In 2018, Mosetti et al. prospectively evaluated PPOP after common pediatric surgery (n = 350), defining it as intermittent or constant pain ≥4 lasting more than 3 months. Pain was assessed using age-appropriate 0–10 pain scales (FLACC scale < 3 years, Wong-Baker Faces 3–6 years, NRS >6 years). They also evaluated effects on daily activities, sleep, and other complications. Prevalence was 6% at 3 months and 4% at 6 months. No association was found between moderate- to severe acute postoperative pain (APOP) in the postanesthesia care unit (PACU) and persistent pain. Other studies have reported higher prevalences. In 2011, in a cross-sectional study, Fortier et al. conducted structured telephone interviews with children aged 2–17 years who had undergone general, urologic, or orthopedic surgery within the previous 10 months. Fifteen of 113 children (13%) reported current surgery-related pain, with a mean intensity of 4.2 on NRS, and interference with daily activities. One of the few recent prospective studies is a 2025 Spanish investigation of risk factors for PPOP after common pediatric surgery in children aged 4–7 years. Using a definition of pain ≥4 at 3 or 6 months, they reported markedly higher prevalences: 35% at 3 months and 27% at 6 months. None of these previous studies has used the ICD-11 definition of PPOP: pain persisting for more than 3 months after surgery, pain that begins or worsens after surgery, is located in the surgical area, is associated with pain-related distress, and interferes with daily activities.

A recent meta-analysis published during the completion of this study estimated the prevalence of PPOP in the pediatric population at a remarkably high 28% following major surgery. The definition of PPOP used in the included studies was pain at different levels lasting more than 3 months after surgery. None of the included studies used the ICD-11 definition of PPOP. The high prevalence of PPOP found highlights the inconsistency of current evidence, emphasizing the need for large prospective studies.

A considerable proportion of children (approximately 15% to 25%) experience persistent pain in daily life, which can lead to significant personal suffering, including school non-attendance and social isolation, and represents a serious public health concern. Among hospitalized children, 24%–27% report moderate to severe pain, most surgery-related, and as many as 80% self-report current pain during hospitalization. Pain management in children is frequently inadequate, and those who develop long-term pain appear to be at greater risk of ongoing pain-related problems than adults. Since surgery is a potential trigger for pain, PPOP is a critical issue to address in pediatric care.

Regarding risk factors for persistent pain, gender differences have been observed in childhood pain conditions such as headache and abdominal pain, with girls reporting more pain than boys. Clinical studies on postoperative pain are consistent with this pattern, suggesting that both APOP and PPOP are more common in girls. Regarding age, some studies suggest that younger children have a lower risk of PPOP, whereas other studies find no protective effect once confounders are accounted for. Psychological factors also appear influential. Children are highly affected by caregiver behavior, and elevated parental anxiety surrounding surgery has been identified as a potential risk factor. Parental catastrophizing, mental health problems, and chronic pain have similarly been associated with increased pain in children. Evidence suggests that parental influence on a child’s pain response may even increase as more time passes after surgery.

The 4P study (Persistent Postoperative Pediatric Pain) is a prospective observational multicenter study following children undergoing common pediatric surgeries in Sweden between 2023 and 2024. This predefined secondary analysis focuses specifically on PPOP with the aim of describing the prevalence, characteristics, and exploratory risk factor associations of PPOP. The primary outcome was defined as recurrent pain ≥4 lasting for over 3 months after surgery. Persistent pain was further characterized regarding its impact on various activities and whether anatomically localized at the site of surgery, and we also present prevalences based on the ICD-11 definition of PPOP. By examining in detail the small subgroup of children who develop PPOP and describing the characteristics that distinguish them, this analysis aims to improve our understanding of why some children develop PPOP while others do not.

This study was approved by the Swedish Ethics Review Authority on December 1, 2022 (Dnr 2022-04821). The research protocol was preregistered at clinicaltrials.gov under NCT06035042, and a study protocol has been published. Children aged 1–17 years scheduled for one of the ESPA-defined pediatric surgical procedures (inguinal hernia, circumcision/hypospadias/cryptorchidism, adenoidectomy/tonsillectomy/tonsillotomy, appendectomy, acute orthopedic fracture surgery) were recruited from 10 hospitals in southern Sweden in 2023–2024. As this was an observational study, the methods used for anesthesia and analgesia, as well as surgical techniques, varied according to local practice. Exclusion criteria included: repeated surgery, inability of the child or caregiver to speak/read Swedish, and inability to understand the implications of participation. Patients aged 15 years or older provided written and oral consent themselves. For younger children, caregivers provided consent after receiving written information a few days before surgery, and in-person information upon hospital arrival. For participants under 15 years, consent from both legal guardians was required, in accordance with Swedish Ethical Review Authority regulations.

PPOP was documented using the data management software Entermedic (Entergate, Halmstad, Sweden), which was programmed to send automated text-message questionnaires at the prespecified follow-up time points of 3 and 6 months after surgery, including reminders when necessary. All participants received two reminders to answer the follow-up. Thereafter, responding was not possible, as the time frame for follow-up would have been misleading, and the responses were then handled as missing values. The questionnaires answered were complete. Entermedic is certified according to the international security standard (ISO 27000:1) and is completely adapted to the European Union’s requirements of the General Data Protection Regulation. The service is also adapted to comply with Swedish law for patient data reporting, holding, and management. Furthermore, Entermedic is approved by the Swedish Medical Products Agency.

Before surgery, all legal guardians (or patients aged 15 years and older) completed a questionnaire addressing preoperative pain: recurrent pain before surgery (yes/no), pain intensity (FLACC, FPS-Revised, or NRS depending on age), duration of pain, and whether it affected normal activities. We also asked whether the child had experienced pain in the 24 h prior to surgery (yes/no) and whether analgesics had been offered. Sleep quality and anxiety were assessed similarly with a yes/no question, including duration and impact on daily activities. Self-reported parental stress (NRS 0–10) was recorded at 24 h, 3 and 6 months after surgery. The levels of stress at the time of the respective pain measurements were used for this analysis. Levels ≥4 were used when dichotomizing the stress level for logistic regression.

At 3 and 6 months postoperatively, a text-message questionnaire was sent to assess current pain using the same age-appropriate scale introduced at the hospital visit. For children aged 1–3 years, we used the FLACC (Face/Legs/Activity/Cry/Consolability Pain Scale, 0–10); for ages 4–14, the FPS-Revised (The Faces Pain Scale-Revised, 0–10); and for ages 15–17 the NRS (Numeric Rating Scale, 0–10). Higher scores indicated more pain, with zero representing

Subject of Research: Health

Article Title: Persistent postoperative pediatric pain: a secondary analysis of the 4P prospective observational multicenter study

Article References: Persson, A. K. M., & Broman, J. (2026). Persistent postoperative pediatric pain: a secondary analysis of the 4P prospective observational multicenter study. Frontiers in Pain Research, 7, Article 1930534. https://doi.org/10.3389/fpain.2026.1930534

Image Credits: AI Generated

DOI: 10.3389/fpain.2026.1930534

Keywords: chronic pain, pain after surgery, pediatric pain, persistent pain, postoperative pain, Persistent, postoperative, pediatric, pain, secondary, analysis, prospective