Trends in vitamin B12 and D determinations in the Netherlands

Radboudumc, Institute for Health Sciences, IQ Healthcare department, Nijmegen: Dr. JLJM Müskens, medical biologist; dr. RB Kool, senior researcher (also project manager of ‘Doen or leave?’); Dr. SA van Dulmen, senior researcher (also project manager of ‘Doen or leave?’); Dr. F. Atsma, senior epidemiologist and methodologist; prof.dr. G. Westert, medical sociologist (also professor of Quality of Health Care and Health Services Research and director of IQ healthcare). Coöperatie VGZ, Arnhem, the Netherlands: Dr. M. Maessen, lead customer intelligence expert.

Conflict of interest

Conflict of Interest and Financial Support: ICMJE forms containing the authors’ Declaration of Interests are available online with this article.

Accountability

Coöperatie VGZ made its data available for this study and helped with the analysis. Nils van Herpen and Jurgen Smolders of VGZ in particular contributed to generating the required datasets.