title: The Power of Flash Mob Research: Conducting a Nationwide Observational Clinical Study on Capillary Refill Time in a Single Day.
abstract: Capillary refill time (CRT) is a clinical test used to evaluate the circulatory status of patients; various methods are available to assess CRT. Conventional clinical research often demands large numbers of patients, making it costly, labor-intensive, and time-consuming. We studied the interobserver agreement on CRT in a nationwide study by using a novel method of research called flash mob research (FMR).
  
  
  
  Physicians in the Netherlands were recruited by using word-of-mouth referrals, conventional media, and social media to participate in a nationwide, single-day, "nine-to-five," multicenter, cross-sectional, observational study to evaluate CRT. Patients aged ≥ 18 years presenting to the ED or who were hospitalized were eligible for inclusion. CRT was measured independently (by two investigators) at the patient's sternum and distal phalanx after application of pressure for 5 s (5s) and 15 s (15s).
  
  
  
  On October 29, 2014, a total of 458 investigators in 38 Dutch hospitals enrolled 1,734 patients. The mean CRT measured at the distal phalanx were 2.3 s (5s, SD 1.1) and 2.4 s (15s, SD 1.3). The mean CRT measured at the sternum was 2.6 s (5s, SD 1.1) and 2.7 s (15s, SD 1.1). Interobserver agreement was higher for the distal phalanx (κ value, 0.40) than for the sternum (κ value, 0.30).
  
  
  
  Interobserver agreement on CRT is, at best, moderate. CRT measured at the distal phalanx yielded higher interobserver agreement compared with sternal CRT measurements. FMR proved a valuable instrument to investigate a relatively simple clinical question in an inexpensive, quick, and reliable manner.
authors.affiliation: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands. Electronic address: j.alsma@erasmusmc.nl.
authors.forename: Jelmer
authors.initials: J
authors.lastname: Alsma
authors.affiliation: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors.forename: Jan L C M
authors.initials: JLCM
authors.lastname: van Saase
authors.affiliation: Section Acute Medicine, Department of Internal Medicine, VU University Medical Centre, Amsterdam, the Netherlands.
authors.forename: Prabath W B
authors.initials: PWB
authors.lastname: Nanayakkara
authors.affiliation: Department of Internal Medicine, Onze Lieve Vrouwe Gasthuis, Amsterdam, the Netherlands.
authors.forename: W E M Ineke
authors.initials: WEMI
authors.lastname: Schouten
authors.affiliation: Department of Internal Medicine, Radboud University Medical Centre, Nijmegen, the Netherlands.
authors.forename: Anique
authors.initials: A
authors.lastname: Baten
authors.affiliation: Department of Infectious Diseases, Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: Martijn P
authors.initials: MP
authors.lastname: Bauer
authors.affiliation: Section Acute Medicine, Department of Internal Medicine, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Frits
authors.initials: F
authors.lastname: Holleman
authors.affiliation: Emergency Department, Department of Internal Medicine, University Medical Center Groningen, Groningen, the Netherlands.
authors.forename: Jack J M
authors.initials: JJM
authors.lastname: Ligtenberg
authors.affiliation: Department of Internal Medicine, Division General Medicine, Section Acute Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; Maastricht University, Department of Health Services Research, and CAPHRI School for Public Health and Primary Care, Maastricht, the Netherlands.
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Stassen
authors.affiliation: Department of Internal Medicine, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Karin H A H
authors.initials: KHAH
authors.lastname: Kaasjager
authors.affiliation: Maastricht University, Department of Health Services Research, and CAPHRI School for Public Health and Primary Care, Maastricht, the Netherlands; Department of Internal Medicine, Máxima Medical Centre, Eindhoven, the Netherlands; Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands.
authors.forename: Harm R
authors.initials: HR
authors.lastname: Haak
authors.affiliation: Department of Internal Medicine, Rijnstate Hospital, Arnhem, the Netherlands.
authors.forename: Frank H
authors.initials: FH
authors.lastname: Bosch
authors.affiliation: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Emergency Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors.forename: Stephanie C E
authors.initials: SCE
authors.lastname: Schuit
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D035843:Biomedical Research; D002196:Capillaries / Q000502:physiology / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D003625:Data Collection / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D018579:Patient Selection; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D013997:Time Factors
keywords: biomedical research; capillary refill time; data collection; physiology