Add-back therapy use and its impact on LA persistence in patients with endometriosis.

OBJECTIVES: Persistence and compliance in women with endometriosis who are receiving gonadotropin-releasing hormone agonists (GnRH-a) may be limited by its hypoestrogenic side effects. Use of concomitant therapy with norethindrone acetate (NA), estrogen, estrogen/progestin combinations, or other progestin (i.e., 'add-back therapy' [ABT]) is recommended to alleviate these side effects. This retrospective study evaluated ABT utilization and its effect on compliance and persistence in patients with endometriosis taking the GnRH-a leuprolide acetate (LA) depot suspension.

METHODS: A retrospective analysis of a large pharmacy claims database identified patients who started LA therapy from 2002 to 2004 for the treatment of endometriosis. Patients were identified as having received ABT if they started 7 days before, or within 45 days of the last LA fill.

RESULTS: A total of 1285 women with endometriosis who began using LA were identified with 12 months of evaluable data: 211 (16.4%) used concomitant NA therapy, 116 (9.0%) used concomitant estrogen-based therapy, 28 (2.2%) used concomitant combination estrogen- and progestin-based therapies, 56 (4.4%) used concomitant progestin-based therapy, and 874 (68.0%) did not use any ABT. Mean (+/-SD) LA persistence in women receiving NA-based ABT was 5.83 +/- 2.98 months, compared with 4.25 +/- 2.62 months for those not using ABT (P < 0.0001). Average medication possession ratio was 0.43 +/- 0.20 for women receiving NA-based ABT versus 0.32 +/- 0.18 for those not receiving any ABT (P < 0.0001). Patients < 30 years of age were most likely to continue therapy longer and have greater compliance compared with the older age group cohorts (P < 0.01). Patients who used ABT continued to do so for 3.79 +/- 3.21 months.

LIMITATIONS: Limitations of this study include those associated with the use of retrospective claims databases: It does not include any information regarding the patient's pain symptoms, disease severity, or other factors, which could correlate to compliance and persistence.

CONCLUSIONS: Among women using LA therapy for endometriosis, only 32% used any type of ABT, and these patients had significantly higher persistence and compliance with LA therapy compared to no ABT user group.