Participants and refusers in a telephone interview about hormone replacement therapy were equally likely to be taking it

Abstract 

Objective

To address a major concern in pharmacoepidemiology studies related to whether the characteristics of responders are different from those who refuse to participate.

Study design and setting

We compared utilization of postmenopausal hormone replacement therapy (HRT) in women who agreed to participate in a telephone interview on HRT utilization and in women who refused to participate in the telephone interview. Information on HRT utilization among responders and refusers was independently available to us from a claims database (the Healthcare Management Alternatives, HMA, in Philadelphia), showing drugs dispensed to these patients.

Results

Out of a random sample of 213 women selected from the claims database whom we contacted, 154 (72.3%) women agreed to participate and 59 (32.7%) women refused. Among the 154 women who agreed to participate, 79 (51.3%, 95% CI: 43.1–59.4%) were shown by the database to have been dispensed an HRT during the 15-month period January 1995 through March 1996. Among the 59 women who refused to participate, 30 (50.8%, 95% CI: 37.5–64.1%) were shown by the database to have been dispensed an HRT during the same period.

Conclusion

Thus, we have evidence that use of HRT was almost identical in responders and nonresponders.

Keywords:  Nonresponse, Selection bias, Drug recall, Hormone replacement therapy, Claims database, Pharmacoepidemiology