Limits...
Cohort study examining tamoxifen adherence and its relationship to mortality in women with breast cancer.

McCowan C, Shearer J, Donnan PT, Dewar JA, Crilly M, Thompson AM, Fahey TP - Br. J. Cancer (2008)

Bottom Line: Longer duration was associated with better survival but this varied over time.Increased duration of tamoxifen reduces the risk of death, although one in two women do not complete the recommended 5-year course of treatment.A significant proportion of women have low adherence to tamoxifen and are at increased risk of death.

View Article: PubMed Central - PubMed

Affiliation: Division of Community Health Sciences, University of Dundee, MacKenzie Building, Kirsty Semple Way, Dundee DD2 4BF, UK. c.mccowan@chs.dundee.ac.uk

ABSTRACT
Increasing duration of tamoxifen therapy improves survival in women with breast cancer but the impact of adherence to tamoxifen on mortality is unclear. This study investigated whether women prescribed tamoxifen after surgery for breast cancer adhered to their prescription and whether adherence influenced survival. A retrospective cohort study of all women with incident breast cancer in the Tayside region of Scotland between 1993 and 2002 was linked to encashed prescription records to calculate adherence to tamoxifen. Survival analysis was used to determine the effect of adherence on all-cause mortality. In all 2080 patients formed the study cohort with 1633 (79%) prescribed tamoxifen. The median duration of use was 2.42 years (IQR=1.04-4.89 years). Longer duration was associated with better survival but this varied over time. The hazard ratio for mortality in relation to duration at 2.4 years was 0.85, 95% CI=0.83-0.87. Median adherence to tamoxifen was 93% (interquartile range=84-100%). Adherence <80% was associated with poorer survival, hazard ratio 1.10, 95% CI=1.001-1.21. Persistence with tamoxifen was modest with only 49% continuing therapy for 5 years of those followed up for 5 years or more. Increased duration of tamoxifen reduces the risk of death, although one in two women do not complete the recommended 5-year course of treatment. A significant proportion of women have low adherence to tamoxifen and are at increased risk of death.

Show MeSH

Related in: MedlinePlus

Calculation of adherence and duration.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2600703&req=5

fig1: Calculation of adherence and duration.

Mentions: Each prescription for tamoxifen was analysed and the number of days covered by that prescription recorded from the number of dispensed tablets and daily dose. The duration of tamoxifen therapy was calculated from the number of days between the first and last prescription and the coverage of the last prescription. The adherence index for each patient was calculated by: summing the coverage for all the prescriptions for each patient, dividing it by the duration, and then converting this to a percentage (see Figure 1). The adherence index was calculated across the entire duration of therapy whether this exceeded 5 years or not. Based on the existing literature (Murthy et al, 2002; Wei et al, 2002; Partridge et al, 2003) patients with an adherence index less than 80% were deemed to have ‘low adherence' (Osterberg and Blaschke, 2005).


Cohort study examining tamoxifen adherence and its relationship to mortality in women with breast cancer.

McCowan C, Shearer J, Donnan PT, Dewar JA, Crilly M, Thompson AM, Fahey TP - Br. J. Cancer (2008)

Calculation of adherence and duration.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2600703&req=5

fig1: Calculation of adherence and duration.
Mentions: Each prescription for tamoxifen was analysed and the number of days covered by that prescription recorded from the number of dispensed tablets and daily dose. The duration of tamoxifen therapy was calculated from the number of days between the first and last prescription and the coverage of the last prescription. The adherence index for each patient was calculated by: summing the coverage for all the prescriptions for each patient, dividing it by the duration, and then converting this to a percentage (see Figure 1). The adherence index was calculated across the entire duration of therapy whether this exceeded 5 years or not. Based on the existing literature (Murthy et al, 2002; Wei et al, 2002; Partridge et al, 2003) patients with an adherence index less than 80% were deemed to have ‘low adherence' (Osterberg and Blaschke, 2005).

Bottom Line: Longer duration was associated with better survival but this varied over time.Increased duration of tamoxifen reduces the risk of death, although one in two women do not complete the recommended 5-year course of treatment.A significant proportion of women have low adherence to tamoxifen and are at increased risk of death.

View Article: PubMed Central - PubMed

Affiliation: Division of Community Health Sciences, University of Dundee, MacKenzie Building, Kirsty Semple Way, Dundee DD2 4BF, UK. c.mccowan@chs.dundee.ac.uk

ABSTRACT
Increasing duration of tamoxifen therapy improves survival in women with breast cancer but the impact of adherence to tamoxifen on mortality is unclear. This study investigated whether women prescribed tamoxifen after surgery for breast cancer adhered to their prescription and whether adherence influenced survival. A retrospective cohort study of all women with incident breast cancer in the Tayside region of Scotland between 1993 and 2002 was linked to encashed prescription records to calculate adherence to tamoxifen. Survival analysis was used to determine the effect of adherence on all-cause mortality. In all 2080 patients formed the study cohort with 1633 (79%) prescribed tamoxifen. The median duration of use was 2.42 years (IQR=1.04-4.89 years). Longer duration was associated with better survival but this varied over time. The hazard ratio for mortality in relation to duration at 2.4 years was 0.85, 95% CI=0.83-0.87. Median adherence to tamoxifen was 93% (interquartile range=84-100%). Adherence <80% was associated with poorer survival, hazard ratio 1.10, 95% CI=1.001-1.21. Persistence with tamoxifen was modest with only 49% continuing therapy for 5 years of those followed up for 5 years or more. Increased duration of tamoxifen reduces the risk of death, although one in two women do not complete the recommended 5-year course of treatment. A significant proportion of women have low adherence to tamoxifen and are at increased risk of death.

Show MeSH
Related in: MedlinePlus