Review
Outcomes from global adult outpatient parenteral antimicrobial therapy programmes: A review of the last decade

https://doi.org/10.1016/j.ijantimicag.2013.09.006Get rights and content

Abstract

Outpatient parenteral antimicrobial therapy (OPAT) has become a global treatment modality since its advent in 1974. The multicentre outcome registries that were employed at the turn of the century to demonstrate the benefits and challenges in this treatment setting have been discontinued. In the intervening years, trends in clinical, patient satisfaction, programmatic and economic outcomes have been shown in sporadic cohort analyses from around the globe. These outcomes are generally reassuring and compare well with previous registry data. However, meaningful comparison of a range of key outcomes is hampered by a lack of uniformity to outcome reporting. In addition to ‘whole programme’ outcome reports, several studies have detailed real-world outcomes in OPAT pertaining to specific conditions and populations. This work has shown how prospective data collection in the OPAT setting can yield valuable insights into the effectiveness and safety of the management of many conditions, such as osteoarticular infection and endocarditis, in a diverse range of populations and increasingly from different countries. Enhanced and perhaps more uniform outcome surveillance in this fashion now constitutes good practice and will enable the benefits and risks of this treatment modality to be shared both in novel and established OPAT arenas.

Introduction

Outpatient parenteral antimicrobial therapy (OPAT) is a treatment modality that allows patients to reside in the community while receiving intravenous (i.v.) antimicrobials. It was first described in 1974 in the USA to treat infectious exacerbations of cystic fibrosis and has been readily adopted there and in other parts of the world as an acceptable standard of infection management [1], [2]. Indeed, recent UK guidance for antimicrobial stewardship recognises the value of OPAT within a stewardship programme [3].

Also known as outpatient and home parenteral antimicrobial therapy (OHPAT), community-based parenteral anti-infective therapy (CoPAT) or delivered as part of ‘hospital in the home’ (HIH) services, OPAT has been defined by the Infectious Diseases Society of America (IDSA) as ‘the provision of parenteral antimicrobial therapy in at least 2 doses on different days without intervening hospitalization’ [4]. A variety of delivery methods have been described. A patient will generally receive a drug with a suitably long half-life via an infusion or bolus. Patients may visit a clinic or ‘infusion centre’, or have the drug administered at home by a visiting nurse, trained friend or family member. In certain cases a patient or carer may also be trained to administer. OPAT can be used either to facilitate early discharge from hospital or to avoid admission [5], [6].

OPAT is delivered by infectious diseases services as well as medical and emergency departments in conjunction with microbiologists. In the USA, the hospitalist movement has adopted OPAT as a key service [7]. OPAT constituted 25% of all infectious diseases consultation requests at one centre [8]. Perceived benefits include clinical efficacy, patient convenience as well as economic savings. Indeed, patient and economic considerations have been key drivers of OPAT uptake by healthcare providers [5]. However, the implicit reduction in the immediacy of clinical supervision necessitates close monitoring of individual patients and governance of OPAT programmes in order to ensure outcomes are satisfactory and adverse events are minimised [9].

The evidence to support the value of OPAT primarily stems from non-controlled cohort studies. Indeed, randomised studies to identify benefit and risk are few [10], [11]. A trial of home versus hospital i.v. treatment of infections conducted in Brisbane, Australia, was limited by difficulties with recruiting a representative sample [12]. Subset analyses of antibiotic trials have been employed, but randomisation and matching an OPAT group to an inpatient group with a similar level of co-morbidity is challenging [13], [14], [15]. Most experts would no longer regard a randomised controlled trial as ethical as OPAT has become a standard of care. Therefore, therapeutic benefit and risk have previously been principally demonstrated by cohort analysis using OPAT outcome registries [2], [5], [16].

A decade ago, the value of multicentre registries was highlighted in terms of their ability to monitor quality within and between programmes over time, and in terms of their usefulness as a tool to monitor the performance of new treatments against more established ones [16]. The 24-site US OPAT registry, which ran from 1997 to 2000, provided a crucial vehicle for collecting evidence in this field. This registry was adapted for use in Italy and the UK and allowed some international comparisons [2]. Whilst the US registry is no longer operational, there are new initiatives to re-establish such useful systems [5], [17], [18]. Good-quality prospective data collection, with clear outcome and safety measures, is now considered good practice in OPAT [19]. Furthermore, OPAT programme metrics are recommended as one of six key components of OPAT care [20]. This review aims to report outcomes of a range of OPAT programmes over the last decade. Although heterogeneity of outcome reporting does not allow systematic analysis of the data, we seek to trace trends in clinical and economic outcomes and to highlight areas of new practice in this growing field.

Section snippets

Methods

A literature search was performed using Medline and Embase from 1 January 2002 until 24 July 2013 using the search terms ‘OPAT’, ‘OHPAT’, ‘outpatient parenteral antibiotic therapy’, ‘CoPAT’ and ‘hospital in the home’. Non-English language and non-adult studies were excluded. Abstracts were then screened for relevance by one author. Additional literature was identified from reference lists of articles found on the original search. Studies evaluating general ‘hospital in the home’ programmes that

Cohort descriptions

There have been several OPAT reports detailing ‘whole programme’ outcomes. The largest published cohorts come from Singapore and Glasgow (UK) [18], [21]. The Singapore group has maintained a collaborative database across two major hospitals since 2006 and has collected 2229 first OPAT episodes. Glasgow has prospective data from a similar number of first OPAT episodes spanning the first decade of the 21st century. Other recent reports come from London and Sheffield (both UK) as well as a smaller

Economic outcomes

Paladino and Poretz [5] have noted that whilst OPAT costs tend to be less than inpatient equivalents, a holistic pharmacoeconomic analysis comparing these two modalities is required. Such an analysis should take into account factors such as the potential reduction in nosocomial infections, cost of re-admissions, and patient factors such as the ability to return to work.

In the absence of such studies, the majority of the economic data that support OPAT are the savings accrued from real or

Patient satisfaction outcomes

Most published general OPAT cohorts have included some kind of patient satisfaction survey. These are recommended as a way of monitoring quality of service over time [19], [20].

The Sheffield group surveyed OPAT patients with a 61% response rate; all but one of the respondents stated that they would choose to undergo OPAT again [23]. In London there was a 47% response rate overall and 81/84 stated they would choose OPAT again [22]. In Dublin all patients were surveyed, all said they would choose

Outpatient parenteral antimicrobial therapy outcomes in specific conditions

A number of studies report experience with some outcomes for a range of specific infections. These data are instructive in supporting our understanding of the value and effectiveness of OPAT in these settings.

Outpatient parenteral antimicrobial therapy outcomes in specific groups

Recent literature has featured work describing outcomes in groups of patients who have traditionally been difficult to treat on OPAT programmes. By broadening the reach of OPAT, further patient-orientated and economic gains can be made. As OPAT success and safety relies heavily on patient and social factors, monitoring of OPAT in these special groups is an emerging and important activity.

Conclusion

OPAT offers clinicians and patients an important alternative to inpatient care. The evidence base to support its impact and value needs to grow in quantity and quality. For any such intervention it is important to show at least equivalent clinical and microbiological effectiveness, safety and perhaps added value in terms of fiscal advantage. Other important measures include an improvement in the quality of life or a reduction in hazards associated with hospitalisation. The economic benefits

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