Core Outcome Measures in Effectiveness Trials

Rapid Review protocol for Post Operative Pain Outcome Measures Study (POPOS)

General Information

Acute post-surgical pain is a form of acute pain which occurs after surgical trauma leading to an unpleasant sensory and emotional experience associated with inflammatory, autonomic, endocrine, metabolic, physiological and behavioural responses.

Pain after surgery continues to be a significant problem in UK hospitals, with 1 in 2 patients reporting moderate to severe pain. This is despite several attempts to highlight the issue and the expansion of pain services.

One of the reasons for this is that for acute pain many different instruments are used to assess pain in both research, quality improvement and clinical practice6 but there is no consensus of which outcomes should be adopted to allow for a national benchmarking process. Such a set of outcomes could be used to create a database nationally and at individual sites to drive improvement.

Systematic reviews do exist which have led to suggested core outcomes for clinical trials of analgesics7; such reviews usually focus on quantitative measures of pain intensity and have not been subject to acceptability analysis by either healthcare professionals or patients. This project however aims to provide a core set of outcome measures, both objective and patient reported, to be used in clinical settings and in quality improvement programmes that are acceptable both to healthcare professionals and patients. Therefore the overall project aims to identify both what measures are used and how these outcomes should be measured.

A full systematic review of outcome measures used to measure acute perioperative pain across many types of surgery is an ambitious undertaking and involves evidence of quality (reliability, validity, responsiveness etc). It is recognised that rapid reviews are a form of knowledge synthesis in which components of the systematic review process are simplified or omitted to produce information in a timely manner. To inform a full systematic review, and to identify heterogeneity in reporting, this rapid review has been devised to more clearly determine the scope of the full review protocol and specifically to identify relevant populations, study types, pain assessment categories and sources of bias. It is anticipated that this rapid review is the first part of the process to develop a set of core outcome measures by highlighting heterogeneity in reporting.

Dr Harriet Kemp, Imperial College London
Dr Charlotte Small, University of Birmingham
Dr Dev Srivastava, NHS Highlands
Dr Kirstie Haywood, University of Warwick

Further Study Information

Current Stage:
November 2017 - March 2018
Funding source(s):
No confirmed funding

Health Area

Disease Category
Anaesthesia & pain control

Disease Name
Acute post surgical pain

Target Population

Age Range
16 - 110


Nature / type of Intervention


Systematic review

Rapid contextual review ahead of full systematic review

Review question(s)
1. What outcome measures are used to assess pain in the adult acute post-surgical population?
2. How frequently is pain assessed in studies of acute post-surgical pain?
3. What domains do the outcome measures cover – categorized as per the 6 core domains of the IMMPACT guidelines (intensity, physical recovery, emotional response, adverse events, global judgment and satisfaction with treatment) as well as novel categories identified.
4. What types of studies report acute post-surgical pain outcomes (including operation type, analgesic intervention, study method)?

Since this is rapid review, the search will be restricted to three databases that are anticipated to yield the broadest evidence: Medline, EMBASE and Cochrane Systematic review database. A sample of clinical trials registers will also be searched ( and ISRCTN). Conference proceedings will not be included.
The search will include terms for the target population (post-surgical pain) and methods for measuring outcome (pain assessment). Search terms will be based on previous systematic reviews and where possible will be mapped to MeSH subject headings. For full search terms see Appendix 2.

Acute post-surgical pain: acute pain occurring after a surgical or operative intervention

Adults (aged 16 years or older) undergoing a surgical procedure in whom post-surgical pain is assessed.

Any intervention classified as ‘surgical’ or ‘operative’ by the study author, where pain is assessed after intervention.

Types of studies
This review will not be restricted to randomized controlled trials but will include systematic reviews, observational studies (cohort, cross-sectional and case-control), surveys and quality improvement reports. It will not include case reports or editorials.

Inclusion Criteria
• Acute post-surgical patients
• Participants aged 16 years or older at entry to the study
• Studies measuring acute post-surgical pain at least once following a surgical intervention as a primary or secondary outcome measure
• Studies measuring acute post-surgical pain in hospital environment (including after daycase surgery)
• Studies published in the last 3 years prior to current search date (restricted to limit size of search)
• English language studies only
• Studies with retrievable abstract and full-text or, in cases where only abstracts or trial registration summaries are available

Exclusion criteria
• Studies using exclusively qualitative methods
• Studies with <30 participants as these are less likely to influence practice
• Non-empirical or theoretical reviews, reports or books
• Studies investigating the effect of non-surgical acute pain
• Studies investigating pain after nonpainful interventions which may be categorized as operative eg. GI endoscopy

Primary outcome
Name, type or domain and frequency of pain outcome measure used

Secondary outcomes
Type of study using outcome measure, study primary outcome measure, type of intervention, any measure of healthcare professional or patient acceptability of outcome measure.

Data extraction
Studies will be screened by a single reviewer for eligibility in two stages: 1) Screening of titles and abstracts; and 2) Reviewing the full text of short-listed articles according to the inclusion/exclusion criteria. Two reviewers will each extract data from half of the studies selected. Each reviewer will also verify data extracted from one in every 20 studies examined by the other reviewer (picked at random from the list of studies included). Disagreements on the extracted data will be discussed to reach consensus, and a third reviewer will resolve any remaining discrepancies following this process.

The following data will be extracted from eligible studies:
Publication year, study design, country of main study site, sample size, surgery type, analgesic intervention being studied (if applicable), primary outcome measure for study, names of pain outcome measures used, domain or category of pain outcome measures, whether the measure is a single or composite measure, frequency of pain outcome measures used, method of reporting outcome measure (paper/electronic), method of recording outcome measure (eg. questioning by healthcare professional, researcher, self report), evidence of validation of pain outcome measure, location of recording outcome measure (eg recovery, ICU, ward, discharge lounge), other psychological or functional outcome measures used.

Risk of bias
Since this rapid review aims to determine only types of outcome measure used, risk of bias assessment will not be used but will be fully assessed in the full systematic review.

Strategy for data synthesis
To summarize the findings, a descriptive report will be produced to describe both the characteristics of studies reporting outcome measures in acute post-surgical pain and the type and frequency of use measures used. Any type of methods for assessing acceptability of use of outcome measures will also be summarised.

Analysis of subgroups/subsets
1. Outcome measures identified will be categorized by various strategies:
a) Outcome measure involves a clinical intervention/judgment/interpretation versus directly patient reported
b) Outcome measure aimed to identify intensity versus quality of pain
c) Outcome measure was a direct measurement versus a proxy eg. remedication or adverse event
d) Outcome measure was a single measure versus a composite scale
e) Outcome measure expressed inference with function (including physical or psychological) versus not

2. The types of outcome measures used will be analyzed based on surgical characteristics:
a) surgical specialty, severity, intervention
b) location of capture eg. general ward versus intensive care versus day case discharge lounge
c) type of analgesic intervention being examined by the study
d) Type of study methodology
e) Geographical location of study

Dissemination plan
The results of the report will be dissemination to the British Pain Society via its acute pain specialist group and to the POPOS steering committee. We will submit the manuscript for peer-review in a scientific journal. The findings will also be presented at scientific conferences.

Stakeholders Involved

Clinical experts
Patient/ support group representatives

Study Type

COS for clinical trials or clinical research

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