Het volume van chirurgische ingrepen en de impact ervan op ... - KCE

KCE Reports 113 Volume Outcome 39
4.1.5 Linkage of the databases
MCD and MFD were obtained for the year 2004. These were linked to data from the
Common Sickness Funds Agency (IMA-AIM) in order to obtain out-of-hospital mortality
and socio-demographic characteristics. A second linkage was established with clinical
data from the Belgian Cancer Registry (BCR), but only for the oncologic procedures.
Readmissions were analysed with MCD-MFD for the year 2005.
Figure 4.1 gives a schematic overview of the linkage between MCD/MFD, IMA-AIM and
BCR databases. This linkage was performed in four phases of which detailed flow charts
are provided in Appendix 14.
Figure 4.1: Linkage of databases for the KCE study Volume-Outcome
4.2 DATA DEFINITIONS
4.2.1 Primary data selection in MCD 2004
For each condition or procedure, the primary selection of hospitals stays was selected
from the MCD-MFD data based on a combination of codes, which are detailed in the
results section:
• ICD-9-CM diagnosis code (principal or secondary diagnosis)
• ICD-9-CM procedure code
• NIHDI procedure code.
Principal and secondary diagnosis are defined as follows in the coding handbook of the
Belgian Ministry of Health: 110
• The principal diagnosis is defined as the condition which, after
examination of the patient, is the principal reason for admission of the
patient. The coding handbook specifies that the principal diagnosis is NOT
the one present at the time of admission, but rather the one that is made
after examining or even operating on the patient.
• The secondary diagnoses are defined as the conditions that are present
during the hospital stay in addition to the principal diagnosis, or that
develop during the stay and have an impact on patient care (e.g. effect on
the treatment given or on length of stay) during that stay. Examples of
secondary diagnoses are:
o complications of the principal diagnosis;
o complications of surgical or medical care during the current stay;
o associated conditions;
o active pre-existing conditions.