Number needed to treat approach shows benefits of combination therapies for acne

Key takeaways:

• Of the seven treatments evaluated, only one was a triple-combination therapy.
• Result showed the fixed-dose, triple-combination had the best number needed to treat rating vs. dual combinations.

Using the number needed to treat approach, researchers found that fixed-dose, triple-combination clindamycin phosphate 1.2%/adapalene 0.15%/benzoyl peroxide 3.1% gel had the most favorable efficacy rating, according to a study.

In the absence of head-to-head trials, the number needed to treat (NNT) is a common measurement tool to evaluate the efficacy of different medications.

“NNTs are helpful in a few ways,” Steven R. Feldman, MD, PhD, professor of dermatology, pathology and social sciences and health policy at Wake Forest University School of Medicine, told Healio. “First, data from different studies can be converted into NNT giving a common currency for comparison. Second, NNTs are easily interpreted, unlike an odds ratio, as an NNT permits a clear understanding of the magnitude of an effect. Finally, NNT can be used with patients to give them a clear understanding of effect size.”

Steven R. Feldman

In practice, choosing the medication with the lowest NNT, assuming all treatments are equal in safety profiles and cost, physicians and patients are more guaranteed to see the treatment outcome they want.

In this study, the authors used the NNT method to evaluate the efficacy of seven combination medications for acne. After collecting and assessing results from multiple pivotal trials, the authors found that all seven medications had an NNT less than 10, meaning 10 patients needed to be treated to get one additional treatment response vs. vehicle.

According to two pivotal trials, fixed-dose, triple-combination clindamycin phosphate 1.2%/adapalene 0.15%/benzoyl peroxide (BPO) 3.1% gel exhibited the most favorable NNT values of 4 and 5. It had a treatment success rate of approximately 50%, which was higher than any other treatment.

Closely following was the adapalene 0.3%/BPO 2.5% combination gel with an NNT of 5 and a treatment success rate of 33.7%.

Tretinoin 0.1%/BPO 3% cream had the largest NNT range between trials of 4 to 9 as well as a lower treatment success rate of 26.8%. The remaining four treatments had NNTs ranging from 6 to 8.

“Not surprisingly, the results show that using combination treatments in acne are more effective than monotherapy agents,” Feldman told Healio. “Combination products also have the advantage of less complex treatment regimens. Adherence to topical treatment can be abysmal. Making the regimen as simple as possible and using a highly effective approach are rational ways to improve treatment adherence and outcomes.”