The six-minute walk test in patients with pulmonary sarcoidosis

Background: The 6-min walk test (6MWT) is a useful tool to assess prognosis and functional impairment in various pulmonary diseases.

Aims: To evaluate functional capacity during various stages of pulmonary sarcoidosis and develop a scoring system clinical radiological physiological score (CRP) that can potentially be used to assess the functional status among patients with sarcoidosis.

Materials and methods: We performed a retrospective study on 26 patients diagnosed with pulmonary sarcoidosis from 2001 to 2007. All patients completed the 6MWT. The parameters assessed during the test included spirometry, arterial blood gas, 6-min walk distance (6MWD), Borg dyspnea score, and initial and end oxygen saturation.

Results: Females covered a significantly shorter distance than males (343 m (223-389) vs. 416.5 m (352-500); P < 0.0001). In addition, females had a significantly lower SpO₂ at the end of the 6MWT than males (90.5 (61-99) vs. 96 (75-98); P < 0.03). The 6MWD was inversely correlated with the final Borg score (ρ = -0.603, P = 0.004) and the CRP score (ρ = -0.364, P = 0.047) and positively correlated with forced expiratory volume in 1 s (FEV₁) % ( ρ = 0.524, P = 0.006) and forced vital capacity (FVC) % (ρ = 0.407, P = 0.039).

Conclusions: Female gender, FEV₁%, final Borg score, FVC%, CRP score, and SpO₂ at the end of the 6MWT are associated with reduced 6MWD. It appears that Saudi patients diagnosed with sarcoidosis have a markedly reduced walking distance compared with other races. The effect of race and ethnicity and the utility of the CRP score as a potential marker to assess functional status require further exploration.