Existing data sources for clinical epidemiology: the Danish Quality Database of Mammography Screening Vivian Langagergaard (1), Jens P. Garne (2), Ilse Vejborg (3), Walter Schwartz (4), Martin Bak (5), Anders Lernevall (1), Nikolaj B. Mogensen (6), Heidi Larsson (7), Berit Andersen (1), Ellen M. Mikkelsen (7).
(1) Department of Public Health Programs, Randers Hospital (2) Department of Breast Surgery, Aalborg University Hospital (3) Diagnostic Imaging Center, Copenhagen University Hospital, Rigshospitalet (4) Center of Mammography, Odense University Hospital (5) Department of Pathology, Odense University Hospital (6) Department of Radiology, Ringsted Hospital (7) Department of Clinical Epidemiology, Aarhus University Hospital
Table 2. Clinical quality indicators based on the first round of Background and Purpose nationwide mammography screening in Denmark Propotion/ The Danish Quality Database of Mammography Screening (DKMS) was established in 2007, Number of women Clinical quality indicators ratio (95% CI) when screening was implemented on a nationwide basis and offered biennially to all Danish Recall women aged 50-69 years. Here, we present results for quality assurance from the first round of a Recalled women/All women screened (standard <5%) national screening. Capital Region of Denmark 3982/139 987 2.8% (2.8-2.9)
Region Zealand 2477/91 113 2.7% (2.6-2.8) Methods North Denmark Region 2351/48 980 4.8% (4.6-5.0) The steering committee for the DKMS defined eleven organizational and clinical quality indicators Central Denmark Region 3456/115 717 3.0% (2.9-3.1) and standards to monitor the Danish breast cancer screening program: participation, screening Region of Southern Denmark 3165/123 026 2.6% (2.5-2.7) Total 15,431/518 823 3.0% (2.9-3.0) interval, time to result, radiation dose, recall, interval cancers, invasive tumors, node negative
cancers, small cancers, breast conserving therapy, and ratio of surgery for benign to malignant Invasive breast tumors Women with invasive cancers/ lesions. We calculated the relevant proportions and ratios with 95% confidence intervals for each a All women with cancer (including DCIS) (standard ≥80% and ≤90%) quality indicator. All indicators were assessed on a national and regional level.
Capital Region of Denmark 1059/1235 85.7% (83.7-87.7)
Region Zealand 753/882 85.4% (82.9-87.6) Table 1. Organizational quality indicators based on the first round of nationwide mammography screening in Denmark North Denmark Region 400/434 92.2% (89.2-94.5) Propotion/ Central Denmark Region 963/1096 87.9% (85.8-89.7) Number of women Organizational quality indicators ratio (95% CI) Region of Southern Denmark 933/1110 84.1% (81.8-86.2)
P r o p o r t i o n o f i n v i t e d w o m e n w h o p a t i c i p a t e d i n t h e s c r e e n i n g p r o g r a m Total 4108/4757 86.4% (85.3-87.3) Screened women/All women invited (standarda >75%) Node negative cancers Capital Region of Denmark 139,987/191,279 73.2% (73.0-73.4) Women with node negative invasive carcinomas/ Women operated on for invasive carcinomas (standarda >70%) Region Zealand 91,113/111,522 81.7% (81.5-81.9)
North Denmark Region 48,980/75,260 65.1% (64.7-65.4) Capital Region of Denmark 682/1008 67.7% (64.7-70.5)
Central Denmark Region 115,717/149,817 77.2% (77.0-77.5) Region Zealand 500/717 69.7% (66.2-73.1)
Region of Southern Denmark 123,026/142,161 86.5% (86.4-86.7) North Denmark Region 237/385 61.6% (56.5-66.4)
Total 518,823/670,039 77.4% (77.3-77.5) Central Denmark Region 590/876 67.4% (64.1-70.5)
Region of Southern Denmark 605/892 67.8% (64.6-70.9) Time from screening to result Women who received their result ≤10 days after screening/ Total 2614/3878 67.4% (65,9-68,9) a All women screenedb (standard >95%) Small cancers Capital Region of Denmark 30,345/139,841 21.7% (21.5-21.9) Women with invasive carcinomas ≤1 cm/ Women operated on for invasive carcinomas (standarda ≥25%) Region Zealand 71,778/90,931 78.9% (78.7-79.2)
North Denmark Region 27,373/40,996 66.8% (66.3-67.2) Capital Region of Denmark 279/718 38.9% (35.3-42.5) Central Denmark Region 111,911/115,708 96.7% (96.6-96.8) Region Zealand 274/717 38.2% (34.6-41.9) Region of Southern Denmark 121,700/123,006 98.9% (98.9-99.0) North Denmark Region 66/228 28.9% (23.2-35.3) Total 363,107/510,482 71.1% (71.0-71.3) Central Denmark Region 196/591 33.2% (29.4-37.1)
a) Standards are defined by the steering committee for the Danish Quality Database of Mammography Screening (DKMS) based on the fourth edition of the European Guidelines for Region of Southern Denmark 312/840 37.1% (33.9-40.5) Quality Assurance in Breast Cancer Screening and Diagnosis, b) 8341 women were excluded because the date of result was undisclosed. Total 1127/3094 36.4% (34.7-38.1)
Ratio of surgery for benign versus malignant lesions Results Women operated for benign lesions/ Of 670,039 women invited for mammography, 518,823 (77.4%) participated. Seventy-one percent Women operated for malignant lesions (incl. DCIS) (standarda Ratio: ≤1:4)
of the women received the result of their mammography examination within 10 days of screening Capital Region of Denmark 131/1196 1:9.1 (Table 1). Table 2 shows results for the clinical quality indicators. Three percent of the participants Region Zealand 119/857 1:7.2
were recalled for further investigation. Among all detected cancers, 86% were invasive cancers, North Denmark Region 119/430 1:3.6
and the proportion of women with node negative cancers was 67%. There were 36% women with Central Denmark Region 178/1033 1:5.8
small cancers, and the ratio of surgery for benign lesions to malignant lesions was 1:6.3. A total Region of Southern Denmark 198/1147 1:5.8
of 80% of women with invasive cancers were treated with breast conserving therapy. Screening Total 745/4663 1:6.3 interval and interval cancers were not relevant in the first round, and data regarding radiation Breast conserving therapy dose were not available at the time of evaluation. Women with invasive carcinomas treated with breast conserving therapy/ Women operated on for invasive carcinomas (standarda >50%)
Capital Region of Denmark 811/1022 79.4% (76.7-81.8)
Conclusions Region Zealand 628/726 86.5% (83.8-88.9)
Overall, the quality indicators showed satisfactory quality in the first round of national breast North Denmark Region 271/389 69.7% (64.8-74.2) cancer screening in Denmark. The DKMS is a potentially valuable tool for improving quality and Central Denmark Region 670/887 75.5% (72.6-78.3) conducting research in the field of breast cancer screening. Region of Southern Denmark 770/905 85.1% (82.6-87.3) Total 3150/3929 80.2% (78.9-81.4)
a) Standards are defined by the steering committee for the Danish Quality Database of Mammography Screening (DKMS) based on the fourth edition of the European Guidelines for Quality Assurance in Breast Cancer Screening and Diagnosis.