title: Reliability of conditioned pain modulation: a systematic review.
abstract: A systematic literature review was undertaken to determine if conditioned pain modulation (CPM) is reliable. Longitudinal, English language observational studies of the repeatability of a CPM test paradigm in adult humans were included. Two independent reviewers assessed the risk of bias in 6 domains; study participation; study attrition; prognostic factor measurement; outcome measurement; confounding and analysis using the Quality in Prognosis Studies (QUIPS) critical assessment tool. Intraclass correlation coefficients (ICCs) less than 0.4 were considered to be poor; 0.4 and 0.59 to be fair; 0.6 and 0.75 good and greater than 0.75 excellent. Ten studies were included in the final review. Meta-analysis was not appropriate because of differences between studies. The intersession reliability of the CPM effect was investigated in 8 studies and reported as good (ICC = 0.6-0.75) in 3 studies and excellent (ICC > 0.75) in subgroups in 2 of those 3. The assessment of risk of bias demonstrated that reporting is not comprehensive for the description of sample demographics, recruitment strategy, and study attrition. The absence of blinding, a lack of control for confounding factors, and lack of standardisation in statistical analysis are common. Conditioned pain modulation is a reliable measure; however, the degree of reliability is heavily dependent on stimulation parameters and study methodology and this warrants consideration for investigators. The validation of CPM as a robust prognostic factor in experimental and clinical pain studies may be facilitated by improvements in the reporting of CPM reliability studies.
authors: Pain Research, Department of Surgery and Cancer, Imperial College London, London, United Kingdom.
authors: Donna L
authors: DL
authors: Kennedy
authors: Pain Research, Department of Surgery and Cancer, Imperial College London, London, United Kingdom.
authors: Harriet I
authors: HI
authors: Kemp
authors: Population, Policy and Practice Programme, UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom.
authors: Deborah
authors: D
authors: Ridout
authors: Department of Neurology, Rambam Health Care Campus, Technion Faculty of Medicine, Haifa, Israel.
authors: David
authors: D
authors: Yarnitsky
authors: Pain Research, Department of Surgery and Cancer, Imperial College London, London, United Kingdom.
authors: Andrew S C
authors: ASC
authors: Rice
mesh_terms: D000328:Adult; D003213:Conditioning, Psychological; D016208:Databases, Factual; D006801:Humans; D010146:Pain; D059408:Pain Management; D010147:Pain Measurement; D015203:Reproducibility of Results