Adaptation of the Medical Research Council Dyspnea Scale and the Oxygen Cost Diagram for its use in Puerto Rico.

INTRODUCTION: Dyspnea is a common and disabling symptom for patients with chronic lung diseases. The Medical Research Council Dyspnea Scale (MRC) and the Oxygen Cost Diagram (OCD) are widely used instruments validated in English to measure breathlessness.
OBJECTIVE: To translate and culturally adapt the MRC and the OCD for its use in Puerto Rico.
METHOD: The scales were translated to Spanish and back translated. They were tested in patients attending a pulmonary clinic to assess its relevance and comprehension. Subjects answered the instruments, had a structured clinical interview and provided feedback. A multidisciplinary committee analyzed the source of misunderstanding using the input of the subjects, the clinical physicians, and the evaluators; made adjustments, and retested the instruments until inconsistencies were not observed.
RESULTS: Placing emphasis on time spent walking instead of distance traveled improved the discrimination between grade two and three in the MRC. In the OCD, placing the activities to the right side eased the interpretation of the scale. Numerical symbols were eliminated to minimize discomfort in the severely impaired subjects reluctant to mark the line near zero. Reversing the order of both scales encouraged a thorough reading of the activities from minimal to high energy demanding eliciting a more fitting response compared to structured clinical interview especially in the severely ill patient.
CONCLUSION: Using cross-cultural research methodologies to translate the MRC and OCD allowed the identification of differences in conceptualization when assessing the severity of dyspnea in Puerto Rico. Further testing is needed to confirm psychometric properties.