Condition category
Not Applicable
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Particularly in the course of life-threatening illnesses (e.g. stroke, myocardial infarction, chronic obstructive pulmonary disease) longer ventilation can be necessary. Generally the duration and the amount of ventilation hours has been increasing. With increasing patient age the duration of ventilation procedures rises as well. The aim is to find and prevent potential errors and improve in-hospital quality regarding this high-risk procedure. Due to the association between ventilation, life-threatening illnesses and age of patients there is a risk of a high patient mortality (death rate) while performing ventilation for over 24 hours. The aim of this study is to find out whether the mortality of patients who were ventilated for over 24 hours improves due to an organized collegial consultation ("Peer-Review").

Who can participate?
Hospitals in Germany that are members of the Association Initiative Quality in Medicine and that treated 10 patients in 2016 who were ventilated for over 24 hours

What does the study involve?
Hospitals with the highest in-hospital deaths of patients who were ventilated for over 24 hours
are randomly allocated into two groups. The intervention group gets a standardized peer review about ventilation from educated peers from a different hospital in the IQM network. The control group does not get a peer review. Participating hospitals that are not categorized to the highest in-hospital mortality of ventilated patients are allocated to observation only. The in-hospital mortality of patients who receive ventilation for over 24 hours is compared between the groups one year before and one year after the peer-review procedure.

What are the possible benefits and risks of participating?
Benefits include a possible reduction of in-hospital death rates due to better quality of care for the high-risk group of ventilated patients.

Where is the study run from?
Center for Evidence-based Healthcare (Germany)

When is the study starting and how long is it expected to run for?
January 2017 to June 2019

Who is funding the study?
Innovation fund of the Joint Federal Committee (Germany)

Who is the main contact?
Mr Felix Walther

Trial website impress-effektivitaet-des-iqm-peer-review-verfahrens-zur-verbesserung-der-ergebnisqualitaet-ein.13

Contact information



Primary contact

Mr Felix Walther


Contact details

Center for evidence-based healthcare
Fetscherstraße 74
+49 (0)351 4581 9710

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Effectiveness of the “IQM”-Peer-Review-Procedure to improve in-patient outcome-quality - a pragmatic cluster-randomized controlled trial (IMPRESS)



Study hypothesis

The IMPRESS Study evaluates a complex quality-intervention on the basis of a cluster-randomized controlled trial. This trial primarily aims to investigate if outcome-quality (mortality) improves due to a (IQM)-peer-review procedure. The “Association Initiative Quality in Medicine” (IQM) is a non-profit-organization with optional membership of German or Swiss acute care hospitals. IQM is an interhospital community which serves as the basis for communication and improvement of inpatient-healthcare quality. The IQM-peer-review-intervention is a standardized, structured collegial case-discussion and consultation of specially trained healthcare professionals. The goal of this intervention is to identify and eradicate error-potentials in structure and/or processes of care and to eventually improve in-house-quality. Observational studies suggest effectiveness of the peer review procedure, but controlled investigations are missing.

Hypothesis: The IQM-Peer-Review Procedure, a standardized collegial consultation procedure, improves in-patient care and decreases in-patient mortality of patients ventilated >24h.

Ethics approval

Ethics committee TU Dresden; registered at institutional review board (IRB): Office for Human Research Protections (OHRP); identification numbers: IRB00001473 and IORG0001076; Date of approval: 24/04/2017

Study design

Cluster randomised controlled trial

Primary study design


Secondary study design

Cluster randomised trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details to request a patient information sheet


Primary: ventilation >24h
Secondary: stroke, heart attack, COPD, pneumonia, colorectal resection


The IMPRESS study is a two-armed cluster-randomized controlled intervention trial embedded in a prospective hospital-cohort study. 385 IQM-member-hospitals from Germany are invited to participate. 60 hospitals with the highest in-hospital-mortality of patients who were ventilated >24h are randomized into equally sized intervention group (receiving peer review consultation) and control group (standard care). The randomization procedure followed a block-randomization with a constant block-length of 10 clinics per block. The study coordination of the Center for evidence-based healthcare, TU Dresden developed the randomization list. To build balanced groups the participating hospitals will be stratified according to the number of patients/year (median-split) and hospital ownership (public, private, non-profit, university hospital).

Within 4 months after randomization the intervention group gets one standardized peer-review (intervention) regarding ventilation structures and processes through educated peers from a different hospital in the IQM network between the 06/01/2017 and 12/31/2017. The control group will not get any peer-review intervention regarding ventilation procedures between the 06/01/2017 and 12/31/2017. Participating hospitals which are not categorized to the highest in-hospital mortality of patients who were ventilated >24h will not be randomized and will be assigned to the observation group.

To secure high data quality and safety the data-processing and data-analyzing sites are separated. The data analysts are blinded/masked to the allocated group of hospitals. Two analyses are planned. First, in the confirmatory analysis the primary outcome will be evaluated. Second, the explorative analysis will evaluate the secondary outcomes. Every participating hospital of intervention, control or observational group will be analyzed for the years 2016, 2017 and 2018.

Intervention type



Drug names

Primary outcome measure

Age- and sex-adjusted mean inpatient mortality rate of hospitals in the intervention or control group within one year before (baseline) and one year follow-up after the peer-review procedure (post-intervention). The primary outcome is measured for patients who receive ventilation >24h

Secondary outcome measures

Age- and sex-adjusted mean inpatient mortality rate of every participating hospital regardless of observation, intervention or control group in 2016, 2017 and 2018. The secondary outcome is measured for patients who receive ventilation >24h and colorectal resection or patients with myocardial infarction, stroke, COPD and pneumonia, respectively. For all analyses the unit of analysis is the hospital, not the individual patient.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Member of the Association Initiative Quality in Medicine
2. Located in Germany
3. Treating 10 patients in 2016 who were ventilated > 24h
4. Consented into the study in the written form

Participant type


Age group




Target number of participants

All IQM member hospitals (N=385) were invited to participate. 239 hospitals applied to participate into the 3-armed study: 1) 30 intervention-hospitals 2) 30 control-hospitals 3) 177 observation arm

Participant exclusion criteria

Does not meet inclusion criteria

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Center for Evidence-based Healthcare
Fetscherstraße 74

Sponsor information


German Research Centre for Air and Space Travel (DLR)

Sponsor details

Heinrich-Konnen-Str. 1

Sponsor type




Funder type


Funder name

Innovation fund of the Joint Federal Committee

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

A publication in high impact-peer-reviewed journals is planned. The aim is to fully publish the results of confirmatory and exploratory analysis by 06/01/2020.

IPD sharing statement
The datasets generated during and/or analysed during the current study are not expected to be made available. The transfer and use of hospital-accounting data of every hospital underlies the German medical data protection laws due to a patient-relevance and an anonymization and its transfer is strictly bounded to the use of the IMPRESS study due to the patient-relevant details and is guaranteed in the participant (hospital) information sheet. This highly sensitive data is held in a separate position/ organization of trust which will aggregate and anonymize the data. After this process the Center for Evidence-based healthcare will get the data for the realization of the confirmatory and exploratory analysis.

Intention to publish date


Participant level data

Not expected to be available

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes