Physical Activity and Respiratory Muscle Strength in Patients with Sarcoidosis: An Observational Study

Health-Related Quality of Life Assessment in Sarcoidosis

Health-related quality of life (HRQoL) is of major concern to patients with sarcoidosis. HRQoL impairment is the most common reason to treat the disease. Advances in patient-reported outcome (PRO) methodology offer the promise to use these instruments to follow quality of life in individual patients with sarcoidosis over time. Several HRQoL issues will be highlighted including their clinical importance, common causes in patients with sarcoidosis, the construction and use of PROs in clinical sarcoidosis trials, methods to adapt PROs to monitor HRQoL in individual patients with sarcoidosis, and the approach to improving HRQoL in this disease.

Pulmonary Function in Pulmonary Sarcoidosis

The pulmonary function test (PFT) has been widely used in sarcoidosis. It may vary due to the severity, extent, and the presence of complications of the disease. Although the PFT of most sarcoidosis patients is normal, there are still 10-30% of cases who may experience a decrease in the PFT, with a progressive involvement of lungs. Restrictive ventilatory impairment due to parenchymal involvement has been commonly reported, and an obstructive pattern can also be present related to airway involvement. The PFT may influence treatment decisions. A diffusing capacity for carbon monoxide (DLCO) < 60% as well as a forced vital capacity (FVC) < 70% portends clinically significant pulmonary sarcoidosis pathology and warrants treatment. During follow-up, a 5% decline in FVC from baseline or a 10% decline in DLCO has been considered significant and reflects the disease progression. FVC has been recommended as the favored objective endpoint for monitoring the response to therapy, and an improvement in predicted FVC percentage of more than 5% is considered effective.

Six-minute stepper test for evaluating functional exercise capacity in patients with sarcoidosis

BACKGROUND

Researchers and clinicians may benefit from alternative tests that do not require large physical spaces or corridors for simply evaluating functional exercise capacity in the clinical practice.

OBJECTIVE

Aim of this study was to investigate whether six-minute stepper test (6MST) is a valid tool for measuring functional exercise capacity in patients with sarcoidosis.

METHODS

Thirty-six patients with sarcoidosis and 18 healthy controls were evaluated with 6MST and six-minute walk test (6MWT). Patients performed 6MST twice. Cardiovascular and symptom responses to tests including heart rate, blood pressure, SpO₂, levels of dyspnea and fatigue were recorded.

RESULTS

Receiver operating characteristic (ROC) curve analysis revealed an area under the ROC curve of 0.74 for 6MST in identifying the patients and controls, indicating acceptable discriminative ability. Patients performed significantly worse in 6MST compared to controls (277±54 vs 349±87 steps; p<0.001). 6MST was able to explain 66% of variance in 6MWT (p<0.001), and there was a strong relationship between 6MWT and 6MST (r = 0.812). SpO₂ responses to tests were similar, however, 6MST generated more severe heart rate, dyspnea and fatigue responses. Intraclass correlation coefficient calculated for initial and retest scores of 6MST was 0.990, indicating excellent test-retest reliability. However, there was a systematical improvement (∼4%) in retest 6MST scores.

CONCLUSIONS

6MST is a valid and reliable alternative test for measuring functional exercise capacity in sarcoidosis. 6MST may also help better testing the upper limits of cardiac system and physical endurance as it is more physically demanding than 6MWT.