Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective for pain caused by osteoarthritis, but their usefulness is limited by side effects. Tramadol combined with acetaminophen is recommended, according to the new American Pain Society guidelines, for the treatment of osteoarthritis pain when NSAIDs alone cannot provide adequate pain relief. This study is an extension of an earlier study evaluating the efficacy of tramadol/acetaminophen in the treatment of osteoarthritis flares. Rosenthal and colleagues hypothesized that the combination of tramadol/acetaminophen would be safe and effective in a subset of elderly patients.

Eligible patients 65 years and older had symptomatic osteoarthritis of the hip or knee for one year or longer, were taking a stable dosage of an NSAID or a cyclooxygenase-2 inhibitor, and were in general good health. Patients were randomized to receive an initial single dose of one to two pills of tramadol/acetaminophen or placebo at the first sign of an osteoarthritis flare. After that, patients could take one to two pills up to four times a day as needed, while continuing their regular NSAID regimen.

Primary outcomes were pain intensity and pain relief, scored according to a four-point assessment. Secondary outcomes included overall medication assessment, efficacy over time, and osteoarthritis symptoms, with the latter assessed using a specialized scoring system, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), based on a five-point scale. Patients assessed pain before the first dose and at regular intervals up to four hours after the dose.

The subset studied included 113 elderly patients, with a dropout rate of 17.4 percent in the tramadol/acetaminophen group and 9.1 percent in the placebo group, primarily because of adverse events. Pain intensity scores decreased by 2.10 in the tramadol/acetaminophen group and by 1.63 in the placebo group. Decreases in pain intensity and pain relief scores showed statistically significant improvement in the tramadol/acetaminophen group compared with the placebo group. WOMAC scores were significantly better in the treated group in two of three subscales and in an overall derived score, as were investigator and patient overall medication assessments. These results were similar to those of the study group as a whole. Common adverse events among the treated group were nausea, vomiting, and dizziness.

The authors conclude that treating osteoarthritis flares with tramadol/acetaminophen provides significant pain relief over placebo in patients taking a stable dosage of an NSAID.