the first two weeks tend to indicate the severity and therefore after this initial period OPAT may be utilised. Active patient engagement is also essential for a successful treatment pathway, thus any barriers to communication or secondary infections that require additional treatment may reduce the suitability of OPAT.

Benefits and Risks of OPAT

One benefit is the potential cost effective nature of OPAT in comparison to antibiotic therapy provided within the hospital environment, since one study in the UK shows that for inpatient care and OPAT occurring for an equivalent period of time, “OPAT cost 47% of equivalent inpatient national average costs.” Another benefit is that OPAT helps to relieve stress on inpatient services which could help reduce the number of patients occupying beds for antibiotic treatment. The other major benefit is that there is mounting evidence that OPAT is linked to a very low prevalence of infection in a clinical setting.

On the other hand, one critical drawback is that due to the “reduced level of supervision” there may be some form of additional clinical risk. Also, as a result of the antibiotic therapy, other mild conditions may arise such as diarrhoea. Though in some cases complications may be more severe as a result of the parenteral aspect of the treatment. Sometimes, the patients may need to be readmitted which decreases the reliability of the treatment, which means that there should be a form of “24 hour access to clinical support.”

Summary written by Noureldin El Gabry Shaweesh

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