COMPARISON OF AN ANTIINFLAMMATORY DOSE OF IBUPROFEN, AN ANALGESIC DOSE OF IBUPROFEN, AND ACETAMINOPHEN IN THE TREATMENT OF PATIENTS WITH OSTEOARTHRITIS OF THE KNEE.

Bradley JD, et al. N Engl J Med 1991 Jul 11;325(2):87-91

BACKGROUND. The optimal short-term, symptomatic therapy for osteoarthritis of the knee has not been fully determined. Accordingly, we compared the efficacy of a nonsteroidal antiinflammatory drug, ibuprofen, given in either an antiinflammatory dose (high dose) or an analgesic dose (low dose), with that of acetaminophen, a pure analgesic.

METHODS. In a randomized, double-blind trial, 184 patients with chronic knee pain due to osteoarthritis were given either 2400 or 1200 mg of ibuprofen per day or 4000 mg of acetaminophen per day. They were evaluated after a washout period of three to seven days before the beginning of the study, and again after four weeks of treatment. The major measures of outcome included scores on the pain and disability scales of the Stanford Health Assessment Questionnaire (range of possible scores, 0 to 3), scores on the visual-analogue scales for pain at rest and pain while walking, the time needed to walk 50 ft (15 m), and the physician's global assessment of the patient's arthritis.

RESULTS. Seventy-eight percent of the patients completed four weeks of therapy. No significant differences were noted among the three treatment groups with respect to failure to complete the trial because of noncompliance or adverse events. All three groups had improvement in all major outcome variables, and the groups did not differ significantly in the magnitude of improvement in most variables. The mean improvement (change) in the scores on the pain scale of the Health Assessment Questionnaire was 0.33 with acetaminophen (95 percent confidence interval, 0.14 to 0.52), 0.30 with the low dose of ibuprofen (95 percent confidence interval, 0.09 to 0.51), and 0.35 with the high dose of ibuprofen (95 percent confidence interval, 0.13 to 0.57). Side effects were minor and similar in all three groups.

CONCLUSIONS. In short-term, symptomatic treatment of osteoarthritis of the knee, the efficacy of acetaminophen was similar to that of ibuprofen, whether the latter was administered in an analgesic or an antiinflammatory dose.

SEVERITY OF KNEE PAIN DOES NOT PREDICT A BETTER RESPONSE TO AN ANTIINFLAMMATORY DOSE OF IBUPROFEN THAN TO ANALGESIC THERAPY IN PATIENTS WITH OSTEOARTHRITIS.

Bradley JD, Katz BP, Brandt KD.

OBJECTIVE: To determine whether greater pain intensity at initiation of treatment predicted better response to ibuprofen than to acetaminophen in subjects with knee osteoarthritis (OA).

METHODS: Data from 182 patients with knee OA who had taken part in a 4 week randomized, double blind, parallel comparison of 4,000 mg/day acetaminophen vs either 1,200 or 2,400 mg/day ibuprofen were reanalyzed using Pearson correlation coefficients for baseline pain severity, treatment assignment, and treatment response. Pain measures were visual analog scales for overall pain, resting pain, and walking pain. Baseline pain severity was divided into low, medium, and high tertiles, and treatment related differences in pain response were sought with pairwise t tests. Two-factor analysis of variance (ANOVA) models were used to seek interactions between baseline pain severity and treatment group, which would indicate differential drug treatment responsiveness.

RESULTS: Greater baseline pain predicted greater pain relief with all 3 treatments. Patients with a high level of baseline rest pain appeared to respond better to ibuprofen 2,400 mg/day than to the other treatments, but this difference was not evident after correction for multiple statistical tests. ANOVA did not reveal significant differences in response to the 3 treatments or a significant interaction.

CONCLUSION: Our data suggest that acetaminophen and ibuprofen are comparably effective in treating knee OA pain, even when the pain is severe.