Administrative claims: a novel approach in monitoring long term adherence to anti-hormonal therapy in breast cancer.

Abstract

#1135 Background:
 Anti-hormonal therapy (AHT) is a key component of therapy that improves survival in breast cancer. However, many women do not complete the prescribed treatment course. There is currently limited reliable information regarding long-term adherence to AHT. We hypothesize that health payer administrative claims for prescription benefits may allow more reliable monitoring of AHT use.
 Methods:
 Claims for women diagnosed with breast cancer between 2001 and 2003 from a single insurance carrier covering about 1/3 of the regional population were matched to disease stage and treatment information from the National Cancer Data Base (NCDB) for women treated at NCDB hospitals in Western New York. Claims were searched for AHT drugs identified by National Drug Codes (NDC). Start date, end date, type of agent, switch in drugs, patterns of discontinuation, and dates of insurance coverage eligibility were recorded. A compliance index was attributed to each patient, reflecting the ratio of AHT claims identified, over the ideal number of claims that should have been recorded based on treatment start date.
 Results: 
 AHT was initiated in 230 women at a median of 165 days from breast cancer diagnosis. Stage was 0: 3.5%; I: 54.3%; II: 33.4%; III: 7%; unknown: <2%. Tamoxifen was the first AHT agent in 66.5% of cases. A switch in agents occurred in 36.1% women. There was a gap in prescription renewal in 57% of patients. The average gap length was 5.9 months. The maximum gap duration was 1 month in 27% of cases; however 16% of patients had a treatment gap of 6 months or more. The annual compliance rate for the study population was 79.6%, 60.9%, 52.7%, 24.1% and 6.9% for each of the 5 consecutive years of treatment. After adjusting for time from start of AHT, the compliance index was ≤0.66 in 50% of women. Less than 20% of patients had an index of 1.0 .
 Discussion: 
 Administrative claims data combined with cancer stage data proved to be effective at defining gaps in use of AHT among breast cancer patients. By applying this strategy, we found that over 50% of women treated with AHT had gaps in treatment averaging 6 months. The annual compliance rate to AHT decreased steadily over each of the 5 years of treatment. Real time monitoring of administrative claims for patients who start AHT can identify those who discontinue treatment and may allow counseling on side effects and benefits and improve treatment compliance and outcome. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1135.