Therapeutic interchange of conjugated and esterified estrogens in a managed care organization.

A program designed to curb increases in drug costs in an HMO by substituting esterified for conjugated estrogens was developed and studied. Patients were voluntarily switched from conjugated to esterified estrogens at an HMO in Washington State. Women were informed about the conversion through newsletters and during clinic and pharmacy visits and received physician and pharmacist counseling. Cost savings were estimated, and patient acceptance was evaluated by interviewing women in four groups, including women who were switched from conjugated to esterified estrogens and then switched back (C-E-C group), women who were not switched (C-C group), and women who were switched to esterified estrogens and not switched back (C-E group). During the first six months, 14,601 (89.2%) of 16,364 women taking conjugated estrogens were switched to esterified estrogens; of these, 13,654 (93.5%) continued taking esterified estrogens for at least six months. The HMO avoided $653,119 of an expected $750,000 cost increase for oral estrogen therapy during the first year of the program. A total of 754 women were interviewed; 65.8% in the C-E-C group and 78.4% in the C-E group reported being satisfied with the information they received. The conversion experience was rated as positive by 28.3% of women in the C-E-C group and 41.5% of women in the C-E group, negative by 25.1%, and 8.9%, and neutral by 46.6% and 49.6%. An HMO avoided a large increase in drug costs by substituting esterified for conjugated estrogens; only 6.5% of patients were switched back to conjugated estrogens at their physicians' or their own request; most patients thought the conversion was a neutral or positive experience.