Tjarco Koppenaal

Council for Public Health and Health Care, Netherlands, 's-Gravenhage, South Holland, Netherlands

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Publications (2)6.83 Total impact

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    ABSTRACT: The increasing prevalence of diabetes suggests a gap between real world and controlled trial effectiveness of lifestyle interventions, but real-world investigations are rare. Electronic medical registration facilitates research on real-world effectiveness, although such investigations may require specific methodology and statistics. We investigated the effects of real-world primary care for patients with type 2 diabetes mellitus (T2DM). We used medical records of patients (n=2,549) with T2DM from 10 primary health care centers. A mixed-effects regression model for repeated measurements was used to evaluate the changes in weight and Hemoglobin A1c (HbA1c) over time. There was no statistically significant change in weight (+0.07 kg, P=0.832) and HbA1c (+0.03%, P=0.657) during the observation period of 972 days. Most patients maintained their physical activity level (70%), and 54 % had an insufficient activity level. The variability in the course of weight and HbA1c was because of differences between patients and not between health care providers. Despite effective lifestyle interventions in controlled trial settings, we found that real-world primary care is only able to stabilize weight and HbA1c in patients with T2DM over time. Medical registration can be used to monitor the actual effectiveness of interventions in primary care.
    No preview · Article · May 2012 · Journal of clinical epidemiology
  • Tjarco Koppenaal · Joris Linmans · J André Knottnerus · Mark Spigt
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    ABSTRACT: The Pragmatic-Explanatory Continuum Indicator Summary (PRECIS) tool was designed to classify randomized clinical trials (RCT) as being more pragmatic or explanatory. We modified the PRECIS tool (called PRECIS-Review tool [PR-tool]) to grade individual trials and systematic reviews of trials. This should help policy makers, clinicians, researchers, and guideline developers to judge the applicability of individual trials and systematic reviews. To illustrate the usefulness and applicability of the PR-tool, we applied it to two systematic reviews. Each included RCT was scored on the 10 PRECIS domains on a scale of 1-5. After this scoring, a 10-domain average for each individual trial and for the systematic review a single domain average and an overall average was calculated. One review was more pragmatic with an average score of 3.7 (range, 2.9-4.6) on our PR-tool, whereas the other review was more explanatory with an average score of 1.9 (range, 1.1-3.3). The results also suggest that the included studies within each systematic review were rather uniform in their approach, although some domains seemed more prone to heterogeneity. The PR-tool provides a useful estimate that gives insight by estimating quantitatively how pragmatic each RCT in the review is, which methodological domains are pragmatic or explanatory, and how pragmatic the review is.
    No preview · Article · Apr 2011 · Journal of clinical epidemiology

Publication Stats

28 Citations
6.83 Total Impact Points


  • 2012
    • Council for Public Health and Health Care, Netherlands
      's-Gravenhage, South Holland, Netherlands
  • 2011
    • Maastricht University
      • Department of General Practice
      Maestricht, Limburg, Netherlands