Clinical Study A Simple Step Test to Estimate Cardio-Respiratory Fitness Levels of Rheumatoid Arthritis Patients in a Clinical Setting

properly cited. Purpose. Exercise tests represent an important clinical tool to evaluate cardio-respiratory fitness and to predict future adverse cardiovascular events. However, use of such tests in patients with rheumatoid arthritis (RA) is relatively uncommon despite wellestablished evidence that low exercise capacity and high CVD mortality are features of this disease. Therefore, this study examined the validity and reliability of a sub-maximal step test for use in RA patients. Methods. Thirty patients (24 females) (mean ± SD age 53 ± 10 years) performed a sub-maximal step test on two occasions to estimate the criterion measure of cardio-respiratory fitness (VO 2 max ). A further maximal cycling test provided a direct fitness measurement (VO 2 peak ). Pearson correlation coefficient, intraclass correlation coefficient (ICC), Bland and Altman plots, and 95% limits of agreement (LOA) were used to determine the validity and reliability of the sub-maximal test. Results. EstimatedVO 2 max correlated well with directly measuredVO 2 peak ( = 0.79, LoA ±5.7 mL⋅kg −1 ⋅min −1 ). Test-retest reproducibility for estimatedVO 2 max was excellent (ICC = 0.97, LoA ±2.2 mL⋅kg −1 ⋅min −1 ). Conclusion. The sub-maximal step test studied here represents a valid and reproducible method to estimate cardio-respiratory fitness in RA patients. This test may be useful for the assessment and management of CVD risk in a clinical setting