Criterion Validity of Screening Tools and Field-Based Tests for Health-Related Physical Fitness in Inflammatory Bowel Disease.

Background: Monitoring health-related physical fitness (HRPF) may benefit proactive Inflammatory Bowel Disease (IBD) management. However, knowledge regarding HRPF in patients with IBD is limited and gold standard tests are impractical for widespread use, necessitating simpler methods.

Aim: This study evaluated the criterion validity of screening tools and field-based tests compared to gold standard tests for HRPF in patients with IBD.

Methods: Adult patients with IBD completed screening tools, field-based tests, and gold standard tests for HRPF. Criterion validity was examined through (intraclass) correlation coefficients and Bland-Altman plots. Predictive capacity of the screening tools was examined with receiver operating curve analysis.

Results: Among 53 included patients, screening tools demonstrated poor-to-moderate validity compared to the cardiopulmonary exercise test (CPET) for cardiorespiratory fitness. Very strong correlations were found for four-site skinfold thickness and multi-frequency bioimpedance analysis (BIA) with deuterium oxide dilution for body fat percentage (ICC = 0.90, ICC = 0.93), and between the steep ramp test and CPET (r = 0.95) for cardiorespiratory fitness. The steep ramp test also correlated strongly with isokinetic quadriceps (r > 0.75) and hamstring (r > 0.74) strength. Hand-held dynamometry and the sit-to-stand test showed strong correlations with hamstring strength (r > 0.80, r > 0.76). Negligible correlations were found for field-based tests compared to isokinetic quadriceps and hamstring endurance.

Conclusions: Four-site skinfold thickness and BIA showed good agreement with the gold standard for body fat measurement. The steep ramp test demonstrated strong correlations with the gold standard tests for cardiorespiratory fitness and quadriceps and hamstring strength, while hand-held dynamometry and the sit-to-stand test showed strong correlations with hamstring strength.