Relationship of compliance with hormone replacement therapy to short-term healthcare utilization in a managed care population.

OBJECTIVE

To identify healthcare utilization characteristics that distinguish female members of a managed care organization (MCO) who remained compliant with hormone replacement therapy (HRT) from those who had poor compliance during an 18-month period and to estimate the cost of HRT to an MCO.

STUDY DESIGN

A retrospective cohort design in a population of continuously enrolled female members of an MCO.

METHODS

All female members of the Lovelace Health Plan 40 years of age or older who began HRT between January 1, 1993, and June 30, 1994 (n = 1158). Compliance was determined by calculating an estrogen medication possession ratio based on pharmacy fills over 18 months. "High compliers" (n = 427) were defined as those purchasing at least 80% of their recommended days supply, and "low compliers" (n = 269) as those purchasing less than 20%. Healthcare encounters and costs of high and low compliers were compared.

RESULTS

High compliers were younger (P < 0.01), more likely to be non-Hispanic white than Hispanic (P < 0.0001), and had higher costs for obstetric/gynecologic care (P < 0.0001) and non-HRT prescriptions (P < 0.0001). Low compliers had higher point estimates of costs and encounters for all other categories of care, but differences were statistically significant only for emergency department visits (P < 0.001).

CONCLUSIONS

The added cost of HRT did not result in higher total healthcare utilization and costs, as women who complied well with therapy had decreased utilization and costs in other categories of care. Differences in subcategories of healthcare utilization suggest that level of HRT compliance reflects differences in how women access healthcare.