Pain Research


University of Michigan study to compare two pain regimens commonly prescribed following outpatient surgical procedures

Researchers to receive $4 million to compare effectiveness and safety of NSAID and opioid treatments

For the millions of patients in America who undergo low-risk outpatient surgeries each year, pain management is among the top issues they face when recovering at home. A new study led by University of Michigan researchers seeks to identify the most effective and safest prescribing strategy to relieve acute pain after a patient heads home after surgery.

The CARES study — Comparing Analgesic Regimen Effectiveness and Safety After Surgery — will compare how well prescription non-steroidal anti-inflammatory drugs (NSAIDs) and opioid treatments relieve acute pain after surgery, the harms of each treatment option, and the effects of each treatment option on additional post-surgery outcomes. The study has been approved for more than $4 million in funding(link is external) from the Patient-Centered Outcomes Research Institute (PCORI).  

Mark Bicket, MD, PhD
Mark Bicket, M.D., Ph.D., is the CARES study's principal investigator. 

Principal investigator Mark Bicket, M.D., Ph.D., said despite how commonly opioids and NSAIDs are prescribed, patients and providers have little comprehensive evidence to directly compare which option may be best for patients after they are discharged.

“Both NSAIDs and opioids are routinely and successfully used to treat pain following low-risk surgeries, but patients and their surgical teams may have concerns about the potential for under-treating pain with NSAIDs and the possible harms from unnecessary exposure to opioids,” said Bicket, an Assistant Professor of Anesthesiology and Co-Director of the Opioid Prescribing Engagement Network(link is external). “We are grateful for partners like PCORI for investing in studies like this as we work to advance our knowledge of patient experiences and help patients and their providers make important decisions on how best to manage pain.”

The study is also being led by co-principal investigator Karim Ladha, M.D., M.Sc. at St. Michael’s Hospital – Unity Health Toronto. “CARES has the potential to meaningfully impact patient care choices by producing evidence to fill critical knowledge gaps regarding the comparative effectiveness and safety of NSAID versus opioid analgesic regimens,” said Ladha, who co-directs the Patient-centred Innovation in Anesthesia Clinical care and Evaluation (PINNACLE) research group.

The clinical trial will enroll 900 adults undergoing one of three common low-risk surgical procedures — gallbladder removal, inguinal hernia repair, and breast lumpectomy — in a randomized study to receive either an NSAID plus acetaminophen or opioid plus acetaminophen regimen to manage pain following their procedure. The study will include four primary enrollment sites that represent diverse communities and a mix of practice environments: Michigan Medicine, Henry Ford Health System in Detroit, Barnes Jewish Hospital in St. Louis, and Unity Health Toronto.

Project team members will follow up with patients for up to six months. Participants will use a smartphone app to answer questions to determine outcomes related to their pain relief immediately following surgery, adverse medication-related symptoms including sleep disturbance, and additional longer-term key outcomes that may impact their quality of recovery over time, such as chronic pain, opioid misuse, and substance use. 

The project team worked with patient partners and additional stakeholders to ensure the study addresses questions most important to these groups.

“The balance between pain relief and avoiding side effects can be one of the most challenging aspects of making informed decisions about surgery. The CARES Trial will help to shed new light on that by including important insight from patients as well as providers,” said Rachel McDuffie, who serves as part of the research team to help represent the voice of patients both during the trial and later when sharing results of the project. 

The study is expected to last three years. Funding for the study has been approved pending completion of a business and programmatic review by PCORI staff and issuance of a formal award contract.

“Pain medicine has a number of key research gaps — and yet pain is ubiquitous,” Bicket said. “CARES will be the first rigorous comparison of these two pain regimens that follows patients as they recover after surgery, and will help to inform decisions that impact the care of more than 16 million adults in the United States who undergo these types of surgical procedures.”

PCORI is an independent, nonprofit organization authorized by Congress in 2010. Its mission is to fund research that will provide patients, their caregivers, and clinicians with the evidence-based information needed to make better-informed healthcare decisions. For more information about PCORI’s funding, visit