Does topical diclofenac relieve osteoarthritis pain?

Diclofenac demonstrated statistical superiority across all age groups when compared with placebo, based on pain and physical function measured on the WOMAC Index. Its effects were modest, however.

At 12 weeks, patients younger than 65 years showed pain improvement of -5.8 vs -4.7 for placebo (a 5.5% improvement on the 20-point scale) and improvement in physical function of -17.9 vs -14.2 (a 5.4% improvement on the 68-point scale). Patients older than 65 years demonstrated pain improvement of -5.3 vs -4.1 for placebo (6% improvement on the 20-point scale) and physical function improvement of -15.5 vs -11.0 for placebo (6.6% improvement on the 68-point scale).

Dermatitis was more common in the diclofenac groups, with a NNH of 30 in patients younger than 65 years and 19 in patients older than 65 years.

Diclofenac gel effectively treated hand OA for as long as 6 weeks in a randomized, double-blind, placebo-controlled trial of 809 men and women older than 39 years. Pain scores on a 100-point visual analog scale improved when compared with placebo alone.³ At 6 weeks, topical diclofenac reduced pain scores by 45% compared with 36% for placebo (P=.023). Pain reductions also were greater in the diclofenac group at 8 weeks, although not statistically different.

Oral diclofenac works well, too, but has more GI adverse effects

An RCT of 622 patients (40-85 years of age) with symptomatic and radiographically diagnosed OA of the knee compared topical diclofenac solution (75 mg/d) with oral diclofenac (50 mg 3 times a day) and found similar efficacy at 12 weeks, with no significant difference between oral and topical preparations for pain, physical function, and stiffness measured with the WOMAC Index (P=.23, .06, .24, respectively).⁴ Oral diclofenac produced more adverse GI side effects than the topical solution (48% vs 35%; P=.0006).

RECOMMENDATIONS

The Agency for Healthcare Research and Quality states that topical and oral NSAIDs reduce knee OA pain equally.⁵

The Guidelines of the American Academy of Orthopaedic Surgeons, American College of Rheumatology, European League Against Rheumatism, Osteoarthritis Research Society International, and National Institute for Health and Care Excellence all state that clinicians may consider topical NSAIDs for patients with mild to moderate OA of the knee or hand, particularly in patients with few affected joints or a history of sensitivity to oral NSAIDs.⁶