Relief Efficacy of Lidocaine Versus Morphine for Acute Renal Colic in the Emergency Department

RELIEF-RC: Relief Efficacy of LIdocaine Versus morphinE For Acute Renal Colic in the Emergency Department

The opioid epidemic continues to be a major public health crisis in the United States. According to the Center for Disease Control, approximately 8 million Americans reported misusing prescription opioids in 2023, with over 5 million Americans reporting that they suffer from opioid use disorder. The United States government estimates that 105,000 people died from drug overdose in 2023, and approximately 80,000 of those deaths can be attributed to opioids (~76%). In acknowledgement of the opioid crisis, we wish to contribute to ongoing efforts to reduce unnecessary and excessive opioid prescription.

In 2012, researchers in Iran published a randomized controlled trial comparing intravenous (IV) lidocaine to IV morphine for acute renal colic, reporting that 90% patients responded "successfully" in the lidocaine group versus 70% in the morphine group. They also concluded that there was a statistically significant difference between pain scores between the two groups at all time points, favoring the lidocaine group. However, the study was conducted at a single emergency department in Tabriz, Iran, with a relatively homogenous patient population, and the researchers did not explicitly define their primary outcome variable for what constituted a "successful" response in the treatment groups. The investigators of this study aim to build upon this preliminary evidence by recruiting a more diverse population to improve generalizability and by predefining pain-reduction thresholds to allow for more meaningful comparison between the interventions.

Purpose

● To determine whether IV lidocaine is more efficacious than IV morphine in decreasing or resolving acute renal colic pain refractory to initial treatment with parenteral ketorolac

Primary Objective ● To compare the efficacy of IV lidocaine versus IV morphine in achieving at least 50% reduction of pain score at 30 minutes for renal colic requiring rescue medication after initial treatment with parenteral ketorolac

Secondary Objectives

• To compare reduction in pain scores at 15, 60, and 90 minutes between the two intervention groups;
• To determine if there is a statistically significant difference in emergency department length of stay (ED LOS) between the two intervention groups
• To determine if there is a statistically significant difference in need for further rescue medications between the two intervention groups
• To determine the incidence of adverse effects between the two intervention groups
• To evaluate whether there is a correlation between age and efficacy of treatment between the two intervention groups

Study Design This study is a prospective randomized controlled trial. Study participants will be randomized to receive either IV lidocaine or IV morphine if they fail initial standard treatment with parenteral ketorolac for suspected acute renal colic.

Study Date Range and Duration The estimated study period will be from 1/1/2026 to 12/31/2027.

The study will be carried out for two calendar years, and may be halted early when sufficient participant enrollment has occurred.

Number of Study Sites

1. Loma Linda University Medical Center - Adult Emergency Department (Adult ED)
2. Loma Linda University Medical Center - East Campus Advanced Urgent Care (AUC)

Primary Outcome Variables

● Response to treatment: pain assessment using a numeric rating scale (0 to 10) at 30 minutes

Secondary and Exploratory Outcome Variables

• Response to treatment: pain assessment using a numeric rating scale (0 to 10) at 15, 60, and 90 minutes
• Adverse events attributed to IV lidocaine or IV morphine
• ED LOS
• Need for additional rescue medications after either IV lidocaine or IV morphine

Study Population Study participants will be enrolled from patients who have suspected renal colic as determined by the treating clinician at the Loma Linda Adult ED or AUC.

Number of Participants This study seeks to enroll at least 248 patients over the study period, with at least 190 patients required to achieve a standard statistical power of 80%. Patients will be randomized into two groups - 124 patients per group.

Study Schedule All data and information, including consent and screening, will be gathered during the course of a patient's single visit at the Loma Linda Adult ED or AUC.

Inclusion Criteria:

In order to be eligible for inclusion in the study, an individual must meet all of the following criteria:

• Age ≥ 18 years at time of visit
• Able and willing to consent for participation in study
• Documentation of suspected renal colic as primary complaint as evidenced by reported flank pain, back pain, abdominal pain, or groin pain, or as determined by the treating clinician
• Requires additional treatment due to inadequate analgesia or clinical suspicion of unsafe discharge secondary to pain after initial treatment with parenteral ketorolac

Exclusion Criteria:

Any individual who meets any of the following criteria will be excluded from participation in this study:

• Age < 18 years
• Use of analgesia for renal colic within 6 hours prior to clinician evaluation
• Inability or unwillingness to consent for participation in study
• Experienced a severe adverse event that required clinician intervention after initial treatment with parenteral ketorolac
• Documented history of allergic or anaphylactic reaction to NSAIDs, lidocaine, or morphine
• Documented history of cardiac arrhythmias
• Documented history of chronic use of opioid medications for unrelated diagnoses
• Currently pregnant
• Documented history of end-stage renal or hepatic dysfunction
• Clinical contraindications to NSAIDs, lidocaine, or morphine per clinician discretion