br Conclusion Follow up support and rehabilitation programs
Conclusion: Follow-up, support, and rehabilitation programs for women diagnosed with breast cancer must address a wide range of psychological and physical conditions to limit the consequences on working life.
A prolonged DETANONOate of sick leave is common after a breast cancer diagnosis. During the first year after diagnosis, women with breast cancer spend on average 180 days on sick leave or disability pension, mainly because of intense treatments followed by a period of convalescence . While around 70e80% of women with breast cancer are able to return to work within one year [2e4], they
* Corresponding author. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, PO Box 281, SE-171 77, Stockholm, Sweden. E-mail address: [email protected] (A. Plym).
remain at an increased risk of both sick leave and disability pension for several years [1,5e7]. In a recent study, over 30% of all women with breast cancer had received disability pension within a ten-year period after diagnosis, compared with 14% in the back-ground population . The risk appears not only to be elevated in women with advanced stage disease, another study found that women with stage I breast cancer were at nearly doubled risk of disability pension compared with population controls .
Despite the increased risk of leaving the labor market prema-turely after a breast cancer diagnosis, the underlying causes have rarely been studied. A few previous studies have reported that fa-tigue, lymphedema, and impaired arm/shoulder function nega-tively influence return to work, sick leave, and work ability
[6,9e13], but for other conditions data are sparse or results have been conflicting . Only one earlier study has examined cause-specific sick leave and disability pension . In that Swedish study, 42% of days on sick leave and 12% of days on disability pension in year five after diagnosis were attributed to breast cancer, without specification of the other causes.
In the present study, we assessed the risk of cause-specific sick leave, disability pension, and the competing event death following a breast cancer diagnosis in a population-based cohort of Swedish women, both in comparison with breast cancer-free control women and by tumor characteristics and treatment. We also examined the contribution of post-diagnostic intermediate events on the risk of cancer-specific disability pension. We hypothesized that elevated risks of prolonged sick leave and disability pension not only reflect disease progression, but also psychological and physical morbidity secondary to breast cancer diagnosis and treatment.
2. Material and methods
2.1. Study design and population
We performed a population-based register study using data available in the Breast Cancer Data Base Sweden (BCBaSe), a research database based on the Breast Cancer Quality Registers in €
Stockholm-Gotland, Uppsala-Orebro, and the Northern regions of Sweden. The quality registers include data on tumor characteristics and treatment for 99% of all women diagnosed with breast cancer and residing in the capture areas , which together include approximately 60% of the Swedish population. By means of individual-level record-linkage, the quality registers have been enriched with data on sick leave and disability pension from the MiDAS database held by the Swedish Social Insurance Agency, ed-ucation and labor market participation from the Longitudinal Integration Database for Health Insurance and Labour Market Studies held by Statistics Sweden, cause of death from the Cause of Death Register and hospital visits from the Patient Register, both held by the National Board of Health and Welfare. BCBaSe also in-cludes a randomly selected cohort of breast cancer-free control women, matched on year of birth and county of residence (1:5 ratio) as described previously .
We identified all women aged 30e64 years diagnosed with stage I-III breast cancer (UICC TNM classification, 7th edition)  between January 1, 2000 and December 31, 2012 and their controls, excluding women with receipt of disability benefits prior to diag-nosis and women on sick leave one month prior to diagnosis. This resulted in a final study population of 16,603 women with breast cancer and 63,773 control women (Table 1). Follow-up started from the date of diagnosis and ended on death, emigration, reaching age 65, or end of follow-up (December 31, 2013), whichever came first.
2.2. Cause-specific sick leave and disability pension
The Swedish Social Insurance Agency grants sick leave compensation to individuals with an income from work or unem-ployment benefits if work capacity is reduced because of disease or injury, and disability pension to residents aged 30e64 years in case of permanently reduced work capacity. Since the employer usually reimburses day 2e14 of a sick leave spell, only sick leave >14 days were included. Based on the main diagnosis reported by the certifying physician according to the International Classifications of Diseases (ICD-9/ICD-10), we defined the outcomes of primary in-terest as sick leave and disability pension attributed to cancer, mental disorders (i.e. depression, anxiety and stress-related disor-ders), musculoskeletal disease, cardiovascular disease, inflamma-tory disease, fatigue, pain, or insomnia, and lymphedema-related