Core Outcome Domains For Chronic Pain Clinical Trials
IMMPACT Recommendations
Rationale for Recommendations
Variability in outcome assessments has impeded evaluation of efficacy & effectiveness of chronic pain treatment. To facilitate meaningful evaluation, a standard set of outcome domains is recommended. Investigators may augment the core domains with others that are specific to the situation or treatment being studied.
Development of a core set of outcomes would:
Facilitate comparison & pooling of data
Encourage more complete investigation & reporting of relevant outcomes
Encourage development of cooperative multicenter projects Simplify the process of reviewing research proposals, manuscripts, & publications Allow clinicians to make more informed clinical decisions
Objective of IMMPACT
To develop consensus on outcome domains that would transcend specific chronic pain syndromes
Procedures
27 people representing academia, government, & pharma Participants selected to represent
health care disciplines: anesthesia, biostats, clinical pharmacology, epidemiology, geriatrics, internal medicine, neurology, nursing, oncology, pediatrics, physical medicine, psychology, rheumatology Pharmaceutical industry An attorney
General Issues
In a clinical trial, pain reduction & safety are necessary outcome variables but they are not sufficient for evaluation of overall benefit or harm. The domains of importance in a clinical trial should:
match the purpose of the study measure positive & negative outcomes of treatment be appropriate for the chronic pain syndrome studied & specific characteristics of the sample.
Applicability
These recommendations are most applicable to clinical trials designed to evaluate efficacy or effectiveness of treatments for chronic pain. Assessment of these core domains is NOT a requirement. If one or more domains are not included in a clinical trial, reasons for exclusion should be justified a priori. There will be clinical trials in which the core domains will require modification
mild pain; single dose studies; studies of infants, children, & cognitively impaired
Core Domains
Pain Physical functioning Emotional functioning Participant rating of global improvement Other symptoms & adverse events Participant disposition
Adherence to treatment, reasons for withdrawal
IMMPACT II
Convened to develop consensus recommendations for specific measures of each of the core domains
Criteria for selection of core outcome measures
Appropriateness of content & conceptual model of measure Reliability Validity Responsiveness (sensitivity to change) Interpretability Precision of scores Respondent & administrator acceptability Respondent & administrator burden & feasibility Availability & equivalence of alternate forms & methods of administration Availability & equivalence of versions for different cultures or languages
More on criteria
Criteria given greatest weight:
Appropriateness of content Reliability Validity Responsiveness Participant burden
Measures lacking published information on these criteria were not recommended.
Recommended Outcome Measures
Pain
11-point numerical rating scale of pain intensity Use of rescue analgesics Categorical rating of pain intensity when numerical rating is problematic
Physical functioning (either measure)
Multidimensional Pain Inventory Interference Scale Brief Pain Inventory Interference items
Emotional functioning (either measure)
Beck Depression Inventory Profile of Mood States
Ratings of global improvement & satisfaction
Patient Global Impression of Change Passive capture using open-ended prompts Details of recruitment & progress thru trial using CONSORT guidelines
Symptoms & adverse events
Participant disposition