Purpose: This study aimed to evaluate the presence of recall bias when patients retrospectively report cough scores.
Patients and Methods: Patients who underwent lung surgery between July 2021 and November 2021 were recruited for this study. We retrospectively assessed the severity of cough within the past 24 hours and the past 7 days using a 0– 10 numerical rating scale. Recall bias was defined as the difference between the scores reported on the two assessments. Patients were grouped based on the longitudinal change in cough scores from pre-operation to 4 weeks after discharge using group-based trajectory models. Using generalized estimating equation to explore the factors influencing recall bias.
Results: Overall, 199 patients were analyzed and demonstrated the three distinct trajectories of post-discharge cough: high (21.1%), medium (58.3%), and low (20.6%). Significant recall bias was found in week 2 for the high-trajectory patients (6.26 vs 5.10, P < 0.01) and in week 3 for the medium-trajectory patients (2.88 vs 2.60, P =0.01). Among all recall bias, 41.8% were of underestimation, and 21.7% of overestimation. The high trajectory group (β=1.14, P < 0.01) and measurement interval (β=0.36, P < 0.01) were risk factors for underestimation, while post-discharge time (β=− 0.57, P < 0.01) and measurement interval (β=− 0.13, P =0.02) were protective factors for overestimation.
Conclusion: Retrospective assessment of post-discharge cough in patients who underwent lung surgery will introduce recall bias, with a tendency of underestimation. The high-trajectory group, interval time and post-discharge time are influencing factors of recall bias. For patients with severe cough at discharge, a shorter recall periods should be employed for monitoring, due to the large bias that results from a longer recall period.
Keywords: patient-reported outcome, lung surgery, cough measurement, recall bias