Name Alwin Schierenberg
Date defense  29 October 2019
(Co) promotoren prof.dr. N.J. de Wit, prof.dr. M.J.M. Bonten, dr. P.C.J. Bruijning-Verhagen
Title thesis Molecular Diagnostics among Patients with Gastroenteritis in General Practice

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Gastroenteritis (GE) is one of the most frequently occurring infectious disease and has a relatively high consultation rate in general practice. In the Netherlands, 5 to 12% of patients with GE consult their general practitioner (GP), amounting to 240 to 600 thousand consultations annually. Although the disease course of GE is in generally favorable and self-limiting, in some patients diagnostics feces testing (DFT) may be indicated to guide further clinical management. DFT and subsequent guided antibiotic treatment may especially be necessary in patients working in healthcare or the food-industry, and in high-risk patients, such as immune-compromised patients, frail elderly, and young children. Traditionally, general practitioners used microbiological culture and microscopy to identify bacteria and parasites causing gastroenteritis. In recent years, molecular-based techniques, such as polymerase chain reaction (PCR), have become available as an alternative to traditional diagnostic modalities. PCR allows for highly sensitive identification of DNA or RNA of multiple enteropathogens in a single stool sample, with shorter turnaround times, improved sampling convenience and diagnostic yield as compared to conventional techniques. While conventional DFT requires up to 4 days before results become available, PCR-based DFT generally takes less than 24 hours. Although these relevant differences between PCR and conventional DFT are likely to influence patient management, healthcare use, and associated costs, an evaluation of the introduction of PCR-based DFT in general practice has not yet been performed. We evaluated the effect of the introduction of PCR-based DFT testing on the management of GE in general practice, as well as on GE-related costs. From our research we can conclude that the current management of patients with GE in general practice – now comprising PCR-based DFT – poorly aligns with guideline indications for empirical antibiotic treatment and DFT. Furthermore, the introduction of PCR is associated with increased use of DFT, healthcare costs per GE episode, and detection and treatment of non-pathogenic protozoa. Additionally, using broad-panel DFT instead of current practice targeted DFT can improve the clinical decision regarding antibiotic treatment in 1 in every 12 patient. These findings need to be interpreted with care, as we were not able to quantify the potential clinical benefits of PCR testing over conventional DFT. However, we conclude that improving adherence to clinical practice guidelines is pivotal to improve current clinical management of GE in general practice. This includes updating of existing guidelines using all available (and new) evidence, increasing awareness among GPs and patients about the proper use of diagnostic and therapeutic resources and stimulating the use of reliable information to patients. When updating the current guideline on gastroenteritis, the position of (broad-panel) PCR-based DFT needs to be more explicitly discussed, describing the different types of indications within the diagnostic workup (e.g. public health or patient’s health perspectives for DFT) and the potential drawbacks and benefits of PCR testing for patients.