Supplementary Material for: Validity and discriminative value of activity questionnaires in youth with Type 1 Diabetes

Introduction: Prospective data quantifying physical activity levels in Australian youth with T1D is lacking. Structured questionnaire instruments may provide useful information but have not been evaluated in youth with type 1 diabetes (T1D). The objective of this study was to evaluate the validity of three paediatric physical activity (PA) questionnaires in young people with T1D and their ability to differentiate those not meeting PA guidelines of 60 minutes of moderate-to-vigorous PA (MVPA) per day from those who do. Methods: Eighty youth with T1D (42 boys, 38 girls; age: 13.1 ± 2.6 years; BMI: 20.2 ± 3.9 kg.m-2; HbA1c: 58.5 ± 10.1 mmol/mol, T1D duration: 5.4 ± 3.1 years) wore an Actigraph GT3x accelerometer for 7 days and on day 8 completed three self-report PA instruments; i) the Physical Activity Questionnaire (PAQ); ii) Previous Day Physical Activity Recall (PDPAR) and; iii) a single item physical activity scale (SIPAS). Validity coefficients for each instrument using accelerometry-derived MVPA minutes were determined using Spearman’s correlation coefficient. Receiver operator characteristic (ROC) curves were generated and optimal cut-points determined. Results: Mean daily MVPA minutes were 46.6 ± 25.5 minutes; 21/80 participants (26%) achieved an average of ≥ 60 MVPA minutes per day. The PAQ had the highest validity coefficient (r = 0.53; p < 0.001), followed by the single item tool (r = 0.39; p < 0.001) and PDPAR (r = 0.09; p = 0.4). Area under the ROC curve was 0.7, 0.5, and 0.7 for the PAQ, PDPAR, and single-item tools, respectively. Optimal cut points for sensitivity and specificity were i) a PAQ composite score of 2.8 (66.1% and 66.7%), ii) 75 MVPA minutes on the PDPAR (59.3% and 47.6%), and iii) 4.5 days on the SIPAS (71.2% and 38.1%). Conclusion: The PAQ has moderate to high criterion validity and showed moderate ability to discriminate between T1D youth meeting PA guidelines from those who do not. The single-item question had low to moderate construct validity, while the PDPAR did not correlate with objectively measured PA levels. The feasibility of incorporating the PAQ into clinical care for youth with T1D warrants further evaluation.