When Are You Recovered? Defining Cutoff Points Using the Acute Respiratory Tract Infection Questionnaire

Acute respiratory tract infections (ARTIs) are a heterogenous group of diseases. Often, it is difficult to obtain a precise diagnosis in general practice but also difficult to determine when the patient is recovered. The lack of a precise definition of recovery after ARTI complicates scientific research aiming to optimize diagnostics and compare treatments. The study aimed to define cutoff points to determine the end of an ARTI as a proxy for recovery in patients diagnosed with ARTI in general practice using a validated patient-reported outcome instrument; The ARTI Questionnaire (ARTIQ).

A total of 259 participants was divided in 2 groups-1 with ARTI and 1 without. Histograms and area under the curve were calculated for each of the 5 dimensions within the ARTIQ to evaluate the discriminative effect. For the most discriminative dimensions receiver operating comparison curves were performed to determine relevant cutoff points for having or not having ARTI symptoms and serve as a proxy for recovery in clinical research.

The highest discriminative effect was found in 2 dimensions: "physical-upper airways" and "physical-lower airways." When combining these dimensions, the area under the curve was 0.97. Sensitivity, specificity, and predictive values were calculated for selected cutoff points.

Cutoff points serving as proxy for recovery from ARTI using a patient-reported outcome were identified. The specific cutoff point for a certain research project must be selected considering the specific clinical situation of interest.