Artwork by Kathleen Sluka

For most people, pain goes away when an injury heals. But for some people, pain after surgery can linger, and can last for years or even a lifetime. The Acute to Chronic Pain Signatures (A2CPS) project is a bold research initiative - the largest and most comprehensive of its kind - being carried out by a nation-wide consortium of researchers. The findings will help researchers to develop better, more individualized treatments for patients and to better understand the complex biological processes underlying chronic pain.

About A2CPS


A2CPS will collect questionnaires, blood samples and brain imaging from 2,800 participants before and for up to 12 months after having total knee replacement or thoracic surgery.


Many diseases can be diagnosed, tracked and predicted with biological markers, or biomarkers, but none are yet known for chronic pain. The major aim of A2CPS is to find biomarkers or bio-signatures of the transition to chronic pain.


The A2CPS consortium is organized into four main hubs, with over 100 investigators and staff around the country. Our researchers span a wide range of expertise, from basic scientists to clinicians to data management experts.


In addition to biological specimens, A2CPS also collects different types of data from our participants, including patient-reported outcomes (PROs) and quantitative sensory testing (QST), among others.


The term “omics” refers to the collection of information about the molecules found in our blood, which can tell us about the activity of genes, proteins, lipids and metabolites in our cells and tissues.

Brain Imaging

Previous studies have identified “signatures” of brain activity that reflect a painful experience, and others that predicted who was more likely to develop chronic pain. A2CPS will include brain-imaging data in our search for biosignatures of chronic pain.


A2CPS Investigator Dr. Joe Zhou named Fellow by American Association of Physicists in Medicine 

Published November 2022

Congratulations to Dr. Xiaohong Joe Zhou, PhD, DABR, DABMP, who was recently named a Fellow by the American Association of Physicists in Medicine (AAPM). Dr. Zhou currently serves as a professor of radiology, neurosurgery and biomedical engineering at the University of Illinois at Chicago and Chief Medical Physicist at UI Health. At A2CPS, Dr. Zhou plays a pivotal role in collecting and analyzing our brain imaging data, one of many types of biomarkers we are investigating.  

Semi-annual A2CPS Consortium Meeting — October 27th, 2022

Published October 2022

Our semi-annual A2CPS consortium meeting is coming up! Join us virtually on Thursday, October 27th from 2-5pm EST and hear from invited speakers Patrick Tighe, Yenisel Cruz-Almeida, and Etienne Vachon-Presseau. Register here!

IASP 2022 World Congress on Pain

Published October 2022

Pain researchers — were you in Toronto for the 19th World Congress on Pain? Check out our Twitter feed to learn more and see what you missed! #IASP2022

[Pictured, left to right: Chad Brummett, Laura Frey-Law, Dana Dailey, Katerina Zorina, Luda Diatchenko, Tor Wager, Steve Harte, Dan Clauw, Kathleen Sluka, Stephani Sutherland, Giovanni Berardi, Rick Harris]

Optimization of Imputation Strategies for High-Resolution Gas Chromatography–Mass Spectrometry (HR GC–MS) Metabolomics Data

Published May 2022

A major aim of A2CPS is to identify biomarkers and biosignatures of the transition to chronic pain. That includes metabolomics, in which metabolites are detected in the blood using technology called gas chromotography-coupled mass spectroscopy (GC-MS). In a new paper published in the journal Metabolites, A2CPS investigator Michael Olivier and colleagues find new ways to optimize data handling from their GC-MS experiments. Congrats to the metabolomics team!