Jeannette B. Peters

An Integral assessment framework of health status in chronic obstructive pulmonary disease (COPD).

Background: To date, many health status instruments exist, but the validity of these instruments is questionable. This is caused by the fact that health status is poorly defined.Purpose: To develop a validated framework that improves conceptual insight into health status and its domains.Methods: Based on theoretical and clinical considerations, we defined the domains of health status into concrete sub-domains by formulating conceptual models. Guided by these conceptual models, for each sub-domain, existing instruments were selected. We validated the conceptual models in the data of 168 COPD patients. Using factor analysis, underlying concepts in the data were identified.Results: The resulting framework included physiological functioning, complaints, functional impairment, and quality of life. These main domains were shown to be subdivided into 15 sub-domains.Conclusions: The present study shows that health status consists of conceptually distinct sub-domains. Integral assessment of health status thus entails measuring all sub-domains. Existing instruments measure only few sub-domains. Integral assessment of health status thus requires the combination of different instruments. The present framework of health status can help in composing such a battery of instruments. Patient profiles obtained by the framework are essential in individualizing treatment.

Inaccuracy of Estimating Peak Work Rate from Six-Minute Walk Distance in Patients with COPD

Abstract Introduction. The cardiopulmonary exercise test (CPET) and the 6-minute walk test (6MWT) are used to prescribe the appropriate training load for cycling and walking exercise in patients with chronic obstructive pulmonary disease (COPD). The primary aims were: (i) to compare estimated peak work rate (Wpeakestimated) derived from six existing Wpeak regression equations with actual peak work rate (Wpeakactual); and (ii) to derive a new Wpeak regression equation using six-minute walk distance (6MWD) and conventional outcome measures in COPD patients. Methods. In 2906 patients with COPD, existing Wpeak regression equations were used to estimate Wpeak using 6MWD and a new equation was derived after a stepwise multiple regression analysis. Results. The 6 existing Wpeak regression equations were inaccurate to predict Wpeakactual in 82% of the COPD patients. The new Wpeak regression equation differed less between Wpeakestimated and Wpeakactual compared to existing models. Still, in 74% of COPD patients Wpeakestimated and Wpeakactual differed more than (±) 5 watts. Conclusion. In conclusion, estimating peak work load from 6MWD in COPD is inaccurate. We recommend assessment of Wpeak using CPET during pre-rehabilitation assessment in addition to 6MWT.

The Use of Regression Equations to Estimate Peak Work Rate in People with COPD - Reply from the Authors

1. Program Development Centre; CIRO+, centre of expertise for chronic organ failure; Horn, the Netherlands2. Department of Medical Psychology; Radboud University Nijmegen Medical Centre; Nijmegen, the Netherlands3. Department of Pulmonary Diseases; Radboud University Nijmegen Medical Centre; Nijmegen, the Netherlands4. Rehabilitation Centre Breda; Revant Rehabilitation Centre; Breda, the Netherlands5. Department of pulmonary diseases, VU Medical Centre, Amsterdam, the Netherlands6. Asthma Centre Heideheuvel; Merem Behandelcentra; Hilversum, the Netherlands7. Director; CIRO+, centre of expertise for chronic organ failure; Horn, the Netherlands8. Department of Respiratory Medicine; Maastricht University Medical Centre (MUMC+); Maastricht, the Netherlands9. Department of Respiratory Medicine; Erasmus Medical Center; Rotterdam, the Netherlands10. Sports Training; CIRO+, centre of expertise for chronic organ failure; Horn, the Netherlands