Abstract A112: Time trend and spatial pattern in the use of hormone replacement therapy in Taiwan before and after WHI trial report
Authors: Chiang Po-Huang , Tsai Eng-Mei , Chang Yen-Chen 
Published: January 2014

Background: In 2002, trial by Women's Health Initiative that reported the long-term risks of hormone replacement therapy (HRT) of postmenopausal women. Combined estrogen and progestin hormone use outweighed the benefit for women health. This study aimed to examine the time trend and spatial patterns of HRT use and determine whether the declines occurred in Taiwan.

Methods: The present study analyzed HRT utilization and influencing factors by the postmenopausal or osteopenic Taiwanese women. We investigated a case-control cohort analysis of a national health insurance (NHI) claimed dataset. NHI outpatient services claimed data of 82,478 beneficiaries aged above 40 had a principal diagnosis of postmenopause (ICD-9-CM Diagnosis Code 627) and osteopenia (ICD-9-CM Diagnosis Code 7330) were included in this study. HRT utilization trend was examined by different diagnostic codes, specialists, hospital level, hospital ownership, physicians' gender and age, also patients' resident area. The geographic variations of HRT use were obtained from 6 national insurance branches to compare the utilization rates before and after 2002. The highest use of HRT of region (eastern branch) was selected with 2,447 cases to compare the risk of usage and duration of HRT. Spatial patterns of rate change of breast cancer incidences between 1998-2002 and 2003-2008 were obtained from Taiwan Cancer Registry to examine changes in spatial trends in relations to HRT use and high mammography screening hospitals.

Results: A reduced frequency of use of HRT was reflected in the decrease in hormone prescriptions after 2002. The largest drop was occurred between 2002 and 2003(from 51.5% to 37.9% in 2003). Similar reducing trend of use HRT was also showed in different specialists (8.1% drop in Obstetrics & Gynecology, 4% drop in Orthopedics and 12.8% drop in other department between 2002 and 2003). The HRT use rate for women visited clinic in 2002 and 2003 dropped from 56.2% to 42.8%, but slow decrease between 2004 to 2007 (37.3% in 2004, 34.8% in 2005, 35.0% in 2006 and 34.7% in 2007). There are slight increase use rate between 2005 and 2006. In 2008, there was another larger drop of 3.4%. The eastern branch compared with other branches between two period of time (2000-2002 and 2003-2008). Relative risk of 1.47 (95% CI: 0.72-3.00) before 2002 and 1.57 (95% CI: 0.81-3.11) after 2002. Spatial patterns showed the increasing breast risks in central and southern region (rural area) compare with northern region (metropolitan area). The increase of age-adjusted incidence rate in central and southern region outweighed the increase rate of HRT use. In the contrast to these regions, an increasing rate of HRT use did not observe the similar effect in northern metropolitan regions.

Discussion: To our knowledge, this is the first Taiwan study to examine the link between population-level declines in use of hormone replacement therapy among postmenopausal women with different levels of utilization. Spatial observation was also indicated the different between breast incidence and HRT use in Taiwan. Spatial observation found the different pattern change between HRT use and breast incidence rate in term of geographic prospect and urbanization level. Further long-term investigation to determine whether the geographic accessibility and availability of breast screening programs do affect the ascending breast cancer risk.

Citation Format: Po-Huang Chiang, Eng-Mei Tsai, Yen-Chen Chang. Time trend and spatial pattern in the use of hormone replacement therapy in Taiwan before and after WHI trial report. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A112.