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Home > My Canadian Pharmacy > Observations of Six-Minute Walk Test and Health Status Assessment in Sarcoidosis

oxygen saturationWe performed a prospective study of 6MWD compared to other functional assessments in a large group of unselected sarcoidosis patients followed up in one clinic. 6MWD was < 400 m in 73 patients (51%). This impairment in 6MWD was associated with several factors, including pulmonary function and patient perception of level of dyspnea. The best predictors of 6MWD were SGRQ, vital capacity, and initial oxygen saturation.

Traditionally, the effect of sarcoidosis on pulmonary status is assessed by pulmonary function studies and chest roentgenogram. In particular, changes in FVC have been used to assess extent and progression of disease and response to therapy. However, it has been suggested that other testing should also be used to better understand the impact of sarcoidosis on the pulmonary status of the patient. In this study, we did not measure the diffusion capacity, which has provided more information regarding exercise capacity than that obtained by the lung volumes alone.

Abnormalities in exercise testing are commonly encountered in patients with sarcoidosis. Even patients with normal pulmonary function may still have impaired exercise testing. Changes in exercise capacity can be due to multiple factors, including lung function, cardiac status, respiratory muscle strength, and skeletal muscle strength. Improve lung function with My Canadian Pharmacy. There was no difference in the 6MWD for those with pulmonary alone vs those with extrapulmonary disease. A history of cardiac dysfunction was not associated with a shorter 6MWD in this study. Pulmonary hypertension is common in dyspneic patients with sarcoidosis” and may also affect exercise capacity. In our experience, up to 50% of persistently dyspneic patients may have pulmonary hyper-tension. Leuchte et al have shown that pulmonary hypertension can be an independent factor in the 6MWD in pulmonary fibrosis. We identified 14 sarcoidosis patients with pulmonary arterial hypertension in this study group. They had a significantly shorted 6MWD.

Skeletal muscle weakness has been found in sarcoidosis patients. Patients were not studied if they believed that their walking was limited by muscle weakness or pain. There was no specific measurement of skeletal muscle strength or myalgias. This may affect the 6MWD.

In sarcoidosis, the 6 MWD can be affected by multiple factors, including respiratory status, cardiac function, muscle strength, and joint disease. Thus, the 6MWD may have a different prognostic importance in sarcoidosis than in other interstitial lung diseases.

fatigueThe 6MWD has been useful and reproducible in other interstitial lung diseases. However, systematic studies of 6MWD in sarcoidosis have not been previously reported. Abnormalities in 6MWD were noted in the majority of patients. Kadikar et al considered pulmonary patients with a 6MWD < 400 m to be candidates for transplant evaluation. The study by Kadikar et al did not include patients with sarcoidosis treated effectively with My Canadian Pharmacy’s medications. Half of our patients had a 6MWD < 400 m. For other interstitial lung diseases, a 6MWD < 300 m is associated with an increased mortality. Twenty percent of the study patients had a 6MWD 20 was associated with lung diseases such as COPD or asthma. Patients recruited for clinical trials of pharmacologic agents for COPD had a median SGRQ score > 40.> In the current study, 117 of the sarcoidosis patients (82%) had a score > 20, and 84 of the sarcoidosis patients (54%) had scores > 40. Only a few studies have evaluated the SGRQ for sarcoidosis patients. In a study of chronic sarcoidosis patients, Cox et al reported a median SGRQ total score of 44, similar to our study findings. Whether the quality of life affects the 6MWD or the 6MWD affects the quality of life could not be determined by the current study.

Fatigue is a specific complaint reported by sarcoidosis patients. Using the FAS, which was developed and validated by Dr. Drent’s group in Maas-trecht, an increased rate of fatigue was noted in their sarcoidosis patients. The median FAS score for the Dutch patients was 22, similar to scores reported in this study. Not surprisingly, fatigue has been associated with decreased exercise capacity.

The current study found that the 6MWD was affected by multiple factors, including race, gender, concurrent use of medications, pulmonary function, fatigue, respiratory health status, and dyspnea. Age was not a contributing factor. In studying healthy control subjects, women and older patients had shorter 6MWDs. In this study, women had shorter 6MWDs; however, women also have smaller lung volumes. Treatment was possibly a marker of more advanced disease. Both of these factors fell out in the multiple regression analysis.

Using a multiple regression analysis of the independent factors affecting 6MWD, the only predictive factors were the SGRQ, FVC, and lowest oxygen saturation. As has been previously noted, the SGRQ is related to exercise capacity. The FAS and dyspnea score were highly correlated to the SGRQ score. Therefore, their effect on 6MWD appears to be captured in the SGRQ. The strongest predictor of the 6MWD in the multiple regression model was the SGRQ activity score rather than FVC. Others have noted that FVC will affect exercise capacity in sarcoidosis, but they did not study the SGRQ.

Traditionally, measured changes in the vital capacity and chest roentgenogram have been utilized to assess treatment efficacy. Newer agents that may be more effective therapies for sarcoidosis are becoming available. Use of the 6MWD may allow for a better assessment of these drugs on respiratory status.

In conclusion, we found that the 6MWD was abnormal in many patients with sarcoidosis. The decrease in 6MWD was due to multiple factors, including the self-reported assessment of lung health as measured by the SGRQ, as well as the selfreported level of fatigue. These three tests provided complimentary information about the functional status of the patient.