Our research focusses on methodological and applied research concerning the selection, development, and evaluation of measurement instruments. The measurement instruments often concern outcome measures, and often concern patient-reported outcomes, but we also study other measurement instruments.

Our research is embedded in the Knowledge Center on Measurement Instruments of VUmc and the Amsterdam Public Health research institute. Our group initiated and chairs the Clinimetrics working group of the VU University Medical Center.

Main topics and projects

Methodological papers on measurement properties
Developing and optimizing methods for instrument development and evaluation is one of our main research interests. Relevant methodological papers on issues of reliability, measurement error, interpretability, and systematic reviews of outcome measurement instruments from our group can be found here. In addition, we apply these methods developing and evaluating a broad range of measurement instruments in various fields including musculoskeletal disorders, rheumatology, neurology, dermatology, reconstructive surgery, palliative care, elderly care, ophthalmology, audiology, and many others.

COnsensus-based Standards for the Selection of health Measurement Instruments (COSMIN). The international COSMIN initiative was founded by members of the Measurement group. It aims to improve the selection of health measurement instruments in research and clinical practice by developing tools for evaluating the quality of measurement instruments, such as a taxonomy and definitions of measurement properties, the COSMIN checklist for assessing the methodological quality of studies on measurement properties, a guideline for systematic reviews of patient-reported outcome measures, a database of such reviews, and a guideline for selecting outcome measurement instruments for Core Outcome Sets.

A Core Outcome Set (COS) represent a minimum set of outcomes (domains) that should be measured and reported in all clinical trials of a specific condition. A COS helps to standardize the outcomes measured in clinical trials, facilitate meta-analyses of trial results and prevent outcome reporting bias. Our group participates in important international initiatives in this field, such as the COMET initiative, Outcome Measures in Rheumatology (OMERACT), and Harmonizing Outcome Measures for Eczema (HOME), the Cochrane Patient Reported Outcomes Methods Group, and the Cochrane Skin Group Core Outcome Measures Initiative (CSG-COUSIN). Members of our group coordinate(d) or participate(d) in the development of a number of COSs for various health conditions, including rheumatic diseases, low back pain, eczema, vitiligo, interdisciplinary multimodal pain therapy, obesity, knee osteoarthritis, diabetes, etc. Furthermore, members of our group recently established the COS focus group of the Amsterdam Public Health research institute.

Patient-Reported Outcomes Measurement Information System (PROMIS). PROMIS is a set of highly efficient, intelligent Patient-Reported Outcome Measures(PROMs) to evaluate and monitor physical, mental, and social health in adults and children. PROMIS was developed in the US by six large research centers and the National Institute of Health. It is currently embedded in the international PROMIS Health Organization and is being implemented world-wide. PROMIS can be used in the general population and in individuals living with chronic conditions, in research as well as in clinical practice. PROMIS item banks were developed with Item Response Theory and can be used as Computerized Adaptive Tests (CAT), in which a computer selects questions from an item bank, based on answers to previous questions. The Dutch-Flemish PROMIS group is an initiative of members of the Measurement group, and aims to implement PROMIS in the Netherlands and Flanders.

Research Integrity 
Our interest in research integrity originates from the fact that problems with research integrity mainly concern methodological issues. Research on research integrity is gaining momentum. The Netherlands Research Integrity Network offers an information source for teachers and scholars interested in fostering responsible conduct of research and organizes many closed and open meetings of different stakeholders. Research projects concern selective reporting and selective citation. And surveys on research climate, the occurrence of research misbehavior and its causes are conducted in Amsterdam and all Dutch academic institutions. In 2017 we organized the 5th World Conference on Research Integrity.

Members of the Measurement group wrote a textbook (Measurement in Medicine) on measurement theories, methods, and criteria for evaluating and selecting instruments.
Twice a year, we teach a 3-day course in Clinimetrics (Dutch course, English course), based on this text book. We also offer a 1½ day course on research integrity the is preceded by a module of e-learning.

Other relevant initiatives and organizations

Patient-Reported Outcome Measure (PROM) toolbox. Our group contributed to the development of the PROM toolbox, which was developed by the "Zorginstituut" in collaboration with the Dutch expertise network of Patient-Reported Outcomes. The toolbox consists of a road map with tools for the selection and application of PROMs in health care.

International Consortium for Health Outcomes Measurement (ICHOM). ICHOM is a non-profit organization that promotes the development and application of global Standard Sets of outcomes that matter to patients for the most relevant medical conditions.

International Society of Quality of Life Reseach (ISOQOL). ISOQOL is a non-profit society to advance the scientific study of health-related quality of life and other patient-centered outcomes to identify effective interventions, enhance the quality of health care and promote the health of populations. The Dutch affiliated organization, ISOQOL-NL, is a network of researchers interested in the measurement of patient-reported outcomes in research and clinical practice. ISOQOL-NL organizes national meetings about twice a year on measurement issues. This provides a podium for exchange of research ideas and results among Dutch researchers interested in measurement.

Mapi Research Trust
Mapi Research Trust is a non-profit organization dedicated to improving patients' quality of life by facilitating access to Patient-Centered Outcome (PCO) information. It also houses 4,000 PCO questionnaires, as well as their 40,000 translations into some 170 languages (see PROQOLIDTM).