Study questions

The overall study design is a two centre, prospective observational incidence study with a nested case control study. The study design is shown in Figure 1.



Figure 1: ECONI study


1. Observational cohort study on incidence of HAI

This surveillance work is led by Health Protection Scotland. ECONI nurses will review patients’ clinical data (microbiology samples, antibiotic prescribing and clinical notes). No additional tests or treatments will be required for patients. Data collected will be collated from information collected routinely during patients’ clinical care. The survey will record minimal information on all patients with HAI, ward, type of HAI, date of admission and CHI number, causative organism, and resistance to antibiotics of the causative organism. These data will be transferred to NHS Health Protection Scotland and used to link to routinely collected national datasets.

Cohort study questions: This study will determine the incidence and type of HAI in hospital.

1.1.         What are the demographic characteristics of patients with and without HAI?

1.2.         What proportion of all patients acquires HAI?

1.3.         In which specialties are HAI found?

1.4.         What type of infections are present?

1.5.         How long do patients with and without HAI stay in hospital and what is the addition LOS attributable to HAI?

1.6.         When in the patients stay did the HAI appear?


2. Case control study Objective: Estimate the impact of HAI on care in hospital

In this work package we will investigate risk factors, causative pathogens and estimate the burden of HAI on NHS services in hospitals. Patients (or the patients guardian or welfare attorney or nearest relative if the patients is not able to consent for themselves) will be told about the study and asked if they are willing to participate and provide consent to complete a number of questionnaires. This will include case note review of care in hospital by ECONI nurses and a patient questionnaire.

Case control study questions (in hospital)

2.1.         What are the risk factors for HAI within hospital?

2.2.         What are the causative organisms of these infections?

2.3.         What is the impact on EQ-5D scores for patients with and without infection during their hospital stay?

2.4.         What is the in-hospital excess resource use (n) and costs (n*£) associated with HAI? (Resource use in-hospital will include: Length of stay, days in ICU or other significant facilities, device use, operation and antibiotic prescribing). This will take NHS perspective.

2.5.         Establish the relative costs of different types of HAI in hospital.


3. Case control longitudinal study Objectives: Investigate the impact of HAI on care post discharge

In this work package we will investigate the burden of HAI on community care services, other post discharge costs, social care costs, private patient costs and finally calculate total societal costs due to HAI. There will be two elements to this work package, firstly a questionnaire sent to patients one month, three month, six months and one year post discharge. These responses will be linked to routine data in order to complete the objectives. Secondly a sub-set of those patients who completed the questionnaire will be asked to participate in a qualitative interview.

Case control study questions: Longitudinal follow up

3.1.         How many HAI were identified post discharge, what type of infections and how many HAI have led to readmissions?

3.2.         What is the effect of HAI on patients’ Health Related Quality of Life?

3.3.         What is the effect of HAI on NHS care post discharge? (this will include the number and cost of GP visits, District nursing, Pharmacy costs, NHS 24 and hospital outpatient visits).

3.4.         What is the effect of HAI on patients’ personal care (This care could be provided by social services or the patients families). This will include number of events and cost of these events. This will be assessed from the perspective of patients and social services.

3.5.         What is the impact of HAI on ability to work?

3.6.         What is the total burden to the NHS of HAI? This will be expressed in terms of bed days and number of outpatient episodes of care.

3.7.         What is the total societal economic cost of HAI? We will calculate total societal costs using all estimates of cost.

Three objectives will be addressed entirely from the interview part of the case control study.

3.8.         How was the patient’s life affected by the infection?

3.9.         What do the patients think could have improved their experience of the infection?

3.10.      What was the overall impact on patient’s families due to HAI?


4. Develop a framework to support decision making for future investment in Infection Prevention and Control (IPC)

This work package will not involve any patient interaction. It will develop a framework to support modelling for decision making for future investment in Infection Prevention and Control (IPC) based on data collected within the ECONI study described above. The information collected during the first three phases will be used to model possible outcomes of infection prevention and control measures. A model will be developed which could be utilised:

a.            To explore the impact of two (or more) alternative approaches to HAI reduction.

b.            To estimate/elicit the total expected cost and total expected benefits (and to whom).

c.             To allow assessment to see if benefits outweigh costs.

d.            To model the costs of HAI by infection type and overall.