CHICAGO – Norethindrone acetate is a well-tolerated, effective option to decrease both endometriosis-related pain and bleeding among adolescents.
The synthetic progestin was effective for all stages of endometriosis in a retrospective analysis, and 67% of patients reported no side effects, Dr. Daniel Kaser said at the annual meeting of the North American Society for Pediatric and Adolescent Gynecology.
"We conclude that progestin-only oral therapy should be considered a valuable tool in adolescents with endometriosis, regardless of stage of disease," he said.
Norethindrone acetate is used in clinical practice in combination with other hormones for contraception and for hormonal suppression of endometriosis-associated pain. To date, there have been no reported studies on the efficacy of oral progestins in adolescents with endometriosis, said Dr. Kaser, a gynecologist with Children’s Hospital Boston.
Dr. Daniel Kaser
Dr. Kaser and his colleague, Dr. Mark Laufer, chief of gynecology at Children’s, reported on 129 adolescents with surgically diagnosed endometriosis treated with norethindrone acetate from 1992 to 2010 by one gynecologist at a single children’s hospital. From a starting dose of 5 mg, patients were asked to self-titrate by increasing doses of 2.5-mg increments over the course of 2 weeks until they induced amenorrhea and had decreased pain. In the analysis, 68% achieved the maximum approved dose of 15 mg.
Consistent with clinical experience and other reports, most of the patients had early-stage disease (100 patients had stage 1, 25 had stage 2, none had stage 3, and 4 had stage 4). Their mean age was 16.4 years (range, 12-21 years) and mean body mass index was 23.9 kg/m2 (range 12-37 kg/m2).
The most common indication for progestin-only therapy was failure of combined oral contraceptives (53.5%), followed by migraine headaches with aura (25%), he said.
When all stages of endometriosis were pooled, norethindrone acetate significantly reduced the self-reported mean pain score from 5.6 to 2.6 and mean bleeding score from 7.2 to 3.4, Dr. Kaser said. When stratified by disease severity, norethindrone acetate still significantly reduced pain and bleeding scores in all stages of endometriosis.
Mean pain scores decreased for patients with stage-1 disease from 7.2 at baseline to 3.4 at the most recent clinic visit or upon discontinuation, from 5.6 to 2.8 for stage 2, and from 7 to 1.3 for stage 4. Mean bleeding scores decreased from 2.1 to 0.5 (stage 1), from 1.6 to 0.2 (stage 2), and from 1.5 to 0 (stage 4).
"Due to the fact that all of these patients have surgically confirmed endometriosis, we feel the study population is homogenous and the results should be externally valid to adolescents with endometriosis," he said.
The average duration of therapy was 11.3 months (range, 1-36 months), with 69% of patients still using norethindrone acetate at their most recent visit. Among those who stopped therapy, 70% did so because of persistent pain or bleeding. Interestingly, 15.5% of patients actually down-titrated their dose because of the persistence of pain, and of those who did, 60% had success on the lower dose, he said.
The most common side effects, reported by 14% of patients each, were weight gain and mood swings. Acne was reported by 10%, hot flushes by 8%, headache by 4%, and nausea by 3%.
The most common prescription upon discontinuation was GnRH-agonists plus add-back therapy with norethindrone acetate (52.5%), followed by continuous estrogen/progesterone (32.5%), Dr. Kaser said.
Dr. Kaser and Dr. Laufer reports no conflicts of interest.