Background The FeverApp registry uses ecological momentary assessment (EMA) to collect parental data on pediatric fever for scientific research. The mobile app FeverApp educates parents on safe fever management and serves as a fever diary. Objective The focus of this study was to evaluate the completeness and concordance of the EMA-based FeverApp registry with regard to its data quality from a multilevel perspective. Methods Structured descriptions of fever episodes by health care professionals from an office were used as reference. The number of children, their sociodemographic data, and agreement of fever episodes, with maximum temperature, intake of antipyretics and antibiotics, and physician visits, were compared with the entries in the corresponding physician’s reference records. The data quality indicators for completeness, meaning the extent to which the necessary data for the registry has actually been submitted, and concordance, which is the correspondence of the value of a data element with a reference source, were chosen to analyze whether EMA may be a suitable method for this kind of registry. Results In both data sources, 1012 children were available for comparison over 16 months. The completeness of gender (1012/1012, 100%) and date of birth (1004/1012, 99.2%) information was high, and the mismatches were 0.69% (7/1012) and 1.19% (12/1012), respectively, between the sources. Of these 1012 children, 668 (66%) registered fever episodes in FeverApp. They relate to 534 families with 953 fever episodes in the reference records and 1452 episodes in the FeverApp registry. Of the 534 families, 183 (34.3%) refrained from visiting the office during fever episodes but nevertheless documented them in FeverApp. Largest part (766/1452, 52.75%) episodes were recorded exclusively in the FeverApp registry by 371 (371/534, 69.5%) families. The remaining 686 (47.2%) episodes of 391 (58.5%) children from 351 (65.7%) families were comparable with the reference data source in terms of physician visits, medication, and temperature. The completeness ranged, depending on the kind of variable, from 11.5% to 65% in the registry and from 7.6% to 42.6% in the office. The 953 fever episodes reported by the reference office consisted of 681 (71.5%) acute and 272 (28.5%) past episodes. In FeverApp, most past (262/272, 96.3%) but less acute (424/681, 62.3%) episodes have been entered. The concordance rates were varied: 90.2% for antibiotic use, 66.6% for antipyretic use, 61.7% for physician visits, and 16% for the highest temperature during the fever episode. Conclusions Both sources delivered only partial data, and the rates of completeness and concordance depended on the kind of variable. However, the FeverApp registry showed higher documentation and precision rates than professional records for all considered variables. Therefore, EMA may play a unique supplement for research in ambulatory care. FeverApp could support pediatric offices, especially during the pandemic.

Objectives Mobile health applications could be means of educating and changing behaviours of their users. Their features and qualities determine the sustainability of use. The FeverApp with two main features of information and documentation is a research-based app. In this observational cohort study, to evaluate the influential predictors of use, users’ feedback on the FeverApp, were analyzed. Methods Feedback is given using a structured questionnaire, four Likert items and two open questions regarding positive and negative impressions, available via app menu. Conventional content analysis (inductive approach) on the two open questions was performed. Comments were grouped into 12 codes. These codes were grouped hierarchically in an iterative process into nine subcategories and lastly into two main categories ‘format’ and ‘content’. Descriptive and quantitative analysis were performed. Results Out of 8243 users, 1804 of them answered the feedback questionnaire. The features of the app ( N  =  344), followed by the information aspect ( N  =  330) were most frequently mentioned. Documentation process ( N  =  226), request for new features or improvement of the current ones ( N  =  193), and functioning ( N  =  132) were also highlighted in users’ feedback. App's ease of use, design and being informative were important for the users. The first impression of the app seems important as the majority of feedback were given during the first month of using the app. Conclusion In-app feedback function could highlight shortcomings and strengths of mobile health apps. Taking users’ feedback into consideration could increase the chance of sustained use. Besides ease of use and clear, likeable designs, users want apps that serve their needs while saving time.

Zusammenfassung Ziel der Studie Die Machbarkeit und Modellhaftigkeit eines App-basierten Eltern-Registers ist aufzuzeigen. Methodik Die FeverApp als interaktives Erfassungsinstrument und die zugrundeliegende Datenstruktur des Registers werden vorgestellt. Die bisherigen Rekrutierungsbemühungen werden veranschaulicht und die Temperaturverteilung, sowie die Verteilung von Fieberereignissen im Jahr 2020 werden analysiert. Ergebnisse Die FeverApp sammelt erfolgreich Daten in ein zentrales Register. Wie jede Studie informiert sie zudem über das aktuelle Wissen. Die naturalistisch erfassten, aktuellen Werte können auf die Krankheitssituation mehrere Ebenen (Messung, Fieberphase, Individuum, Familie, Praxis, Land) in Bezug auf die Krankheitssituation darstellen. Die Methoden zur Datensammlung müssen Pandemie-bedingt flexibel entwickelt werden. Das erste Rekrutierungsziel von 2400 Fieberphasen in den ersten zwei Jahren wurde erreicht, die landesweite Verbreitung steht noch aus. Es zeigt sich, dass die Körpertemperatur nicht unbegrenzt steigt; Fieber erreicht im Mittel 39 Grad auch ohne Antipyretika, wobei in seltenen Fällen auch Temperaturen jenseits von 41 Grad ohne Schäden erreicht werden. Weiterhin lässt sich im Vergleich mit einer Referenzpraxis zeigen, dass Fieberphasen in der App umfassender erfasst werden können, d. h. inklusive Infekte, die nicht zur Vorstellung in der Kinderpraxis kommen. So erfüllt die FeverApp den Einsatz von Registern modellhaft bei an sich Gesunden mit Infekten und bildet eine Mehrebenendiagnostik ab. Schlussfolgerung Die FeverApp konnte sich als unterstützendes Werkzeug grundsätzlich etablieren, das Register kann mit der eingesetzten Methode reliabel Daten erfassen und bildet die aktuelle Infektlage ab. Bei der Erforschung der Frage, wie sich Infekte in der Post-Covid- Zeit entwickeln, könnte die App eine wertvolle Aufgabe leisten.

Parents’ confidence regarding their children’s fever is a key factor in its management and there is still unnecessary anxiety and associated antipyretic overuse. The FeverApp application collects naturalistic real-time data on febrile infections and educates parents on fever management. Logistic regression examined the associations between (1) parental confidence and (2) antipyretics use with fever relevant parameters. First entry data of 3721 children (mean age 21 months; SD 22.97) was assessed. A total of 58.0% of parents felt confident upon first fever documentation. Warning signs [OR = 0.49, 95% CI: 0.40–0.61], dehydration [OR = 0.65, 95% CI: 0.52–0.81], fever [OR = 0.67, 95% CI: 0.57–0.80] and having a female child [OR = 0.77, 95% CI: 0.66–0.90] had the highest negative association with parental confidence. Antipyretics were used initially in 14.7% of children. Fever had the highest positive [OR = 2.58, 95% CI: 1.89–3.50] and well-being the highest negative association with antipyretic use [OR = 0.37, 95% CI: 0.22–0.63). In the first entry data, parental confidence was related to children’s health condition in a reasonable medical manner. The use of antipyretics was mostly associated with febrile temperature, but also low well-being. Thus, associations were partly in accordance with recent guidelines.

Febrile infections are common in childhood. Children can be infected with SARS-CoV-2, but their course is milder than in adults. So far, a comparison between febrile infections with a positive or negative Corona test with the Omicron variant is missing. The data used are from the FeverApp registry, which collects parent-reported data on febrile infections in children and informs about fever management. A comparison of symptomatic differences between episodes with a positive or negative Corona test was performed using Χ2-tests. During the Omicron wave, reported tests doubled and positive test results nearly 12-folded. In episodes with positive Corona saliva tests, more cough, fatigue, disturbed smell/taste, limb pain, sore throat, signs of serious sickness, and touch sensitivity were reported. Children with a negative Corona test show more tonsillitis, teething, any pain symptoms, earaches, and rashes. Thus, there are some significant differences between febrile infections with a positive or negative Corona test, but symptoms are present on both sides. The omicron variant seems to be more infectious than the alpha or delta variants in children, but the symptoms remain mild and do not differ much from other febrile infections.