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Volume–outcome relationship in transcatheter aortic valve implantations in Germany 2008–2014: a secondary data analysis of electronic health records
  1. Klaus Kaier1,2,
  2. Vera Oettinger2,
  3. Holger Reinecke3,
  4. Claudia Schmoor4,
  5. Lutz Frankenstein5,
  6. Werner Vach1,6,
  7. Philip Hehn1,
  8. Constantin von zur Mühlen2,
  9. Christoph Bode2,
  10. Manfred Zehender2,
  11. Jochen Reinöhl2
  1. 1 Institute for Medical Biometry and Statistics, Faculty of Medicine and Medical Center–University of Freiburg, Freiburg, Germany
  2. 2 Department of Cardiology and Angiology I, Heart Center Freiburg University, Freiburg, Germany
  3. 3 Division of Vascular Medicine, Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany
  4. 4 Clinical Trials Unit, Medical Center–University of Freiburg, Freiburg, Germany
  5. 5 Department of Cardiology, Angiology, Pulmonology, University of Heidelberg, Heidelberg, Germany
  6. 6 Department of Orthopaedics and Traumatology, University Hospital Basel, Basel, Switzerland
  1. Correspondence to Dr Klaus Kaier; kaier{at}


Objectives We examine the volume–outcome relationship in isolated transcatheter aortic valve implantations (TAVI). Our interest was whether the volume–outcome relationship for TAVI exists on the centre level, whether it occurs equally for different outcomes and how it develops over time.

Design Secondary data analysis of electronic health records. The comprehensive German Federal Bureau of Statistics Diagnosis Related Groups database was queried for data on all isolated TAVI procedures performed in Germany between 2008 and 2014. Logistic and linear regression analyses were carried out. Risk adjustment was applied using a predefined set of patient characteristics to account for differences in the risk factor composition of the patient populations between centres and over time. Centres performing TAVI were stratified into groups performing <50, 50–99 and ≥100 procedures per year.

Setting Germany 2008–2014.

Participants All patients undergoing isolated TAVI in the observation period.

Interventions None.

Primary and secondary outcome measures In-hospital mortality, bleeding, stroke, probability of ventilation >48 hours, length of hospital stay and reimbursement.

Results Between 2008 and 2014, a total of 43 996 TAVI procedures were performed in 113 different centres in Germany with a total of 2532 cases of in-hospital mortality. Risk-adjusted in-hospital mortality decreases over the years and is lower the higher the annual procedure volume at the centre is. The magnitude of the latter effect declines over the observation period. Our results indicate a ceiling effect in the volume–outcome relationship: the volume–outcome relationship is eminent in circumstances of relatively unfavourable outcomes. Alongside improving outcomes, however, the volume–outcome relationship decreases. Also, a volume–outcome relationship seems to be absent in circumstances of constantly low event rates.

Conclusions The hypothesised volume–outcome relationship for TAVI exists but diminishes and may disappear over time. This should be taken into account when considering mandatory minimum thresholds.

  • valvular heart disease
  • health economics
  • cardiology
  • adult cardiology

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  • Contributors KK and JR developed the research question and designed the methodology. VO, HR, LF, CvzM, CB, MZ and JR provided the medical knowledge of German TAVI practice informing the study design. KK defined the categories, outcomes and measures and developed and implemented the formal analysis and statistical data with support from WV and CS. KK and JR collected the data and evidence. KK, VO and WV interpreted and contextualised the results. KK and PH wrote the initial draft of the article, with JR contributing. All authors participated in the critical revision of the article and provided final approval of the version to be published.

  • Funding The article processing charge was funded by the German Research Foundation (DFG) and the University of Freiburg in the funding programme Open Access Publishing

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement No additional data available.

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