ORLANDO – A 6-week course of doxycycline is an effective alternative to prednisolone for initial treatment of bullous pemphigoid in elderly patients, who may be particularly vulnerable to the potentially serious side effects of steroids.

While not as effective or quick-acting as prednisolone, doxycycline effected a cure in 74% of elderly patients who received it for 6 weeks in the Bullous Pemphigoid Steroids and Tetracyclines (BLISTER) Trial. More importantly, however, patients who took the antibiotic experienced half as many serious adverse events as those who took prednisolone (18% vs. 36%), Karen Harman, MD, said at the annual meeting of the American Academy of Dermatology.

“While the strategy of initiating treatment with doxycycline is not as effective, it was within the noninferiority margin, and it displayed a superior long-term safety profile,” said Dr. Harman, a consultant dermatologist at the Spire Leicester (England) Hospital. “It’s a trade-off of rapidly controlling itchy blisters, but avoiding serious side effects.”

The trial results will be published in the March 6 issue of The Lancet, she added.

BLISTER randomized 253 elderly patients with bullous pemphigoid to an initial, 6-week course of either 200 mg doxycycline/day or 0.5 mg/kg prednisolone/day. After the induction period, treatment could be adjusted as needed.

The primary efficacy outcome was blister count at 6 weeks; patients with fewer than three blisters were considered treatment successes. The primary safety outcome was the proportion who experienced an adverse event of at least grade 3 (severe, life-threatening, or fatal) related to the study medication.

The study was conducted at 54 centers in the United Kingdom and Germany, said Dr. Harman, who was also a primary investigator on the trial. It was a pragmatic noninferiority trial.

“We knew from the beginning that doxycycline would not be as effective as prednisolone. We estimated that we would see a 25% reduced efficacy, but we were prepared to accept that if we could also see an improvement in safety of at least 20%.”

Patients were a mean of age of 78 years, although about a quarter were 85 years or older. They scored a mean of 70 points on the 0-100 point Karnofsky scale of functional independence, with 100 being completely functionally independent.

A score of 70 means the patient is capable of self-care but cannot engage in normal activity or work because of disease. About 10% were unable to care for themselves and 42% unable to work.

Over the year-long trial, 33 patients dropped out. The most frequent reason for withdrawal was death – not an unexpected occurrence in such an elderly and infirm group, Dr. Harman noted. There was no significant difference in deaths between the treatment arms. Another 39 withdrew consent during the study. Adverse events caused three patients to drop out (two in the doxycycline group and one in the prednisolone group). One patient taking doxycycline was unable to tolerate the study medication and dropped out.

At 6 weeks, treatment succeeded in 74% of the doxycycline group and in 91% of the prednisolone group. This was an adjusted absolute treatment difference of 18% – well within the 25% margin of noninferiority.

Baseline disease severity didn’t interact with either of the drugs’ effectiveness. Prednisolone was more effective in every severity class. Among those with mild disease, the success rates were 76% with doxycycline and 97% with prednisolone. Among those with moderate disease, success rates were 78% and 97%. Among those with severe disease, both drugs were slightly less effective, with success rates of 65% and 75%.

Adverse events of grade 3 or greater occurred in significantly fewer patients taking doxycycline (18.5% vs. 36.6%), an adjusted difference of 19%. This was close to the 20% gain in safety the investigators hoped for.

Adverse events were common, however, with 82% of patients on doxycycline and 64% on prednisolone experiencing at least one mild-moderate event. Most of these in the doxycycline group were gastrointestinal, Dr. Harman noted.

About twice as many patients taking prednisolone had an event with a maximum of grade 3 (22% vs. 11%). The proportion with a maximum event of grade 4 was 4% in each group. Eleven in the prednisolone group and three in the doxycycline group died (9.7% vs. 2.5%).

The trial had several secondary efficacy outcomes.

Doxycycline had a slower onset of action, as evidenced by the significant difference in high blister count at week 6 (26% vs. 8.7%). At 6 weeks, 20.5% of the doxycycline group and 4% of the prednisolone group experienced treatment failure and chose to switch to the other treatment arm. Adherence was also worse in the doxycycline group, with 19% missing more than 3 consecutive days of treatment vs. 5% in the prednisolone group.

The trial also included a quality of life measure for the entire 52 weeks. Through week 26, this favored prednisolone, again reflecting the slower disease control of doxycycline. Thereafter, quality of life was similar between the two groups.

The trial was run in collaboration with the Nottingham Clinical Trials Unit, the UK Dermatology Clinical Trials Network, and the Medical Research Council Clinical Trials Unit. Dr. Harman had no financial disclosures.

msullivan@frontlinemedcom.com

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For bullous pemphigoid, doxycycline noninferior to prednisolone, but safer