A Randomized Controlled Trial of Topical Analgesia Post-Hemorrhoidectomy (TAPH Trial)

BACKGROUND: Postoperative pain remains the greatest problem after hemorrhoidectomy. Pain is hypothesized to arise from bacterial infection, sphincter spasm, and local inflammation. OBJECTIVE: A randomized controlled factorial trial was conducted to assess the effects of metronidazole, diltiazem, and lidocaine on post-hemorrhoidectomy pain. DESIGN: A double blinded randomized controlled factorial trial. SETTINGS: A multicenter trial was conducted in Auckland, New Zealand. PATIENTS: 192 Participants were randomized (1:1:1:1) into four parallel arms. INTERVENTIONS: Participants were randomized into one of four groups receiving topical treatment with 10% metronidazole (M), 10% metronidazole + 2% diltiazem (MD), 10% metronidazole + 4% lidocaine (ML), or 10% metronidazole + 2% diltiazem + 4% lidocaine (MDL). Participants were instructed to apply to the anal verge 3 times daily for 7 days. MAIN OUTCOME MEASURES: The primary outcome was pain on the visual analogue scale on day 4. The secondary outcomes included analgesia usage, pain on bowel motion, and functional recovery index. RESULTS: There was no significant difference in the pain and recovery scores when diltiazem or lidocaine was added to metronidazole (score difference between presence and absence of D in the formulation: -3.69, 95% CI: -13.3, 5.94, p = 0.46; between presence and absence of L: -5.67, 95% CI: -15.5, 3.80, p = 0.24). The combination of MDL did not further reduce pain. Secondary analysis revealed a significant difference between the best (ML) and worst (MDL) groups in both pain and functional recovery scores. There were no significant differences in analgesic usage, complications, or return to work between the groups. No clinically important adverse events were reported. The adverse event rate did not change in the intervention groups. LIMITATIONS: Topical metronidazole was utilized in the control group, rather than a pure placebo. CONCLUSION: There was no significant difference in pain when topical diltiazem or lidocaine, or both, was added to topical metronidazole. Clinical trial registration identifier: NCT04276298