Agreement between oral contraceptive users and prescribers: implications for case-control studies

Area of Science:

• Reproductive health
• Epidemiology
• Pharmaceuticals

Background:

• Case-control studies on oral contraceptives (OC) risk misclassification bias.
• Accurate long-term OC use recall is crucial for epidemiological studies.
• This study evaluated patient recall accuracy against prescriber records.

Purpose of the Study:

• To assess agreement between women's lifetime oral contraceptive (OC) use histories and prescriber records.
• To identify factors influencing the accuracy of OC use recall.
• To determine if recall accuracy is sufficient for case-control studies on breast cancer and OC use.

Main Methods:

• A case-control study involving 218 women (127 breast cancer patients, 91 controls) who used OCs.
• Personal interviews with aided recall using OC images and a life-span calendar.
• Prescriber record retrieval and comparison with patient-reported OC histories.

Main Results:

• Patient-prescriber agreement on OC brand (including dosage) was 70%.
• Agreement on start/stop dates was within one year for about 50% of women.
• Recall accuracy decreased for lower socioeconomic status, healthy women, and distant past usage.

Conclusions:

• Agreement on total OC duration was adequate for detecting moderate duration-response relationships.
• Factors like socioeconomic status and recall period impact OC use history accuracy.
• Despite limitations, patient recall may be sufficient for certain epidemiological analyses.