A Nationwide Flash-Mob Study for Suspected Acute Coronary Syndrome

Angel M.R. Schols, MD, PhD; Robert T. A. Willemsen, MD, PhD; Tobias N. Bonten, MD, PhD; Martijn H. Rutten, MD; Patricia M. Stassen, MD, PhD; Bas L. J. H. Kietselaer, MD, PhD; Geert-Jan Dinant, MD, PhD; Jochen W.L. Cals, MD, PhD


Ann Fam Med. 2019;17(4):296-303. 

In This Article

Abstract and Introduction


Purpose: Our primary objective was to evaluate the Marburg Heart Score (MHS), a clinical decision rule, or to develop an adapted clinical decision rule for family physicians (FPs) to safely rule out acute coronary syndrome (ACS) in patients referred to secondary care for suspected ACS. The secondary objective was to evaluate the feasibility of using the flash-mob method, an innovative study design, for large-scale research in family medicine.

Methods: In this 2-week, nationwide, prospective, observational, flash-mob study, FPs collected data on possible ACS predictors and assessed ACS probability (on a scale of 1–10) in patients referred to secondary care for suspected ACS.

Results: We collected data for 258 patients in 2 weeks by mobilizing approximately 1 in 5 FPs throughout the country via ambassadors. A final diagnosis was obtained for 243 patients (94.2%), of whom 45 (18.5%) received a diagnosis of ACS. Sex, sex-adjusted age, and ischemic changes on electrocardiography were significantly associated with ACS. The sensitivity of the MHS (cut-off ≤2) was 75.0%, specificity was 44.0%, positive predictive value was 24.3%, and negative predictive value was 88.0%. For the FP assessment (cut-off ≤5), these test characteristics were 86.7%, 41.4%, 25.2%, and 93.2%, respectively.

Conclusions: For patients referred to emergency care, ACS could not be safely ruled out using the MHS or FP clinical assessment. The flash-mob study design may be a feasible alternative research method to investigate relatively simple, clinically relevant research questions in family medicine on a large scale and over a relatively short time frame.


The Marburg Heart Score (MHS), a clinical decision rule based on 5 signs and symptoms (Table 1), has shown promising results in assisting family physicians (FPs) to identify patients with a low probability of acute coronary syndrome (ACS) as the underlying cause of chest pain in the primary care population.[1–3] In contrast to the History, Electrocardiogram, Age, Risk factors, and Troponin (HEART) score validated in emergency departments, additional diagnostic tests, such as electrocardiography (ECG) or cardiac troponin, are not included in the MHS.[4–6] Recently, a large meta-analysis of 3,099 primary care patients with chest pain identified 2 additional predictors of ACS, that is, the FP's suspicion of a serious diagnosis and a pain that feels like pressure.[7] However, the validity of the MHS and other possible predictors—including the FP's clinical assessment, which is infrequently assessed and compared with decision rules—in safely ruling out ACS in otherwise referred primary care patients is unclear.[3,8,9]

Assessing the accuracy of clinical decision rules in family practice requires large prospective studies, which are time consuming and costly. Recently, an innovative research method, the flash-mob method, has been used in hospital-based studies, allowing for the investigation of 1 simple research question on a large scale and over a short time frame.[10,11] Flashmob research is based on the concept of flash mobs, "a large public gathering at which people perform an unusual or seemingly random act and then disperse, typically organized by means of the Internet or social media."[12] Previous research has shown the numeric strength of multiple hospitals and professional and social networks in flash-mob research to obtain sufficient data over a short time period.[10,11] The geographically widespread organization of family medicine and the relatively few numbers of relevant patients per FP are complicating factors in large-scale conventional research, which might be overcome in part by this method. To the best of our knowledge, this flash-mob method has not been used in a nationwide study in family medicine.

The primary aim of this prospective study was to evaluate the MHS or to develop an adapted clinical decision rule for FPs to safely rule out ACS in patients referred to secondary care for suspected ACS. Our secondary aim was to evaluate the feasibility of using the flash-mob method for large-scale, relatively inexpensive, and rapid research in family medicine.