hta_ knee intro.qxp - Ministero della Salute

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chapter 6 for the systematic review of the evidence from formal studies). In particular, our aim
was to collect, for each prosthesis model (identified by model name and manufacturer), performance
estimates at 5 (and possibly 10) years’ follow-up.
7.2 Methods for the identification and analysis of the knee registers
We identified knee registers accessing the EFORT portal with related web-links 35 . For each
register, we downloaded the last available periodic report.
We were interested in collecting performance data for each knee system, i.e. revision (or survival)
rate expressed as a percentage at a set follow-up period, reported in one or more registers.
We performed a systematic comparison of the indicators of performance presented in the periodic
reports.
To compare data from registers with data from clinical studies, we took into account the detail
of reporting of the population receiving the prosthesis. In particular, as the patient age was one
of the inclusion criteria of our systematic review, we decided to consider this variable to stratify
performance data for each specific implant model. We looked at each register’s last published
periodic report for the data we needed and, when these were not reported, or when they were
presented in an unsuitable format for our analysis, we corresponded with a key-person (e.g. the
register’s coordinator) asking for additional data.
7.3 Results
By accessing the EFORT website we obtained 9 periodic reports: 6 from European countries
and 3 from non-European countries (Table 7.1). By contacting key-persons we also became aware
of other national registers (e.g., Austria, Czech Republic, France, Hungary, Italy, Slovak Republic,
and Switzerland). However these registers are in their early implementation phases and no periodic
reports were available for our analysis. We also intended to consider data from the Italian
regional arthroplasty registers (Table 7.1). Two out of 21 regions (Emilia-Romagna and Lombardia)
are currently using a register for knee implants.
7.3.1 Comparison of format and content
Among the 9 periodic reports of national registers identified (Table 7.1), none presented the
data in the format we needed. From our comparison of the indicators of performance we noted
that considerable heterogeneity in data reporting existed. The more important finding is that data
referring to the implant survival, recognised by EAR/EFORT as one of the most important variables
and included within the main aims of an arthroplasty register (see EFORT website 33 ), were
often missing in the periodic reports or were reported only in cumulative form (e.g., per method
of fixation, per age group).