Acetaminophen, indomethacin, and diclofenac are equivalent
A double-blind RCT in a university hospital ED in Hong Kong compared patients older than 16 years with “isolated painful limb injury” after trauma who received combinations of analgesics or placebo.3 Patients were recruited during typical work-week hours (Monday to Friday, 9 am to 5 pm) and randomized into 4 groups: acetaminophen 1 g plus placebo (66 patients), placebo plus indomethacin 25 mg (71 patients), placebo plus diclofenac 25 mg (69 patients), or acetaminophen 1 g plus diclofenac 25 mg (94 patients).
Each patient was given the group’s designated combination of analgesics in the ED and asked to rate pain on a 0-to-100 visual analog pain scale (VAPS) at 0, 30, 60, 90, and 120 minutes after administration. Patients then left the ED with a 3-day course of their analgesic combination and were instructed to take the medication 4 times daily on the first day and 3 times daily thereafter. Patients recorded pain scores on the VAPS 3 times daily after discharge and at follow-up 5 to 8 days after initial presentation. Intention-to-treat analysis was done for patients lost to follow-up. A change in VAPS of 13 was considered clinically significant.
All groups started with similar pain scores (30 at rest and 70 with activity) and didn’t achieve clinically significant pain relief within the first hour (mean change in VAPS <13). At 90 minutes, all groups achieved a mean change in VAPS >13, with no statistically significant difference between the groups. Adverse effects were rare (7% total), and none were severe (no gastrointestinal hemorrhage or renal damage).
Outside the ED, the acetaminophen-diclofenac combination group showed the greatest pain score reduction at every time point at rest and with activity, but none of the reductions were statistically or clinically significant (results presented graphically). No difference was found between the groups in number of patients who completed the course of analgesics, took additional analgesia, tried Chinese medicine, or returned to the ED within 30 days.
Limitations to the study included that the medication dosages may be much lower than typical dosages given in the United States and therefore lack applicability. The study also didn’t include a true placebo arm.