The adherence paradox: guideline deviations contribute to the increased 5-year survival of breast cancer patients.
BACKGROUND
In German breast cancer care, the S1-guidelines of the 1990s were substituted by national S3-guidelines in 2003. The application of guidelines became mandatory for certified breast cancer centers. The aim of the study was to assess guideline adherence according to time intervals and its impact on survival.


METHODS
Women with primary breast cancer treated in three rural hospitals of one German geographical district were included. A cohort study design encompassed women from 1996-97 (N = 389) and from 2003-04 (N = 488). Quality indicators were defined along inpatient therapy sequences for each time interval and distinguished as guideline-adherent and guideline-divergent medical decisions. Based on all of the quality indicators, a binary overall adherence index was defined and served as a group indicator in multivariate Cox-regression models. A corrected group analysis estimated adjusted 5-year survival curves.


RESULTS
From a total of 877 patients, 743 (85 %) and 504 (58 %) were included to assess 104 developed quality indicators and the resuming binary overall adherence index. The latter significantly increased from 13-15 % (1996-97) up to 33-35 % (2003-04). Within each time interval, no significant survival differences of guideline-adherent and -divergent treated patients were detected. Across time intervals and within the group of guideline-adherent treated patients only, survival increased but did not significantly differ between time intervals. Across time intervals and within the group of guideline-divergent treated patients only, survival increased and significantly differed between time intervals.


CONCLUSIONS
Infrastructural efforts contributed to the increase of process quality of the examined certified breast cancer center. Paradoxically, a systematic impact on 5-year survival has been observed for patients treated divergently from the guideline recommendations. This is an indicator for the appropriate application of guidelines. A maximization of guideline-based decisions instead of the ubiquitous demand of guideline adherence maximization is advocated.
Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Square J5, 68159, Mannheim, Germany. christian.jacke@zi-mannheim.de.
Christian O
CO
Jacke
Department of Gynaecology and Obstetrics, Krankenhaus Nordwest, Frankfurt am Main, Germany. albert.ute-susann@khnw.de.
Ute S
US
Albert
Department of Gynaecology, Gynaecological and Obstetrics, Breast Center Regio, University of Marburg, Marburg, Germany. kalder@med.uni-marburg.de.
Matthias
M
Kalder
D001943:Breast Neoplasms / Q000401:mortality* / Q000628:therapy; D019468:Disease Management; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D005858:Germany / Q000453:epidemiology; D019983:Guideline Adherence; D006801:Humans; D008875:Middle Aged; D016016:Proportional Hazards Models; D019984:Quality Indicators, Health Care / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D013997:Time Factors