Analysis of Adherence, Persistence, and Surgery Among Endometriosis Patients Treated with Leuprolide Acetate Plus Norethindrone Acetate Add-Back Therapy

BACKGROUND: Endometriosis affects over 10 million women in the United States. Depot leuprolide acetate (LA), a gonadotropin-releasing hormone agonist, has been used extensively for the treatment of women with endometriosis but is associated with hypoestrogenic symptoms and bone mineral density loss. The concomitant use of add-back therapies, specifically norethindrone acetate (NETA), can alleviate these adverse effects. OBJECTIVE: To compare adherence to and persistence with LA treatment and time to endometriosis-related surgery among women treated with LA plus NETA and women treated with LA plus other add-back therapies or LA only. METHODS: This retrospective analysis was conducted using Truven Health MarketScan Commercial Claims and Encounters Database. Women with a diagnosis of endometriosis (ICD-9-CM code 617.xx) who initiated LA (index date) in 2005-2011 were selected for inclusion. Additional requirements were 12 months of continuous enrollment pre- and post-index and no evidence of endometriosis-related surgeries pre-index or up to 30 days post-index; no pre-index use of estrogen or noncontraceptive hormones; and no diagnoses of uterine fibroids, malignant neoplasms, infertility, or pregnancy. Patients were characterized as using NETA; other add-back therapies (estrogens, progestins, or estrogen-progestin combinations); or no add-back therapy. Adherence to and persistence with LA were measured over the 6 months following the index date using outpatient medical and pharmacy claims. Patients were considered adherent if their proportion of days covered was greater than or equal to 0.80. Persistence was operationalized as time to discontinuation, defined as a continuous gap of > 60 days without LA on hand. Time to endometriosis-related surgery (laparotomy, laparoscopy, excision/ablation/fulguration, oophorectomy, and hysterectomy) was measured over the 12 months following the index date. Surgeries were identified from inpatient and outpatient medical claims using procedure codes. Outcomes were compared among cohorts using multivariable logistic and Cox proportional hazards regression models controlling for demographics and baseline clinical characteristics. RESULTS: The final sample included 3,114 women, with a mean age of 36.9 years. The majority of women used LA only with no add-back therapy (n = 1,963, 63.0%), while 15.1% (n = 470) used NETA, and 21.9% (N = 681) used other add-back therapies. During the 6-month follow-up, more patients in the LA plus NETA cohort were adherent to LA therapy compared with LA only (47.2% vs. 31.5%, P < 0.001), and fewer patients discontinued (37.9% vs. 59.6%, P < 0.001). Additionally, fewer patients underwent endometriosis-related surgery in the 12 months after LA initiation in the LA plus NETA cohort (12.6% vs. 16.9%, P = 0.021). In multivariable models, women who initiated LA plus NETA or LA plus other add-back therapies had a higher likelihood of being adherent to LA than LA only patients (OR = 1.91, 95% CI = 1.55-2.36 and OR = 1.95, 95% CI = 1.63-2.34) and lower likelihood of LA discontinuation (HR = 0.54, 95% CI = 0.46-0.63 and HR = 0.59, 95% CI = 0.52-0.68). NETA patients had a lower surgery rate in the 12-month post-index period compared with other add-back patients (HR = 0.68, 95% CI = 0.50-0.93) or LA only patients (HR = 0.69, 95% CI = 0.52-0.92). CONCLUSIONS: For women with endometriosis, treatment with LA and concomitant add-back therapies was associated with better adherence to and persistence with LA over the 6 months following initiation, compared with treatment with LA only. The increased adherence and persistence to LA may translate into decreased need for surgical intervention, although fewer endometriosis-related surgeries were only observed in the 12 months following LA initiation for patients using concomitant NETA add-back therapy. These results support an increased and earlier use of NETA add-back therapy among women who initiate LA.