Usefulness of the culturally adapted oxygen-cost diagram in the assessment of dyspnea in Puerto Rico.

Objective: Breathlessness is a common and disabling symptom of pulmonary disease. Measuring its severity is recommended as such measurements can be helpful in both clinical and research settings. The oxygen-cost diagram (OCD) and the Medical Research Council (MRC) dyspnea scale were developed in English to measure severity of dyspnea. These scales were previously translated to Spanish and adapted for use in a Hispanic population. The objective of this study is to assess the psychometric properties of these scales. We propose the scales correlate well with measures of physiological impairment.

Methods: Subjects having pulmonary disease rated their perceptions of dyspnea using the scales, performed a spirometry test, and did a 6-min walk. Spearman correlation coefficients (p) were used to correlate dyspnea scores with spirometric parameters and distance walked (6MWD).

Results: Sixty-six patients having stable asthma (n = 36), chronic obstructive pulmonary disease (n = 19), or interstitial lung disease (n = 11) participated in the study. OCD scores showed a significant correlation with FEV1 (p = 0.41; p < 0.01), FEV1% (p = 0.36; p < 0.01), FVC (p = 0.44; p < 0.01), and FVC% (p = 0.37; p < 0.01) in the study population. The OCD scores were highly correlated with 6MWD (p = 0.59, p < 0.01). The MRC dyspnea scale showed significant inverse correlation with FEV1 (p = -0.34; p < 0.01) and 6MWD (p = -0.33; p < 0.05), but the correlations were weaker compared to the correlations with the OCD scale.

Conclusion: The severity of breathlessness as measured by the adapted Spanish OCD showed a moderate to high correlation with spirometric parameters and 6MWD; therefore, the adapted OCD should prove to be useful in Puerto Rico.