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, 2 (11), e1915105

Association of Early Postoperative Pain Trajectories With Longer-term Pain Outcome After Primary Total Knee Arthroplasty


Association of Early Postoperative Pain Trajectories With Longer-term Pain Outcome After Primary Total Knee Arthroplasty

Jasvinder A Singh et al. JAMA Netw Open.


Importance: Studies to date have not comprehensively examined pain experience after total knee arthroplasty (TKA). Discrete patterns of pain in this period might be associated with pain outcomes at 6 to 12 months after TKA.

Objectives: To examine patterns of individual post-TKA pain trajectories and to assess their independent associations with longer-term pain outcome after TKA.

Design, setting, and participants: This prospective cohort study combined data from a national US TKA cohort with ancillary pain severity data at 2 weeks and 8 weeks after the index TKA using a numeric rating scale. All participants received primary, unilateral TKA within the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) national network of community sites in 22 states or at the lead site (University of Massachusetts Medical School). Participants had a date of surgery between May 1, 2013, and December 1, 2014. The data analysis was performed between January 13, 2015, and July 5, 2016.

Exposures: Pain trajectories in the postoperative period (8 weeks).

Main outcomes and measures: Index knee pain at 6 months after TKA using the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain scale. Group-based trajectory methods examined the presence of pain trajectories in the postoperative period (8 weeks) and assessed whether trajectories were independently associated with longer-term pain (6 months).

Results: The cohort included 659 patients who underwent primary TKA with complete data at 4 points (preoperative, 2 weeks, 8 weeks, and 26 weeks). Their mean (SD) age was 67.1 (8.0) years, 64.5% (425 of 659) were female, the mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) was 30.77 (5.66), 94.5% (613 of 649) were white, and the mean (SD) preoperative 36-Item Short Form Health Survey physical component summary and mental component summary scores were 34.1 (8.2) and 53.8 (11.4), respectively. Two pain trajectory subgroups were identified at 8 weeks after TKA: patients who experienced fast pain relief in the first 8 weeks after TKA (fast pain responders, composing 72.4% [477 of 659] of the sample) and patients who did not (slow pain responders, composing 27.6% [182 of 659] of the sample). After adjusting for patient factors, the pain trajectory at 8 weeks after TKA was independently associated with the mean KOOS pain score at 6 months, with a between-trajectory difference of -11.3 (95% CI, -13.9 to -8.7).

Conclusions and relevance: The trajectory among slow pain responders at 8 weeks after surgery was independently associated with improved but greater persistent index knee pain at 6 months after TKA compared with that among fast pain responders. Early identification of patients with a trajectory of slow pain response at 8 weeks after TKA may offer an opportunity for interventions in the perioperative period to potentially improve the long-term pain outcomes after TKA.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Singh reported receiving consultant fees from Crealta/Horizon, Fidia, UBM LLC, Medscape, WebMD, the National Institutes of Health (NIH), and the American College of Rheumatology (ACR); receiving personal fees from Clinical Care Options, Clearview Healthcare Partners, Putnam Associates, and Spherix; receiving other support from OMERACT (an organization that develops outcome measures in rheumatology and receives arms-length funding from 36 companies), Food and Drug Administration arthritis advisory committee, Veterans Affairs rheumatology field advisory committee, and UAB Cochrane Musculoskeletal Group Satellite Center on Network Meta-analysis; owning stock options in Amarin Pharmaceuticals and Viking Therapeutics; being a member of the executive committee of OMERACT and the Veterans Affairs rheumatology field advisory committee; being editor and director of the UAB Cochrane Musculoskeletal Group Satellite Center on Network Meta-analysis; and previously serving as a member or chair of the following committees: ACR annual meeting planning committee and quality of care committee; ACR meet the professor, workshop, and study group subcommittees; and ACR criteria and response criteria subcommittee. Dr Nobel reported receiving grants from the NIH and Canadian Institutes of Health Research during the conduct of the study. Ms Yang reported receiving grants from the Agency for Healthcare Research and Quality (AHRQ) during the conduct of the study. Dr Saag reported receiving research grants from Amgen, Ironwood/AstraZeneca, Horizon, Merck, Sobi, and Takeda Pharmaceuticals and receiving consultant fees from Abbott, Amgen, Ironwood/AstraZeneca, Bayer, Bristol-Myers Squibb, Horizon, Lilly, Merck, Pfizer, Radius, Roche/Genentech, Sobi, and Takeda Pharmaceuticals. Dr Franklin reported receiving grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases, Patient-Centered Outcomes Research Institute, and AHRQ outside the submitted work. No other disclosures were reported.


Figure.. Pain Trajectory in Fast Pain Responders and Slow Pain Responders at 8 Weeks After Total Knee Arthroplasty
Probability of moderate to severe pain is scaled 0 to 1 (lower indicates less probability, while higher indicates greater probability). The shaded areas are 95% CIs. Using the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain scale (range, 0-100; 0 represents extreme knee problems, and 100 represents no knee problems), a preoperative score of 50 to less than 70 indicates moderate pain, and 0 to less than 50 indicates severe pain. The KOOS items are rated by the patient on a 5-point Likert-type scale (range, 0-10; 0 represents no problems, and 10 represents extreme problems), with each of the 5 scores calculated as the sum of the items included. Using the Likert-type 2-week and 8-week pain scale, a preoperative score of 5 to 6 indicates moderate pain, and 7 to 10 indicates severe pain.

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