Results

Participant flow

A total of 90 patients with clinically suspected renal colic were enrolled and randomized between July and December 2022. Forty-five participants were allocated to receive IV lidocaine and 45 to receive IV ketorolac. All randomized participants received the allocated intervention, completed the study, and were included in the final analysis. No participants were lost to follow-up, withdrawn, or excluded after randomization; therefore, outcome data were available for all participants. The participant flow through the study is illustrated in Figure 1.

Figure 1: CONSORT flow diagramCONSORT: CONsolidated Standards Of Reporting Trials

Baseline characteristics

The baseline demographic and clinical characteristics of the study participants were comparable between the two treatment groups (Table 1). The mean age was 42.2 ± 15.2 years in the IV lidocaine group and 41.6 ± 14.6 years in the IV ketorolac group. Most participants were between 19 and 50 years of age (60.0% vs. 68.9%, respectively). There were 24 men (53.3%) and 21 women (46.7%) in the lidocaine group compared with 27 men (60.0%) and 18 women (40.0%) in the ketorolac group. Diabetes mellitus was present in 10 patients (22.2%) receiving lidocaine and six patients (13.3%) receiving ketorolac, while hypertension was reported in 10 (22.2%) and 17 (37.8%) patients, respectively.

Characteristic | Intravenous lidocaine (n = 45) | Intravenous ketorolac (n = 45)
Age (years), mean ± SD | 42.2 ± 15.2 | 41.6 ± 14.6
Age 19-50 years, n (%) | 27 (60.0) | 31 (68.9)
Age 51-64 years, n (%) | 18 (40.0) | 14 (31.1)
Male, n (%) | 24 (53.3) | 27 (60.0)
Female, n (%) | 21 (46.7) | 18 (40.0)
Diabetes mellitus, n (%) | 10 (22.2) | 6 (13.3)
Hypertension, n (%) | 10 (22.2) | 17 (37.8)

Primary outcome

The primary outcome was successful pain relief, defined as a reduction of at least three points on the VAS from baseline, assessed 30 minutes after administration of the study medication. Successful pain relief was achieved in 31 of 45 patients (68.9%) in the IV lidocaine group compared with 27 of 45 patients (60.0%) in the IV ketorolac group (Table 2). The absolute risk difference was 8.9% (95% CI: −10.8% to 28.6%). The relative risk of treatment success with IV lidocaine compared with IV ketorolac was 1.15 (95% CI: 0.84-1.56). The difference between the treatment groups was not statistically significant (χ²(1) = 0.776, p = 0.378, φ = 0.093), indicating a small effect size.

Outcome | Intravenous lidocaine (n = 45) | Intravenous ketorolac (n = 45) | Statistic
Successful pain relief, n (%) | 31 (68.9) | 27 (60.0) | χ²(1) = 0.776, p = 0.378
Unsuccessful pain relief, n (%) | 14 (31.1) | 18 (40.0) | 
Absolute risk difference (95% CI) | 8.9% |  | −10.8% to 28.6%
Relative risk (95% CI) | 1.15 |  | 0.84-1.56
Effect size (Phi coefficient, φ) |  |  | 0.093

Secondary outcomes

Rescue Analgesia

Rescue analgesia with IV nalbuphine was administered to participants who did not achieve the predefined criterion for successful pain relief at 30 minutes. Consequently, 14 patients (31.1%) in the IV lidocaine group and 18 patients (40.0%) in the IV ketorolac group required rescue analgesia. Consistent with the primary outcome analysis, the difference between groups was not statistically significant (χ²(1) = 0.776, p = 0.378, φ = 0.093).

Adverse Events

Both study medications were generally well tolerated (Table 3). Three patients (6.7%) in the IV lidocaine group experienced transient dizziness during drug administration, which was self-limiting and did not require any intervention. Two patients (4.4%) in the IV ketorolac group developed mild hypersensitivity reactions that resolved following treatment with IV pheniramine. No serious adverse events, treatment discontinuations, or deaths occurred in either treatment group. The overall incidence of adverse events did not differ significantly between groups (Fisher's exact test, p = 1.000).

Outcome | Lidocaine (n = 45) | Ketorolac (n = 45) | p-value
Any adverse event, n (%) | 3 (6.7) | 2 (4.4) | 1.000†
Transient dizziness, n (%) | 3 (6.7) | 0 | -
Mild hypersensitivity reaction, n (%) | 0 | 2 (4.4) | -
Serious adverse events, n (%) | 0 | 0 | -
Treatment discontinued, n (%) | 0 | 0 | -

Outcome completeness

Outcome data were available for all randomized participants. There were no missing data, and all analyses were performed on the complete study population according to their allocated treatment groups.