Clinical diagnosis of seasonal influenza by physicians: a retrospective observational study.

OBJECTIVE: To elucidate the diagnostic accuracy of pretest probability of influenza (%) by physicians and the factors affecting the clinical diagnosis. DESIGN: Retrospective, single-centre observational study. SETTING: A community primary care clinic in Japan. PARTICIPANTS: The participants were recruited from a database of studies conducted during the influenza season from December 2017 to April 2019. PRIMARY OUTCOME MEASURE: Sensitivity and specificity of the physician's clinical diagnosis of influenza recorded in the medical record as pretest probability. RESULTS: A total of 335 patients (median age, 31 years; male, 66.6%) were analysed in this study. The area under the curve (AUC) of the physician's pretest probability was 0.77. At a cut-off value of 30%, the sensitivity and negative likelihood ratio were 92.0% (95% CI 86.7 to 95.7) and 0.19 (95% CI 0.11 to 0.33), respectively. At a cut-off value of 80%, the specificity and positive likelihood ratio were 90.8% (95% CI 85.4 to 94.6) and 4.01 (95% CI 2.41 to 6.66), respectively. The AUCs of patients who had and had not taken any medications before visiting the clinic were 0.77 (95% CI 0.69 to 0.85) and 0.78 (95% CI 0.71 to 0.84), respectively. The AUCs of patients with type A and B influenza were 0.78 (95% CI 0.72 to 0.84) and 0.76 (95% CI 0.70 to 0.82), respectively. The AUCs of vaccinated and unvaccinated patients were 0.80 (95% CI 0.72 to 0.88) and 0.76 (95% CI 0.63 to 0.89), respectively. The AUC for patients less than 12 hours after onset was 0.69 (95% CI 0.51 to 0.88), and that for patients aged younger than 6 years was 0.69 (95% CI 0.49 to 0.88). CONCLUSIONS: The physician's pretest probability of influenza (%) may be useful for both definitive and exclusionary diagnoses within the limits of our study.

Factors associated with children's seasonal influenza diagnosis by their guardians: a prospective observational study in Japan.

Introduction Children's influenza diagnosis by their guardians has been reported to be highly accurate, but clinical factors that improve the reliability of a guardian's diagnosis are unclear. Aim To determine the accuracy of guardians' influenza diagnosis of their children, investigate clinical factors that improve the diagnostic accuracy, and determine the additional clinical value of the guardian's diagnosis. Methods A prospective observational study was conducted at a primary care clinic in Japan from December 2017 to April 2019. Pre-examination checklists completed by guardians accompanying children aged Results A total of 112 patient pairs of child (median age, 6 years) and guardian (mother, 81.2%; father, 16.1%; grandmother, 1.8%; other, 0.9%) were included in the analysis. The AUC for guardians' influenza diagnosis was higher in mothers (0.72), as well as pairs with children with a history of influenza (0.72), guardians who were aware of the influenza epidemic (0.71), and unvaccinated children (0.76), than in other guardians. After multivariate analysis, the AUC increased significantly from 0.79 to 0.85. Discussion Guardians' influenza diagnosis for their children was highly accurate. We identified factors that improve the accuracy of the guardians' diagnosis and demonstrated that the guardians' diagnosis can support physicians' diagnostic accuracy.

Factors associated with seasonal influenza self-diagnosis: a prospective observational study in Japan.

This prospective observational study, conducted at a community clinic in Japan during the influenza season, from December 2017 to April 2018 aimed to investigate the accuracy of factors used for influenza self-diagnosis. Data were collected from pre-examination checklists issued to patients with suspected influenza and electronic medical records. Receiver operating characteristic (ROC) curve analysis was performed using a rapid influenza diagnostic test as the reference standard, and 2 × 2 contingency tables were analysed at each cut-off point. We analysed data from 290 patients (72.8% males, median age: 38 years, interquartile range: 26-50 years). The area under the ROC curve (AUC) for patients who were aware of other patients presumed to have influenza within close proximity was 0.74 (95% confidence interval (CI): 0.66-0.82). The AUCs for patients with a history of influenza, unvaccinated status, cough, or nasal discharge were 0.68 (95% CI: 0.60-0.75), 0.66 (95% CI: 0.59-0.73), 0.67 (95% CI: 0.59-0.75), and 0.70 (95% CI: 0.62-0.78), respectively. The sensitivity, specificity and positive likelihood ratio at a 90% cut-off point was 19.5% (95% CI: 13.5-26.6%), 94.1% (95% CI: 88.7-97.4%) and 3.31 (95% CI: 1.57-6.98). The sensitivity, specificity and negative likelihood ratio at a 10% cut-off point was 95.5% (95% CI: 90.9-98.2%), 9.6% (95% CI: 5.2-15.8%) and 0.48 (95% CI: 0.20-1.16). After multivariate logistic regression analysis, the AUC increased significantly from 0.77 (95% CI: 0.70-0.83) to 0.81 (95% CI: 0.76-0.86) when self-diagnosis-related information was added to basic clinical information. We identified factors that improve the accuracy and validity of influenza self-diagnosis. Appropriate self-diagnosis could contribute to the containment efforts during influenza epidemics and reduce its social and economic burden.