Convergent validity of commonly used questions assessing physical activity and sedentary time in Swedish patients after myocardial infarction

Background Guidelines recommend regular physical activity (PA) and decreased sedentary time (SED) for patients after myocardial infarction (MI). Therefore, valid self-assessment of PA is vital in clinical practice. The purpose of this study was to assess the convergent validity of commonly used PA and SED questions recommended by the National Board of Health and welfare (NBHW) and national SWEDEHEART-registry using accelerometers as the reference method in patients after MI. Methods Data were obtained 2017–2021 among Swedish men and women (180 assessments). Participants answered five commonly used PA and SED-questions (by NBHW and SWEDEHEART) and wore an accelerometer (Actigraph GT3X) for seven days. Convergent validity was assessed gradually by; Kruskall Wallis-, Sperman rho, Weighted Kappa- and ROC-analyses. Misclassification was explored by Chi-square analyses with Benjamini–Hochberg adjustment. Results The strongest correlation (r = 0.37) was found for the SED-GIH question (NBHW). For PA, no specific question stood out, with correlations of r = 0.31 (NBWH), and r = 0.24–0.30 (SWEDEHEART). For all questions (NBHW and SWEDEHEART), there was a high degree of misclassification (congruency 12–30%) affecting the agreement (0.09–0.32) between self-report and accelerometer assessed time. The SED-GIH, PA-index and SWEDEHEART-VPA had the strongest sensitivity for identifying individuals with high SED (0.72) or low PA (0.77 and 0.75). Conclusion The studied PA and SED questions may provide an indication of PA and SED level among patients with MI in clinical practice and could be used to form a basis for further dialogue and assessment. Further development is needed, since practical assessment tools of PA and SED are desirable