A retrospective case-control study of non-compliances preceding foodborne outbreaks originating from food service premises

Abstract

More than half of the foodborne outbreaks originate from food service premises (FSPs). Recognizing non-compliances observed during food control inspections and their association with outbreaks is important so that new measures to prevent outbreaks can be developed.We conducted a retrospective case-control study to compare food control inspection grades between outbreak and non-outbreak FSPs. A total of 105 outbreaks meeting the study inclusion criteria were identified from among 337 outbreak investigation reports in Finland in 2015–2021. Four randomized matched non-outbreak control FSPs were selected for each outbreak FSP. Inspection grades were compared using a paired t-test or a Wilcoxon signed-rank test. In addition, we studied the association between the time from the preceding inspection to the point of the outbreak and the grade of the preceding inspection. Furthermore, inspectors’ verbal descriptions of the inspection findings were analyzed by comparing n-gram incidences between outbreak and control FSPs.When outbreaks with the weakest strength of evidence (on a 4-level scale) were excluded and only the inspection preceding the outbreak was considered, the inspection grades for outbreak FSPs regarding the monitoring of employees’ health status were inferior compared to the control FSPs (p = 0.02). When comparing the grades of all available inspections prior to the outbreak, there was a difference not only in monitoring employees' health status (p = 0.04), but also in the verification of hygiene proficiency (p = 0.02). Non-compliance in the verification of hygiene proficiency might imply deficiencies in food safety knowledge, which can result in many types of non-compliance.We also demonstrated that the closer the preceding inspection was to the outbreak, the worse the inspection grades were. This implies that the observed non-compliances may lead to outbreaks in a short time if not corrected, and that a prolonged inspection interval might result in critical non-compliances in FSPs that have previously received satisfactory inspection grades. These results can be used to develop food control focus points and inspection frequency.