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The research

References

These studies evaluate perioperative nutrition and surgical physiology generally and do not evaluate PREP™ specifically. Each figure on our homepage comes from the peer-reviewed studies below.

  1. Prehabilitation

    186 clinical trials and 15,684 surgical patients

    Source

    McIsaac DI, Kidd G, Gillis C, et al. Relative efficacy of prehabilitation interventions and their components: systematic review with network and component network meta-analyses of randomised controlled trials. BMJ. 2025;388:e081164.

    https://doi.org/10.1136/bmj-2024-081164
  2. Prehabilitation

    Half the risk of complications (OR 0.52)

    Source

    Cascavita CT, Hall AE, Shariati K, et al. Exercise- and nutrition-based prehabilitation programs in surgery: a systematic review and meta-analysis. J Am Coll Surg. 2026;243(1):168-181.

    https://doi.org/10.1097/XCS.0000000000001891
  3. Abdominal surgery

    9 in 10 missed protein goals

    Source

    Constansia RDN, Hentzen JEKR, Hogenbirk RNM, et al. Actual postoperative protein and calorie intake in patients undergoing major open abdominal cancer surgery: a prospective, observational cohort study. Nutrition in Clinical Practice. 2022;37(1):183–191.

    https://doi.org/10.1002/ncp.10678
  4. Abdominal surgery

    Up to 10% thigh muscle lost

    Source

    Hardy EJ, Hatt J, Doleman B, et al. Post-operative electrical muscle stimulation attenuates loss of muscle mass and function following major abdominal surgery in older adults: a split body randomised control trial. Age Ageing. 2022;51(10):afac234.

    https://doi.org/10.1093/ageing/afac234

    Supporting

    Hogenbirk RNM, van der Plas WY, Hentzen JEKR, et al. Postoperative muscle loss, protein intake, physical activity and outcome associations. British Journal of Surgery. 2023;110(2):183–192.

    https://doi.org/10.1093/bjs/znac384
  5. Mixed surgery types

    ~2.5× infection odds

    Source

    Skeie E, Koch AM, Harthug S, et al. A positive association between nutritional risk and the incidence of surgical site infections: a hospital-based register study. PLoS One. 2018;13(5):e0197344.

    https://doi.org/10.1371/journal.pone.0197344

    Supporting

    Allegranzi B, Bischoff P, de Jonge S, et al. New WHO recommendations on preoperative measures for surgical site infection prevention: an evidence-based global perspective. Lancet Infectious Diseases. 2016;16(12):e276–e287.

    https://doi.org/10.1016/S1473-3099(16)30398-X
  6. Older adults

    1.6× delirium odds

    Source

    Han D, Liang Y, Chen Q, Wang X, Chen X. Association between the Geriatric Nutritional Risk Index and postoperative delirium: a meta-analysis. Frontiers in Psychiatry. 2026;17:1826824.

    https://doi.org/10.3389/fpsyt.2026.1826824

Study references

  1. McIsaac DI, Kidd G, Gillis C, et al. Relative efficacy of prehabilitation interventions and their components: systematic review with network and component network meta-analyses of randomised controlled trials. BMJ. 2025;388:e081164. doi:10.1136/bmj-2024-081164https://doi.org/10.1136/bmj-2024-081164
  2. Assouline B, Cools E, Schorer R, Kayser B, Elia N, Licker M. Preoperative exercise training to prevent postoperative pulmonary complications in adults undergoing major surgery: a systematic review and meta-analysis with trial sequential analysis. Ann Am Thorac Soc. 2021;18(4):678-688. doi:10.1513/AnnalsATS.202002-183OChttps://doi.org/10.1513/AnnalsATS.202002-183OC
  3. Katsura M, Kuriyama A, Takeshima T, Fukuhara S, Furukawa TA. Preoperative inspiratory muscle training for postoperative pulmonary complications in adults undergoing cardiac and major abdominal surgery. Cochrane Database Syst Rev. 2015;(10):CD010356. doi:10.1002/14651858.CD010356.pub2https://doi.org/10.1002/14651858.CD010356.pub2
  4. Irani JL, Hedrick TL, Miller TE, et al. Clinical practice guidelines for enhanced recovery after colon and rectal surgery from the American Society of Colon and Rectal Surgeons and the Society of American Gastrointestinal and Endoscopic Surgeons. Dis Colon Rectum. 2023;66(1):15-40. doi:10.1097/DCR.0000000000002650https://doi.org/10.1097/DCR.0000000000002650
  5. Weimann A, Braga M, Carli F, et al. ESPEN practical guideline: clinical nutrition in surgery. Clin Nutr. 2021;40(7):4745-4761. doi:10.1016/j.clnu.2021.03.031https://doi.org/10.1016/j.clnu.2021.03.031
  6. Kok DE, Arron MNN, Huibregtse T, et al. Association of habitual preoperative dietary fiber intake with complications after colorectal cancer surgery. JAMA Surg. 2021;156(9):827. doi:10.1001/jamasurg.2021.2311https://doi.org/10.1001/jamasurg.2021.2311
  7. American Diabetes Association Professional Practice Committee for Diabetes. 16. Diabetes care in the hospital: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(suppl 1):S339-S355. doi:10.2337/dc26-S016https://doi.org/10.2337/dc26-S016
  8. Molenaar CJL, van Rooijen SJ, Fokkenrood HJP, Roumen RMH, Janssen L, Slooter GD. Prehabilitation versus no prehabilitation to improve functional capacity, reduce postoperative complications and improve quality of life in colorectal cancer surgery. Cochrane Database Syst Rev. 2023;(5):CD013259. doi:10.1002/14651858.CD013259.pub3https://doi.org/10.1002/14651858.CD013259.pub3
  9. Zhao L, Zhu H, Mao W, Zhou X, Xie Y, Li L. Effects of perioperative cognitive function training on postoperative cognitive dysfunction and postoperative delirium: a systematic review and meta-analysis. Front Neurol. 2023;14:1146164. doi:10.3389/fneur.2023.1146164https://doi.org/10.3389/fneur.2023.1146164
  10. Niklasson A, Finan PH, Smith MT, et al. The relationship between preoperative sleep disturbance and acute postoperative pain control: a systematic review and meta-analysis. Sleep Med Rev. 2025;79:102014. doi:10.1016/j.smrv.2024.102014https://doi.org/10.1016/j.smrv.2024.102014
  11. Akdemir C, Turan SA, Balcı MF, et al. Preoperative sleep quality and anxiety as predictors of postoperative pain and recovery in gynecologic oncology surgery: a prospective observational study. J Psychosom Res. 2026;201:112496. doi:10.1016/j.jpsychores.2025.112496https://doi.org/10.1016/j.jpsychores.2025.112496
  12. Marsman M, Kappen TH, Vernooij LM, van der Hout EC, van Waes JA, van Klei WA. Association of a liberal fasting policy of clear fluids before surgery with fasting duration and patient well-being and safety. JAMA Surg. 2023;158(3):254-263. doi:10.1001/jamasurg.2022.5867https://doi.org/10.1001/jamasurg.2022.5867
  13. Tang E, Rodriguez RM, Srivastava A, et al. Impact of short duration smoking cessation on post-operative complications: a systematic review and meta-analysis. J Clin Anesth. 2025;106:111967. doi:10.1016/j.jclinane.2025.111967https://doi.org/10.1016/j.jclinane.2025.111967
  14. Chow WB, Rosenthal RA, Merkow RP, Ko CY, Esnaola NF. Optimal preoperative assessment of the geriatric surgical patient: a best practices guideline from the American College of Surgeons National Surgical Quality Improvement Program and the American Geriatrics Society. J Am Coll Surg. 2012;215(4):453-466.https://ww2.facs.org/media/inyehw0d/acsnsqipagsgeriatric2012guidelines.pdf