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Key points from the evidence

Outpatient parenteral antimicrobial therapy (OPAT) [In development]
Healthcare Improvement Scotland
  • The published evidence relating to OPAT clinical effectiveness, safety and different models of care is limited to three systematic reviews of mainly single-arm case series and cohort studies. Selection bias was inherent in most primary studies as patients were allocated to OPAT, inpatient care, or specific OPAT models based on clinical criteria and therefore likely differed in infection type, severity of infection, co-morbidities, and other characteristics.
  • Evidence on the effectiveness and safety of OPAT services should be interpreted with caution due to the likelihood of differences in underlying patient characteristics between OPAT and inpatient care.

Effectiveness and safety of OPAT compared with inpatient care

  • A systematic review (128 studies total; 21 comparative) comparing adult OPAT with inpatient care found no differences in duration of therapy (6/9 studies) and inconclusive results for infection cure and improvement rates (six studies).
  • In another systematic review (19 studies) comparing OPAT at home with inpatient care in children, there were no significant differences in treatment failure rate. Seven out of 15 studies reported significantly longer treatment duration in children treated with OPAT at home. This may be due to less frequent reviews of infection status in children at home. Results for readmission to hospital were not reported (two studies) or not statistically significant (four studies).
  • A third systematic review of different age groups (44 studies total; two comparative) reported mean hospital readmission rates with OPAT as 6.4% in mixed age populations (25 studies), 5.2% in adults aged >60 (five studies), and 8.7% in children aged <18 (four studies). No data on inpatients were presented due to the lack of comparative studies.
  • In the systematic review comparing adult OPAT with inpatient care, there were no differences in patient mortality in five out of six studies. There were no differences in drug-related side-effects in six studies, OPAT had fewer drug-related side-effects in two studies, and data were not extractable from two studies. There was a suggestion of an increased number of venous access line-related complications in OPAT patients in two studies, and two studies found no difference in this outcome.
  • Few adverse events (range 0 to 2) were reported for either OPAT or inpatient care in the ten studies reporting this outcome in the systematic review of home-based OPAT in children.
  • The review of OPAT in different age groups reported:
    • Mean vascular access device-related complication rates of 3.9% in mixed age groups (21 studies), 18.5% in older adults (>60 years; three studies) and 14.6% in children (<18 years; five studies).
    • Mean drug-related adverse event rates were 5.4% in mixed age groups (23 studies), 5.5% in older adults (four studies), and 9.8% in children (five studies).
    • The mean mortality rate was 0.5% in mixed age groups (12 studies) and 2.1% in older adults (three studies). No studies reported mortality in children.
    • Data on safety outcomes were not available for inpatients due to the lack of comparative studies.

Comparing OPAT models of care

  • In a systematic review (128 studies) comparing four different models of adult OPAT care with inpatient care:
    • Single-arm studies reported similar mean infection cure and improvement rates across different OPAT models of care: self-administration 91.3%, specialist nurse administered 90.6%, general nurse administered 90.0%, and outpatient clinic attendance 88.3%.
    • For each OPAT model compared with inpatient care, there were a maximum of four studies for each outcome.
    • No differences in duration of treatment were found for any model of OPAT compared with inpatient care.

De novo cost minimisation analysis

  • An SHTG de novo cost-minimisation analysis found that all evaluated OPAT service delivery models were consistently less costly compared with inpatient care.
    • Cost models were developed for the indications that represent the majority of infections treated via OPAT in the UK: skin and soft tissue, complex urinary tract, bone and joint, diabetic foot, bronchiectasis, and intra-abdominal infections.
    • The extent of cost reductions associated with OPAT relative to inpatient care was sensitive to the underlying infection and OPAT model of care.
    • Across the different infections modelled, the cost of OPAT (excluding oral therapies) ranged from 23% to 51% of the cost of an equivalent inpatient stay for patients with short-term infections and ranged from 22% to 56% for longer-term infections.
    • Self-administration (bolus IV) was associated with the lowest costs per OPAT treatment episode across all infection types, and nurse home visits the highest cost.
    • As a component of OPAT services, supervised oral therapies were associated with substantial cost reductions for the treatment of orthopaedic (bone and joint) and diabetic foot infections.

Patient and social aspects

  • Two qualitative studies from England (n=32; n=12) and one from Scotland (n=20) explored patient experiences and views on OPAT.
    • Participants in all three studies were adults, although one study was based on parents of children who had received OPAT.
    • The main perceived benefits of OPAT, regardless of model of care, were avoiding unnecessary hospital admissions, enjoying the comforts and security of home, and reduced disruptions to daily life (including work).
    • Clear communication between the OPAT team and patients, and between the hospital and community healthcare, was highlighted as being important to patients.
    • Concerns described by patients related to travel, the impact of OPAT on family and friends, a perceived risk of hospital-acquired infections, fears about returning to daily life and line-related complications, perceived premature transition to oral antimicrobials, and cleanliness of the home environment for home-based care.
    • In an analysis of patients in north-east Scotland, the main reasons for not self-administering OPAT were a lack of awareness it was a treatment option, a perception that hospital staff were the most appropriate people to deliver antimicrobial therapy, and anxiety about potential complications with self-administration.
  • A cross-sectional study in NHS Lothian (n=4,944 in univariate analysis; n=4,902 in multivariate analysis) identified significant inequities in access to OPAT services, with people from the most deprived socioeconomic group and women being significantly less likely to be referred for OPAT. 

Editorial Information

Last reviewed: 08/02/2021

Author email(s): his.shtg@nhs.scot.