Ketorolac for Moderate to Severe Abdominal Pain in Children

Background/Rationale: Appendicitis is the most common emergent surgical diagnosis among children between 5-17 years in age and accounts for 8000 admissions annually. Diagnosing appendicitis is time consuming (4-6 hours) as it requires laboratory tests and ultrasonography. This occurs while patients experience significant abdominal pain secondary to infection and localized or generalized peritonitis. Opioids have been the most prescribed analgesic for patients with suspected appendicitis, despite an ongoing opioid crisis. Our research shows that 60% of physicians use morphine or other opioids, while 40% will use non-steroidal anti-inflammatory drug (NSAID) or other non-opioids. Even though ketorolac (NSAID) is commonly used in the Emergency Department (ED) for renal colic, abdominal pain and migraine headaches, and has a safer side effect profile than morphine, all such uses in children are "off label" as there are virtually no controlled trials for children to inform practice.

Objective: To determine if it is feasible to conduct a large multi-centre randomized non inferiority trial comparing ketorolac to morphine for treating moderate to severe abdominal pain, in children 6 years in age or older, with clinically suspected appendicitis.

Hypothesis: We hypothesize that it will be feasible to conduct a large trial based on a recruitment rate of ≥40% of eligible patients approached for consent.

Study Design: Our trial is a single-centre, block randomized, non-inferiority, double-dummy, doubleblind, feasibility pilot trial. Patients ≥ 6 years in age, who have ≤ 5 days of moderate-severe pain as defined by our validated 11-point verbal numeric rating scale (VNRS) ≥ 5 and are being investigated for suspected appendicitis with intravenous (IV) access in situ or ordered, will be randomized to either: (1) IV ketorolac 0.5 mg/kg up to 30 mg (intervention) + IV morphine placebo, or (2) IV morphine 0.1 mg/kg up to 5 mg (active control) + IV ketorolac placebo. The total sample size is 100 participants. The study drugs will be identical in appearance, consistency and smell. The double-dummy design will ensure blinding is maintained for bedside clinical staff, research personnel and patients. Our study prioritized patient comfort and will largely mimic standard care. Pharmacologic co-interventions will be allowed but limited to acetaminophen (commonly used as first-line therapy). Participants in both groups will be allowed rescue therapy (morphine 0.5 mg/kg) within 60 minutes of our intervention. We will screen the ED daily for eligible patients as well as include all eligible patients for the New Investigator Fund (NIF)-funded quality improvement pathway we employed to streamline care for all ED appendicitis patients. We have a robust research program in the ED that includes students, a full-time research coordinator and several paid research assistants who screen eligible patients and approach them for consent and enrollment. Our entire project can be completed with NIF support within an 18-month study period.

Primary Outcome: Feasibility of our study design is the primary outcome of this pilot trial. Primary feasibility outcomes include: (1) proportion of patients consented from total eligible patients approached; (2) proportion of patients who completed clinical outcome assessment; and, (3) proportion of missing items on individual data collection forms. Our feasibility threshold is to recruit at least 40% of eligible patients who were approached to consent. Other thresholds include recruiting ≥8 participants/month on average and having at least 90% of participants complete all the outcome assessments at 30, 60, 90 and 120 minutes.

Summary: Acute pain in children and youth is an area that is understudied and affects thousands of Canadian children. Despite short -and long-term adverse effects including dependence, and well designed comparative effectiveness trials, opioids continue to be overused in surgical patients. Ketorolac is a promising well-established NSAID that is available for IV, has a better short-term side effect profile and is not known as a substance of misuse. Our pilot will provide valuable feasibility data for a larger, future multicenter trial.

Inclusion criteria

• Age 6.0 years to <18 years: Children aged < 6 years of age at low risk for appendicitis and often present atypically.46,47
• Duration of abdominal pain ≤ 5 days: Children with longer durations of acute abdominal pain are less likely to have appendicitis.18,48
• A clinical decision to investigate for appendicitis as a possible etiology by the ED MD or RN. The physician or bedside nurse are suspicious of a diagnosis of appendicitis as a cause for the abdominal pain as reflected by the initiation of the appendicitis medical directive (an advanced nursing directive that allows nurses to order tests for patients with suspected appendicitis) and order laboratory tests and/or advanced imaging or directly consult pediatric surgery to rule out appendicitis.
• Patient has an IV cannula in situ or ordered to be placed: we will not include patients without an IV ordered or established in order to ensure the study intervention is limited to the study drugs and is not associated with the performance of any invasive procedures.
• Currently experiencing moderate to severe pain: self-reported pain score ≥5 using the VNRS at the time of enrollment.

Exclusion criteria

• Previous enrollment in trial (to ensure all observations are independent and not paired)
• NSAID use within 3 hours and/or opioid use within 2 hours prior to recruitment to avoid over-dosing and confounding
• Caregiver and/or child cognitive impairment precluding the ability to self-report pain or respond to study questions
• Chronic pain requiring daily analgesic use for other indications (e.g. naproxen for juvenile idiopathic arthritis): confounding
• History of gastrointestinal bleeding, peptic or duodenal ulcer disease or inflammatory bowel disease, coagulation disorders, prior cerebrovascular bleeding, known arterio-vascular malformations: Bleeding risk
• History of chronic and active renal disease, excluding renal calculi and urinary tract infections
• History of chronic and active hepatocellular disease (excludes biliary stones, cholangitis or biliary duct pathology), as ketorolac is metabolized in the liver.
• Known pregnancy at the time of enrollment, a positive pregnancy test in females ≥ 12 years in age or breastfeeding females due to the risk of premature closure of patent ductus arteriosus
• Known hypersensitivity to NSAIDs or opioids (e.g. naproxen, ibuprofen, acetylsalicylic acid, ketoprofen or ketorolac, morphine, hydromorphone, fentanyl)
• Absence of a parent/guardian for children who are < 16 years in age: youths who are ≥16 years can provide us with informed consent without the permission of a guardian
• Inability to obtain consent due to a significant language barrier, in the absence of a native language translator